7mm BR Brass Necked Down for 6mm Dasher?

[tdogg]

Hello,

First let me introduce myself. I've been lurking for a bit and finally purchased a 6mm Dasher from Bob Lee Swagger here on the forum. I am new to benchrest shooting but not new to shooting or reloading. I shoot IDPA and USPSA and really enjoy it. In working up hunting loads for my 7mm Mag I really enjoyed the challenge of finding that sweet load and being able to shoot accurately out to 300-400 yd (about as long as I would take a shot at any big game animal hunting). I haven't shot much past that range but plan on it here shortly.

On to my question:
I have the opportunity to pick up a large box (~500 or more) of 7mm BR brass (Remington head stamp) for next to nothing. After looking at the specs for the 7mm BR it is shorter than the 6mm Dasher by about .040 inches. Do you think during the fire forming the brass will elongate out to spec? Is the 7mm BR case too short to function in the 6mm Dasher as is? The handful of brass he gave me to figure out if it will work all measure about 1.510-1.515 inches. Any thoughts on using these 7mm BR cases? Is there something that I’m missing that is different between these cases?
If they are useable I was going to run them through the FL sizing die to resize the necks down to 6mm. I was then going to neck expand and neck turn for my Dasher chamber. Next I would load up the rounds and fire form them to my chamber. Finally I would FL resize, clean up primer pockets, trim to length (if needed), and sort by weight. Any thoughts on that plan? Can I just run them through a 6mm sizing die to reduce the neck diameter down to 6mm? Am I nuts for spending this much time to rework this brass?

Thanks in advance for any assistance.

Cheers,
Toby

 

[wapiti25]

The R-P brass does not have the small flash hole that the 6mm br Lapua does. Some think the small flash hole is more accurate. R-P brass does not have the case wall uniformity that Lapua does. If you use the 7mm BR brass leave the neck at 7mm for a false shoulder to fire form with. The R-P brass can be used but not my first choice.

 

[boltfluter]

I would not put all that effort into Remington brass. I have done this myself. Big waste of time. Brass is soft and to short unless you use the old style of reamer designed for this length of brass. Just my personal opinion. Sorry to burst your bubble.

Regards, Paul

www.boltfluting.com

 

[tdogg]

Well I think I will go see if he will give me ~100 or so cases for testing (he might just give me the entire box for free). If anything it will let me perfect my fireforming method for the Dasher on the cheap brass.

I'm waiting on the rifle, K&M Neck turning tool, and the die's to arrive in the mail. I have a really old jug of International Clay's that I intend on using for fireforming with the cream of wheat method. I may try the jam method as well with some IMR4064 or maybe IMR4350.

Cheers,
Toby

 

[CatShooter]

Cases often get SHORTER when fireforming.... so watch out for that. I shot R-P cases before Lapua came out with it - they are OK

If you need to turn your necks, turn them before necking down... then anneal them.