Shot my .375AI today. On the 3rd shot ejected brass had 2-3 fairly large dents in the shoulder area. Chamber was clean as After cleaning the barrel I clean the chamber with a dry patch. Load was reformed .340 WBY brass, 85 gr. BL-C(2) @35 gr. Speer, CCI 250 LRM primers. This was the 3rd. loading of this brass.
Anybody have any ideas---some sort of gas blow back of some sort. Never had anything like this happening in over 50 yrs. of reloading!
This is a .375 H&H top load from Hodgdons annual loading magazine.

HELP----Hip

Dents on the shoulder after firing is sometimes due to low pressure. Is it possible to load a picture of the case?

Happened to me when my .375 Wby had the bullets move under recoil. That was with W 760 and the cases were not full / nearly compressed as with the usual 4831's. Your load seems "full", though so bullets in the magazine moving under recoil of previous shots is doubtful. A mystery.

is there soot on the case neck? what weight bullet? two things if the bullet in the magazine is moving under recoil. the brass could be work hardened being AI. I would aniel the brass and try again.
I had a similar problem with a 243 AI. low powder charge could cause the problem or a combo of all three

Is it possible that they were dented from hitting the ground after ejection?

WHAT was the COAL...and what is the cartridge water volume...and what barrel length???

The load you mentioned was a top load for a standard 375 H&H, NOT the AI version.

The 375 H&H AI has a volume about 105 gr according to QL's sample(similar to the 375 Weatherby) and the standard 375 H&H is about 95 gr, about 10% LESS volume, which means your load was about 10% LESS volume or 10% LESS PRESSURE/VELO, roughly and numerically speaking(depending on the factors you didn't list) which might have caused the problem.

Compare the 375 AI and the 375 WBY using Varget, H4895 and H380 in the same manual to get some idea of the variation.

Basically...I think you had powder/pressure blow-by due to the neck not sealing the chamber due to low pressure caused by a number of factors, non of which can be know precisely because firing a round is a destructive process and all the components are used up...BUT

The problem could be caused by any/all of the solutions mentioned, or maybe a fluke load with a wrong/low powder charge, or...who knows.

I've had strange things happen that I couldn't explain that could be caused by many factors.

I would increase the load density by increasing the load by a few grains, SLOWLY, or by going to a different powder listed in the manual for BOTH the 375 AI and the 375 WBY Varget, H4895, H380 or trying RL-15, 760 and Chrono the loads to see what your velos compare to published loads...

All rifles are different, your AI chamber could be cut slightly larger therefore increasing the volume even more...the only way to know for certain is to measure the case volume and chronoing the load,

Luck

Hi Guys,

Thanks for the reply's. I'll add some more info.

Not capable of posting pics--sorry.

I single load at the range for safety---no bullet movement.

None of my brass ever hits the ground unless I drop it.

Load is a MAX standard .375 H&H Hogdgens load.

Brass shouldn't be work hardened after just 3 mild reloadings.


I don't have any reloading manual data for the Ackley only for the Weatherby (Hornady) to compare.

The fired brass was pretty clean only a LITTLE bit of soot mark on the neck, none on the shoulder where the dents are.

I have fired max loads listed for both the standard H&H and the Weatherby using 270 gr. bullets with no problem. They both seemed pretty mild in my rifle.

Rifle is a Win. M70 Stainless classic 1995 with a 23" bbl. with a brake added to that.

I have a feeling it is too mild a load but don't know how that can happen.

It MAY be too mild of a load but I've loaded many cast bullet and severely reduced loads without this ever happening before.

Hip

I would think that brass could never be indented when in a chamber and subjected to pressure from firing.The dent must occur after or during ejection.Are you sure that you did not drop this case and pick it up off the ground.

I've been at this game a day or two now and the only time a collapsed shoulder happened was when the powder charge was too low or too slow and mostly in the bad old days when reloading data was sparse and you did the deed by the seat of your pants.

I don't use BLC2 much anymore because there are too many much better powders available nowadays, but I do have a few rifles/calibers that go back 30-40 years that started out on BLC2 and the loads were the most accurate at the time so I just didn't change.

I checked several of my reloading resources plus ran QL which decided to phuchup and give some really ridiculous numbers, which showed that load was WAY up there in pressure and velocity and by default you should have had flattened primers and sticky extraction, but you had the opposite.

Ball powders can act very squirrely now and then, but I've never had any problems with BLC2 in the smaller and mid sized cases...I just don't use it in mag size cases.

I have 3-375 cals...H&H, Ruger and JDJ and shoot a lot of 200-235 gr bullets at squirrels but use more 760, RL-15-17, H380 and now CFE223.

Do an online search for 375 H&H AI, there are a few sites covering it that might help.

I would also suggest getting up to date reloading manuals and maybe a modern interior ballistics program if you want to mess about with wildcats...they are a world unto themselves.

Luck

You have a combination of low pressure and hardening necks. What is happening is the pressure is to low to blow out the neck of the case against the barrel to form a gas seal. Some gas is getting past the neck and travels back along the case. That is what is causing those dents. The cure 1/ anneal your case necks and 2/ change your powder. If using 235 gr Speers I would suggest IMR 4064.

For any non believers you may want to find a copy of the Speer # 10 loading manual. Go to page 59 and read about it. There is also pictures of the collapsed cases. Also in the list of powders recommended by Speer for the 235 gr bullet for the 375 H&H, BLC2 is not listed. I would suggest staying with a bulky powder that nearly fills the case. It will likely result in more consistant pressures.

Out of curiosity, would freebore length have any effect on this phenomena?

Yes, it can, do to the lower pressure before the slug hits the bore.

Cases can be indented only when oil or oil residue is on the case shoulder, this can happen in the "resizing die process" or from fireing in the "rifles chamber". In which case you can reload the case in question and fire form the case to a perfect shoulder..These oil dents would be from shoulder to base of neck every time. If low pressure is the demon, then the necks would be black btw.

I don't see how it could be otherwise as pressure comes from within the case and blows the shoulder out,not in so unless oil is on the sholder how could it be otherwise??

A low pressure load should not do this in my opinion..Lots of folks shoot low pressure loads in their deer rifles for target, turkeys and to deal with recoil as well as low pressure lead bullets without this problem..therefore I can only assume that oil residue or perhaps grease was on the case shoulder when fired.??? Just my opinion, however I have never had such a problem, nor heard of it before today..

Furthermore you state its a book max load, therefore it seems impossible that the shoulders could be indented by shooting as a max load would definitely iron the shoulder out.

The other option is corrosion in the area of the chamber where the cases are creased/dented. That is the worst scenario.

Thanks for all the input.

Today I broke down the remaining loads, then annealed the cases. They are drying now. I will load them up with a heavier bullet and slower power---Imr 4064, H414 or RL17 and reshoot them either Wed. or Thurs.

Additionally I called the Tech staff at Sierra bullets and the tech I talked to said he had the same problem with necking up .300 RUM to .338. He feels it is due to work hardened brass and too low pressure. He said the annealing worked for him so I'm giving that a try, it certinly shouldn't hurt.
The reason I'm using BL-C 2 Is I have a few pounds that I don't use for anything else anymore so I was going to shoot it up while becoming more familar with the rifle and caliber.
I'll give an update after my range visit!

Thanks All----Hip

Along with blackened necks,another obvious indication of low pressure would be the primer sticking out from the primer pocket so that it will not allow for the case to slip into a shell holder.I would suspect further low pressure could cause a hang fire.

quote:

Originally posted by Atkinson:
Cases can be indented only when oil or oil residue is on the case shoulder, this can happen in the "resizing die process" or from fireing in the "rifles chamber". In which case you can reload the case in question and fire form the case to a perfect shoulder..These oil dents would be from shoulder to base of neck every time. If low pressure is the demon, then the necks would be black btw.

I don't see how it could be otherwise as pressure comes from within the case and blows the shoulder out,not in so unless oil is on the sholder how could it be otherwise??

A low pressure load should not do this in my opinion..Lots of folks shoot low pressure loads in their deer rifles for target, turkeys and to deal with recoil as well as low pressure lead bullets without this problem..therefore I can only assume that oil residue or perhaps grease was on the case shoulder when fired.??? Just my opinion, however I have never had such a problem, nor heard of it before today..

Furthermore you state its a book max load, therefore it seems impossible that the shoulders could be indented by shooting as a max load would definitely iron the shoulder out.

The other option is corrosion in the area of the chamber where the cases are creased/dented. That is the worst scenario.

When resizing, the pressure is coming from outside the case.

If the necks don't seal during firing it is caused by hardened necks or low initial pressure.
Use a powder with the faster burning rate!
Zeke

quote:

I don't see how it could be otherwise as pressure comes from within the case and blows the shoulder out,not in so unless oil is on the sholder how could it be otherwise??

Extreme example of "click........................bang" surplus Pakistani ammo and the forward part of the case collapsing. If the case does not seal the chamber the differential pressure causes the case to collapse.

I broke down the remaining 12 rds. that I had loaded----annealed the cases and loaded them up with 84 gr. IMR 4064, CCI 250s and 270 gr. Speer BTs. The load is 2/10 of a grain heavier than Hornady's max Weatherby load. They shot great and no signs of high pressure or heavy bolt lift. I guess the necking up of the brass and a couple of loadings was indeed enough to work harden the brass and the low pressure did seem to cause the dents.
Problem solved and something learned----I hope!

Hip

Good man! (I am personally happy, as a reader of posts, when the OP both follows up on his/her questions and posts final results.)

It would have been nice to see a picture of the case-neck,shoulder and primer.

shootaway----The primers were always nicely rounded, not at all flattened. There necks also had no issues as well as the shoulders. The dents location were below where the shoulder ended in the upper part of the body.
I feel the problem was with the work hardened necks and shoulders upon firing the bullet would exit the case but the brass did not seal the chamber due to lower pressure. Then the gas flowing to the area of least resistance traveled down the body of the brass and dented it.

Hip