Thoughts on 7mm-08 Ackley Improved... is it worth the effort and added cost?

[MCMXI]

I have a couple of new Criterion 7mm-08 Rem barrels (1:8 twist, 1/2-28 muzzle threads) for a Kimber 84M Montana along with a couple of spare receivers, bolts, triggers (TriggerTech) and stocks (AG Composites) and am thinking about putting all of the pieces together. I was looking at PT&G reamers since I'll need a finishing reamer and noticed the 7mm-08 AI. Comparing the reamer drawings in PT&G's chamber prints book it looks like I could run the AI reamer into the short chamber without issue. I have quite of bit of 7mm-08 Rem ammunition, brass, Redding match dies etc., but don't own a 7mm-08 Rem since selling a Savage Weather Warrior last year. So there's the cool factor with the AI and maybe 100 fps of extra velocity, but I'd need dies ... so what say you? Is the view worth the climb?

Options include the following:

• Building a 7mm-08 Rem and 7mm-08 AI and selling the Rem
• Building one Rem or one AI and saving the additional barrel as a spare although it's unlikely I'd shoot out the barrel since this a hunting rifle
• Building two 7mm-08 Rems and selling one
• Building two 7mm-08 AIs and selling one

 

[troy fairweather]

Yes, do it. The 7-08 I very good an ai just makes it better. Everybody talks about the speed but the other benefits are better to me. What's the mag length if he the kimber.

 

[stillquietvoice]

You could build one if each, the AI does offer some advantages especially with an 8 twist barrel.

 

[MCMXI]

What's the mag length if he the kimber

About 2.84" . SAAMI spec for the 7mm-08 Rem is 2.8" max COL. Not sure about the AI. I couldn't find cartridge or chamber drawings online. Luckily I have PT&G's "The Gunsmiths Book of Chamber Prints" which is very helpful.

Everybody talks about the speed but the other benefits are better to me.

Can you elaborate? What other benefits.

 

[MCMXI]

You could build one if each, the AI does offer some advantages especially with an 8 twist barrel.

If I do that I think I would sell the 7mm-08 Rem since I don't need both, and the AI offers more performance and a cool factor.

Come to think of it, maybe I should sell one as a rifle "kit" and let the new owner figure out what they want to do with it.

 

[stillquietvoice]

About 2.84" . SAAMI spec for the 7mm-08 Rem is 2.8" max COL. Not sure about the AI. I couldn

That's a better mag length than my rem 700 sps, 2.81 in longest oal I can use is 2.807 and still feed from the magazine.

 

[stillquietvoice]

If I do that I think I would sell the 7mm-08 Rem since I don't need both, and the AI offers more performance and a cool factor.

Well the 8 twist will stabilize longer, higher bc bullets at similar speeds as the 7mm08 with mid weight bullets offering longer ranges. More they don't erode the throat as fast either.

 

[MCMXI]

I'd want to shoot a 139gr or 145gr Barnes LRX bullet which would require some jump so the box length shouldn't be an issue for either.

 

[LoonWulf]

I have a couple of new Criterion 7mm-08 Rem barrels (1:8 twist, 1/2-28 muzzle threads) for a Kimber 84M Montana along with a couple of spare receivers, bolts, triggers (TriggerTech) and stocks (AG Composites) and am thinking about putting all of the pieces together. I was looking at PT&G reamers since I'll need a finishing reamer and noticed the 7mm-08 AI. Comparing the reamer drawings in PT&G's chamber prints book it looks like I could run the AI reamer into the short chamber without issue. I have quite of bit of 7mm-08 Rem ammunition, brass, Redding match dies etc., but don't own a 7mm-08 Rem since selling a Savage Weather Warrior last year. So there's the cool factor with the AI and maybe 100 fps of extra velocity, but I'd need dies ... so what say you? Is the view worth the climb?

Options include the following:

• Building a 7mm-08 Rem and 7mm-08 AI and selling the Rem
• Building one Rem or one AI and saving the additional barrel as a spare although it's unlikely I'd shoot out the barrel since this a hunting rifle
• Building two 7mm-08 Rems and selling one
• Building two 7mm-08 AIs and selling one

.284 Shehane..........





Ok perhaps too long, in which casen7-08AI

 

[horsey300]

Can you elaborate? What other benefits.

Idk if you'd gain much velocity, but the biggest sell I see for the ai on ANYTHING, is better brass life and more efficient powder burn, and still able to shoot factory when needed, for sheer velocity, look at data for a plain jane 7-08 Barnes 145, then look at data for plain jane 140-150 cup and core, the higher speeds that I'm used to seeing in a c&c vs mono should be easily attainable for the ai.
Edited to add the info past post that I autopilot posted.

 

[horsey300]

.284 Shehane..........





Ok perhaps too long, in which casen7-08AI

Thief! I knew eventually the shehane would snag you!

 

[LoonWulf]

Thief! I knew eventually the shehane would snag you!

Need the correct action size tho......

 

[MCMXI]

@horsey300, thanks for those points. I've never heard of the .284 Shehane!

 

[troy fairweather]

Lapua is making 284win brass this year.

 

[horsey300]

Need the correct action size tho......

https://www.gunbroker.com/item/888463875
https://www.gunbroker.com/item/888389401
Hmmmmm

 

[WisBorn]

The 280AI is gaining popularity over the 280 Remington with ballistics close to 7mm Rem Mag. The 7mm-08AI should be close to the 280 Remington.

The fast twist of the barrels you have should be paired with the extra velocity gain from the AI.

The biggest reason to go with the 7mm-08AI is the cool factor. Build the AI and wait on the second rifle and see if you love it or not

Have fun with your new rifle!

 

[MachIVshooter]

I've personally never felt AI was worthwhile on .308 based cases, but then, you're not giving up anything either, since you can still shoot factory loads in it, so just a question of the reamer rental and die cost being worth it to you.

My only 7mm-08 is an integrally suppressed shop demo with an 18" barrel that's ported from 14.5", so I don't think the little extra capacity would do much of anything in my case. I'm still getting 150s out of it at 2,641 FPS average with H414 loads, and it sounds like a pellet rifle, save for the sonic crack further out.

 

[gotboostvr]

If you're building a rifle that's intended to be very accurate, you're also doing lots of brass prep. AI'ing it will at the very least help preserve the brass that you're sorting and culling by weight, annealing, uniforming etc etc etc.

That's where I see the benefit of AI'ing some cartridges. It's easier to do it now, than later.

 

[MCMXI]

Thanks for the comments and observations.

Build the AI and wait on the second rifle and see if you love it or not

I kind of want to be done with all of these project rifles and get things sorted out and tidied up, but I think I'm going to take your advice and build one 7mm-08 AI and take it from there.

 

[Gtscotty]

I'm jealous, that sounds exactly like what I've been thinking about as a do everything rifle for a couple years! 18"-20" threaded 7mm-08 AI 8-twist on one of my preferred actions (Kimber/Tikka/M70) in a light CF stock. I always lose steam when I start adding up buying a donor rifle, getting a custom contour tube, short, thin and threaded, getting a nice stock and paying someone to put it all together.

I'm be interested to hear how the builds go, I might even be a potential customer if you sell one off! Any concerns on using a 1/2"x28 thread with the .284 groove diameter? 1/2x28 has been fine on my 6.5, but I'd guess at some point the thread root to groove thickness gets a bit thin?

 

[MCMXI]

I'm jealous, that sounds exactly like what I've been thinking about as a do everything rifle for a couple years! 18"-20" threaded 7mm-08 AI 8-twist on one of my preferred actions (Kimber/Tikka/M70) in a light CF stock. I always lose steam when I start adding up buying a donor rifle, getting a custom contour tube, short, thin and threaded, getting a nice stock and paying someone to put it all together.

I'm be interested to hear how the builds go, I might even be a potential customer if you sell one off! Any concerns on using a 1/2"x28 thread with the .284 groove diameter? 1/2x28 has been fine on my 6.5, but I'd guess at some point the thread root to groove thickness gets a bit thin?

The barrels are 22" long but could be cut back of course. Kimber uses 7/16-28 on .30 cal rifles so 1/2-28 on .284 is only an improvement over what's currently being used. I'd most likely run a Hellfire universal adapter on the muzzle and buy a really lightweight can, maybe a TBAC. Fortunately I have everything on hand for the two rifles so I'm not having to wait on parts. I can order a reamer from PT&G or rent one locally from 4D reamer rentals in Kalispell.

I'll definitely keep you updated and give you first refusal on the parts or a finished rifle. I could even send the barrel to Nick if you wanted it shorter.

 

[Nature Boy]

Ackley-ize it and you don’t need to trim brass

 

[MachIVshooter]

Any concerns on using a 1/2"x28 thread with the .284 groove diameter?

Not at all on a sporter in a relatively sedate cartridge. I would recommend larger on a .28 Nosler or 7mm RUM that's intended for long range precision, but I do 1/2-28 even on .300 win mags for hunting rifles when that's all the barrel will support.

My 7mm-08 integral has 1/2-28 muzzle threads, biggest I could do with the flutes on the Patriot barrels.

 

[Legionnaire]

Taggin' in. I came close to building a 7mm-08 AI; had an action to work with and already had the dies. Then I got sidetracked by the .280 AI. I still think about building a 7mm-08 AI on a Remington Model 7, but I already have 7s in 7mm-08 and 7 SAUM. Not sure the AI would buy me much at this point, other than the coolness factor. Still, I think about buying a McGowen barrel in 7mm-08 AI and trying it on the Model 7 that currently wears a .243 AI barrel. A set of .308 AI headspace gauges will work for .243, .260, and 7mm-08 AI as well. But I sold the dies to a vet who couldn't find any.

Any of the AIs are cool in my opinion. The casual conversations at the range when someone asks, "What are you shooting today?" get fun when you tag on "Ackley Improved" and show them a fire-formed case.

 

[troy fairweather]

If I do that I think I would sell the 7mm-08 Rem since I don't need both, and the AI offers more performance and a cool factor.

Come to think of it, maybe I should sell one as a rifle "kit" and let the new owner figure out what they want to do with it.

I'd like a price quote on the kit and what would be in it lol, don't know how it find a action tho.