6mmBR Remmington

[Brian_K]

Hi Guys,

Need a little advice if you can. I've just purchased a s/h 6mmBR. Nice rifle, but when I came to check the COAL with a 105gr SCENAR fitted in the Hornady gauge, it came out at 2.227 with the bullet just touching the lands.

I'm beginning to think this barrel (a 1:8 Pac-Nor) has been chambered with a 6mmBR Remmington reamer......does this sound about right?
If so and considering the 1:8 twist, what do you reckon is the lightest bullet I could use in this barrel (I'm looking to use it mostly for 100 to 300yds)

I've shot some 105gr SCENARS and A-Max. Did OK, but I think the rifle can do better.

Any help appreciated.

Brian

 

[jerrschmitt]

The old Remington 6MM BR chamber accepts a case .040" shorter than the 6 MM BR Norma or later 6 MM BR Remington. I wouldn't think that a newer case would fit in the old chamber particularly with a bullet seated. I don't use the 105 Scenar but my 105 AMAX are seated 2.350 to the lands.

 

[Brian_K]

I took my information from here: http://en.wikipedia.org/wiki/6mm_BR

I assume the case shown under the heading "Design" is the 6mmBR Remmington??

It shows a COAL of 2.200" which is about where I am at. The only difference I can see is a small change in the head of the case.

I've just sold a Unique Alpine in 6mmBR which had a COAL of 2.324 so that seems to be about right for a 6mmBR NORMA chamber.

Brian

 

[jerrschmitt]

New Lapua brass measures 1.556-1.557″. CIP spec for the 6mm BR Norma case is 1.5598″. The SAAMI OAL spec for 6mm BR Remington is 1.560″, essentially the same. However Remington originally produced the brass at 1.520″ OAL, and some older reamers reflect this shorter length. If you have an older rifle you probably want to have the neck extended to shoot modern brass, with 1.560″ max length. The Lapua brass is headstamped 6mm BR Norma-Lapua. We trim all our cases to 1.555″ when any one reaches 1.560″ or longer

The above was taken from:
http://www.accurateshooter.com/cartridge-guides/6mmbr/#26585

I have one of the older rifles with the short Remington chamber and I know of a local gunsmith that still uses a reamer for those old guns.

I would be more inclined to think that the reamer used in your chamber was setup for a shorter bullet and not a cartridge case issue. The Wikipedia article appears correct as far as it goes. It just doesn't go far enough.

 

[Brian_K]

"I would be more inclined to think that the reamer used in your chamber was setup for a shorter bullet and not a cartridge case issue. The Wikipedia article appears correct as far as it goes. It just doesn't go far enough."

Thanks, that's about the conclusion I came to. I've ordered some Berger 80gr FB Varmint in the hope they will shoot well in my short chambered 1:8 barrel.

Any other suggestions would be appreciated.

Brian