Primers blowing out in 300 Blackout
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Wil Terry
Member
WHY are you using small pistol primers ??
My mistake..... #400 CCI, edited my original post
Yeah, primers totally blown out of brass, made a mess of my bolt, got jammed up a bit after ejection. Primer pocket does not look expanded at all.
gamestalker
member
What your describing sounds like a typical high pressure situation. If it were me, I would pull some and check the charges against a scale one more time. It could be that you forgot to zero the scale, scale might have inadvertently been set to the wrong charge, heavier bullet than intended, or misidentified powder.
GS
GS
W.E.G.
Member
Is the primer "blowing" out or is it just falling out?
When I think of a primer "blowing" out, I'm thinking of the metal being torn, puctured or such.
Primers fall out of cases all the time.
High pressures can expand the primer pocket, or multiple firings just allow it to get loose.
If your brass is bad, it won't help, but I would otherwise not use "standard" small rifle primers in any AR-type rifle. I've used MAGNUM small rifle primers in my AR's for nearly two decades now. I had all sorts of primer-issues before I made the switch. Since then, all of two primers have fallen out of reloaded ammo fired in my AR's. I have no idea where one of the primers went. The other tied up my rifle quite nicely.
When I think of a primer "blowing" out, I'm thinking of the metal being torn, puctured or such.
Primers fall out of cases all the time.
High pressures can expand the primer pocket, or multiple firings just allow it to get loose.
If your brass is bad, it won't help, but I would otherwise not use "standard" small rifle primers in any AR-type rifle. I've used MAGNUM small rifle primers in my AR's for nearly two decades now. I had all sorts of primer-issues before I made the switch. Since then, all of two primers have fallen out of reloaded ammo fired in my AR's. I have no idea where one of the primers went. The other tied up my rifle quite nicely.
Not real sure if they fell out or blew out. What I can say is these are my first 300 Black rounds I've loaded. Obviously something wrong, I only loaded five rounds first, and these were them. I'm gonna go back to the bench and load five or ten more rounds and test them some more. I did go buy a box of commercial 300 black today and shoot them to make sure my gun isn't doing something weird, gun is freshly built too. So I'll see.
KansasPaul
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So you said that the cases are .223 cut downs. Are you certain that the length is correct? Your powder weight is right in the middle of the range so there shouldn't be any problems there, assuming that your weights are correct. I would go back through all of your reloading steps. start with case length, powder weight, COL, etc.
Blessings,
Paul
Blessings,
Paul
Gussers
Member
I'd use the small rifle magnum primers. They have a thicker cup that's less prone to slam fire in guns with a free floating firing pin. I've never had one pop out either... And I've worked up loads well beyond load books' max. Even with mild pressure signs.
Were good military brass that you reamed out the pockets to remove the crimp?
Were good military brass that you reamed out the pockets to remove the crimp?
gamestalker
member
OK, it's beginning to sound as though they fell out, rather than pierced or blown apart due to a high pressure situation. This is a completely different circumstance that encompasses a different realm of possible causes.
Based on the fact that it's a new build, I would first give the new rig a complete going over just to eliminate the firearm as the culprit.
I would then check to see if the pockets are within specification. If you had to prep the pockets, it's entirely possible they might have had too much material removed, thus creating a loose fit.
Also, are you seeing any signs of gas leakage on the bolt face, or on the case head? That would help in your process of elimination.
GS
Based on the fact that it's a new build, I would first give the new rig a complete going over just to eliminate the firearm as the culprit.
I would then check to see if the pockets are within specification. If you had to prep the pockets, it's entirely possible they might have had too much material removed, thus creating a loose fit.
Also, are you seeing any signs of gas leakage on the bolt face, or on the case head? That would help in your process of elimination.
GS
I have some test brass, both RP factory and converted LC, that I have been working up loads in and it must have been fired over a dozen times. The primer pockets started getting too loose to use but never did one "blow out" A couple did fall out, and could be pressed back in easily.
Once fired converted brass should be fine for awhile. 15.5 Grs of W296 should be OK with a 150 Gr bullet, certainly not a starting load, but OK.
Case too long and jammed into throat?
Neck diameter too big?
Bullet set back?
I did a chamber cast of my BLK chamber. Now I know for sure my brass is not too long and my loaded neck diameter is not too big. I double checked because I was loading some .310 bullets, which my gun happened to like a lot.
Once fired converted brass should be fine for awhile. 15.5 Grs of W296 should be OK with a 150 Gr bullet, certainly not a starting load, but OK.
Case too long and jammed into throat?
Neck diameter too big?
Bullet set back?
I did a chamber cast of my BLK chamber. Now I know for sure my brass is not too long and my loaded neck diameter is not too big. I double checked because I was loading some .310 bullets, which my gun happened to like a lot.
Somewhere between load 10 more rounds and I did go buy a box of new commercial ammo the thought should have occurred to compare your reloads with new factory ammo. Measure before and again after, There is more to forming cases than pulling the handle.
It is possible the case is doing a lot of travel in the chamber, I know, the firing pin strikes the primer, then everything takes off to the front of the chamber etc..
A good habit to get into is measure before and again after, then measure again after sizing. Your focus is the primer, the problem could be case travel .
F. Guffey
kimbernut
Member
Primers
Do new primers go in snugly, loosely, or will not stay in?
By chance did you or your source anneal your brass? Over annealed brass will blow out primers and distort the case head if it doesn't blow up on the first firing.
Do new primers go in snugly, loosely, or will not stay in?
By chance did you or your source anneal your brass? Over annealed brass will blow out primers and distort the case head if it doesn't blow up on the first firing.
Rottweiler
Member
How many times were the cases fired BEFORE they were made into .300 BLK?
longdayjake
Member
Grassman,
Were your primer pockets reamed or swaged? I have quite a bit of experience with reloading military surplus stuff and I can say that most people that ream their primer pockets take it too far and end up ruining the casing. Swaging is by far the better way to go if you don't want to decrease the life of the brass. If they are reamed, my guess is that they got reamed too deep and can no longer hold a primer well enough to keep it in the pocket.
Were your primer pockets reamed or swaged? I have quite a bit of experience with reloading military surplus stuff and I can say that most people that ream their primer pockets take it too far and end up ruining the casing. Swaging is by far the better way to go if you don't want to decrease the life of the brass. If they are reamed, my guess is that they got reamed too deep and can no longer hold a primer well enough to keep it in the pocket.
They were reamed, I've loaded thousands of rounds of 223,308 and 22-250 and never had this happen.
bluetopper
Member
Never messed with the 300 Blk, but could you even over charge with 296 if you wanted to?
No, cases are not ejecting fine. But I don't see any expansion on the spent brass.
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