how short is too short...

[20PPC]

On my grandsons 30 PPC I am using Lapua 220 Russian brass the chamber length is 1.520 .
With the 220 brass once its necked up to 30 the brass shortens to 1.455 - 1.478 and I've tried to get as many as I can trimmed to 1.465 for an average.
My question is how short is too short, I know I've lost some case capacity and ill have to stay on top of keeping the barrel clean to avoid the carbon ring but do you lose any accuracy by having a shorter ocl than if it was within .010 of the chamber length.
Getting ready to neck up some Grendel brass to see if it might work better or if it's going to be additional work for no gains.

 

[Dusty Stevens]

No problem as long as you know. Id fireform them before trimming as long as theyre not too long to start with

 

[jackieschmidt]

I started out with a 30 PPC before I went to the 30BR. My reamer had a OAL of 1.510.

One problem with necking up cases that much Is the shoulder keeps getting pushed back. I solved that problem by first fireforming a 220 Russian to make it a 6PPC, then I fired a loaded 6PPC in a 30BR chamber to blow the neck out to full 30 caliber.

Pretty drawn out, but by blowing the cases out rather than mechanically necking them up, much of the length is retained.

That being said, I really do not know how much the shorter OAL of your cases will affect accuracy. The 30PPC with top quality match bullets, such as a BIB 112, is brutally accurate.

 

[Sniper338]

I started out with a 30 PPC before I went to the 30BR. My reamer had a OAL of 1.510.

One problem with necking up cases that much Is the shoulder keeps getting pushed back. I solved that problem by first fireforming a 220 Russian to make it a 6PPC, then I fired a loaded 6PPC in a 30BR chamber to blow the neck out to full 30 caliber.

Pretty drawn out, but by blowing the cases out rather than mechanically necking them up, much of the length is retained.

That being said, I really do not know how much the shorter OAL of your cases will affect accuracy. The 30PPC with top quality match bullets, such as a BIB 112, is brutally accurate.

I fired a loaded 6PPC in a 30BR chamber to blow the neck out to full 30 caliber

A 30BR chamber?

 

[SmokinJoe]

The best FF regimen I ever used in the 30BR was to take a junk barrel and rechamber it with a special long necked reamer, then load up the cases with Bullseye and seat a plastic ball in them. After firing them they are nice and straight and much longer than when enlarged with a mandrel (1.555 vs 1.518). If you can work something out similar to this you can make brass that will closely fit your chamber. ABSOLUTELY don't use anything but a plastic ball or spitwad sort of plug, NO BULLETS with this fast burning powder. After FF run your neck turning expander in and turn as you normally do.

 

[Ccrider]

I had the same question but did not post it. Hydroformed Dasher brass comes out around 1.531 and fireformed comes out around 1.550.
Evidently the extra length is coming from the wall of the case. Prior threads say the difference in length does not matter. I decided to trim to the shortest length and go from there.

 

[20PPC]

last night I took some 6.5 Grendel brass and ran it through my Harrels fl bushing die pushing the shoulder back where it measured the same as the ff 220 brass, I then necked up to 30 cal. and and measured oa length and it was 1.5005.
I neck turned it and the bolt closes with slight resistance, it appears the Grendel brass is the way to go.

 

[jackieschmidt]

I fired a loaded 6PPC in a 30BR chamber to blow the neck out to full 30 caliber

A 30BR chamber?

Sorry, I meant 30PPC chamber.

 

[Sniper338]

Sorry, I meant 30PPC chamber.

I was just reading to learn, it just didnt making since to me so I questioned that. Thanks.

 

[dgeesaman]

I had the same question but did not post it. Hydroformed Dasher brass comes out around 1.531 and fireformed comes out around 1.550.
Evidently the extra length is coming from the wall of the case. Prior threads say the difference in length does not matter. I decided to trim to the shortest length and go from there.

I didn’t realize the fireforming method had so much effect on brass length.

Now I understand how some people have made Lapua 6PPC brass that’s over 1.500 long. With my fireforming method I would consistently get 1.485 and no more.

 

[antelopedundee]

No problem as long as you know. Id fireform them before trimming as long as theyre not too long to start with

I was just looking up some data for the 6.5-06 on the Hodgdon site and they trimmed their cases/s to 2.484 or .01 shorter than nominal for an .06 case. Why would they do that?