Loose primer pocket in 280AI

[TrapperBR549]

I recently had a rifle rebarreled to 280AI. I had a difficult time finding brass but I did find 2 boxes of Factory Nosler loaded ammo. I shot a box of them, uniformed the primer pockets with the Sinclair tool and deburred the flash holes.
I loaded them with IMR-4831, CCI mag primers and 175grn ABLR's, working my way up from minimum to max load according to Nosler's loading data. I saw no signs of pressure so I eased up .5 grains at a time. I never had a flattened primer, hard bolt lift, or ejector marks on the brass.
I decapped, uniformed, sized a second time and went to prime them and 4 of the first 9 I primed had very loose primers, a couple not even staying in the case.
So I am scratching my head trying to figure it out.
Is it simply a matter of too hot of a load? While I exceeded the maximum listed powder charge my velocity was not higher than listed (my barrel is 24" vs 26" for the Nosler data) and as I said, no other signs of pressure were observed.
Would using magnum primers have anything to do with it?
Anything to do with uniforming them? I have done this with my 300 win mag everytime and haven't had any issues after 3 loadings now.
Any other thoughts or words of wisdom?
Thanks,
Todd

 

[NZ_Fclass]

Anecdotally, the "original" Nosler brass was made by Norma. I had a couple of boxes and loaded with RL22. Chronyed at 2980fps with a 150g Swift Scirrocco. Crazy, but a great hunting load from a 22in barrel. Never had a loose primer and loaded the ammo several times ("several is an ISO expression for "didn't make a note of it"). I also fire formed some from used Winchester .280, which started to show signs of separation after the first reload.
I doubt that the Nosler brass is still made at Norma. It is usually brass quality that governs the extent of loose primers. One could say "shoot a lighter load" etc, but that is not why you shoot a 280AI ! I suggest that you try fire forming from a variety of cases and also try some loads with H1000 or IMR7828.

 

[358WCF]

I dunno about wisdom, but here are some thoughts.

Barrel length matters re: velocity, it seems more evident the smaller the bore diameter. Velocity=pressure.

It would take a real serious effort to screw up the primer pockets with a preset uniforming tool.

Magnum primers provide a hotter/longer duration spark than standard primers, not necessarily more pressure. Mostly powder type/charge, but the combination of everything controls pressure.

If the primer pockets became loose after your reloads I would say the loads were excessive for that particular combination of components. Maybe not over pressure, & if not, the brass would still seem to be the limiting factor in your case.

I've read that commonly used pressure "signs" dont usually appear until you're well beyond SAAMI max. like somewhere up around 70-75Kpsi. With no pressure measuring equipment other than a .0001" micrometer, I use case life as a control for my tendency to hot rod things. If the brass is still usable (snug pockets) after 5 firings of a chosen load, it's considered a safe load as long as I dont change any of the components in any way... including lot #s.

I've used certain lot #s of IMR4831 that were faster than certain lot #s of IMR4350. Keeping that in mind, loading manuals are guides rather than exact recipes. Your stuff, my stuff, & their stuff will not necessarily be the same & it matters sometimes.

As a further example... I changed brass brands, all else exactly the same as in a good below max previous load. After backing off the (weighed) powder charge by 5% & loading a series of five 4-shot groups working upward 1/2 gr at a time, I lost a primer with a locked bolt on the 2nd shot of the lowest charge. The 1st shot appeared normal with "maybe" a little more feel to the bolt lift, but had notably higher velocity. I should have been more cynical than excited at the speed achieved. Glad to be wearing glasses that day as my cheek & forehead felt some hot particles escaping rearward.

 

[TrapperBR549]

I found a few boxes of older Remington 280 unprimed brass that I formed with the Red Dot, cornmeal method. It worked very well. I loaded those once and fired them after forming, prepped, sized and primed them again with all the pockets holding up. I worked my way up and some had above published powder charges but no typical signs of pressure. I was using H1000 with those and cci mag primers.
The reason I wanted to try the 4831 is I was getting some crunch when seating bullets over the H1000.
I do have some 7828 so I might give that a go.
I guess my next step is to see if the Remington brass holds up better.
This is my wife's elk/mulie rifle so I want them fairly hot, fairly accurate, and very reliable.

 

[ParallaxFree]

Signs of high pressure may not have been obvious, but that's the reason your primer pockets have expanded, period.

Many times we push velocities in wildcats because improved performance is the object to begin with. In my 280 AI and 6mm-22 I've discovered the brass has a great deal to do with how hard they can be pushed. In 22-6mm I can obtain almost 100 fps more with 257 Roberts +P brass before expanding primer pockets prematurely. Experiment with different brass for your 280 AI and you'll come to the same conclusion.

Also, as another poster mentioned, I don't waste bullets or cause meaningless barrel wear either to fireform 280 AI brass, preferring 700x and Cream of Wheat.

 

[garandman]

I would think exceeding your max charge is unrelated to exceeding your max velocity, as exceeding max charge can still exceed max PSI at the action / chamber / throat even if you are under max velocity at the muzzle (due to shorter bbl) Powder burn rates seem to be the key here, and mag primers can exacerbate that. DIsclaimer: I'm not a physicist / engineer / ballistician, and the thoughts here are potentially worth roughtly whatcha paid for them,

Danger, Will Robinson. I never exceed max charge by more that 0.1 - 0.2 gr. No probs thus far.

 

[TrapperBR549]

Signs of high pressure may not have been obvious, but that's the reason your primer pockets have expanded, period.

Many times we push velocities in wildcats because improved performance is the object to begin with. In my 280 AI and 6mm-22 I've discovered the brass has a great deal to do with how hard they can be pushed. In 22-6mm I can obtain almost 100 fps more with 257 Roberts +P brass before expanding primer pockets prematurely. Experiment with different brass for your 280 AI and you'll come to the same conclusion.

Also, as another poster mentioned, I don't waste bullets or cause meaningless barrel wear either to fireform 280 AI brass, preferring 700x and Cream of Wheat.

Thanks for the input. I couldn't find brass so when I found a couple boxes of factory ammo I bought them and these are the primer pockets that are failing.
The Remington brass that I fireformed I used red dot and cornmeal with a little poly stuffed in the end, worked perfect.

 

[edwardware]

Before declaring them loose, try a different brand of primer. I have a batch of .375H&H that you can primer with your finger with mid '80s CCI, but is perfectly snug with mid-90s WLR.

The interference in interference fit varies between brand and decade.