Leaking Primer Pockets? Bad Brass? Bad Primers?

[Bulldog Firearms]

Shot a match this morning. Hot day, 104F according to Kestrel in shade. Barrel now has about 200 rounds on it and first stage I was consistently high. Wasn't a member of the club so I couldn't check velocity prior to match, I had some suspicion that barrel may have sped up since my last chrono session. Shot two matches back to back, both of them 60 rounds, so before that I had approximately 80 rounds on barrel at last chrono session. In a 60 round match there was 14 that I noticed with leakage.

MPA Curtis Custom Axiom "24 unsuppressed.
6mm Creedmoor
Virgin Hornady Brass - not prepped beyond inspecting for bur and chambering inside case mouth.
115 DTAC (uncoated)
FGMM 210 Primers - lot has not exhibited any errant behavior in other guns.
40.6 RL16 thrown on a FX-120i.
2.805 OAL - .02 Off Lands
2.45 BTO (Hornady Comparator)
Sub half moa accuracy and sub 10 fps SD and sub 20 ES.
3001 FPS average (upped it 3050 at second stage to get dope to line up).

No signs of overpressure during either match. No sticky bolt or extraction. Though some show a slight ejector swipe whereas none did at 77F when I did load development.

10 pieces pulled from match on bottom that are unaffected. Top 14 show primer leakage.


A close up of most egregious ones.

What's going on here? Someone out there mentioned that he thought perhaps load was too hot and that was why there was leakage. I doubt that because I've never seen a primer leak until now. I've had blown primers before and pierced, but never leaking.

 

[Bradu]

Those primers look pretty flat but I am on my phone and can't see the pics all that well. I would see about loading 5 pieces of brass to see how long the primer pockets would last with that load. I think you are going to have to back it down some.

I had issues with Winchester primers flattening out just like that and the were pin holes in the edge of the cup with the minimum book load. I found out it was a common problem with Winchester primers and switched to CCI and never had another problem. The primers didn't flatten out any either. It may be worth trying another primer to see if it goes away. I just reread your post though and seen it's not an issue in other guns. Mine did it in multiple rifles so it may just be too hot.

 

[260shooter]

Those primers are flattened, and leaking because the loads are now way overpressure . You are right at the point of blowing primers. I would back down 1-1.5 grs and ladder back up in .2 gr increments. Between your barrel speeding up from break in and increased temps the load has obviously speed up and now is over pressure. If you have a bunch of this ammo loaded, wait till a cold winter day to shoot it.

 

[918v]

I vote you’re too close to the lands with that combo. Anytime you have a heavy for caliber bullet with a too fast a powder and you’re close to the lands you run the risk of this.

 

[supercorndogs]

Ejector marks are a big pressure warning. So are primers falling out of brass and leaking. I wouldn't be surprised if the above comment is spot on, seeing as how some show bad pressure signs and some don't.

 

[BigTex]

That's overpressure.

 

[47guy]

I vote you’re too close to the lands with that combo. Anytime you have a heavy for caliber bullet with a too fast a powder and you’re close to the lands you run the risk of this.

this right here^^^

and to add to this....the barrel speeding up is typical...in the 5 6CM barrels i shot i usually found a load at 41.9-42.1g of H4350 somewhere between 100 and 200 rounds id back the charge down .4g to stay in my node then around 700 rounds id up the charge .2g then toward the end another .2g.

the issues your having now are another reason i dont like bullets close to the lands..i always start .020 off and rarely adjust seating.

id suggest either backing off .4g or seating the bullets at .020 off the lands...thats all i shot in my 6CM and 115s are not seating sensitive

 

[Gunfighter14e2]

If your stick won't shoot a good group w/o pressure when hot, your load pressure cold, is too high. A 25-35 fps difference is not going to make any difference at all, except on a ballistic scale.

 

[Bradu]

this right here^^^

and to add to this....the barrel speeding up is typical...in the 5 6CM barrels i shot i usually found a load at 41.9-42.1g of H4350 somewhere between 100 and 200 rounds id back the charge down .4g to stay in my node then around 700 rounds id up the charge .2g then toward the end another .2g.

the issues your having now are another reason i dont like bullets close to the lands..i always start .020 off and rarely adjust seating.

id suggest either backing off .4g or seating the bullets at .020 off the lands...thats all i shot in my 6CM and 115s are not seating sensitive

It says he's .020 off the lands which is what you are recommending

 

[djarecke]

A 24" 6mm Creedmoor shooting 115's at 3000 to 3050 FPS is extremely hot. Unless that's a crazy fast barrel, that seems outside of what I would expect to get for velocity.

 

[260284]

You also need to watch for a carbon ring with Re16. I would say you need to back your load off though. I have had some carbon issues with Re16 in my 6.5 Creedmoor.

 

[RTH1800]

I agree with above, EXCEPT, you are having two issues.
One is the over pressure events.
Secondarily, you are have seeing the barrel speed up due to round count. That portion is not related to the over pressure event.

Good luck and back those loads off.

 

[Bulldog Firearms]

Went out and shot this morning with a different lot of brass. 84F, 3017FPS SD 4, ES 9 over 9 rounds. No swipe, no leakage. Wished I had more time to let it get hot but such is life. Still flattened primers.

I'm still going to run some brake cleaner down barrel and see if I can shoot old batch, I'm having some erratic stuff happen with a 6.5-284 and RL16. I think there is definitely carbon ring issues there.

You guys think that 3K is super fast with DTACs in 6CM? Also that RL16 is a too fast powder?

I am .020 off lands. .020 is the same as .02.

 

[natdscott]

Shot a match this morning. Hot day, 104F according to Kestrel in shade.

No signs of overpressure during either match. No sticky bolt or extraction. Though some show a slight ejector swipe whereas none did at 77F when I did load development.




A close up of most egregious ones.

What's going on here?

How much sign of overpressure do you need? Case heads and primers like that are akin to getting belted in the head with an 8 lb sledge. I think you need to reevaluate how you view "signs of overpressure in a match" because bolt behavior is FAR from the only indicator. Get in the habit of looking at other factors...like pikcing up cases and looking at the bottoms before continuing to fire the rest of the match.

There is some variance between rifles, but you should NOT have that much cratering, and those primers are WAYYYYY too flat, so if you see that kind of thing in the middle of the match...

...there is NO shame in changing your strategy based on new information. Stop firing and go home to adjust loads.

I'd be kinda surprised if you didn't blow a few of those pockets, with that much leakage. Punch out a few and see.

 

[natdscott]

... Wished I had more time to let it get hot but such is life. Still flattened primers.


You guys think that 3K is super fast with DTACs in 6CM? Also that RL16 is a too fast powder?

I'm sorry, but you sound damned flippant in that first sentence. The second sentence, and some others, seem to indicate that the logical part of your brain thinks you MAY have a serious problem, but the words coming out seem to indicate you aren't allowing yourself to be too concerned.

Trouble with doing the same bad things over and over is that sooner or later, Murphy will catch up with you.

About the speeds and powder: It doesn't MATTER what we THINK, and it doesn't MATTER what YOU THINK.

What matters is that that rifle is SCREAMING at you (along with some of us) to tilt the powder jug LESS.

Do that.

-Nate

 

[Milo 2.5]

Went out and shot this morning with a different lot of brass. 84F, 3017FPS SD 4, ES 9 over 9 rounds. No swipe, no leakage. Wished I had more time to let it get hot but such is life. Still flattened primers.

I'm still going to run some brake cleaner down barrel and see if I can shoot old batch, I'm having some erratic stuff happen with a 6.5-284 and RL16. I think there is definitely carbon ring issues there.

You guys think that 3K is super fast with DTACs in 6CM? Also that RL16 is a too fast powder?

I am .020 off lands. .020 is the same as .02.

First off, 3K probably is not too fast in a 6 creed, I know a guy running them up to 3200fps with RL26 and Lapua brass. A different brand of brass, say small prime stuff may not exhibit anything you are seeing. RL 16 would not be my choice with a dtac, diff powders build pressures in different fashions, and I'm sure your load is peaking early. When I say early, were talking milliseconds, like 0.38 - 0.40 ms, blah blah.
I can say from running RL16 in my rifles and friends, your cleaning regimen may change, I've yet to see a rifle using it that does not build carbon in the first 4-5 inches of the barrel, and it is tough to get out if burned in. BR shooters do not have issues because they clean hard every 75rds, going 250-300 rds w/o cleaning will bring issues.
As for flat primers, not a true indication of pressure, especially with new brass, most new brass grows .004-.006 on the first firing, meaning the brass is slammed into bolt face, couple this with the fact than when you fire the gun, not only is energy spent to get your bullet moving, I'm sure it's trying to push your primer out too< give you flat primers. Unless there is something wrong around your ejector hole, if you are getting marks, you're into over pressures, simple.
You say you tried a different lot of brass with no issues, it very well could have been weak brass that caused your issues, hornady has their share of complaints. But I wouldn't bank on it here, I'd revisit what you are doing, it may be a component change needed, or a drop in charge weight.

 

[Milo 2.5]

Went out and shot this morning with a different lot of brass. 84F, 3017FPS SD 4, ES 9 over 9 rounds. No swipe, no leakage. Wished I had more time to let it get hot but such is life.

Here's the deal, we can all give advice and preach, but you need to duplicate your conditions in that match and come to your own conclusions. RL16 is supposed to be one of the best in stability, but if you bake your ammo, or loaded rds in a black mag in the sun you've changed the game.
You say 14 cases with leakage, did the 14 come on one stage, or were they rds 8,9, and 10 off 4 different stages? Hot ambient temp ammo in a hot chamber ups pressure. Couple this with drag created in the first part of your barrel(carbon buildup if present) Bam. Start eliminating things one at a time.

 

[260284]

I use Re16 in my 6.5 Creedmoor and for me it is more stable than H4350, but you will need to clean your barrel more often than with H4350. No matter what, your load is TOO HOT. Back it off, find another node, and go with it.

 

[47guy]

It says he's .020 off the lands which is what you are recommending

you are correct i miss read .002

 

[47guy]

I use Re16 in my 6.5 Creedmoor and for me it is more stable than H4350, but you will need to clean your barrel more often than with H4350. No matter what, your load is TOO HOT. Back it off, find another node, and go with it.

How do you know it’s more stable?
Have you actually done any testing with RL16 and 4350?

 

[spife7980]

How do you know it’s more stable?
Have you actually done any testing with RL16 and 4350?

In a 6mm but it echoes other tests that I’ve seen in rl16

 

[47guy]

I’ve heard the same thing but have never seen any actual testing...from the chart you posted it does look quite a bit more stable than 4350.

 

[918v]

you are correct i miss read .002

.020” may still be too close. Back it off to .040” to 050” it might shoot better.

.020” is not a magical number. It won’t make your gun shoot tight groups. Jump is just one variable in the equation.

 

[pitdog85]

i cant see the photos the Op posted they don't show up for some reason but how do you know your primers are leaking? Some of mine go in VERY loosely however I haven't observed any leaking that I know of?

 

[spife7980]

i cant see the photos the Op posted they don't show up for some reason but how do you know your primers are leaking? Some of mine go in VERY loosely however I haven't observed any leaking that I know of?

The are really sooty and show that something burning is leaking out of them onto the headstamp

 

[natdscott]

i cant see the photos the Op posted they don't show up for some reason but how do you know your primers are leaking? Some of mine go in VERY loosely however I haven't observed any leaking that I know of?

As stated, if there's carbon all over the case head, you have a problem. Bolts of used rifles show the abuse as a ring of gas-cut pitting around the firing pin hole at the same diameter as a large/small primer pocket. Kinda hard to miss, and impossible to deny...

It's also impossible to solve without a lathe and a fair amount of skill.

For everybody's reference, Gre-Tan is pretty good at fixing bolts.

-Nate

 

[RTH1800]

And anything else.?

 

[Bulldog Firearms]

Stuff is over-pressure, wish I could shoot the 110 SMK in this rifle. But OAL is like 2.92 at .02 off and would have to get different mags and inlet feed ramp accommodate the longer OAL.

Messed with the brass last night and some primer pockets are wrecked, still holds them, but just barely. First time using Hornady brass, didn't expect to see this with what I felt was a more 'modest' load. I suspect some of this comes from longer strings of fire in quite hot environments. My MPA rifle has a thermometer that MPA put on the chamber area and it was continually reading 140-150F immediately after each stage.

My version of quickload doesn't have a 6mm creedmoor in the cartridge database, wish I could get an estimation of the pressure to get an idea of how crap the brass is vs how nuts the load is.

 

[Bulldog Firearms]

Had a few rounds left over of factory Hornady 108 ELD-M, shot them, had pressure issues with those, definitely a carbon ring developed since I shot the same lot with 0 pressure signs prior. Last round I shot, was sticky bolt lift, combined with a blown primer pocket. Going to buy a bore scope and see how bad it is.