Brass Case Head Separation after 6 firings

[Rflshootr]

I like to jam the bullets hard like was previously mentioned, plus I put a VERY THIN coat of oil on the case just before I fire it. That helps it not to grip the chamber wall and keep pressure on the bolt face. Keep your bolt lugs lubed as well.

 

[nksmfamjp]

then later found the chamber too long. - Dangerously long!= Cases separate, and screw you and your rifle up = BAD DAY. - I caught it and nothing happened. The neck-sized rounds would not fit in a stock .338 WM. Too long! - Sold it to a gunsmith who fixed it.

May I ask you how could you accommodate a too long chamber and make it safe?

 

[Rflshootr]

May I ask you how could you accommodate a too long chamber and make it safe?

The barrel has to be removed and set back to proper head space.

 

[Carolinadx]

- Opened up to .338"
- Used .30 Gibbs sizing die to establish false neck
- 11g WSF, fill COW to the base of the shoulder, and then stuff with a cotton ball (packed)
- Shoot and clean barrel as required.

Virgin Peterson brass started with .001X" thicker than Hornady. I do not have the thickness after COW, but I can measure them for you. I do not worry about it until one full load firing off the chamber.

ADDED:

View attachment 365678
From L-R

1 - .35 Whelen Hornady virgin brass
2 - After running through .30 Gibbs sizing die
3 - After COW fireforming
4 - After firing off the chamber with a full load

Great share. Thank you

 

[Deleted member 109523]

I just want to say that I love this forum for the conversations like this. I haven't been down the road of fireforming wildcats yet but plan to in the near future. I absolutely love discussions like this one. Thank you all for your experiences.

Ditto

 

[chav0_12]

Keep reading. When you think you have seen everything, guess again. There is some very smart people here, and items with information is always coming. As one person said here. It's my morning fix.

For sure. I've been around for quite a while and learn a lot. There's always something interesting.

 

[nksmfamjp]

The barrel has to be removed and set back to proper head space.

….or you could fireform and blow the shoulder forward, right? That was kind of my point. Shooting brass with too much gap to bolt face is what creates head separation. In a controlled environment, like hand loads for a custom rifle, things like proper fireforming can make it work. I get that cutting a bit off and rechambering would be best.

 

[MagnumManiac]

I have formed about a dozen different cases over the years. Most have been Ackley cases and the rest have been similar based on the 416 Rigby case, for which I use hydro forming dies after annealing the parent case.
I honestly think it depends on 2 factors; the brand of the case and the annealing.
With my 375 Weatherby the step up from the H&H case was too large for a neck up and false shoulder, same goes for my 416 Rigby based cases…so, the best method I have found is COW. No stretching occurs, the shoulders are fully formed yet slightly round and headspace is set correctly.
Have tried jammed, caused head separations on the third firing with 22-250AI, also tried mid range loads jammed, same results.
Have used false shoulders and COW, that worked out fine, it also works forming belted cases to headspace off the shoulder and I haven't had a separation yet.
I run several Win Model 70's, if you're checking you shoulder bump with the firing pin installed in the bolt STOP! Remove it and check your bump, otherwise you'll get false readings, the firing pin spring will alter where the bolt face is in regard to your measurement if using a comparator system.

Cheers.

 

[Bravo 4]

Improving Peterson brass they told me to anneal down the shoulder and case body a bit, and to lube the case a little. As mentioned make sure the action lugs are lubed, as they should be.
I have a hydro forming die for my .375 Snipetac but do not like using it. You have to smack it pretty dang hard with a heavy hammer (with it screwed into the press with the ram all the way up) to half-a$& push the shoulder forward. Then you have to fireform to get a sharp shoulder. Not worth my time and don't want to damage the press.

 

[LongBomber]

When you made your "false shoulder" how much longer was it than your normal length? Ie how much was your size die backed off (turned out) when sizing the neck back down?

 

[Rflshootr]

….or you could fireform and blow the shoulder forward, right? That was kind of my point. Shooting brass with too much gap to bolt face is what creates head separation. In a controlled environment, like hand loads for a custom rifle, things like proper fireforming can make it work. I get that cutting a bit off and rechambering would be best.

No, not right! A 338 Win Mag that was mentioned is a belted case. If it was chambered way too deep, the recess for the belt is way too deep as well. That causes an unsupported area just ahead of the belt which is very dangerous. Blowing the shoulder forward is fine on a non-belted case if done properly, but not on a belted case that is going to leave an unsupported area just ahead of the belt.

 

[FEENIX]

I have Whidden hydraulic forming die that I can pre-form 7MM STW, 8MM RM, .300 H&H (most challenging), .358 STW, .375 H&H, .416 RM to my .30 LARA.

From L-R
1 - Virgin 8MM RM brass
2 - After a couple of whacks with the hydraulic forming die
3 - After running through the .30 LARA sizing die (also made by Whidden)
4 - After firing off the chamber with a full load

It is still fully functional but I use an old (IIRC, it was built in 1972) specifically set up for hydraulic forming.

 

[Trangieboy]

If you're going to jam on either a bullet or a false shoulder, you need to be only just able to close the bolt. LOTS of jam

 

[can1010]

even if a belted mag is properly head spaced of the belt like it should be i have seen new brass .010-.014 short at the shoulder so you are always moving the shoulders forward. I started using a false shoulder on all belted cases years ago and it has solved a couple of problems. First i don't get head separation any longer. Second i don't get the case bulge above the belt or need a collet die to fix the sticky extraction problem caused from the case stretch above the belt weakening it and causing the bulge.