6mm-284 vs 243 AI

[308]

Goal is a 6mm to drive 70 bt's and 75 vmaxes 3700 plus, 1500 round barrel life at least would be nice.

Both calibers have excellent brass available, lapua.

Barrel length 27-28

I already have a 1000 yard rifle so I' looking at 600 yard and less mostly.

I have a friend with a 40x in 6mm remington that drives 70 grain ballistic tips to 3720 and is the most devastating thing I have ever seen on crows. I want to match or exceed the detonation of crows I've seen w/his rifle, and have better brass available, .500 accuracy will be fine a touch more is always better.

Of lesser importance, it would be nice to be able to shoot a little higher bc bullet if I wanted to play on steel to 1000.

What would be the heaviest bullet I could stabilize with a 12 twist, 10 and 9?

What are the pros and cons of these 2 cartridges shooting the varmint bullets.?

What twist would be best for what I want?

Put your 2 cents in on a 6mm-06 AI or 240 Gibbs while your at it.


Look forward to hearing what you have to say about this.

 

[devildoc]

How bout a straight 6mm AI? Only downside is you're stuck with remington and winchester brass.

 

[308]

That is the only reason I don't go with the 6mm ai is the fact that no one makes the good brass, that being said if I happened across a good one at a good price I sure would use it til I shot the barrel out and then go with one of these.

 

[devildoc]

That is the only reason I don't go with the 6mm ai is the fact that no one makes the good brass, that being said if I happened across a good one at a good price I sure would use it til I shot the barrel out and then go with one of these.

A little elbow grease and you can make WIN and R-P brass as good or better as Norma or Lapua. Don't get me wrong, if they had Lapua brass available that's what I'd be shooting out of my 6AI, but as it is I'm getting plenty good accuracy without it. However, I'm trimming, squaring up the case head, primer pocket uniforming, flashhole deburring and wieght sorting.

 

[308]

Devildoc, I know I can make the rem,win brass good with all the tricks of the trade. And if I ended up with a good 6mm rem this is the route I would take. This is what my friend does and with select brass his rem 40x's in 6mm routinely shoot less than 1/2 moa with varmint bullets.

But, I don't have the rifle yet, or brass or dies, so if I'm going to put one together I would just as soon put together something that has good brass already made for it, albeit using 6.5-284 to make the 6-284 or fire forming the 243 to the 243 AI.

At this point I want input from people who already have experience with rifles in this performance envelope and learn from those who have gone before so to speak.

I am a 6mm remington fan, I think its underappreciated, and I am the reason my friend has rifles in this caliber now. Its a shame nosler, or norma or lapua does not make brass for it.

Thanks: 308

 

[buffalorancher]

I have a 6-284 and my idiot ex-hired man had a 243 AI and they both shoot well. My 6-284 is on the edge with high BC bullets and is very picky. I have suspected that that the 6-284 would be better suited to lighter bullets with a slow twist. There are so many good 6 mm bullets I will always own one but my next try will be a 243 AI.

 

[Coyboy]

My 243AI with a 12 twist shoots the 85-87 grain bullets at 3650fps out of a 28" 3 groove. So 70 can be run over 3700.

My 243AI with an 8 twist shoots the 105-107s at 3150 with a 30" barrel. That is not pushing them hard at all.

If your looking for a twist to shoot the 70's fast and stabalize the 107, without the 70's comming apart.............good luck.

 

[308]

I know 1 twist will not do it all. Coyboy sounds like you have the ultimate answer a gun/barrel with a twist for the varmint bullets and the long high bc bullets.

My plan is to shoot the 70-75 grain bullets at 3700 or preferably over, but while I am in the figureing stage I would like to know how heavy a bullet a 12 twist will stabalize? and a 10 and a 9.

308

 

[Iron Worker]

I shoot a 6x284 with a 26" Hart BBL 10" twist. I can get 3,900 (70gr NBT)on a warm day with 56.3grs of H4350. 87gr V-max I can get almost 3,600 with 53.5 grs of H4350 and both loads shoot under 1/2 MOA at 100 yds. My hart 10"twist will not stabalize a 95gr VLD.

 

[shiredude]

I can get +3600 w/ 87 v-max's out my ackley. It's an 8 twist, so I mainly shoot the 107's. Have played around w/ 80 gr BT's but they dont give me the consistency. You might think about a plain ole 10 twist and go w/ the v-max's. THose going almost 3700 are nearing 257 weatherby performance. I'm sure they would play hell on crows as well!

 

[Iron Worker]

Shiredude why did you have to mention the 257 Weatherby ? I have a Rem 700 formerly 22-250 now 6x284 so I wonder if this means a short action? Any how I might like to have the next barrel chambered for 257 Weatherby? I wonder if my action will alow that?