6mm Rem AI fire forming


Well-Known Member
Jan 4, 2015
Assawoman VA
So I’m going to rebarrel a savage I have and am strongly considering either a 6mm Rem or 6mm Rem AI both in a 1-8 or 1-9 twist. I have a decent stock of factory 6mm Rem ammo already and that is part of the reason I’m going to “build”. I love Ackley rounds and my go to 280AI shoots 280Rem very accurate, I’m wondering what has your experience been with accuracy when fire forming 6mm Rem in and AI? I will state that I’m super cheap so just shooting to fire from brass isn’t something I like doing.
Hopefully my rambling makes sense
All my Wildcats are AI.
I’ve had no issue creating an accurate shootable/huntable load with the standard case. Once I shoot about 50-100 rounds I’ll develop a fully fire formed load.

Some cases (pun intended) don’t have much stretch others you’ll increase quite a few grains (H20 weight).

So basically don’t waste components if not needed.

Joining Welcome Home GIF

Fireforming loads can be better than initial AI loads even, with how much the case moves in that first shot there's a lot of leeway for pressure that the brass sucks up. Random 243 loads have been the easy button in my AI, I shot up all the old loads in the new barrel just fine.

I did a 7 twist and it shoots Berget 105, 108, 109 great. I wouldn't go slower than an 8 because that gets you the 105 Hybrid. Unless it's a dedicated varmint gun that will only shoot sub-80gn bullets, and then I'd be looking at a 10 or a 12 with a short throated chamber.
I have a 6mmAI on a Savage action. I picked a cheap & fairly long bullet to fireform, just loaded a stout load & jammed them a little; the fireformed cases look great. The fire forming load shot surprisingly well to boot. According to Sierra, the 6mm is one of the best cases to improve as it allows quite a bit of extra capacity.

I ran 10,12, and 14 twists on the 6 Rem AI.

Depending on what the application was, I ran 70g nosler ballistic tips fire forming at 3850+ with
48.5-50.5g of Win 760 with a Federal 210 primer, formed load was 51.5g, and this is a load I used while shooting chucks, coyotes, and jackrabbits.

you can fire form with 14g of Bullseye and cream of wheat, a tuft of paper towel on top to stop the spillage.

80g Sierra Bllitz BT in a 14 twist Shilen, zero freebore with R19 with CCI 250 is real world at 3800 fps.

Hope this helps
I will state that I’m super cheap so just shooting to fire from brass isn’t something I like doing.
Hopefully my rambling makes sense
I get where you're coming from. I'm under budget constraints so I try to do more with less. On my 260 AI loads I jammed into the lands to fire form. My fire forming loads were more accurate ( average .290" 2760 fps) than my current once fired loads ( .490" 2871 fps). For me I felt that I could more completely fire form by jamming into the lands than COW method using my Rem 700. I have the ejector spring to overcome which is one of the factors why I chose jamming. With a Mauser I'd consider COW since I wouldn't have a ejector plunger spring to overcome. I was lucky and found a good shooting fire forming load to practice shooting out to distance. My once fired loads don't group as well at 100 yards, but have better velocity and ES/SD. So far I'm really happy with the consistency at ranges out to 800 yards with my once fired loads. Near misses on sage rats at that distance :) I'll work on them some more and check out to a mile once the grounds get less muddy out here.
243AI here. Fire forming loads are just as accurate as fore formed in mine. Low ES&SD. Just use quality components. Work great for hunting as well. Most of the parent cases were completely satisfactory for the intended purpose. Your simply "improving" some of the best attributes and correcting some of the worst.
on Rem ejectors, I remove them and cut the spring to where the length puts the ejector just barely beyond the rim of the bolt nose, then install the cross pin. By cutting the ejector spring length, the brass is laying right outside of the rifle when firing on the bench and beside my right foot when shooting offhand in the field.

A 260 AI is my next build.

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