New Build: 6mm Rem vs. 243 Win

[NWdan]

As a kid I my first bolt rifle was a Remington Model 7, 6mm Remington which I still have and use on occasion. I'm thinking of a long range 6mm build, and am having a hard time deciding between 6mm Rem and .243 Win. The rifle would be based on a stainless Remington M700 long action, and probably a 24-26" fast twist 1:7 barrel to shoot the heavier 105 to 115 grain bullets. The rifle would be used primarily for fun, target practice, coyote and deer hunting. I know the .243 has better (Lapua) brass availability but a little less powder capacity. The pros for me of the 6mm is that I have quite a bit of Remington brass on hand, reloading dies, and it should yield a little more velocity. I'd like to hear other's thoughts and opinions on this. Thanks in advance.

 

[Edd]

That decision would be an easy one for me. I'd pick the 6mm.

 

[SBruce]

+1, 6mm over 243.

 

[Backcountry]

Well I would say since you already have all the 6mm stuff than just stick with it. I was thinking the same thing awhile back and just ended up going with a 243 in a factory sps varmint, and that decision was based purely on the price of brass. I like the cheaper brass, but you can get the lapua if you really want to wring it out. I would think the 6mm might be a better option if your running the heavies. Good luck with your decision.

 

[J E Custom]

As a kid I my first bolt rifle was a Remington Model 7, 6mm Remington which I still have and use on occasion. I'm thinking of a long range 6mm build, and am having a hard time deciding between 6mm Rem and .243 Win. The rifle would be based on a stainless Remington M700 long action, and probably a 24-26" fast twist 1:7 barrel to shoot the heavier 105 to 115 grain bullets. The rifle would be used primarily for fun, target practice, coyote and deer hunting. I know the .243 has better (Lapua) brass availability but a little less powder capacity. The pros for me of the 6mm is that I have quite a bit of Remington brass on hand, reloading dies, and it should yield a little more velocity. I'd like to hear other's thoughts and opinions on this. Thanks in advance.

I would go with the 6mm Rem also because you are familiar with it and have all the stuff to
reload it.

If you intend to shoot the 105+ bullet weights you will need to increase the twist rate.(The old
factory barrels had a 1 in 12 twist and that is what killed there popularity compared to the
243 Wins 1 in 10 twist.

I would recomend a 1 in 8 twist that would allow you to shoot any bullet weight without over
rotating lighter bullets.

A quality barrel like a Lilja Stainless will also help the velocity and cleaning.

J E CUSTOM

 

[shortgrass]

1 in 7 1/2 twist is minimum for 115g. bullets. May be too long for an extended magazine box with 107/115g.

 

[Edd]

1 in 7 1/2 twist is minimum for 115g. bullets. May be too long for an extended magazine box with 107/115g.

Why would length be an issue with a model 700 long action? Unless my brain and calculator are out of sync, seating a 115 gr Berger against the lands in a standard 6mm chamber will have an OAL length less than 3.100".

 

[shortgrass]

oops! missed the LA part. Might need to block the mag in that case.

 

[HARPERC]

Wrestled with this dilemma myself some years back, chose 6mm, and haven't looked back.

 

[Trickymissfit]

As a kid I my first bolt rifle was a Remington Model 7, 6mm Remington which I still have and use on occasion. I'm thinking of a long range 6mm build, and am having a hard time deciding between 6mm Rem and .243 Win. The rifle would be based on a stainless Remington M700 long action, and probably a 24-26" fast twist 1:7 barrel to shoot the heavier 105 to 115 grain bullets. The rifle would be used primarily for fun, target practice, coyote and deer hunting. I know the .243 has better (Lapua) brass availability but a little less powder capacity. The pros for me of the 6mm is that I have quite a bit of Remington brass on hand, reloading dies, and it should yield a little more velocity. I'd like to hear other's thoughts and opinions on this. Thanks in advance.

I shoot 105 grain Hornaday Amax bullets with a 1:8 barrel. Never shot any 115's so have no idea what you need for them. I like the 6mm Remington, but case capacity between the .243 and the 6mm are not that far apart in the real world. But the 6mm has a much longer neck length, and will handle those 105's easier. Barrel life with the 6mm is much longer if you plan on doing a lot of shooting with it. Of course you could achive the best of both worlds by reaming the chamber with a 6mmAI reamer and headspacing it off a .243AI gauge. This would give you a 6BG with a 40 degree shoulder angle. (well a little bigger I know) An even better round. (the 6BG uses a 30 degree shoulder and head spaces off a .300 Savage gauge). Ackley said that the 6mm remington was about the max case capacity for the bore size without going into overbore, so the 6mmAI is going to be slightly overbore (best used with 85+ grain bullets). The main advantage of the 6BG is that cases can be formed from generic .243 brass; where the others will need 6mm brass. The "BG" is sorta like a 6BR with a case shoulder deminsion .28" longer. Shoots the 107 Sierras at a tick under 3000fps. A Barrel should last a long long time with it
gary

 

[Outlaw6.0]

That question had me doing some head scratching...
I have a soft spot for the 6mm bore diameter, I started with the 243 win, reamed to 243AI, shot that barrel out & went with the 6mmAI, I also have a 700LA chambered in 6-284 & a DPMS LR-243.

I've shot the 6mm's WAY more than any other bore diameter I own, I would recommend the 6mmAI all the way, the neck length is very nice to have on your side as well as the added velocity & case life, the 6mmAI is a capable cartridge you will really enjoy (although I will admit I was in love with the 243AI as well)

If you don't want to wildcat I would probably offer the 243 win, the ability to utilize Lapua brass is to good to pass on for a factory cartridge & since the velocity is neglible, it should be the clear winner.

 

[NWdan]

Thanks for all the feedback guys, it sounds like I'm on the right track. It would be nice to stay with the 6mm brass and dies, and I have a boy coming up who will probably take over the Model 7 and it'd be nice to be setup the same. I just wanted to make sure there wasn't some issue with the 6mm I wasn't aware of. Even though it'll mean a little more work sorting brass I think that's the way I'll go. Hope everyone is enjoying their holiday weekend.