50 BMG API troubles

[DTrain]

Howdy everyone, I was out testing my API reloads when one of the rounds gave me a surprise. The report was audibly deeper, and immediately after the rifle recoiled I saw a bright white flash. My line of thinking is that the incendiary charge went off in, or shortly after leaving the barrel. However, I checked both the barrel and the brake and saw nothing unusual. The case extracted normally and I saw no signs of excessive pressure so I fired a few more rounds which behaved normally. FWIW, I'm shooting an Ar-50A1, loading it 238.5gr of US 869 behind a pulled and resized M8 projo, seated 0.005" off the lands, with a COL of 5.525".

Has anyone had anything like this happen, or have any ideas what happened?

 

[THEIS]

Hi,

Not a fan of resizing API whatsoever. The internals are already a delicate balance of different components.
For example:

Sincerely,
Theis

 

[DTrain]

Sounds about right and I'm glad I'm not the only one this has happened to. Unfortunately, I have several hundred bullets that may or may not need to be sized. Should I check the diameter and only load the good ones, and then throw out the ones that need sizing? Or is it more like, size the bullets and expect it to happen again?

 

[mcfred]

Has anyone had anything like this happen, or have any ideas what happened?

I had a pulled/sized M8 API go off in the bore once. It was fired in a Lilja barrel at less than 1700fps (wildcat chamber). Recoil was no different, but there was a huge orange flash in the scope field of view, a different kind of muzzle report, and it left a large skidmark in the bore that was quite difficult to scrub out about 23" from the breech. In fact I believe it's still there. I've not looked at it, though I should since I have a decent bore-cam now.

I doubt it's a common occurance, and I wager it's not a good thing to happen.

 

[DTrain]

I had a pulled/sized M8 API go off in the bore once. It was fired in a Lilja barrel at less than 1700fps (wildcat chamber). Recoil was no different, but there was a huge orange flash in the scope field of view, a different kind of muzzle report, and it left a large skidmark in the bore that was quite difficult to scrub out about 23" from the breech. In fact I believe it's still there. I've not looked at it, though I should since I have a decent bore-cam now.

I doubt it's a common occurance, and I wager it's not a good thing to happen.

I have no doubt it's not something one would want to happen. I saw a white flash through my scope and couldn't find anything in my barrel. It was mostly just unsettling on account of it being a new experience for me. I've taken to shaking my bullets and throwing out any of them where I feel a loose penetrator. Hopefully I don't have any more issues.

 

[Oland of Texas]

I've fired API in various calibers/firearms including .50 BMG in my Barrett. Maybe several hundred rounds total between all calibers. Never had anything like that happen and I sure hope I don't.