Fire forming 6mm Al brass

[ballisticsman49]

Could someone please explain the exact process of fire forming brass for the 6mm Al. Also what is the best brass to use,what brand and case). Should I just use normal 6mm brass?
Thanks in advance.

 

[1000yardstare]

BMan49: These are the exact questions going through my mind as I am about to receive a 30 inch, 8 twist McLennon 6AI barrel on a 722 action. From what I have read Win 6mm brass seems the best. Some guys are necking down Norma 7x57 brass and turning the necks but that sounds like too much work to me. Hopefully the barrel is headspaced such that there is resistance when closing the bolt on an unformed 6mm case. If not, I plan to seat the bullet out to jam into the rifling to set the headspace upon firing. The latest Sierra manual has a section on the 6AI and I plan to use a max load of RX22 under 105 gr AMax bullets and fireform at F Class practise at 500 and 600 yds. Will only use fireformed cases for 1000 yds. Like you, I would be interested in hearing tips and techniques from experienced 6AI users.

 

[vlcakc]

Gunamonth's advice is spot on. Just shoot max or near max 6mm Rem loads in the AI chamber. If the chamber is headspaced correctly excessive jamming of the bullet into the rifling isn't necessary and probably wouldn't help anyway. Don't get caught up in the Winchester/Remington/Federal 'best brass' argument. With today's component shortage situation, you usually have to shoot whatever is available. I have had better results with Remington brass in my 6mm AI than other brands. Does this make my choice of brand right and the shooters that prefer other brands of brass wrong? Nope. To me it just shows that the quality of domestic brass is so variable that getting good brass is somewhat the luck of the draw. I've gotten really good brass and really crappy brass at various times with all the domestic brands, Remington, Winchester and Federal included. Good shooting. Vic

 

[Cheechako]

Vic nailed it. It's the luck of the draw. A buddy and I both built 244 Ackley rifles about 10 years ago. I bought a bulk bag of W-W, sorted and weighed them and got 184 good cases out of 200. That's pretty darned good. My buddy went with Remington and had similar results. We were both lucky that day.

Ray

 

[DJ]

I just got done fireforming my first batch of AI brass ever and I used a close to max load of H414 for 6mm rem from Hodgdons website. I didn't need the bullets touching the lands. I also necked down the Norma 7x57 ONLY because I couldn't get my hands on any WW 6mm brass. It is a pain, but a learning experience for sure!! I tried 4 different dies to neck it down and Preacher suggested,on this forum)I use a 257 Roberts fl die then a 6mm fl die and he was right. I tried a 6.5-248 fl to a 6mmAI fl die and that was a disaster. I used a K&M turner to get the neck to a save thickness. Good luck!!
DJ

 

[Ackman]

If the chamber is cut properly, 6mm brass is what to use. If there's no crush on a 6mm case, use .257 or 7x57 and set a false shoulder to where it headspaces correctly. Or if the chamber neck diameter has a lot of slop, you might also want to use the larger brass and neckturn before necking down. It takes some time but if you're not doing many hundred cases it's not such a big deal.

The 6mm case has a lot of body taper and a pretty shallow neck angle. It blows out quite a bit to become an AI. What's a max load for the standard 6mm is an extremely mild 6mmAI load......way below anything you'd ever use in a formed case. To find a good fireform load, start at least at top end for the std 6mm and go up until you reach best accuracy. With W760 and a 70gr bullet that will be around 50gr or so.

For comparison.....with the 257AI which has the same parent case, my fireform load is 50.5/760 with an 87gr bullet.

 

[ballisticsman49]

wow! thanks guys, i definitely found the best forum for that kind of question. But i got another one...
I will be using the rifle for mid-long range varmint/target shooting 400-600yds. I want to use a pill that'l both travel fast and have some hit when it reaches the dogs down field. I think Ill go with the 75 V-Max cause of the fact it can be rocketed out at near 3800 which will undoubtedly result in a lazer like trajectory.
So seen as Ill be using a shorter projectile than '1000yardstare' with the 105 grainer, it won't be touching the rifling/lands will it? So I won't need to worry about that.
Also I think in conclusion to your comments I will begin my fireforming with winchester 6mm rem brass with, a max load?
Do I need to find an accurate fireform load to Ackleyize the cases? Is it so the cases are all perfectly equal? And finally do I have to use the same projectile in fireforming that I plan to use once I have the cases fireformed and preped

Thanks again fellas
B'man49

 

[vlcakc]

There are several good reference articles on fire-forming. One is in the 'Articles Archive' section of this website. Look for '260 Rem Ackley Improved Case-Forming'. The article contains a lot of case forming general information as well as specifics about AI forming. Vic

 

[Ackman]

Look at it this way....with AI cartridges you don't CHOOSE a particular load and then use it to fireform, you FIND an accurate load by working up to it the same as with any other cartridge, then use it in the field. That load won't be far off what you'll be using with formed brass. All the cases will come out perfectly equal. Then with formed brass and the same bullet, start at that same powder charge and go up slowly from there. It won't take a whole lot more to get where you want to be. That's all there is to it. None of this is tricky and fireforming isn't the ordeal that some would make it out to be. It's not wasted barrel life or components or anything else like that, those are useable loads going well faster than the parent cartridge and sometimes not a whole lot slower than with formed brass.

Don't seat into the lands with a varmint gun unless you can always remember to fire every round that's chambered. Jam the lands and eject an unfired round, it'll definitely happen sometime that a bullet sticks. Which leaves a bunch of powder in the chamber and bolt lugs. The gun is out of commission until it's all thoroughly cleaned.

 

[DJ]

ballisticsman49 I think the answers to some of your questions depend on what 6mm pills you have on hand, if you intend to hunt or must get maximum accuracy with your fireform load. I am still working up a load for my rifle,hopefully with 87 vmaxs) but used some old 100gr remington elcheapo bullets to fireform because I was just worried about getting the case blown out so I could start my load development and as you know heavier bullets get you to the high pressure you are looking for with less powder,can you tell I'm cheap and spent all of my money on the norma brass). I wasn't worried about accuracy because the tree the paper came from was already dead. I personally didn't use a maximum 6mm rem load,but close) and about 4 of the 50 I fireformed had slightly rounded shoulders,I would use max knowing what I know now..I'm new to this Ackley stuff too), but that was taken care of with the next loading. If you don't care about how well your fireforming loads shoot....go cheap.....if you are......work up and grin when you can't tell where one hole ends and the other begins!!
Good luck
DJ

 

[ballisticsman49]

Thanks again guys, vic i found that article very informative thanks a lot!
Ackman, you simplified it for me, cheers
And thanks DJ

A lot of help

B'man49