Should I stay with 6mm-06AI?


Well-Known Member
Nov 8, 2009
Timber Lake, South Dakota
I ordered a custom 28" SS 6mm-06AI 1-12 twist from Match Grade Machinery Inc. for my T/C Encore.

I haven't been able to find much info on the round and I have a little time before they start building it. Does anyone have any suggestions about whether to stay with it or switch to a caliber with more data available? Like 6.5-06AI or 6-284AI or something like that. I like the speed and the availability of brass for the 6mm-06AI.

I like the caliber but not the choice in twist. The 1-12 limits the potential of the cartrage. I have a 243-06 with a 1-10 and wish it was a 1-9.
Thanks, I can still change it, can you articulate the advantages to a 10 twist in this caliber? I thought I would be using 70-87gr bullets mostly. I could go heavier on the bullets and faster on the twist though. Let me know if you think I would benefit from a faster twist on this barrel. Thanks

I think you would be better off with the 1-9 it won't restrict you to shooting the light bullets. I reccommend the 95 grain Berger VLD. I get a little over 3500fps out of these they are great for everything, punching holes in paper, varmits, and deer. When I have to put a new barrel on mine it will surely be a 1-9.
Thanks, your advice makes sense to me. I'll call and make the change tomorrow. Are you shooting a 6mm-06AI? I'm also wondering what to form my cases out of. 25-06 or 270 cases? Loads and stuff like that. Up to now, my wildcat experience has only been 7-30 Waters. lol I've been loading standard calibers since 1990 and never anything like this.


well i have spent the last hour trying to find what the difference of your 6mm-06AI and my 243 Super Rock Chucker (thats actually what mine is called) but i am unable to do so. I just tell people its a 243-06 because its more descriptive than a 243 SRC. I found the demintions for the 6mm-06AI on ammoguide but cant find any for the 243 SRC anywhere. From what i can tell by looking at what i found on ammoguide and from measuring one of my 243 SRC cases the only real difference is the sholder angle the 243 SRC has a 30degree shoulder and the 6mm-06AI has a 40 degree angle which means you will be able to get a little more speed out of yours.

As far as cases goes i would use the 25-06 there will be less that has to be formed. You will have to fireform to get your steep sholder angle which just means you will have to load some up and shoot them and dont worry about where they go. Once you pull it out you will be able to tell a difference in the sholder angle. Now your ready to load. Find some cheep bullets to use to fireform so you dont use up all your good ones. I already gave you my reccomendation for bullet now i will reccomend that you try Reloader 17 for your powder. I just did some testing with this powder and the results were impressive. Its about the same burnrate as the H4350 but you will get more speed with the same amount of powder and pressure. I was using a 87 grain VMax and getting 3400fps with 51grains of H4350. Chronoed a 95 Berger at 3535FPS with 51.8 grains of RL17. A heavyer bullet and more FPS and i know the .8 grains aint gonna make that much difference. As far as loads go with the RL 17 i would start with 48grains and work up from there to be safe. If you got any other questions ill PM you my email address so you can ask.

Just make sure that while you are fire forming that you follow proper barrel break in technique. It will make a big difference in ease of cleaning. Some guys even get more accuracy by doing a good break in.

Wow! Thanks for all the info. Its hard to find anyone who has any info on this cartridge. I like the Idea of the 25-06 case prep as well. I don't have any RL17 But I'll pick some up. I have some 4831 and 4831sc. I figured I'd try them if nothing else. I also have some 4350. I should be able to scrounge up some RL17 without much effort.

This is some regular load data for the 6mm-06. You may want to try some slower powders also. H1000, Retumbo, IMR7828, just to see what it does. Some of these calibers will give excellent accuracy with speed to boot. Having a 28" barrel will help to efficiently burn these slower powders and produce results. Just a thought. You more than likely won't find load data for these slow purners, but if you should choose to shoot a 105grn bullet, this should keep you in the 3300 to 3500 fps range. You would just have to do some pressure testing i.e.: move up one grain at a time until you see signs of over pressure (ejector marks, crushed or cratered primers).

6mm-06 @

I went ahead and made a change to the order. Actually two changes. lol I ordered the 10 twist then called back and went with the 8 twist instead. I've heard some talk of bullets disintegrating as they leave the barrel. Do you think there is a chance of that? I'm looking at most likely shooting the heavier VLD bullets. The 6mm-06AI would seem to be suited to slow burning powders with a heavy bullet and 28" bbl.

I've heard some talk of bullets disintegrating as they leave the barrel. Do you think there is a chance of that? I'm looking at most likely shooting the heavier VLD bullets. The 6mm-06AI would seem to be suited to slow burning powders with a heavy bullet and 28" bbl.


Yeah, you push the Berger (J4 jacket is thin) VLD's over 3200fps (known from others complaints on this sight) and you could see some coming apart in flight. Another option would be the 107SMK and the 105 A-max. From what I have heard and read, you can push this bullet as hard as you want and it will stay together. IF you should want to shoot the 115's, then I doubt you will be able to push them fast enough to come apart. Soooo, some food for thought. A 1:8 is a much better choice of twist in this caliber than the 1:12 you originally wanted. I think you will be much happier and be able to shoot farther more accurately.

Last edited:
i have not had any problems with the Bergers comming apart. Like i said earlier im pushing 3515fps with the 95g and 3230 with the 168. Neighbor is shooting 3300 in hisSTW with the 168s and has had no problems. Im NOT saying that it does not happen its just not happened to me yet. How recent has it happened to anybody and has it done it with the new Hunting Bullets Berger makes? Just wondering if maybe the hunting bullets are a little stronger. Hmmm.
Warning! This thread is more than 14 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.