brass sizing issues

[AKArcherdaddy]

Hey guys, I'm having fun playing with my new 260 Rem, but ran into the following issue.

I bought a shoulder bump guage from Sinclair, and am using it along with the ".308 family" insert. I used it to check the base-shoulder length on about 10 cases that were fired in the chamber, and they were all pretty much the same dimension, with .001" of each other. I set my Redding FL bushing die to bump the shoulder back .002", as measured with the same guage. However, after resizing despite bumping the shoulder back the cases are all still a "crush fit" in the chamber, meaning I can get the bolt to close on the resized ronds but it's a sticky, tight fit. This continues to be happen until I bump the shoulder back by about .007". That seems like WAY too much shoulder bump. Am I wrong? I've read on other forums that more than .002 shoulder bump can lead to early case head seperation, and that many bump only 001".

Assuming there is something wrong, any idea what might be the problem? I'm using my 7-08 Rem Redding FL type-S (bushing)sizing die with a .288 neck bushing. The action is an Accutrigger Savage centerfeed short action. My barrel is a Brux barrel chambered with a custom 260 Rem match reamer with a .294 neck and .160 freebore. Brass is Win 7-08 brass necked down and turned to .013" thickness (.290 loaded round diameter) in case that helps.

Thanks!

[Elkbane]

Something doesn't sound right about that, I'd be concerned too.

First thing I'd do is see where the case is contacting the chamber with the dies set for 2k bump. Smoke a case (or I use a black majic marker) from the shoulder to the neck and chamber it several times. I usually just draw 4 lines all the way from the extractor groove to the neck so I can se where I'm getting contact on the case body also. This should tell you where the "tight" spot is on the case - where the marking or smoke is disturbed.

It may be that with the thinner turned necks, the base of the neck that's not geting sized by the bushing gets expanded more upon firing and is causing the contact. If that's the case, when you set the shoulder back 7k it may create enough length clearance from the chamber to allow you to feel loose bolt throw. If the base of the case neck is contacting the chamber, I wouldn't worry about that - it should center up the cartridge nicely center bore every time, but may cause problems if you ever get significant carbon accumulation there (Carbon ring). If you feel the need eliminate contact there, you'll need to use standard type FL sizing die rather than bushing type.

Also, to cover all bases, check to see if you have any crud on the bolt face and that the ejector plunger moves freely down to below surface of the bolt face.....

You might get more responses if this goes into the reloading section...
ELkbane

[AKArcherdaddy]

Thanks Elkbane, I'm thinking along the same lines: the tight spot is at the neck-shoulder junction. I'll try your magic marker method when I get home this afternoon to see if it confirms your suspicions.

As I think about it now, this theory makes more and more sense. I also have a 7-08 bushing neck die too, and when I use it instead of the FL die I don't get any tight closing bolt for several firings. I'll bet when I do FL resize to push the shoulder back, the FL die squeezes the small un-resized portion of the neck/shoulder forward, and this is what becomes the pinch point, not the shoulder itself. Makes sense!

I like using bushing dies since factory dies resize the neck too much (and then re-expand it). At this point it looks like I might be looking at getting a FL die with a custom honed neck (or a full custom die set), since they don't (correct me if I'm wrong!) make a bump die in 260 Rem yet.

As

[mytwo60]

Have you tried using a regular FL 260 die? I am willing to bet you won't have any problems with sticky chambering.

[Elkbane]

I believe you are correct about Forster not making a bump die for 260. I cobbled one together by having the hole in the top of a .243 die honed out to let a fired .260 case pass through, and it worked, but the neck in my chamber was just too sloppy to use bushing dies well - had to size down too much and couldn't control runout with bushings. I finally ended up using a Redding F/L body die for sizing the case body and shoulder to give me the bump I wanted in conjunction with a Lee Collet die for sizing the neck. Had to turn the diameter of the mandrel on the Lee die down a little to control neck tension, but it seems to work OK.

A customized F/L die would be the ticket - haven't gone that route (yet).
Elkbane

[AKArcherdaddy]

Update: I tried a regular 260 Rem sizing die, and it did not solve the problem. Same thing: by the time I stop getting a very sticky bolt when I chamber the resized brass, the should is pushed way to far back.

Using Elkbane's advice I drew four lines the length of a resized case, popped it into the chamber, and forced the sticky bolt open and closed on it five or six times. The lines showed NO WEAR anywhere at the neck and shoulder, but all four lines showed wear about 1/2" above the head of the case, just above the webbing. I started a new post on this in the reloading forum (and now I see this one has been moved to reloading as well) describing this, and asking for advice. Custom dies, or have the chamber honed a bit wider?

I'm looking forward to reading your advice but won't be able to reply for a few days as my wife and I are taking the boys on a 12 mile hike into the mountains, hoping to get them their first black bear. The weather looks great, and summer has finally returned to Alaska!