Fire forming brass questions need help please!

[p5200]

I have loaded some Winchester cases for 204 Ruger ammo and when I went to measure the brass, there was a lot of difference in the measurements? The rifle is a CZ 527 Varmint in kevlar .204. Is there a preferred method to fire form brass other than just load the new brass fire, and measure? I wanted to try just neck sizing the fire formed brass but am concerned with the differences in measurement of the fired brass. I'm using one of these gauges except, mine is for .204 caliber. Thanks for all help! http://www.midsouthshooterssupply.com/item.asp?sku=0004488304

 

[243winxb]

Bolt action? If so, keep loading & shooting while neck sizing till the bolt is hard to close. Now take a measurement. This will be the correct head to datum line meaurement. Light starting loads may not fully expand the brass to fit the chamber. As the body behind the shoulder expands outward to the chamber wall, the shoulder can be pulled back on firing. When you zero the gauge, readings you get may not match what SAAMI has listed. http://www.saami.org/specifications_and_information/index.cfm?page=CC Here is the 204> http://www.saami.org/PubResources/CC_Drawings/Rifle/204%20Ruger.pdf

 

[gamestalker]

I fire form with a good load of slow burning powder and then measure and trim to spec. and go again. I neck size after the initial reloading and when the bolt gets stiff when closing, I bump the shoulder back enough to allow for smooth chambering, and no more than that. But as already mentioned, fire forming brass needs to be done with a full pressure load to completely form to the chamber.

 

[p5200]

Yes, it is a bolt action I usually start low with my loads being pretty new to hand loading so, my loads may be a little light even though they group good. I noticed a little black soot trying to come down the sides of the empty cases and if I remember correctly, that is one of the signs of under pressure loads? I will try increasing by about .2 of a grain at a time and see what that does. Also, I measured some of the new unused brass and there was quite a bit of variance there also. Thanks very much for the suggestions I'll give them a try.

 

[243winxb]

I noticed a little black soot trying to come down the sides of the empty cases and if I remember correctly, that is one of the signs of under pressure loads?

Yes it could be. A dirty neck is ok, but anything getting into the shoulder/body area is low pressure or large chamber. Powders with the slowest burning rates would be more likely to do it. Neck sizing only should fix this after a few loadings. Low pressure/slow powders will not expand the neck, try putting a bullet into the fired brass. If the bullet is tight=low pressure. If bullet drops into the case, pressure OK, the neck has expanded on firing.

 

[Walkalong]

If you are not fire forming with near full pressure loads, you will need to fire the brass again with a full/near full load to fully form it to the new chamber.

 

[Snowbandit]

P.O. Ackley was probably the king of wildcatting in his day and recommends a good stout load for fireforming cases. If you happen across his book, "Handbook for Shooters and Reloaders", it's a wonderful reference. I use mine often.

 

[p5200]

Thanks for the links and all the great info folks!