Converting 7.62 brass to .243

[J_McLeod]

I tried to convert a LC .308 case to .243 today but once it was resized the case measure 2.025. Looking at the Lyman manual, the trim to length to is 2.035 and my case is too short. I found a link to the SAAMI specs on a similar thread and the drawing there for .243 goes all the way down to 2.020. Is this ok to load and shoot? Will the case grow a lot when I shoot it?

http://www.saami.org/PubResources/CC_Drawings/Rifle/243 Winchester.pdf

 

[jwrowland77]

The case will grow as you shoot and resize the cases.

I'd be more worried about if the necks were too thick causing the bullet to pinch in the neck.

 

[Jeremy2171]

The case will grow as you shoot and resize the cases.

I'd be more worried about if the necks were two thick causing the bullet to pinch in the neck.

Exactly...

 

[BrianC636]

I finally shipped your .243 brass today. I'm sorry for the delay. If you can stand to wait another couple of days, you should have it by the weekend

 

[243winxb]

Ok to shoot. You will get a little more throat erosion than normal. A donut may form at the neck/shoulder junction. Some FL dies may not push the shoulder back far enough to chamber freely. Check loaded rounds neck diameter. Not worth doing IMO.

 

[rcmodel]

I'd be more worried about if the necks were two thick causing the bullet to pinch in the neck.

This!

I would be very surprised if the necks don't need turning or reaming to prevent bullet pinch in the chamber when the case expands to release it.

And can't because the necks are too thick.

That can run pressure through the roof real fast.

rc

 

[J_McLeod]

Ok to shoot. You will get a little more throat erosion than normal. A donut may form at the neck/shoulder junction. Some FL dies may not push the shoulder back far enough to chamber freely. Check loaded rounds neck diameter. Not worth doing IMO.

Today was the first time I tried it. I had enough .308 brass and was curious. The way I had the die set up didn't set the shoulder back enough.

How do you turn or ream the neck?

So far, I agree that it's not worth doing, but would like to know how.

 

[Reloadron]

Today was the first time I tried it. I had enough .308 brass and was curious. The way I had the die set up didn't set the shoulder back enough.

How do you turn or ream the neck?

So far, I agree that it's not worth doing, but would like to know how.

Neck Reaming involves removing material from the inside diameter of the neck. This is done using a Neck Reaming setup. Neck Turning on the other hand involves removing material from the outside diameter of the neck. This is done using a Neck Turning setup. So both involve removing material (brass) the main difference being if we remove material from the OD or ID of the case necks.

There are times it is essential to remove material. There was a time I fireformed 220 Russian Lapua brass to make my own 6mm PPC brass for a tight neck chamber. I had to Neck Turn each and every case. I made a gauge from the reamer I used to cut my chamber. Each and every case needed turned and checked because sans turning they would not come close to chambering. That being a simple example of when it is required. When we neck down a case like 308 to 243 (6mm) the extra brass goes somewhere.

Ron

 

[243winxb]

Neck reaming should be done while the neck is held in a special die. Cut undersize to finish with outside neck turning. Lake City 7.62 x 51 NATO brass is what i used, it was a problem. Others online said Rem & Win dont have a problem with a donut or chamber fit, using standard FL die.

 

[nastynatesfish]

I use lapua308 brass. Run it through my 7-98 sizer then the 243. Small donut on neck but they form out on first firing