Fireforming brass what load?

[chuckbuster243]

Hello guys I have a question about fireforming brass. If I am fireforming brass lets say from 7.62x39 commercial to 6.5 Grendel. I have loads developed for already formed same brand brass in 7.62. My question is if lets say I just size the 7.62 to fit into the Grendel and load the load I shoot in the full formed brass and shoot it will the pressure be any different? I just wonder this because the capacity will be the same after forming. The load is just a middle of the road load for a AR much less a bolt action savage. Send me your comments on this subject... Matt

 

[bsekf]

I fireform using the same powder charge, however my loads are below max. Old wildcatter told me that fireform loads usually had lower pressure than the formed case with the same powder charge. Has to do with the case stretch in fireforming.

Do not use a really light load to fireform, you can get some strange presssure spikes using very light loads.

 

[kelbro]

And... you should plan on at least two loads fired through the brass before it is fully fireformed.

 

[Shynloco]

Do not use a really light load to fireform, you can get some strange presssure spikes using very light loads.

AMEN! I've seen an experienced reloader cause a new rifle to explode because he got too cute with a REALLY light load. The casing ended up about half full (or less) causing a pressure pocket inside the casing and the rest was history upon pulling the trigger. He had himself a three piece rifle that thankfully didn't include his face. Use the load you would normally use but stay below max spec.

 

[M-61]

Do not use a really light load to fireform, you can get some strange presssure spikes using very light loads.

AMEN! I've seen an experienced reloader cause a new rifle to explode because he got too cute with a REALLY light load. The casing ended up about half full (or less) causing a pressure pocket inside the casing and the rest was history upon pulling the trigger. He had himself a three piece rifle that thankfully didn't include his face. Use the load you would normally use but stay below max spec.

P.O Ackley years ago had gone to great lengths to find the cause of "DETONATION". He never duplicated it in a lab but the fact was evident in the number of rifles destroyed by this phenomena directly related to 'light' loads and in particular light loads in large capacity cases. It's some fascinating reading as he went to any length to find a cause. I think some loading manuals caution about loading "less than a minimum".
*"HANDBOOK FOR SHOOTERS & RELOADERS" P.O. Ackley 1962 Vols 1&2

 

[Shynloco]

Do not use a really light load to fireform, you can get some strange presssure spikes using very light loads.

AMEN! I've seen an experienced reloader cause a new rifle to explode because he got too cute with a REALLY light load. The casing ended up about half full (or less) causing a pressure pocket inside the casing and the rest was history upon pulling the trigger. He had himself a three piece rifle that thankfully didn't include his face. Use the load you would normally use but stay below max spec.

Just to clarify, the rifle/caliber I made reference to was a Varmint .223 VLP Savage.

 

[Old Navy]

P.O Ackley was working with light charges of slow burners mostly with 4831. This was back in the sixties I believe. Later! Frank

 

[Immike]

One of my buddies was trying to get a light load for his daughter to shoot his new Weatherby and blew that thing all to hell. Thank God she wasn't behind the gun. It blew brass past the bolt and put a ring of cuts on his face but missed his eyes. Made a believer out of me. He needed another new gun and some new underwear!! Don't ever go below the minimum charge or KBOOM. It nearly blew that gun in half.

 

[amlevin]

He needed another new gun and some new underwear!!

Since he wasn't hurt, the worst part was the underwear. The broken gun just goes back in the case but the underwear? Had to wear it all the way back home

For what it's worth, if I want less recoil I would just find a smaller caliber. I leave the light loads for the cheapskates that are looking to save money on powder.

 

[chuckbuster243]

I am not wanting a light load or light recoiling load.. The Grendel Does that anyway. I was just wanting to see what the consensus is on fireforming loads. If you shoot your full house load that you would shoot in full formed brass. Or reduce by a few grains. Yes I am aware of the fact that light loads with slow burning powders is a bomb... I just hear two sides of the story. One being reduce by a few grains and others that say shoot full house (not max) loads. I imprecate the reply's so far and this is some good information we surely need to get out there. Matt

 

[amlevin]

I just hear two sides of the story. One being reduce by a few grains and others that say shoot full house (not max) loads. I imprecate the reply's so far and this is some good information we surely need to get out there. Matt

Other than saving a few pennies, what would be the gain in reducing the load? When I fireform I want to make sure that the case is fully formed into the shoulder and has undergone the initial "stretch". I shoot with very close to my final load, no reduction.