Open ammo troubles

[xjwalt666]

I had a post from last year about this and was able to remedy it but now it's happening again. My normal load is 6.5gr of hs6 with a 124gr rn at 1.165. Gun is a 5" open gun, trubor barrel with no popples, usually run an 9lb recoil spring. I ran out of hs6 so switched over to autocomp and went a little lighter on the charge. Everything is the same except went to 6.0gr of ac. I'm getting primers bulging and shaving off into the firing pin hole and causing light strikes. I know obviously get some hs6 and go back to the old load, but what else could be the cause? I tried going down to an 8lb spring with no difference. I'm not concerned with making major pf since I do mostly steel with it, but had a thought maybe that it's making too much pressure before ejecting since theres more room in the case with less charge and same oal? Is that possible or should I just switch back to hs6 and run it? Any input would be appreciated.

 

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[mro111lland]

Federal primers?

[xjwalt666]

Federal primers?

Winchester small pistol.

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[mro111lland]

If you have an extended firing pin go to Winchester small rifle 

[xjwalt666]

I have an extended firing pin and use winchester small pistol primers. Happens with cci as well.

 

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[xjwalt666]

If you have an extended firing pin go to Winchester small rifle 

I do have a box of small rifle. Maybe I'll give them a go and see if theres a difference.

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[mlmiller1]

Pressure goes down with more space in the case.  Not sure the problem but its not because you have more room...

[xjwalt666]

Pressure goes down with more space in the case.  Not sure the problem but its not because you have more room...

Ok. I wasn't sure if it was because more open space in the case taking longer to propel the bullet if that caused higher pressure. Looks like I'm going back to hs6.

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[Hi-Power Jack]

3 hours ago, xjwalt666 said:

 

  My normal load is 6.5gr of hs6 with a 124gr rn at 1.165.  went to 6.0gr of ac. I'm getting primers bulging and shaving off into the firing pin hole and causing light strikes.

 

I've run loads that light with both HS6 and WAC, with 124 gr JHP's, and never encountered 

primers bulging or shaving.

 

Would you have photos of the "bulging primers" - may not be as bad as you say.

[NoSteel]

Any chance your crimp could be loose and bullet is seeing set back when chambering??  If so that would compress the load and pretty much negate the load change..??

Edited August 13, 2019 by NoSteel

[Hi-Power Jack]

2 minutes ago, NoSteel said:

Any chance your crimp could be loose and bullet is seeing set back 

 

Great thought (set back), but it wouldn't be because of a "loose crimp" -

that would be because the sizing die isn't doing it's job.

 

But, NoSteel is right, if those bullets are setting back, that could cause

a problem.

 

BTW, what velocity are you getting ?

[xjwalt666]

I've run loads that light with both HS6 and WAC, with 124 gr JHP's, and never encountered 
primers bulging or shaving.
 
Would you have photos of the "bulging primers" - may not be as bad as you say.

I do have cases I can take pics of. I will in a little bit. But it's definitely enough to the point upon ejection its shaving off just enough to block the firing pin from making solid contact with the primer. Typically get 2 or 3 rounds off then light strike.

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[xjwalt666]

Any chance your crimp could be loose and bullet is seeing set back when chambering??  If so that would compress the load and pretty much negate the load change..??

Crimp isn't loose. There is no flare left on the case and I fire a round and eject the next one after it chambers and still measures the same.

 
Great thought (set back), but it wouldn't be because of a "loose crimp" -
that would be because the sizing die isn't doing it's job.
 
But, NoSteel is right, if those bullets are setting back, that could cause
a problem.
 
BTW, what velocity are you getting ?

Case od at the crimp is usually .377+/-.0005 or so on average when I do random checks with my mic while loading.

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[xjwalt666]

 
 
BTW, what velocity are you getting ?

Not positive on the velocity of these loads. I haven't had a chance to get the chrono to the range. Just went today to test these loads out for a match this weekend.

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[sauza45]

You need to chrono them to know where you are at.

[xjwalt666]

You need to chrono them to know where you are at.

With the hs6 I was around 1225fps. I did that load when i started using it. But again haven't been able to do the new load.

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[shred]

Check your lugs aren't beat up and causing excessive headspace.  Primers back out of the case a little on ignition, then get smashed back into it as the powder lights.  More room to back out equals more primer that can extrude back into the FP hole when smashing time comes.

 

[xjwalt666]

Check your lugs aren't beat up and causing excessive headspace.  Primers back out of the case a little on ignition, then get smashed back into it as the powder lights.  More room to back out equals more primer that can extrude back into the FP hole when smashing time comes.
 

I'll look into this tonite. I just feel it's odd that it wont do it with the hs6 but does with less autocomp.

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[Aforum55]

I would agree with the case set back. I personally load a 124 with WAC 6.9 grains CCI OAL 1.15. no signs of pressure etc. Just keeps running. I will say if you switch over to SRP with a minor load you can experience breach face erosion around your firing pin hole. I've never experienced that but seen it. The minor load doesn't get enough ignition or pressure to seal primer in pocket.