velocities in manuals

[stubblejumper]

So how many of you believe the velocities printed in loading manuals accurately represent the velocities produced in your rifles?Before I owned a chronograph,I like many others expected that my rifles were producing the book velocities.However after owning a chronograph for many years,I soon learned that although some loads in some manuals do match what my rifles produce,the majority do not.Variations in chamber and barrel dimensions,lot#s of powder,primers and bullets result in variations in velocities produced between guns of up to 200fps even with the same barrel length.As such,the only velocities that I now believe,are those that I read off of the screen on my chronograph.

 

[Levi Garrett]

How true, manuals will also give barrel length, but not twist rate. I would say the numbers listed are for the most part pall park on the fast side.

 

[Republic of Alberta]

Normaly they use custom bbls with minimum SAMI spec cut chambers and bbls. The tight chamber, short lead and smooth bbls produce highest pressure's and as a result highest velocitys.

 

[dan belisle]

But not always. I've owned a couple rifles over the years that would outpace the manuals (and factory ammo specs as well), by a substantial margin (100 fps in one case and 175 in another. On the other hand, I've also had rilfes that consistantly came in 200 fps below what the manual said it would be, even with identical components. I just use the manuals as a guide line. - dan

 

[Fall Guy]

However after owning a chronograph for many years,I soon learned that although some loads in some manuals do match what my rifles produce,the majority do not.

Please expand on the use of majority. Has this been across all calibers? How many?

As a new SC user, I have found that the reload pistol ammo I was shooting was pretty close.

My last trip to the range for rifle diagnositics, I forgot the stupid remote interface cable.

 

[stubblejumper]

I did say rifle as I do not load for handguns.The trend is that the larger chamber dimensions in most factory rifles result in reduced pressure and reduced velocities compared to the minimum spec chambers used in testing for most manuals.This seems to include most chamberings with pretty much equal results.However,a few of my rifles with custom barrels have produced velocities higher than those listed in the manual.I have also seen a couple of factory rifles also produce higher velocities,but in those cases,this was easily explained by a specific lot# of powder that produced more pressure and velocity in all rifles that it was used in.I have probably loaded for 50 rifles in 20 chamberings over the last 25 years.

 

[sunray]

Velocities in the manuals are averages.

 

[stubblejumper]

Velocities in the manuals are averages

They are velocities actually measured in a single test barrel.

 

['Boo]

In MY experience velocities listed in the various manuals are above what is possible with a typical sporting rifle. While some loads may reach these speeds most don't, at least not without going over safe pressure limits. (If I can't get 3 loads out of a case without the primer pockets expanding that is over-pressure! )

I usually look for the average velocity of several manuals to judge the potential of any given load. If I hit that velocity and accuracy is acceptable that is where I stop. I own enough different rifles that I just change cartridges if I want more velocity for any given purpose rather than try and wring every bit of speed out of any one rifle.

 

[prosper]

Velocities listed for a certain charge/bullet combo listed in load manuals often don't agree with the same combo listed in another manual....

 

[Howard]

[QUOTE='Boo]In MY experience velocities listed in the various manuals are above what is possible with a typical sporting rifle. While some loads may reach these speeds most don't, at least not without going over safe pressure limits. (If I can't get 3 loads out of a case without the primer pockets expanding that is over-pressure! )

I usually look for the average velocity of several manuals to judge the potential of any given load. If I hit that velocity and accuracy is acceptable that is where I stop. I own enough different rifles that I just change cartridges if I want more velocity for any given purpose rather than try and wring every bit of speed out of any one rifle.[/QUOTE]

We are also seeing the effects of the influence of corporate lawyers here...

 

[cosmic]

Yes - The lawyer factor - I suspect safety margins are now being added to load data. Easiest way to do this is to establish the load parameters via test, them subtract a grain or two for publishing...

 

[cycbb486]

We are also seeing the effects of the influence of corporate lawyers here...

He has a point here. We must remeber that the data published in these manuals is what can be called Lawyer loads just as factory guns have Lawyer chambers. They are made to be safe. It is not worth the risk to have max data printed. We all know that chamber sizes vary and barrels are not exactly alike thus varying chamber pressures. So to be safe and avoid lawsuits the Lawyer reloading manuals are printed.

We know that to maximize the capability of ones rifle is to start low and work up until the first signs of pressure appear. This would be the max load for that given powder/bullet combination. Loads below that load should be safe. The things that could make that same good load unsafe is temperature change. The use of a chronograph and knowing the temperature outside when the load was developed is very important.

H380 is a prime example of a unstable powder in temp change. I was at the range one day when a guy was shooting his 22-250. He started getting pierced primers or blackening around the primer, (I cannot remeber which it was). He said it wasn't doing it in the early part of winter. The difference was the load was developed in the late Fall/Early Winter. This was in early summer. He was definatley hot on his loads. I knew right away when he showed me a case. I would have never known about H380 but learned about it from some BR shooters in the US on how radical it could be.

JMO
Calvin

 

[Hitzy]

Pressure is directly related to velocity. All things being equal (barrel length, components, etc) to the pubished load and your velocity is lower, then pressure is lower as well. If velocity is higher, then your pressure is higher then published. That's why a chony is a must if you are concerned about pressure. Unless you are waaayy over pressure, primer's and brass don't really give you a good idea of where you are at. Some primers will show cratering with mild loads, some brass will expand at the primer pocket with mild loads......your chrony if your friend

 

[stubblejumper]

All things being equal (barrel length, components, etc) to the pubished load and your velocity is lower, then pressure is lower as well

Of course all things will never be equal.Barrel finish, barrel dimensions,freebore etc can result in two rifles producing the same pressure but different velocities,even with identical components and barrel lengths.Increased freebore allows more velocity with equal pressure.Coating bullets reduces friction and increases velocity with equal pressure.A smoother barrel finish produces less friction just like a coated bullet does, and also allows for increased velocity with the same pressure.

 

[Mudpuppy]

He has a point here. We must remeber that the data published in these manuals is what can be called Lawyer loads just as factory guns have Lawyer chambers. They are made to be safe. It is not worth the risk to have max data printed. We all know that chamber sizes vary and barrels are not exactly alike thus varying chamber pressures. So to be safe and avoid lawsuits the Lawyer reloading manuals are printed.

If you compare data in some older manuals with new ones, the data is the same, there is no such thing as "lawyer loads".

The companies do not have to print "lawyer loads" all they have to do is print a disclaimer saying that the data tested on their equipment under their controlled conditions was safe and you are responsible for what happens if you use that data. This type of disclaimer is all over loading manuals, on-line sources and load development software. It absolves them of responsibility if you get hurt using that data.

Have you ever heard of a company that produces loading manuals being sued for printing dangerous load information? Reloading has been around for a long time, yet there is no case history of lawsuits against the manual companies.

It has been a reloading myth for years that the companies that print the manuals shave a couple of grains from the top loadings to cover their rears. Some people have used this as an excuse to bump up their loads because "they knew they were lawyer loads" and were hurt or had property damaged because of it.
I know someone who split 3 cylinders in a Smith 29 using his "real" top loads, he thought the manual was 10% below the true max charge. S&W replaced the first two cylinders for him but refused to replace the third because they said it was his loads not the gun that was at fault. He threatened to sue them and they told him to go right ahead as they had already done stress analysis on the replaced cylinders that clearly showed overpressure.
His next bright idea was to threaten to sue Sierra and they had their lawyer send him a nice letter clearly explaining their disclaimers in the manual. He never did sue them and he wonders why nobody shoots with him anymore.

The companies that print the manuals do take steps to ensure that the data they print is accurate and safe. Imagine the proofreading that a reloading manual goes through before it's released but they also cover their rears with legal disclaimers, so they are under no obligation to print lawyer loads.

 

['Boo]

Well said Mudpuppy.

A company that prints manuals must have realistic data or they would loose business.

In my opinion every hand-loader MUST have a selection of data from different sources to compare. Even as there are differences between our firearms there are differences between the test guns used by the different manufactures.

As a side not I have always found the data from the bullet manufacturers to be closer to "real life" than that from the powder companies providing you use the exact same recipie as shown. Powder companies have to look at the "worst case" scenario and even though the data usually shows brand and type of bullet used they are aware that a load that is safe with one bullet type may not be with another.

In the end it is the individuals responsibility to determine what is safe in their firearm. I also feel that if said individual is going to try and wring maximum velocity from his loads he MUST own a chronograph. Excess velocity IS an indicator of over-pressure loads yet a lot of people seem to treat it as a bonus.

 

[stubblejumper]

Excess velocity IS an indicator of over-pressure loads yet a lot of people seem to treat it as a bonus.

The problem is deciding what IS excess velocity.If you have three manuals with identical,components and barrel length,yet the maximum velocity varies by 200fps,what manual do you use to determine what maximum velocity is acceptable?

 

['Boo]

The problem is deciding what IS excess velocity.If you have three manuals with identical,components and barrel length,yet the maximum velocity varies by 200fps,what manual do you use to determine what maximum velocity is acceptable?

If I had to draw a line in the sand I would say that if I start edging 2%-3% over the highest listed velocity from several sources using the exact recipe that would be excessive to me at least. Once again this information must be used in conjunction with all other means the average re-loader has at hand to judge pressure. If I was 10% under average maximum velocities shown in several manuals and I was still getting loose primer pockets after 2 or 3 loads I would assume I was close to being over-pressure. If I was getting massive brass flow and was trimming cases after every shot I would be looking at changing loads. Conversely if I was getting slightly over average velocity maximums and all other pressure indicators were absent I would consider that a safe load.

Experience comes into it as well. For example I "KNOW" that 2900 fps using a 180 grain bullet out of a 30-06 must be crowding the pressure limits even though Nosler lists a load pushing close to that velocity. I may be totally wrong but my gut tells me that is too fast.

It is like the judge who was asked to define ####ography. He said while it was impossible to put into words he did know it when he saw it.

 

[stubblejumper]

If I was 10% under average maximum velocities shown in several manuals and I was still getting loose primer pockets after 2 or 3 loads I would assume I was close to being over-pressure.

If I was getting loose primer pockets after 2 or three firings,I know that either the pressure is excessive or that I have a soft batch of brass.

If I was getting massive brass flow and was trimming cases after every shot I would be looking at changing loads.

If I had massive brass flow after firing the first test load,I would pull the bullets and start with a lower charge. I would not fire a second shot with that load.