Early pressure signs

snomad

snomad

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I have not pulled these bullets yet to check charges but here is what happened:
Caliber is 250-3000
Powder is H4895, Winchester LRP.
Bullet is 100 Grain Nosler ballistic tip. COL was 2.52" plus or minus a small variance.
Brass was an assortment with some being older. A light crimp done with Lee Factory Crimp die.
Powder was measured on a digital scale good to two decimal places, 7 loads from min to max, 3 rounds each load. Shots were chronoed. Min load was 32 grains, max was 35. .5 grain increments.
The first group chronoed 2780,2720,2726. Primers were somewhat flat and one case had some drag on bolt lift.
Second group chronoed 2846,2801,2814. Primers were similar with one being even flatter and starting to back out enough to see and feel. Nothing really different with bolt lift.
This is the point at which I stopped. I would have expected to see these signs around 34.5 grains, not 32 and 32.5. Velocities seem to match the loads but not the pressure. Velocities called out are from 2686 to 2988 from min to max.

Ideas??
 
I'm pretty new to reloading as well so maybe this will sound stupid, But crimping can increase pressure, if you're following a recipe that did not call for crimping that could be it.

Flattened primers can also come from too much head space (shoulder to head distance too short).

Hope this help
 
That is not at all unusual, that is why you start with reduced loads, and work up the powder charge. One thing that I never do, is mix brass cases.
 
There is a reason we have START loads. We start there and get a feel for the load/powder. The velocity indicates you are near max. the pressure signs suggets that too.

I have seen a START load that was way over pressure. Some rifles have tight throats, bores, necks, whatever and develop pressure and velocity more than others. Now you know yours is such a rifle.

I suggets you weigh your brass and sort it into batches of 20 rounds that are each within a grain of each other.
 
The action is a Ruger 77.
I thought that the velocity was in line with the load actually. I used this brass to get an initial feel for the loads, rifle. Certainly not the way to get consistency but unusual to have such similarity in signs with 3 different types of brass. I have my puller now and will investigate the charges as well as the weight of the brass types tomorrow and report. I suspect this old brass is way thicker (all 3 types) and will compare it to some newer winchester.
Makes me wonder what would happen with factory ammo that usually is somewhere in the middle of the road loadwise as compared to min/max reloads.
Also, would increasing the COL some reduce pressures in a meaningful way?
 
A primer backing out slightly is NOT a sign of too high pressures!!
This is usually indicative of lower than normal pressures.
However, others have suggested sorting your brass....I concur.
Brass capacity can vary considerably, giving erratic pressure signs.
Regards, Eagleye.
 
I agree except that in combination with flattening of the primers and some resistance with bolt lift I thought that was surely an indication of high pressure.
 
Not necessarily.
Flattened primers and hard bolt lift can be headspace related.
You are using a modern well made rifle. How compatible is your fl sizing with this rifle?
 
Not sure exactly what you mean by compatibility of the FL sizer with the gun. Certainly the cartridge would be tighter in the chamber if I was only neck sizing but I am not sure that would have an impact on pressure or not.
I agree that increasing the COL to 20 thou off the lands should decrease pressure. I have lots of mag room left and have not yet investigated how much I can safely increase COL.
I did pull the bullets and measured the charges; they were as marked and not mixed up or something stupid like that. I am going to check case weights and volumes to see if there is a significant difference next and also check the scale.
The part that is different here is that with all the different calibers I've loaded where I have worked up a load properly and set the COL for these initial rounds at the minimum stated for the bullet or just slightly above I have not had an unexpected pressure problem like this. I will report on the brass next.
 
I can find nothing seriously different with the brass as compared to newer stuff weight wise. One type was about 5 grains lighter which should indicate more case volume if anything. I know this older brass is harder though.
Additionally, I can go about 250 thou closer to the lands (increase in COL) with no magazine problems so this may be the next thing to try. And only to verify it may be the cause. After that it's on to new brass. Just need to get some.
 
snomad said:
I have not pulled these bullets yet to check charges but here is what happened:
Caliber is 250-3000
Powder is H4895, Winchester LRP.
Bullet is 100 Grain Nosler ballistic tip. COL was 2.52" plus or minus a small variance.
Brass was an assortment with some being older. A light crimp done with Lee Factory Crimp die.
Powder was measured on a digital scale good to two decimal places, 7 loads from min to max, 3 rounds each load. Shots were chronoed. Min load was 32 grains, max was 35. .5 grain increments.
The first group chronoed 2780,2720,2726. Primers were somewhat flat and one case had some drag on bolt lift.
Second group chronoed 2846,2801,2814. Primers were similar with one being even flatter and starting to back out enough to see and feel. Nothing really different with bolt lift.
This is the point at which I stopped. I would have expected to see these signs around 34.5 grains, not 32 and 32.5. Velocities seem to match the loads but not the pressure. Velocities called out are from 2686 to 2988 from min to max.

Ideas??
Click to expand...

A quick check of my notes indicated 34gn of IMR4895 was on the verg of being to hot for my 250 Ruger with 100s. Vel was in the 2850fps range.
I have always felt I was pushing pressures to get anything over 2800 in my gun. Granted I have seen 100fps variences in identical chronys :cool:
My gun is very happy with 32.5 4895 & 100gn bullets but I have always had best accuracy by far with Sierra 87gnSPs.
I see your useing Win primers.
For a while I found them to be extremely soft, cratering in loads I knew were ok.
 
First: chrono is as it came. Other rifles I have loaded for seem to be in line velocity wise for the loads created as compared to the books. Usually a little lower as would be expected with barrels shorter than the test ones. I have fired the exact loads in another 250 with similar results except for the pressure signs. Almost to 3000fps. Additionally, if I never had the chrono and made these minimum load cartridges, fired them and saw the pressure signs, I would still be scratching my head as to why.

As for primers and powder: It is H4895. There is a 3 grain variance with this powder min to max which is wide. H4831 is way less forgiving. IMR 4895 is 29.9 to 34 grains min to max (quite a wide grain variance but lower velocities too) so 32 of that is smack in the middle which is a good place to be. 34 would have been max load. A little different with H4895. I have used Win primers in all my reloading, nothing out of line with all that. Cratering can be caused by a too large firing pin hole in the bolt, even with a very mild/min load. Had that in my last one.
I do appreciate the ideas and thoughts here guys. It helps to have a little "conversation" about the unexpected stuff that happens.
On a final note for tonight, earlier in this thread neck thickness was mentioned. When checking distance to the lands to figure what my max COL could be, I noticed that resized brass easily went all the way into the chamber and fell out which is good. However, when I pressed a bullet into a dummy round to check the throat distance they would not fall out anymore. (they were definitely not contacting the lands when this occurred. I am going to check some neck thicknesses next just out of curiousity on the old brass as compared to the newer stuff. And maybe bullet diameter too as these are different bullets I am loading now. Thanks again for the responses.
 
If you do enough reloading you come to the conclusion that there is alwasy something new to screw up what you thought you knew was right. Was working up loads for two BSA 30-06 rifles a buddy and his father in law bought, could not mix brass from one to another and different top loads in each. They couldn`t understand why they couldn`t exchange ammo, so they went with factory ammo. Every rifle is unique and some will make you crazy trying to find a load that works.
 
An update on this problem; I just got some new brass and loaded some rounds with used brass and new stuff. I also increased the COL but am still away from the lands. The two loads with both old and new brass were 32 and 32.5 grains of H4895 as mentioned earlier. Really nothing changed. Primers are still flat although none tried to back out. The bolt lift was not bad at all and there was no marking on the stamp. The weather (temps) was definitely colder though which may have had a slight effect. I forgot my tripod so could not chrony these rounds.
I have two questions: how much lower can I load under the 32 grain minimum to see if the pressure signs disappear? How can headspace affect this early showing of pressure? Too much or too little headspace?
Curiously the ten rounds printed two groups that were two ragged holes.
 
I don't see why you couldn't drop down to 28-30 range in powder, it's a small case.
I'm curious on your sizeing.
Could it be in your rifle your pushing the shoulder back causeing a headspace?
That would cause primers to back out & possible other pressure signs.

Again, I have always found about 2800fps with 100gn bullets to be about max I could get from my M-77 regardless of powder used.
I've seen "claims" of 3,000fps but I'm not comfortable there with any powder I've tried!
At any rate if 100gns @2,800fps won't do the job neither will 100gns @3,000.
 
I agree 2800fps is adequate, but it would be nice to have room to find an accurate load. When I download this caliber I will likely drop well under 2700fps. Please explain what you mean about the shoulder being pushed back and headspace.
I have checked the fired brass against new and the only thing that seems off is that the inside neck diameter of the fired brass is exactly .257" and bullets need to be pushed into this brass by hand. I mentioned earlier that a dummy round when inserted into the chamber by hand would not fall back out. The bullets in those dummy rounds were not contacting the lands and sticking either. They certainly do not drop through the neck as I have seen at times with other calibers. Would these two observations indicate a tight neck in the chamber? I did check the bullet diameter on two different brands and weights and both were bang on at .257" as well.
 
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