Bulging Primers

[Patriot]

Do you know what caused this? I think I do. These are three different rounds loaded
exactly the same way with 26.0 gr of Win748, Win SRP, and fired from the same rifle.

Bulged

Bulged

Normal

 

[Mil-Dot]

If over 60gr bullet I would guess excessive pressure.
Mil-Dot

 

[Patriot]

If over 60gr bullet I would guess excessive pressure.
Mil-Dot

55gr Winchester or Hornady FMJBT

 

[Mil-Dot]

Given the shape and amount of bulge I still think it is a pressure issue (not a heavy firing pin). What are your thoughts (or is this a contest)?

 

[Patriot]

Given the shape and amount of bulge I still think it is a pressure issue (not a heavy firing pin). What are your thoughts (or is this a contest)?

Contest, and it is a pressure issue interestingly enough.

 

[EddieCoyle]

The pressure is too low. The minimum charge of W748 for a 55gr bullet is 26.3gr, and that's only good for a measly 39,000 cup. I think the primers are bulgy like that because they weren't smashed back into the bolt hard enough to flatten them, except for the LC case which has a slightly smaller case volume, and therefore higher pressure.

What do I win?

 

[Supermoto]

+1 on low pressure

 

[Patriot]

The pressure is too low. The minimum charge of W748 for a 55gr bullet is 26.3gr, and that's only good for a measly 39,000 cup. I think the primers are bulgy like that because they weren't smashed back into the bolt hard enough to flatten them, except for the LC case which has a slightly smaller case volume, and therefore higher pressure.

What do I win?

Nothing... 26.0 grains is fine for a 55 grain bullet. Accurate as all hell. This was caused by...


































an obstructed flash hole. Obstructed with corn media. I inadvertently loaded up a bag
of processed brass that I had put aside and hadn't inspected which is the last step in
my cleaning, sizing, cleaning, trimming, inspecting, loading steps. This bag got
mixed in with about ten or twelve other bags of inspected, ready to be loaded cases.
When I realized it (about 60 cases) I pulled about 25 and found nothing so I took a
chance. These two were FTF so when I came home I pulled the bullets and looked at the
flash hole and they appear to be obstructed with a piece of very burnt corn media. I
shot around 140 rounds of various reloads that day and these two from that uninspected
bag were the only problems I encountered.

 

[Supermoto]

did you get a full powder burn on those? did the gun cycle?

 

[Patriot]

did you get a full powder burn on those? did the gun cycle?

No, powder did not ignite. Gun did not cycle. Just a click or at least nothing I could hear
through the hearing protection. If it did make a sound it was very slight as I didn't hear it.

 

[EddieCoyle]

I size my rifle cases on a single stage, and then put a universal decapping die in station 1 to poke out any stray media when they gop on the progressive.

I've never had corncob cause a FTF. It will eventually clog the gas system on the rifle though. You might want to run a long pipe cleaner though there.

 

[Patriot]

I size my rifle cases on a single stage, and then put a universal decapping die in station 1 to poke out any stray media when they gop on the progressive.

I've never had corncob cause a FTF. It will eventually clog the gas system on the rifle though. You might want to run a long pipe cleaner though there.

Yeah, after this I think I am going to do what you do. I size on one setup on the Dillon
and the first station on the loading setup is free so I think I am going to do as you do
and try to avoid another oops altogether in the future. Are you using the RCBS die?

 

[6hold]

Do you know what caused this? I think I do. These are three different rounds loaded
exactly the same way with 26.0 gr of Win748, Win SRP, and fired from the same rifle.

Excellent thread Patriot and great photos too. ​

 

[EddieCoyle]

Are you using the RCBS die?

I use RCBS small base dies to resize, but I use a Lee Universal decapper to "clean" (it's the only Lee die I have left).

 

[Gammon]

I size my rifle cases on a single stage, and then put a universal decapping die in station 1 to poke out any stray media when they gop on the progressive.

I've never had corncob cause a FTF. It will eventually clog the gas system on the rifle though. You might want to run a long pipe cleaner though there.

I use the same system on my 550 to get rid of the odd bit of tumbling media. I never hat a failure to ignite due to these bits of media but they did manage to jam up the trigger in my AR. These corn cob grits were travelling down the barrel, into the gas tube, then into the bolt, and then lodging in the trigger mechanism!

 

[EddieCoyle]

I use the same system on my 550 to get rid of the odd bit of tumbling media.

I think I got the idea from you.

 

[Timberwolf]

According to Winchester's 14th edition freebee, 26.2 is max, as well as the 1999 and the current Hodgdon.

Lyman list at 27.8.

I think that you may have bumped the shoulder down a bit too far, thus increasing the pressure, and creating a false headspace problem.

 

[Patriot]

I think that you may have bumped the shoulder down a bit too far, thus increasing the pressure, and creating a false headspace problem.

Nope, in fact the shoulder is a little higher than I would like due to my sizing die issues.
(Die has been returned to Dillon for rework or replacement as we speak.)

 

[BIG GUN]

No, powder did not ignite. Gun did not cycle. Just a click or at least nothing I could hear
through the hearing protection. If it did make a sound it was very slight as I didn't hear it.

I always polish my brass prior to resizing thus eliminating any chance of flash hole blockage. Then I uniform the primer pockets prior to primer seating.
Maybe slow, but positive.

 

[Patriot]

I always polish my brass prior to resizing thus eliminating any chance of flash hole blockage. Then I uniform the primer pockets prior to primer seating.
Maybe slow, but positive.

I do too BG, but then do it again after I size and de-prime to clean the lube off the brass.
That is when I get the media in the primer hole.