I replaced the factory barrel on my M70 with a Benchmark. The gunsmith cut the chamber on the small size of SAAMI, and I cannot resize my Lapua brass enough in an RCBS FL die. Would a small base die do the job? Hate to toss $100 worth of good brass.

quote:

Originally posted by Brice:
I cannot resize my Lapua brass enough in an RCBS FL die.

What part of your brass is not sized sufficiently with your RCBS die?? Has the shoulder been pushed back JUST enough (.001-.002"), measure difference in shoulder and (just in front of) web diameters for fired vs sized cases. Alternatively, smoke a case and figure out which dimension causes it to chamber hard (or not at all).

Will neck sized cases (fired in your rifle) chamber??

Will factory ammo chamber??

It is quite rare that a small base die is required for a bolt action rifle - even one with a minimal SAAMI chamber. You *may* be able to solve your problem with a small base die, but before you shell out the $$$, you need to figure out which case dimension needs to be reduced further (very likely it is either head-shoulder or case diameter just in front of the case web).

The drawback of a small base die, is that you will work your brass a lot more, and that it will grow in length quite dramatically with each sizing. So unless you NEED a small base die, it would be better to avoid one...

If it is truely such, that your chamber and dies are a total mismatch (rare but I guess it could happen), one other option is to send a couple of cases fired in your rifle to Hornady, and they will make a die matching your chamber perfectly, reducing fired brass dimensions exactly as you specify (e.g. .002-.004 at shoulder and web). Cost:$120 plus shipping.

But do figure out whether your RCBS die can't be made to work first, maybe it just needs readjustment??

- mike

Mike beat me to it.

It is unlikely the base dimension of your brass that is causing it not to chamber -- more likely it is the base-to-shoulder length, or perhaps even the forward body diameter. Some combinations of shell holders and "Full Length" dies will not reduce these brass dimensions sufficiently to chamber in a minimum chamber.

The cure is not necessarily something like a "small base die", but rather can be as simple as grinding a few thousandths off of the lip of you shellholder (or bottom surface of your sizing die) to allow the die to push the shoulder back sufficiently.

A Redding Body Die solved that problem for me on one of my rifles...

You need to smoke a cartridge and find out exactly where the cartridge is binding. Does store bought ammo fit?
I believe this would be a problem for the smith to correct, not you if a F/L resized case won't fit. IMO.

Thank you all for the responses. New brass fits, and cases fired in the rifle fit just right when using the RCBS die. I'm off to Namibia Saturday morning, so will have to check just where the cases are hanging up later.
Thanks again,
Brice

I also wonder.....Are you camming the ram of your reloading press over against the die bottom with the shellholder by a quarter turn?

I find that at least 90% of the time when someone is inquiring about SB dies the above solves these chambering problems

Brian, all the best on your Namibian trip.

quote:

Originally posted by Brice:
cases fired in the rifle fit just right when using the RCBS die.

Is this "RCBS die" a neck sizing die??

If yes, and if cases do not fit after you have sized them your FL sizing die, Id venture there is a 95% chance that you have your FL sizing die not adjusted to push back the shoulder. The FL sizing die will likely size the case body, and in doing so will push forward the shoulder - head-shoulder dimension INCREASES when compared to a fired case. Now the FL sizing die needs to be adjusted to push that shoulder back to or slightly below the fired size.

I use a Stoney Point Head Space Gauge to quantify this effect, and to establish when my FL die is set to push back the shoulder the desired .001-.002".

- mike

If you are setting up the die properly, you don't need anything to tell you you're doing it right.