Help! necking down 7mm08 to 260, dented shoulders

[dvdt]

I'm trying to neck down some Win 7mm-08 brass for my GAP-10 260. I bought some factory ammo and shot it. I setup my Redding FL sizer such that I had 0.003" of bump from my average measured 1x factory brass. The factory ammo was SWAmmo's 260 (shot very well) and it had new Remington 260 brass.

I used a Hornady headspace kit and the .400 bushing. I actually left it attached to the calipers if that matters. I'm pretty confident the die is setup correctly for bumping the shoulder appropriately.

I just switched to imperial sizing wax (LOVE the stuff so far) but with a VERY LIGHT coat of the stuff, I was still denting shoulders.

I've never necked brass down before and this is my first trip to the rodeo reloading for a gasser.

Any tips ?

My understanding of the primary cause for dented shoulders is that you have too much lube on the cases. I had a VERY light coat on there.

I did have some of the wax on the case necks but it was very light.

I had just finished sizing a bunch of 6.5CM. I used considerably more lube there and didn't have a problem.

I did have the expander ball in the FL die when I tried this operation.

I did not size any of the 'factory' Remington cases yet. I haven't cleaned them yet and want to keep my dies in good shape.



Found:
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1898039

Mine is no where near that severe. I'll take my die apart and clean it really well. I *think* I cleaned it before I used it but I can't swear to it. Strange thing was that it was a really light coating and I only sized maybe 10 cases!

 

[Reefman24]

Re: Help! necking down 7mm08 to 260, dented shoulders

To dvdt,
It is quite possible that the resizing wax your using is building up in the die even though you may only be using a light coat, it really doesnt take much to have that hydrallic effect. What I would do is if you have an alcohol based lube, such as dillons, give that a shot. It truly leaves a very light coat of lube on the cases after the alcohol evaporates. If that is still denting your cases then try switching to NECK sizing bushing die, using gradually tighter bushings. If you have those on hand that would almost certainly fix your denting problem.

 

[427Cobra]

Re: Help! necking down 7mm08 to 260, dented shoulders

Clean your die out, try only lubing the body and none on the shoulder or neck. I would also recommend a little less bumpI think the .003 thing comes from M1A and Garands, a GAP AR10 will have a much tighter chamber, .0015-.002 should work.

 

[Greg Langelius *]

Re: Help! necking down 7mm08 to 260, dented shoulders

When I neck down 7-08 to .260, I do not lube the necks or shoulders. I have never had any detectable problem in this process.

I also set the dies up without any bump, preferring to leave a relatively small portion of the neck, where it joins the shoulder, unsized.

This results in some noticeable bolt drag on closure. But once the case is fired, that drag is gone, and the fireforming process effectively completes the resizing process pretty much perfectly.

It's not quite perfectly according to gospel and verse; but the end result is quite satisfactory.

Greg