Does anyone have photos of progressing pressure signs of say flattened primers or stretched heads and such up to and including damaged parts? I was trying to explain to a buddy new to reloading what to look for. Pictures would be better then my explanations
pressure signs progression chart
- Thread starter brybenn
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Most reloading manuals will have this in their front section
Incipient pressure signs, are mostly a fools game. There are so many variables to deal with before things go Kaboom that often as not there aren't any warnings.
Flattened primers occur for other reasons besides extreme pressures. Often as not the ductility of one batch of primers will deviate from another batch.
I've seen primers used in bench rest cases that are frequently in the 60,000+ psi bracket and they look like they've been fired out of cases loaded to moderate 45,000 psi pressures.
I've seen cases with the socalled pressure rings a 1/4in from the rim that have 30+ reloadings on them at moderate pressures.
Often as not when a load goes awry, it has little or nothing to do with with the components.
, except to much powder for the bullet type.
If you want an indicator of high pressure loads that will give your components a reason to fail, get a chrony and shoot over it. Velocities that are substantially higher than normal, equal higher pressures.
In some cases, barrel length will give higher velocities but even that becomes a diminishing factor as you reach maximum, for your rifle, pressures.
Now, just because you decide to load 10% by volume/weight over a certain charge, doesn't mean you will get a 10% increase in velocity. Usually, the rate of diminishing returns brings the increases down to less than 1% increase. If you are getting more than that in the parent case, you are on a dangerous footing.
Your firearm may or may not Kaboom, you may get a split case or case head separation or if you're really lucky, you may just get an imprint of the bolt face on the case face. By then, you've gone way to far and have reached the ultimate breaching point in the ductility of your cases. Such cases, showing these marks should never be reloaded and should be destroyed. A chrony, would have told you that you had problems far before such a condition occurred. In another rifle, that same issue would have been disastrous.
The loading tables, have a very good reason for stating the loads they do. Follow them.
New loading materials are much different than they were 20 years ago. If you're using 20 year old components, you can get away with 20 year old data.
Like it or not, everything changes all of the time. Nothing stays the same, even if it looks the same. Newly manufactured powders, primers, brass, bullets ARE different. They are made from different blends of materials and in many cases, are better. Not in all cases though.
If you have old powders and new brass, use new powder data.
It's not rocket science and is quite simple as long as you stick within the published limits.
It's also a well known fact that even current manuals don't all agree on limitations. The reason for this is the difference in pressure testing. As far as manuals go, take your pick and stick to it. The people that write them up have been known to make mistakes but very seldom. They shoot hundreds of rounds to get those pressure averages and in most instances, never reload the cases because they always use brand new ones. They make a lot more money from a box of fresh cartridges than they do from bulk components.
Flattened primers occur for other reasons besides extreme pressures. Often as not the ductility of one batch of primers will deviate from another batch.
I've seen primers used in bench rest cases that are frequently in the 60,000+ psi bracket and they look like they've been fired out of cases loaded to moderate 45,000 psi pressures.
I've seen cases with the socalled pressure rings a 1/4in from the rim that have 30+ reloadings on them at moderate pressures.
Often as not when a load goes awry, it has little or nothing to do with with the components.
, except to much powder for the bullet type.
If you want an indicator of high pressure loads that will give your components a reason to fail, get a chrony and shoot over it. Velocities that are substantially higher than normal, equal higher pressures.
In some cases, barrel length will give higher velocities but even that becomes a diminishing factor as you reach maximum, for your rifle, pressures.
Now, just because you decide to load 10% by volume/weight over a certain charge, doesn't mean you will get a 10% increase in velocity. Usually, the rate of diminishing returns brings the increases down to less than 1% increase. If you are getting more than that in the parent case, you are on a dangerous footing.
Your firearm may or may not Kaboom, you may get a split case or case head separation or if you're really lucky, you may just get an imprint of the bolt face on the case face. By then, you've gone way to far and have reached the ultimate breaching point in the ductility of your cases. Such cases, showing these marks should never be reloaded and should be destroyed. A chrony, would have told you that you had problems far before such a condition occurred. In another rifle, that same issue would have been disastrous.
The loading tables, have a very good reason for stating the loads they do. Follow them.
New loading materials are much different than they were 20 years ago. If you're using 20 year old components, you can get away with 20 year old data.
Like it or not, everything changes all of the time. Nothing stays the same, even if it looks the same. Newly manufactured powders, primers, brass, bullets ARE different. They are made from different blends of materials and in many cases, are better. Not in all cases though.
If you have old powders and new brass, use new powder data.
It's not rocket science and is quite simple as long as you stick within the published limits.
It's also a well known fact that even current manuals don't all agree on limitations. The reason for this is the difference in pressure testing. As far as manuals go, take your pick and stick to it. The people that write them up have been known to make mistakes but very seldom. They shoot hundreds of rounds to get those pressure averages and in most instances, never reload the cases because they always use brand new ones. They make a lot more money from a box of fresh cartridges than they do from bulk components.
The only way to get reliable data is to use something like this. It is a consumer orientated system that uses a glue on strain gauge, located above the chamber.
But since most people don't have anything like this system, use your eyes and carefully watch what the primers look like as you increase loads. You should see the progression.
Shooting only one load won't give you any basis for comparison, and can in many circumstances be meaningless, or worse, not representative of actual pressures.
But since most people don't have anything like this system, use your eyes and carefully watch what the primers look like as you increase loads. You should see the progression.
Shooting only one load won't give you any basis for comparison, and can in many circumstances be meaningless, or worse, not representative of actual pressures.
My manual just has a pic of 3 empty brass in a black and white photo.
I do have a chrony. My gun (2506) actually passed listed velocity (max 3137fps) without showing any signs. On a max load from the lee manual 1/5 brass had a very slight marking of the bolt face on the head. The primer seemed fine and ejection was no different. It averaged out at 3248fps. I backed off a full grain anyway but am still getting max load velocity with a 22" barrel. 52gr imr4831 5shot average is 3120fps. Max load says 53grs for 3137fps. Doesn't list the barrel length used however.
I double check each charge on a beam scale and a digital scale.
While trying to explain what to look for I was unable to find pictures showing flattened primers or signs of stuck casings or even ruptured primers
I do have a chrony. My gun (2506) actually passed listed velocity (max 3137fps) without showing any signs. On a max load from the lee manual 1/5 brass had a very slight marking of the bolt face on the head. The primer seemed fine and ejection was no different. It averaged out at 3248fps. I backed off a full grain anyway but am still getting max load velocity with a 22" barrel. 52gr imr4831 5shot average is 3120fps. Max load says 53grs for 3137fps. Doesn't list the barrel length used however.
I double check each charge on a beam scale and a digital scale.
While trying to explain what to look for I was unable to find pictures showing flattened primers or signs of stuck casings or even ruptured primers
Most "pressure signs" appear at 65,000 PSI which is way too high.
From everything that I've read on this, the only simple and reliable signs of excessive pressure are:
http://www.longrangehunting.com/articles/rifle-reloading-pressure-1.php
Alex
From everything that I've read on this, the only simple and reliable signs of excessive pressure are:
- higher than normal velocity (almost 100% reliable)
- case head expansion (should easily fit in reloading press shell holder)
http://www.longrangehunting.com/articles/rifle-reloading-pressure-1.php
Alex
Actually 65,000 psi is the design operating pressure for some cartridges, so in fact, you shouldn't see signs of excessive pressure at 65,000psi with those cartridges.The problem is that some pressure signs aren't obvious until over 70,000 psi, which is well above the maximum design pressure .
Given that the maximum listed velocities for a given bullet/powder combination can vary by 200fps or more, from manual to manual, the problem is deciding which data to use as a reference.
I have only seen fired cases not fit the shell holder twice, and in both instances the case heads were expanded by almost .004" which is way more than should ever occur. If you measure the case heads and the expansion is over .001" from a single firing, I would be concerned.
Given that the maximum listed velocities for a given bullet/powder combination can vary by 200fps or more, from manual to manual, the problem is deciding which data to use as a reference.
Stubblejumper, when barrel lengths and bullet weights as well as types are taken into consideration as well as the manual, velocity is still the best rule of thumb to follow for most people. Without pressure, you can't get velocity.
You will also get different pressure levels from 2 rifles from the same manufacturer in the same serial number range. Caution is always the best choice.
I do agree that "MOST" modern actions will easily handle 65,000 psi on a regular basis. The big problem is the brass cases aren't built to handle those pressures, especially after several reloads.
Bench Resters that commonly load beyond 60,000 psi, have rifles that cover most of the angles, like very tight chambers and cases fireformed to every angle, as well as turned necks etc, etc, etc. To suggest to a person shooting an off the shelf rifle, with tolerances that are usually quite generous and often as not sloppy, is treading on dangerous ground.
Now, understand, I have seen several Kabooms. I've even had a couple myself. All except for two were controlled experiments. The others were from a foolish attempt at extreme velocity in an unknown factory altered surplus rifle (sporterized) and an out of battery Kaboom with an Agb42 Ljungman. That was my fault as well. I had done some mods to it, shortening the bbl and building up a double length magazine, pistol grip etc. DUMB, not nearly enough knowledge at the time to understand what I had done. That was close to 35 years ago.
What it did teach me was to respect pressure and what it could do when it overcame it's physical barriers.
Another thing shooting cartridges that needed high pressures to operate taught me was that they were expensive in more ways than one to shoot regularly.
Brybenn, you don't mention the type of rifle you are shooting, or its lineage/age. It may or may not be suited to high pressures. The 25-06, used to have a bad rep for burning out throats on a regular basis when loaded to the max. Problem is, it likes to be loaded to near max or right on max to shoot its best.
It's your rifle, your choice. I think you were smart to back off when you noticed bolt face marks on your cases. 100fps over listed book loads, isn't overly extreme IMHO but along with the bolt face impressions and the IMR4831, rather than H4831, pressures were more than likely getting to the point you should back down. One grain more, can turn some combinations from a hot/safe load into a problem load in a hurry.
There is no reason to go into the rest of it with a speed junky (bin there, done that) You will do it until you learn the hard way. Hopefully through your wallet.
SandRoad, I like your machine. Where did you get it??? Please PM me.
Stubblejumper, when barrel lengths and bullet weights as well as types are taken into consideration as well as the manual, velocity is still the best rule of thumb to follow for most people. Without pressure, you can't get velocity.
You will also get different pressure levels from 2 rifles from the same manufacturer in the same serial number range. Caution is always the best choice.
I do agree that "MOST" modern actions will easily handle 65,000 psi on a regular basis. The big problem is the brass cases aren't built to handle those pressures, especially after several reloads.
Bench Resters that commonly load beyond 60,000 psi, have rifles that cover most of the angles, like very tight chambers and cases fireformed to every angle, as well as turned necks etc, etc, etc. To suggest to a person shooting an off the shelf rifle, with tolerances that are usually quite generous and often as not sloppy, is treading on dangerous ground.
Now, understand, I have seen several Kabooms. I've even had a couple myself. All except for two were controlled experiments. The others were from a foolish attempt at extreme velocity in an unknown factory altered surplus rifle (sporterized) and an out of battery Kaboom with an Agb42 Ljungman. That was my fault as well. I had done some mods to it, shortening the bbl and building up a double length magazine, pistol grip etc. DUMB, not nearly enough knowledge at the time to understand what I had done. That was close to 35 years ago.
What it did teach me was to respect pressure and what it could do when it overcame it's physical barriers.
Another thing shooting cartridges that needed high pressures to operate taught me was that they were expensive in more ways than one to shoot regularly.
Brybenn, you don't mention the type of rifle you are shooting, or its lineage/age. It may or may not be suited to high pressures. The 25-06, used to have a bad rep for burning out throats on a regular basis when loaded to the max. Problem is, it likes to be loaded to near max or right on max to shoot its best.
It's your rifle, your choice. I think you were smart to back off when you noticed bolt face marks on your cases. 100fps over listed book loads, isn't overly extreme IMHO but along with the bolt face impressions and the IMR4831, rather than H4831, pressures were more than likely getting to the point you should back down. One grain more, can turn some combinations from a hot/safe load into a problem load in a hurry.
There is no reason to go into the rest of it with a speed junky (bin there, done that) You will do it until you learn the hard way. Hopefully through your wallet.
SandRoad, I like your machine. Where did you get it??? Please PM me.
I am comparing situations where the bullet type/weight and barrel lengths are identical, yet there is a variation of almost 200fps from manual to manual.
But the relationship is not so constant ,that a graph can be drawn up for a given bullet/powder combination, that will be accurate for all firearms of that chambering, and all lots of powder. If there was, it would be as simple as the loading manual telling you to simply load a given bullet/powder combination, to a given velocity, and you would be developing a specific chamber pressure. However the considerable variances in velocity from manual from manual with a given powder/bullet combination, and a given barrel length, indicate otherwise.
So 300WSM or 300RUM cases won't handle 65,000psi? Given that the design pressures for both cartridges is 65,000 psi, they had better be able to handle 65,000 psi. If you look at the chart below, several cartridges use 65,000 psi as a design pressure.
http://www.lasc.us/SAAMIMaxPressure.htm
I think Stubblejumper has nailed it.
I have fired hundreds of thousands of rounds through calibrated pressure guns in ballistics labs. Pressures have been normal, high, proof rounds and higher. (Our gun would handle up to about 100,000 psi with no problem.)
There is almost no reliable correlation between high pressure and signs, other than velocity. Only two things will give high velocity - higher pressure and longer barrel. The latter is a constant on your rifle, but it might be longer than the one in the book.
Sticky bolt life, shiny marks on bolt face and blown primers do not usually occur at "normal" pressures. They are more likely in proof round range.
I have fired hundreds of thousands of rounds through calibrated pressure guns in ballistics labs. Pressures have been normal, high, proof rounds and higher. (Our gun would handle up to about 100,000 psi with no problem.)
There is almost no reliable correlation between high pressure and signs, other than velocity. Only two things will give high velocity - higher pressure and longer barrel. The latter is a constant on your rifle, but it might be longer than the one in the book.
Sticky bolt life, shiny marks on bolt face and blown primers do not usually occur at "normal" pressures. They are more likely in proof round range.
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The rifle I have is a stevens 200 center feed top load so its new. I had just 1 brass that showed very slight marks of the bolt 3100fps is fast enough for me. And I know a deer or bear won't be able tp tell I've got 52gr instead of 53gr
Thanks for all the replies
Thanks for all the replies
Obviously the best way that a person can estimate the chamber pressure is with specialty equipment made to do just that. However most handloaders do not have access to such equipment, so we must make do with what we have.
That means we look for anything out of the ordinary, whether it is a velocity that is higher that is listed in any of our manuals, expanded case heads, extrusion marks on case heads, or difficult bolt lift and extraction.
If I see any extrusion on the case heads, I back off the load at least a grain for smaller cases, and two grains for larger cases. If the case heads expand .001" or more with a single firing, I back off the pressure charge. If the bolt lift increases, I will back off the powder charge to see if the problem goes away.
Velocity is more complicated, due to the variations from manual to manual, even with identical bullets and barrel length. If the velocity is higher for the bullet/powder combination, than listed in any of my manuals, I back off the powder charge. If the velocity is higher than in some manuals, but lower than that published in other manuals, and I see no other pressure signs, I monitor the primer pockets very closely for at least five loadings.
If the velocity is is within the maximum listed in most or all of my manuals, but I see extrusion marks on the brass, or if the primer pockets are loosening significantly,after only a few firings, I back off the powder charge.
I have seen significant pressure signs appear in some rifles at just over the published starting loads in some manuals, likely due to a minimum spec chamber and barrel. I would not even think of trying the maximum published loads in those rifles.
Some rifles would easily match the velocity listed in the various manuals, yet others would show pressure signs at 150fps below the maximum velocity listed in some manuals, even with the same bullet/powder, and barrel length.
It would be so much easier if every lot of powder was the same, or if every chamber and barrel was the same, or if every manual listed the same velocities for a given bullet/powder/barrel length combination, but unfortunately, that isn't the case.
Even the bullet and powder companies data doesn't agree as to how much velocity you can expect out of a given powder/bullet combination, with a specific barrel length, at a given chamber pressure, so there is no way that us as reloaders without the specialized pressure measuring gear that those companies have, can know for sure what chamber pressures are being developed based solely on chronograph readings.
"I had just 1 brass that showed very slight marks of the bolt."
It takes excess pressure to extrude the case head into the ejector pin hole in the bolt face.
A well made rifle will operate quite well at pressures 10,000 psi over max ..... until the stars don't line up right one day and a case lets go. Then it can get messy.
It takes excess pressure to extrude the case head into the ejector pin hole in the bolt face.
A well made rifle will operate quite well at pressures 10,000 psi over max ..... until the stars don't line up right one day and a case lets go. Then it can get messy.
I do agree that "MOST" modern actions will easily handle 65,000 psi on a regular basis. The big problem is the brass cases aren't built to handle those pressures, especially after several reloads.
So 300WSM or 300RUM cases won't handle 65,000psi? Given that the design pressures for both cartridges is 65,000 psi, they had better be able to handle 65,000 psi. If you look at the chart below, several cartridges use 65,000 psi as a
Those are modern cartridges, designed for modern receivers and barrels.
257 roberts, 7x57, 8x57 even some of the older 30-06 would give you some issues at those pressures. You are correct about what you list but please don't tell the OP that is a general rule of thumb for all cartridge cases. It's one of the main reasons they put belts on original high pressure cases. Not the only reason of course but it was still relavent.
The trick here, is if you don't have enough knowledge of the powders you're using and how they work in different cases under differing conditions, don't exceed listed maximums.
If you do, accept the responsibility as your own.
The return on investment and safety, IMHO really isn't worth the risk.
I know how frustrating it can be when a certain rifle really starts to turn into a tack driver at over max pressures/velocities. The question is, are you prepared for the consequences??
Would you loan that cartridge to a friend to use in his/her rifle???
I've seen more than one Whiz Bang, Killem All Dead load from by buddy take apart a different rifle than it was originally intended for. This isn't rocket science, it's common sense.
I would love to have some pressure testing equipment that doesn't damage the rifle.
I tried to make up a non destructive system out of some load cells that were extremely accurate at weights around 45000 to 75000 pounds. I was unsuccessful and out of my element, to say the least.
I like Sand Roads set up.
Far to many people that don't understand what they are doing, play with extreme pressures.
Most of the comments here are from people with lots of experience and knowledge. They got that way, mostly through experimentation, on their own or had mentors.
If you insist on exceeding reccomended stats, do so with extreme caution and shoot the firearm from a decent machine, like a Lead Sled.
So 300WSM or 300RUM cases won't handle 65,000psi? Given that the design pressures for both cartridges is 65,000 psi, they had better be able to handle 65,000 psi. If you look at the chart below, several cartridges use 65,000 psi as a
Those are modern cartridges, designed for modern receivers and barrels.
257 roberts, 7x57, 8x57 even some of the older 30-06 would give you some issues at those pressures. You are correct about what you list but please don't tell the OP that is a general rule of thumb for all cartridge cases. It's one of the main reasons they put belts on original high pressure cases. Not the only reason of course but it was still relavent.
The trick here, is if you don't have enough knowledge of the powders you're using and how they work in different cases under differing conditions, don't exceed listed maximums.
If you do, accept the responsibility as your own.
The return on investment and safety, IMHO really isn't worth the risk.
I know how frustrating it can be when a certain rifle really starts to turn into a tack driver at over max pressures/velocities. The question is, are you prepared for the consequences??
Would you loan that cartridge to a friend to use in his/her rifle???
I've seen more than one Whiz Bang, Killem All Dead load from by buddy take apart a different rifle than it was originally intended for. This isn't rocket science, it's common sense.
I would love to have some pressure testing equipment that doesn't damage the rifle.
I tried to make up a non destructive system out of some load cells that were extremely accurate at weights around 45000 to 75000 pounds. I was unsuccessful and out of my element, to say the least.
I like Sand Roads set up.
Far to many people that don't understand what they are doing, play with extreme pressures.
Most of the comments here are from people with lots of experience and knowledge. They got that way, mostly through experimentation, on their own or had mentors.
If you insist on exceeding reccomended stats, do so with extreme caution and shoot the firearm from a decent machine, like a Lead Sled.
And the vast majority of rifles being used , are of modern design, with modern steels. The vast majority of cartridge cases in use , are of recent manufacture, and materials. Even cartridges like the 6.5x55 which was originally designed for relatively low pressures, can easily handle 60,000 psi if you are using a modern rifle, with modern cartridge cases. Some data actually lists separate loads for modern rifles chambered in these older chamberings, for this reason.
The trick is to realize that not all loads listed in reloading manuals will be safe in all rifles, so you need to work up your loads while watching for pressure signs. Every manual that I own has a disclaimer to this effect.
Most of the more knowledgeable people , don't own lead sleds or other such devices.
I wrote "Only two things will give high velocity - higher pressure and longer barrel."
That is a bit simplistic. If you are using a given powder, primer and bullet in a given rifle, the only way to get higher velocity is more of that powder and that means more pressure.
If you need more velocity, the next step is a heavier charge of a slower powder. 6.5x55 is a good example of where one can switch from 4350 to RL22 and fill the case to get more velocity at the same pressure.
Hornady did this with their Light magnum offerings a few years back. They used a very slow powder (too slow for ordinary use) and compressed it so much they got an extra 10 grains into the case. This added about 200 fps to the round with no increase in pressure. If one was looking at the pressure curve, it was much more extended. More area under the curve.
If the manual says that your cartridge/bullet with 4831 has a max velocity of 2850fps and 54 gr of powder, the hand loader should note that velocity. When he hits max pressure (which he cannot measure) he will get that max velocity (which he can measure). Depending on his chamber and barrel, he will hit max velocity with a couple of grains of powder more or less than in the book.
If he goes over the speed limit the rifle will not let go, but the safety margin in the rifle is being used up and one day when there is some other minor issue, it can let go.
Because of the significant variation in rifles, this ammo can not be used in another rifle.
That is a bit simplistic. If you are using a given powder, primer and bullet in a given rifle, the only way to get higher velocity is more of that powder and that means more pressure.
If you need more velocity, the next step is a heavier charge of a slower powder. 6.5x55 is a good example of where one can switch from 4350 to RL22 and fill the case to get more velocity at the same pressure.
Hornady did this with their Light magnum offerings a few years back. They used a very slow powder (too slow for ordinary use) and compressed it so much they got an extra 10 grains into the case. This added about 200 fps to the round with no increase in pressure. If one was looking at the pressure curve, it was much more extended. More area under the curve.
If the manual says that your cartridge/bullet with 4831 has a max velocity of 2850fps and 54 gr of powder, the hand loader should note that velocity. When he hits max pressure (which he cannot measure) he will get that max velocity (which he can measure). Depending on his chamber and barrel, he will hit max velocity with a couple of grains of powder more or less than in the book.
If he goes over the speed limit the rifle will not let go, but the safety margin in the rifle is being used up and one day when there is some other minor issue, it can let go.
Because of the significant variation in rifles, this ammo can not be used in another rifle.
I agree 100% , because we are using one rifle, which rules out the variances in chambers, and barrels, that occurs from rifle to rifle.
Just wondering how you explain a situation where a particular gun will not reach the published velocities with a particular bullet/powder combination without pressure signs appearing. In one case involving two 7mmstw rifles, my own rifle would easily reach the highest published velocity listed in any of my manuals, yet another 7mm stw , with the same barrel length, could barely get within 150fps of my rifle, and could not quite reach the lowest maximum velocity published in any of my manuals, without excessive case head expansion, and extrusion signs on the brass. The brass, powder,bullets, and primers were all from the same lots, ruling out any differences in components. The maximum published velocities in my various manuals varied by around 140 fps with the powder/bullet combination that I was using, yet my rifle could match the highest published velocity with good brass life, and the other rifle could not quite reach the lowest maximum velocity published for the same powder/bullet combination.
If you don't accept that it is possible that one rifle simply produces more velocity with equal pressure, how do you explain this?
If you can explain that, the next step is to explain why the maximum velocities listed in my manuals vary by 140 fps in the first place.
Then perhaps, you can explain why the IMR data online lists a maximum velocity of 2872fps for the 223rem using IMR4064, and the 69gr Sierra Matchking, while my Sierra manual list a maximum velocity of 3100fps for the exact same combination, with the same 24" barrel. That is a difference of 228fps.
So are my 223 loads (using that exact combination) that chronograph 3000fps unsafe because they exceed the 2872fps listed by IMR by 128fps, or are they quite safe, because they are a full 100fps under the velocity listed in the Sierra manual?
How do you explain why Barnes used to list higher velocities for their XLC bullets, compared to the X bullets in their data?
Why is it possible to achieve more velocity with equal pressures using moly coated bullets?
If you accept that coated bullets reduce friction, which allows more velocity for the same pressure, then you have to accept that the surface finish of the barrel can also have a similar effect. Of course a hand lapped barrel can have a much smoother finish than most factory barrels.
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