Bulged 209 Primers

[ElDiablo]

First time I’ve seen this. I’m using a .035” thick o-ring in an OEM TC Omega plug which causes the 209 to sit fairly proud of the plug.
Using Fed 209As.
Plug was clean to start (reamed).
Headspace did not seem overly tight. Crush with o-ring measured at about .003-.004”.
Flash hole measured at .029”.
Temps were warm - about 80 degrees.
One 209 to foul then two shots.
First shot 400 gr bullet with 110 grV BH209. Second shot 260 gr bullet with 120 grV BH209.

Two shots yesterday showed that the primers bulged on the unsupported sides. The lower half of the sides are clean so no leakage past the o-ring, but there is slight cratering on the firing pin impression, some flattening and some carbon on the primer face indicating leakage around the primer cup.

Thoughts on what is going on here guys?

 

[michiganmuzzy]

That seems like a lot of bh209 for a 400gr, on a hot day.
Hot being relative

 

[MrTom]

I'm with MM on this. Maybe try a lighter charge of the 209 and see then what they come out looking like..

 

[ElDiablo]

I agree on the big bullet but 120 gr with a 260 gr bullet? That’s a load I often shoot all summer here. Doesn’t seem super high pressure to me.

 

[rangerod]

It seems odd that it would happen with a 260grn bullet. I've been using the Federal's for a long time and never seen that.

 

[michiganmuzzy]

Do you have any other brand primers you can try?

 

[ElDiablo]

Yeah I’ve got Winchester, CCI, Remingtons, Cheddites, Fiocchis and a few others. Maybe try some CCIs?

 

[michiganmuzzy]

Try those Rems too.

 

[billyboy*]

I’m using a .035” thick o-ring in an OEM TC Omega plug which causes the 209 to sit fairly proud of the plug.
Using Fed 209As.
Two shots yesterday showed that the primers bulged on the unsupported sides.
Thoughts on what is going on here guys?

View attachment 34756
View attachment 34755

You may have Answered your own question. Too much of the Primer is Unsupported in the OEM Plug with the .035" Thick O-Ring. Fairly certain Ron Laughlin advises against this & why Jeff Fisk uses a Deeper Primer Socket in his Custom Breech Plug.
Another thought is your Action has Loosened a bit & needs adjusted. I had to Tighten one of mine recently.

 

[ElDiablo]

Going to shoot it next time without the o-ring to see what happens.

 

[MrTom]

I agree on the big bullet but 120 gr with a 260 gr bullet?

Sorry bud....that went right past me. Maybe you got into a bad batch of primers. The black on the cup end is troublesome. Almost appears to be a pressure issue. IUf you're measuring your powder by volume, are you certain the measure didn't slip on you and you're getting a heavier charge than you think you might be tossing?

 

[michiganmuzzy]

Agreement with MrTom, try doing some weighed loads. After you try some different primers, you could try walking back the powder volume to see when it stops bulging and leaking.

 

[ElDiablo]

Yeah, I’m certain the volume is correct. The only other variable is that this is a bottle of mixed lot BH209. I suppose that could be increasing the pressure. Still, I can’t imaging that being a big issue with those little bullets.

 

[michiganmuzzy]

Looks like fully half of the primer is outside the pocket. Even if you could reduce head space a lot you would still get leaking past the cup.

 

[billyboy*]

Going to shoot it next time without the o-ring to see what happens.

You may want to find some that measure .300” + length to get your desired compression / crush fit.

 

[Travis299]

Fired & unfired primer in CVA Accura V2 using Barnes 250 gr T-EZ with 2 pellets of T7. BP has the O-Ring to prevent blowback. FWIW I have never seen any primers deformed in my rifle. I don't understand how the powder charge & bullet weight could cause this problem with the primer. What am I missing & thanks?

 

[scratcherky]

Check your breech plug for orifice erosion.

 

[ElDiablo]

I don't understand how the powder charge & bullet weight could cause this problem with the primer. What am I missing & thanks?

Combination of pressure and the unsupported portion of the primer is the theory.

 

[ElDiablo]

Check your breech plug for orifice erosion.

I did. Slight erosion - Flash hole measured at .029”.

 

[michiganmuzzy]

I was sure that you were going to have a huge flash hole too. Im really surprised that its only .029”.
Did these bulging primers just recently start? Start around the same time you started using those o-rings? Or has this been happening a while?