Fire Forming Brass

[redwingshooter]

Had a question about fire forming brass. Is this a process only reserved for bolt guns or will it work for a semi-auto (ar-15)? I was just curious as my die set came with a neck sizing die and to this point I have not used it. Thanks for the help!

 

[AllenM]

I full length resize on my semi's. May be just me but
I want the brass to cycle without being to tight in the chamber.

On my bolt guns I set the dies to bump the shoulder back 2 thousandths. I have neck sizing dies but prefer to bump the shoulder back some instead.
You have to be careful when measureing your brass after firing from a semi because it may not expand and give you an accurate idea of chamber demention because it starts extracting before expansion is complete.
If you shut the gas system off more than likely you will get a different measurement then with the gas system on.

 

[redwingshooter]

That's pretty much what I thought but wanted to get advice. Thanks, I'll keep full lenght resizing then!

 

[Boomstick]

I also full length re-size. doenst take that long and keeps the shooting going smoothly

 

[sloughfoot]

I have gotten away with neck sizing for a AR15 but I only tried it for slow fire at 600 yards. There was no improvement in accuracy.

I only tried it once, for 22 shots.

What really convinced me I was wrong in doing this, was when a cease fire was called, because of boats in the impact area at Camp Perry. I had to pound the buttstock on the ground to get the unfired round out. There were lots of unfriendly faces all around me wearing orange vests, black and white striped shirts, and a Marine Armorer was also on the way.

I don't need that kind of attention. Plus, it WAS dangerous to the folks around me.

Full length resizing is the only way to go for the AR15. No need to resize too much for ammo to be fired in the same gun though....

 

[Hazwhopper]

Form firing is great way to get the length and to get rid of small dents.