Cases getting Shorter

  • 156 Views
  • Last Post yesterday
fc60 posted this 2 days ago

Greetings,

I completed my third Military Cast Bullet Match today.

I am shooting a 1903-A3 rifle.

I have been using the same LC 63 Match 30-06 cases.

Fired cases you can see/feel the primer raised from the case head.

Using a Wilson Case Gauge, my brass seems to be going in farther and farther with each loading.

Is the issue from reduced powder charges?

I use 21.0 GN of IMR4227 with a 200 GN SAECO RG4 bullet.

How does one go about lengthening the cases back to normal?

I did check the rifle headspace. The Bolt will not close on a NO GO Gauge.

Cheers,

Dave

Attached Files

Order By: Standard | Newest | Votes
Wm Cook posted this yesterday

Congratulations on making your third match! And sorry about the problems you’re having.

Are you FL sizing? What are the measurements before & after sizing? How much pushback are you getting in the cast length, the shoulder push back and the shoulder diameter squeeze?

21.0g of I4227 with a 200 grain bullet in my 308 runs about 1645 and I wouldn’t consider that a reduced powder charge. Some of my cases have been shot >20x and haven’t gained or lost .002. I neck size and it’s shot in an over the counter bolt gun so it’s an apples and oranges comparison to your 03z

I believe reduced pressure case shortening wound be more common in sub Sonic loads. Larry’s done a lot of work on that.

He or John should be able to jump in and help. Thanks, Bill Cook.

Attached Files

  • Liked by
  • RicinYakima
John Alexander posted this yesterday

Shortening the headspace dimension of cases is apparently caused in some calibers and some light loads when the pressure in the primer pocket is enough to drive the case forward a small amount and then the maximum chamber pressure from the powder igniting in some light loads isn't enough to fire form the case to fill the chamber,  This can be avoided by enlarging the flash holes to reduce the pressure in the primer pockets. 

Enlarging the flash hole used to be believed to render the cases dangerous for later use for full charge loads and rifle blow ups were warned against -- which seemed logical. But like a lot of things that seem logical, it isn't true. This was proven by an excellent set of experiments by Larry which showed the oversized flash holes had little, or no, effect on maximum chamber pressure.

One way shortened cases can be restored to full length is by firing loads which have had hard or jacketed bullets seated long so the rounds will only chamber with pressure on the bolt handle. This holds the cartridge back against the bolt face and should safely fire form cases to correct fit in the chamber.

John

Attached Files

  • Liked by
  • John Carlson
Ken Campbell Iowa posted this yesterday

about 3 years ago I made up a nice custom 35 Whelen on a Springfield action for a friend ... after assembly, I decided to use some mild cast loads to check out functioning ... and just maybe to suck him into the cast bullet  hobby ...

used 7 gr 700X, my common load for anything that looks like a 243 or 30-06 case ...   and a RCBS 250 ish casting.  my friend thought it great to shoot his new toy with no shoulder pain even after 20 shots in 5 minutes ...

geepers, in just one firing, I found that 18 out of 20 of 2nd iteration reloads had shortened so much that they wouldn't fire ...   yep, the ol Springfield has a strong FP spring, but mostly the standard 35 Whelen has very little shoulder. 

I didn't pursue this further, and pitched the short cases.  I am inclined to use an Ackley shoulder on the next 35 W. or 358 Winchester rig I build.  I have no trouble with 308 Win or 30-06 cases shortening with these sissy loads and standard primer holes ... at least so far......   using Lee collet dies also.    I have been shooting mostly 308 lately, so will be watching for this.  maybe load a couple repeatedly, one with primer drilled out as per Larry.

BTW, my friend used those newish Barnes solid bullets on his first deer with the 35W at 100-150 yards.  the bullet expanded just like in the ads ... Very Impressive. 

ken in iowa

 

Attached Files

  • Liked by
  • John Alexander
RicinYakima posted this yesterday

Change the extractor for a properly fitted one. The case sitting on the bolt face should only have 0.005" clearance. The case can not go forward with a proper extractor fitted to the case rim. FWIW

Attached Files

Grit City Matty posted this yesterday

It was good shooting yesterday at Paul Bunyan. Perfect weather too. There's some good input here and I hope that you find what you're looking for. Matt

Attached Files

Categories
Search
Popular Tags
This Weeks High Earners
Hot Topics
Close