From 308 to 260 brass

[AussieBluey]

Hi All,
I have a tight chambered 260 and need to form down some 308 Norma once fired brass as well as some unfired Lapua 308.I have tried a Hornady 7mmo8 die and then run the cases into a Redding 260 die.It is a very tight fit and I have adjusted the dies from 2 turns off shell holder through to having the shell holder having full contact with bottom of the die. Factory Remington unfired brass fits the chamber perfectly.Would a 7mmo0 or 260 small base die fix this problem????? I have a couple of hundred cases to do so any help would be great. Thanks again Bluey

 

[gunsandgunsmithing]

I go straight from .308 Lapua brass to .260 in one step and have zero problems with my no turn .260 chamber. I can feel the bolt close on the un-fired brass but that's about it. It fireforms nicely and leaves .002" clearance in the neck portion of the chamber with a loaded round.---Mike Ezell

 

[2644ever]

Bluey, Norma & Lapua brass has thicker case heads,and I suspect your bolt won't close on a Lapua case in .243 Win. Either try a .308 small base sizer,more available in this caliber) or better yet, a .45 ACP trim die from RCBS, that you screw upside down on your press until it contacts the shell holder. It works for me. One last advice: with this little trick, don't forget to lube your cases!

 

[SooStan]

I have a GAP built 260 and when I neck down 308 or neck up 243 I have to neck turn them. The loaded rd. has insufficiant neck clearance. When measured it appears that I have .002 clearance but many fired cases will not accept a bullet in the neck. Accuracy is also fair to poor unless I clean them up a little. Federal and remington is very thick. Winchester 7-08 brass is the only one that seemed to work wth no neck turning, and of course factory rem 260 brass too. A small base die did nothing to change the tight neck problem.

 

[savageboy]

How was the accuracy with the Win 7-08 brass?

I have been having alot of problems- prob. due to me not really knowing what I am doing- with my .260AI and Lapua .308 brass. I fireform Rem 260 brass and it shoots very good. I wanted to try some better brass. I got 300 Lapua .308 brass, took it down to .264 in 2 steps- .284 then .264. Trimmed them and then "cleaned up the necks" w/ a Lyman trimmer. I suspect the prob is with the necks, but I am getting very erratic pressures, erratic accuracy, etc. Any suggestions???

 

[treeman]

savageboy,check the clearance of your loaded rounds to your chamber. also check the consistency of your turned necks. some may be thicker than others.thats all the comes to mind right now. hope this helps with your problem. treeman

 

[SooStan]

The 7-08 brass was fine for accuracy, about the same as 260 rem brass. The win. 7-08 brass is lighter then the rem 260 brass. I agree with treeman about possible problems. What powder are you using. H4350 works well in a standard 260. Some of the guys here use H4831 in the improved version with good results. 140 bergers, 142 sierras and 139 Lapua all shoot well. My best SD and lowest ES have all been with lighter loads. The max loads shoot very well but on paper do not look real good.

 

[dennisinaz]

I have formed a lot of both .243 and .308 Lapua into .260 Remington brass. I got lots or runnout on my cases until I used a K&M expander mandrel and body die to stretch the .243 up compared to a Redding tapered button or just doing it incrementally with two other buttons.

For going down in size, I had to first neck turn the 308 brass and then I sized it first in a 7mm-08 die and then finally a .260 die.

My neck is stamped .294 and is too tight for ANY 308 brass necked down and is even too tight for Lapua .243 necked up. I have to clean it up with a K&N neck turner for good results.

Remington brass gave me dismal accuracy so it was worth it. I bought some Nosler brass which, when sized through either of my full length dies will NOT hold a bullet. The brass at the neck is too thin. Nosler checked out my brass and said that it is within spec,.014 thickness). I can probably buy a smaller bushing, but then I will have to size it twice. No more Nosler brass for me.

Hope this helps

 

[AussieBluey]

Hi Guys,
First off thanks for all the replies and tips. Have fixed the problem at this stage.Here is what I did,
Run all once fired 308 Norma cases into a 308 small base die then run case into seating die to start the forming down. The next step was re-lube cases and rum slowly through a Redding 260 FL die.Last thing was to lightly neck turn down to same diameter as factory 260 brass. You guys were right that the Norma brass is a lot thicker in the neck. Thanks again for all the help. Bluey