6MM AI or 6MM - 284

[Chuckster]

All,
Have a rifle that is currently in 6mmAI (Ackley) and going to rebarrel, want openions on which cartidge would be best. What I do is long range varmint shooting so need 75-90 gr bullet with all the velosity I can get (and still be accurate out to say 700yds) I am considering changing to the 6mm-284 because I could buy good brass in 6.5-284 and neck it down. I would not have to fire form it. Any advice is welcome.
Chuckster

 

[dakor]

6-284 gets my vote you will get about 150 to 200 fps+ more than the 6mm AI and you do not have to fire form. I shoot 95 grain Ballistic Tips out of my 6mm-284 at 3500 FPS+ and the accuracy is out standing. I have a 28inch Hart 9 twist barrel but if you are going to shoot VLD bullets over 95 grains make sure you get an 8 twist.

 

[Chuckster]

dakor
Thanks, for the input, I will be shooting 75-90 gr so will go with a 1-12 twist. could you share your load data?
Thanks
Stan

 

[Chuckster]

Another question, how do you neck the 6.5 down to 6mm??
Thanks
Chuckster

 

[Kanab]

Another vote for the 6mm-284. I have a 1:8 3-groove Pac Nor that shoots the 70gr. BK's and 107 SMK's quite well.

As for necking down, I just ran the new 6.5-284 brass into my full length die with normal lube on the body and the neck. I didn't lose a single case. Depending on your chamber neck diameter you may or may not be required to turn the necks. I ordered a tight neck and an unturned neck will not even chamber.

The 70 grainers do 2.5" often out at 480 yards, with groups in the 0.3XX - o.4XX range at 100 yards, and the 107s give me 8" groups at 1100 yards.

 

[Chuckster]

Don,
Thanks, Great info, I am just about ready to make the decission to 6-284. How is it for barrel life, I expect it will be a barel burner like the AI, but hey you have to pay the piper if your gonna dance!
Do you mind sharing the loads you use?
Thanks
Chuckster

 

[Frank in the Laurel Mts]

As a former reloader of a fast twist 6/284, If you have the time to mess with it they are alot of fun, doing the cases, outside neck turning etc...they will shoot and they will shoot far very very accurately. During our last Groundhog match the winner in the heavy gun I believe was using a 6mm AI and it shot a 5 shot group at 500 yards of 1.332 inches and if you do any long range shooting from a bench that is not easy to do so I'd say they are capable of outstanding accuracy to say the least..a little over an inch and a quarter at 500..awesome, if you think not, try it-you may go a lifetime and not do it with any cartridge..can't wait til' this saturday to see if he can dublicate it.

 

[Kanab]

[ QUOTE ]
Don,
Thanks, Great info, I am just about ready to make the decission to 6-284. How is it for barrel life, I expect it will be a barel burner like the AI, but hey you have to pay the piper if your gonna dance!
Do you mind sharing the loads you use?
Thanks
Chuckster

[/ QUOTE ]

I hate to type in load data just in case I mess up and someone dies.....but....

107s with 51 grains of H4831sc will shoot in the teens at 100 in this rifle.

70s with 55.5 grains of the same is a .4XX shooter. I had the twist set for the long bullets but the light ones do fine too.

I use Lapua and Norma brass and Fed Gold primers, every charge is checked on a scale, brass is prepped. The rifle is nothing fancy. Savage stainless with a Duramax stock. It isn't even bedded. Nightforce 8-32 Benchrest stock, Warne picatinny base, Nightforce rings, Pac Nor supermatch, 27" Light Palma, tight neck.

 

[Chuckster]

Don,
Thanks for the info, I can't make the conversion in time for my Prarie dog hunt in may but will send rifle off when i get back and let Jim Borden work his majic on it.
Thanks
Chuckster

 

[dakor]

As for barrel life I really think if you do not get it hot it will last about as long as a standard 6mm Rem. I mean I am only shooting about 4 to 5 grains more powder than the 6mm Rem I had. As for loads I use mostly R-22 and with a 95 grain Ballistic Tip I am in the 53 to 53.5 grain range depends on how hot or mild the R-22 is. As for your twist I would go with a 10 twist if you go with a 12 twist you will have trouble with most bullets over 85 grains. My dad built one with a 12 twist now he wishes he would have went with a 9 or 10. As for accuracy mine will shoot those 95 grain Ballistic Tips in the 1 1/4inch range shooting 3 shots at 500 yards with my bipod.

 

[Chuckster]

dakor,
Thanks everyone has been very helpful, I have decided to go with the 6mm-284, for the reasons I mentioned at the begining. The wasy I see it I am doubling my barrel life as I won't have to fore form my brass!
Will let everyone know when i get the rifle back and how it works.
Chuckster

 

[brian b]

Chuckster,
I see you made your decision rather quickly (7hrs), if it is not too late let me give you something to think about. I own a gun chambered in both of these rounds,in my experience I would not chamber a 6-284 (again)in anything other than a 1-8" for VLD (105-107gr). it is just too overbore for a 1-9,1-12" shooting 95gr bullets or smaller. I burned up my first 6-284 (1-10")in short order,then I switched to a 1-8" on my second barrel extended my range several hundred yards and as far as barrel life goes only time will tell. as for the 6mm Ack if you are going to shoot 95gr or less it is the only way to go for several reasons, first is that it has such a long neck that you can touch the lands from 55gr to 95gr, the powder capacity is enough smaller that you double your barrel life including fire-forming (contrary to your suggestions) and lastly even though on many posts I have mentioned a hatred for Rem. brass on my 6Rem brass it is surprisingly good but if you want better use Norma 7mauser brass.hopefully I did not offend Bushchook again on this post.
B

 

[Chuckster]

Brian,
Your aruments make sense, now I have to rethink this /ubbthreads/images/graemlins/confused.gif
I have talked to a few gunsmiths and shooters that tell me the 6-284 wouldnt be any harder on barrels than the AI???
When you say short order, how many rounds are you talking about? If I could get this thing to shoot I would stay with the AI but it is driving me nuts and by the time I figure it out the barrel will be toast! Thanks for the input now I'm back to the deciding stage /ubbthreads/images/graemlins/crazy.gif How was acuracy in your 6-284's??

 

[dakor]

I really do not know how you can say even with fire forming you will get better barrel life then a 6-284 when the 6-284 only uses about 3 grains to 4 more grains of powder then a 6mm AI? That is like saying a 22-250 AI will get better barrel life then a 220 swift and that just is not true. I have had my 6-284 for the last 6 years I have over 1100 rounds through it and it still shoots just as good as the first day I shot it. I would say I will get another 1000 rounds or more out of it before I need to have the throat re cut. Chuckster I guess my next question is how far are you going to shoot with this rifle and what are you going to be shooting at? I ask because the 6-284 really shines with bullets that are 90 grains or more. I mean don't get me wrong I can shoot 85 grain bullets around the 3750fps mark but I would rather have the 95 grain going in the 3500fps range. You will also find that the 85 grain bullets and lower do not do as well as the heavier bullets in the wind. So if you are going to be shooting over 400 yards you are going to want to use the heavier bullet.