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#3919505 - 03/21/10 06:26 PM Reloads with backed out primers?
hemiallen Offline
Campfire Guide

Registered: 10/13/08
Posts: 3032
I believe the answer is headspace, but I haven't seen this as prevalent as this before in a bolt gun.

Gun is a rem 700 sps 204 ruger, new WW brass I FL sized in Redding dies, deburred flash hole uniformly, chamfered inside and out, a batch of 10 reloads of 39 SBK and 25.5 H335 powder. 5 of the 10 had flush or below primers, and the other had .001 to .004" primer height above flush, using the depth rod on vernier micrometers. Dragging a precision ruler across case base you can feel the primers are well above the base and also see it. The edges of the primers are rounded, so a hot load isn't the problem, imho.

I had a similar issue many years ago with a contender in 7 tcu, and found the case fit in the chamber deeper than was correct. My fix was to bump the neck up to 30 cal, slowly resize down until the action barely closed, fixing the problem. Some cases in the contender were so deep they soft hit the primer and didn't go off......


I suspect my chamber may be deep and I need to bump all the brass.... but not sure this is the right fix..


Thanks for any suggestions.

BTW, this also has cratering like most newer remingtons from research, but this is not a measurment of the crater.

Allen
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#3919565 - 03/21/10 06:41 PM Re: Reloads with backed out primers? [Re: hemiallen]
1234 Offline
Campfire Regular

Registered: 08/04/02
Posts: 1110
Loc: idaho
back your sizing die off a quarter turn and see what happens.

Ed

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#3919597 - 03/21/10 06:48 PM Re: Reloads with backed out primers? [Re: hemiallen]
ricksmith Online   content
Campfire Ranger

Registered: 02/15/04
Posts: 2069
Loc: sc
You don't need to FL size new brass, you probably moved the shoulder too far. Your die is set incorrectly.Rick.

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#3919725 - 03/21/10 07:16 PM Re: Reloads with backed out primers? [Re: ricksmith]
wildhobbybobby Offline
Campfire Ranger

Registered: 12/26/09
Posts: 2331
Loc: Michigan Yooper
I don't have or load for a .204, but protruding primers, especially with new brass, is often a sign of low pressure. The firing pin drives the minimum dimension case forward into the chamber and the moderate pressure is enough to cause the case walls to grip the chamber walls and for the primer to back out of the case and contact the bolt face, but not enough to cause the case to set back against the bolt face and reseat the primer.

I looked at some H335 data for the .204 after reading your post and it looks like the starting loads and maximum loads in some instances are within 2 to 2.5 grains of each other. One source listed a starting load pressure of 47,000 psi and a maximum load pressure of 56,000 psi with H335, and your load was closer to the starting load than the max load from that source.

So, assuming your rifle's headspace is within spec, it could simply be that your pressures are relatively mild and those new cases are just not fully obturating to completely fill the chamber.

I am certainly not saying that you should get carried away increasing your loads, but I have often seen backed out primers with mild loads in new brass. An excellent example is the 8mm Mauser when used with lightly loaded US factory ammo. The 8x57 in military loads is a real barn burner, producing more power than .30/06 military loads do. However US factories load it to just about duplicate the .32 Special, and I have often seen protruding primers after firing those wimpy factory loads.


Edited by wildhobbybobby (03/22/10 09:30 AM)
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#3919807 - 03/21/10 07:26 PM Re: Reloads with backed out primers? [Re: hemiallen]
4xbear Offline
Campfire Guide

Registered: 04/08/07
Posts: 3848
Loc: Occupied California
Originally Posted By: hemiallen
I believe the answer is headspace, but I haven't seen this as prevalent as this before in a bolt gun.

Gun is a rem 700 sps 204 ruger, new WW brass I FL sized in Redding dies, deburred flash hole uniformly, chamfered inside and out, a batch of 10 reloads of 39 SBK and 25.5 H335 powder. 5 of the 10 had flush or below primers, and the other had .001 to .004" primer height above flush, using the depth rod on vernier micrometers. Dragging a precision ruler across case base you can feel the primers are well above the base and also see it. The edges of the primers are rounded, so a hot load isn't the problem, imho.

I had a similar issue many years ago with a contender in 7 tcu, and found the case fit in the chamber deeper than was correct. My fix was to bump the neck up to 30 cal, slowly resize down until the action barely closed, fixing the problem. Some cases in the contender were so deep they soft hit the primer and didn't go off......


I suspect my chamber may be deep and I need to bump all the brass.... but not sure this is the right fix..


Thanks for any suggestions.

BTW, this also has cratering like most newer remingtons from research, but this is not a measurment of the crater.

Allen


Check that with a case gauge before you do much more. I just had a batch of new Remington .35 Whelen brass that was all short on head space By about .030 so I'm not sold on a deep chamber yet.
I expanded the necks to .375 and ran them through the Whelen die again and the cases were perfect after fire forming. Ya just never know. Bear
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#3919818 - 03/21/10 07:29 PM Re: Reloads with backed out primers? [Re: wildhobbybobby]
hemiallen Offline
Campfire Guide

Registered: 10/13/08
Posts: 3032
Good point on light load
40 Gr. Hornady V-Max H335 2.250" 25.0 3508 47,300 PSI
26.8 3738 56,700 PSI

It does look like a light load, I'll have to try the neck die only and bump up the loads.


After looking over the targets again, a load of 29 grains of H335 behind a 34 grain dogtown gave the best accuracy ( 0.450) and no backed out primers, although they are flat.....

Good point on not needing to FL size brass...

Thanks

Allen
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#3920655 - 03/22/10 02:09 AM Re: Reloads with backed out primers? [Re: hemiallen]
hawkins Offline
Campfire Regular

Registered: 01/22/05
Posts: 1068
Loc: Hawkins, a large metropolitan...
If there wasn't headspace the primers would have no space to
back into. If you lightly oil the case before firing it will
fill the chamber without a "stretch mark". Then adjust your
sizing die.
Good luck!

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#3921150 - 03/22/10 07:01 AM Re: Reloads with backed out primers? [Re: hawkins]
doubletap Offline
Campfire Tracker

Registered: 12/05/07
Posts: 5023
Loc: Atlanta
Can someone shed some light on this? I have read more cons than pros on firing cases with lube on them. Hawkins post sounds reasonable but contrary to advice from others.
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#3921230 - 03/22/10 07:28 AM Re: Reloads with backed out primers? [Re: doubletap]
Huntz Offline
Campfire Tracker

Registered: 10/28/07
Posts: 5453
Loc: N.E.Wisconsin
Originally Posted By: doubletap
Can someone shed some light on this? I have read more cons than pros on firing cases with lube on them. Hawkins post sounds reasonable but contrary to advice from others.


Read that in Precision Shooting 20years ago for fireforming AI brass.Works quite well.
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#3921235 - 03/22/10 07:29 AM Re: Reloads with backed out primers? [Re: doubletap]
hawkins Offline
Campfire Regular

Registered: 01/22/05
Posts: 1068
Loc: Hawkins, a large metropolitan...
I first read about it in Ackley's books. More recently finite
analysis, an measurements indicate that when the case comes back
it is with full force oiled or not. The difference is that an oiled case comes back earlier and expands forward avoiding the
stress mark. I believe that the old timers used to use oiled
cases as "proof loads" because that was the only way to check
the locking.
Good luck!

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