Gunsmithing 7-08 Project - to go Ackley or not.

[mdesign]

I am getting close to starting my 7-08 build and have a question regarding the chamber. My question is should I go with an AI chamber vs. a standard match chamber for better brass/throat life?

I have read that the sharper shoulder angle of an AI chamber makes the forming of a donut less likely and will extend throat life. Anyone know if this is true and that the improvement is really noticable?

I have also read the the 7-08 has problems with donuts but I can't see why it would be any different that a 308. I think both have a 20 degree shoulder.

 

[JCH]

Re: 7-08 Project - to go Ackley or not.

i have problems with donuts too....

 

[wnroscoe]

Re: 7-08 Project - to go Ackley or not.

I'd go non-AI, I hate FFing cases, it's a waste of barrel life

 

[dontstrokeme]

Re: 7-08 Project - to go Ackley or not.

Been looking at 7-08 for about 2 years and this is the first I have heard of "donuts"?

Can you elaborate?

 

[Keith Johns]

Re: 7-08 Project - to go Ackley or not.

NOT. Not. not

The extra case capacity, means you'll need more powder for the same pressure. Sure, you can add even more powder, to get a hair more velocity, but is all that work, money, and testing really worth the minimal extra velocity??

I found that its not, at all

 

[mdesign]

Re: 7-08 Project - to go Ackley or not.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dontstrokeme</div><div class="ubbcode-body">Been looking at 7-08 for about 2 years and this is the first I have heard of "donuts"?

Can you elaborate? </div></div>

Not really as it is something I have read about from time to time but not experienced. The shoulder angle is the same as the 308 and I don't hear anything about a donut problem on that case so I was inclined to think is was hype.

I would prefer not to go with the improved chamber but with all the experience on this site, one can usually get to the bottom of stuff like this. The 7-08 is not known as a barrel burner.

 

[7mmRM]

Re: 7-08 Project - to go Ackley or not.

Go straight 7mm08. You will not be disapointed.

 

[Onemoretime]

Re: 7-08 Project - to go Ackley or not.

7mmRM,
Have you tried the 180 Bergers yet. I'm wondering what velocity you might get if you seat long.

 

[7mmRM]

Re: 7-08 Project - to go Ackley or not.

I have not tried the 180s. Ive been very happy with the 168VLDs @ 2710 in a 22" tube.

 

[JRWALLSIII]

Re: 7-08 Project - to go Ackley or not.

My 7/08 AI will be here in a week or so. Ackleys are not for everyone.

i like something a little diffrent.

To me firforming is not a waste of time. Non fireformed rounds are extremly accurate. You will just shoot a little flatter on down the road.

A straight 7/08 is a great round.

It is all what you want. Everyone would shoot 308 Win. If people didnot like playing with other calibers.

I do belive that my 7/08 Ai with 168 Bergers is going to be a hammer!!!!

 

[sobrbiker883]

Re: 7-08 Project - to go Ackley or not.

Grandpa always said "good thing folks have different tastes, or everyone would want to f*@k grandma".......

I think AI has its place-223 can use the extra zoom, 243 can use a steeper shoulder to help with throat life, etc.
Personally, 7-08 seems OK to me as it is, no AI needed, just my opinion.

 

[olympian]

Re: 7-08 Project - to go Ackley or not.

I would never build a 7mm-08 Ackley. It is already a wonderful cartridge as is.

It you want more case capacity, get a .284 Winchester.

 

[mdesign]

Re: 7-08 Project - to go Ackley or not.

So....is there any truth that the sharper shoulders of an AI cartridge improve throat life? If there is no other benefit than a 100 fps of speed, I think the decision is pretty clear.

The only "donuts" that I have ever seen when reloading is in brass that has been shot 10 or so times and with loads that are on the hot side. Did not seem to be dependent on the shoulder angle.

 

[nicholst55]

Re: 7-08 Project - to go Ackley or not.

The only supposed advantage that I've ever heard claimed for Ackley 'Improved' cartridges other than higher velocity is that the brass flows less, so you have to trim less frequently.

I can't recall ever hearing that they erode the throat any less. When you think about it, how does a cartridge burning <span style="font-style: italic">more</span> powder erode a throat more slowly? Maybe I'm missing something, but... I don't think so.

 

[THUNDERBOLT68]

Re: 7-08 Project - to go Ackley or not.

I have had 7mm 08 AI did not get any extra velocity. i love my 6mm ai it screams. The only advantage is the brass does not flow as much. less trimming. i would stay with standard 7mm-08

 

[sobrbiker883]

Re: 7-08 Project - to go Ackley or not.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: nicholst55</div><div class="ubbcode-body">
I can't recall ever hearing that they erode the throat any less. When you think about it, how does a cartridge burning <span style="font-style: italic">more</span> powder erode a throat more slowly? Maybe I'm missing something, but... I don't think so. </div></div>

243's have a shallow shoulder angle which basically aims the products of combustion at the leade in the throat, the steeper angle of the AI alleviates this a bit. Lots of powder, small bore-you're looking at a barrel burner either way, I just see the AI as the lesser of two evil's.
That's my story and I'm sticking to it.

 

[JRWALLSIII]

Re: 7-08 Project - to go Ackley or not.

If you want more velocity than the 7/08 the 284 Win would be a good choice. You need to run it in a long action, so to a lot of people that is a big down side.

Is the velocity gain worth it???

Maybe, Maybe not.

I will say that barrel life should not even be a factor for this round. A 7/08 AI will get 3 to 4 times the barrel life of the popular 243Win.

Back to the 284 Win. I would run a 280 Ai over the 284 Win (And I already do!!!)

NO need to Fireform.(Nosler makes the brass ready to go) I get velocity that is right at a 7WSM with way less powder, Better barrel life ( I hope), And I can run 4 down and one in the tube without DBM. And Accuracy is great!!!

 

[kink]

Re: 7-08 Project - to go Ackley or not.

Hi my name is Mike and I'm now here and I would like to say hi to all and asks what about the 260 also close to 7/08.

 

[Keith Johns]

Re: 7-08 Project - to go Ackley or not.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">243's have a shallow shoulder angle which basically aims the products of combustion at the leade in the throat, the steeper angle of the AI alleviates this a bit. Lots of powder, small bore-you're looking at a barrel burner either way, I just see the AI as the lesser of two evil's.
That's my story and I'm sticking to it. </div></div>

If thats true, I'd bet its not enough to ever matter. I know 243s are barrel burners, but its probably 98% due to the .308 case and 6mm bore.

For another rumor... I've heard AIs "bounce" the combustion around more than a 20 degree and can hurt accuracy.

I dont much believe either of those

 

[JRWALLSIII]

Re: 7-08 Project - to go Ackley or not.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AZPrecision</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">243's have a shallow shoulder angle which basically aims the products of combustion at the leade in the throat, the steeper angle of the AI alleviates this a bit. Lots of powder, small bore-you're looking at a barrel burner either way, I just see the AI as the lesser of two evil's.
That's my story and I'm sticking to it. </div></div>

If thats true, I'd bet its not enough to ever matter. I know 243s are barrel burners, but its probably 98% due to the .308 case and 6mm bore.

For another rumor... I've heard AIs "bounce" the combustion around more than a 20 degree and can hurt accuracy.

I dont much believe either of those </div></div>

AZ you may want to reaearch the AI on 6mmbr. They are by no means inaccurate. I have lots of tagets to prove that

 

[wnroscoe]

Re: 7-08 Project - to go Ackley or not.

The AI version of any case certainly does not hurt accuracy. I have a 6 Dasher that will prove that point, it's a 6BR Imp.

 

[steve123]

Re: 7-08 Project - to go Ackley or not.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mdesign</div><div class="ubbcode-body">I am getting close to starting my 7-08 build and have a question regarding the chamber. My question is should I go with an AI chamber vs. a standard match chamber for better brass/throat life?

I have read that the sharper shoulder angle of an AI chamber makes the forming of a donut less likely and will extend throat life. Anyone know if this is true and that the improvement is really noticable?

I have also read the the 7-08 has problems with donuts but I can't see why it would be any different that a 308. I think both have a 20 degree shoulder. </div></div>

I've contemplated the same thing.

The only two applications I can see using 708AI is #1 with AW 10 shot double stack mags.That way you could seat 180's out to max mag length and take advantage of the extra capacity.I haven't done the measurements to make sure that the bullet will not sit too far in the case.

Or build one in a long action with barrel life as a main consideration.

Or how about a 7mm Creedmoor AI.

Steve

 

[Downzero]

Re: 7-08 Project - to go Ackley or not.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: .257</div><div class="ubbcode-body">If you want more velocity than the 7/08 the 284 Win would be a good choice. You need to run it in a long action, so to a lot of people that is a big down side. </div></div>

.284 win was, originally, a short action cartridge. Many use it in a long action on here to maximize performance with heavy bullets, but .284 is not "long action only."

 

[OlManDow]

Re: 7-08 Project - to go Ackley or not.

I dont see any caveat here about headspace. I hope you are aware that Ackley chambers use a Go headspace gauge .004 shorter than the non-improved version, and use the non-immproved calibers Go gauge as the No-Go. Else you can't fire factory ammo in it without case failures.

OlManDow

 

[Keith Johns]

Re: 7-08 Project - to go Ackley or not.

You may want to read my post again. I said that was a rumor I heard, and that don't believe it.
I've owned an ackley too. Shot well.

 

[Clark]

Re: 7-08 Project - to go Ackley or not.

I got a deal on 26" Lothar Walther CM barrel blanks in 7mm 1300 taper = ~ 53 ounces finished
I got a deal on Hornady 7MM .284 DIA 162GR BIG GAME POLY CARB TIP 28452 bullets and moly coated them

Comparing cartridge performance with Quickload and Quicktarget at close to optimum powder choice and 65kpsi:
7mmT/CU ........................26.1 gr H335 2330 fps -471 yards
7-30 Waters ........................30 gr W748 2456 fps -395 yards
7mmBR ...........................31.2 gr W748 2510 fps -360 yards
7mm IHMSA .......................40.2 gr Re17 2704 fps -247 yards
7mm-08 .......................40.6 gr IMR4895 2789 fps -198 yards
7mm-08AckleyImproved .........43.6 gr Re15 2833 fps -171 yards
7x57mm ...........................44.6 gr Re15 2843 fps -165 yards
7x57mmAckleyImproved .........46.4 gr Re15 2873 fps -150 yards
284Win .........................50.0 gr IMR4350 2890 fps -172 yards
280Rem ............................53.5 gr H414 2961 fps -152 yards
7mm Rem short action ultra mag 55.5 gr Re17 3015 fps -73 yards
280RemAckleyImproved ........57 gr IMR4350 3019 fps -71 yards
7mmRemMag ......................68.2 gr Re22 3129 fps -15 yards
7mmRem ultra mag ............83.3 gr IMR7828 3130 fps -15 yards
7mmWeathMag ....................71.8 gr Re22 3170 fps +7 yards
7mmSTW .............82.2 gr Ramshot Magnum 3158 fps 0 yards

*The 7mm IHMSA, 7mm-08, 7mm-08AckleyImproved, 7x57mm, 7x57mmAckleyImproved, 280Rem, and 280RemAckleyImproved have 1889 Mauser case heads [7.65x53mm parent] with large Boxer primer pockets and 65,000 psi is a reasonable max pressure for handloads.
*The 7mmBR 1889 Mauser case heads [7.65x53mm parent, 6mmBR parent] with small Boxer primer pockets and could have gone to 80,000 psi:
*The 7mmRemMag, 7mmWeathMag, and 7mmSTW have a 1912 H&H case head [375 H&H parent] and could have gone to 70,000 psi.
*The 7mmTCU has a 1950 Rem case head [.222 Parent] with small Boxer primer and could have gone to 75,000 psi
*7x30 Waters has a Winchester 1895 case head [ 30-30 parent] and could have gone to 70,000 psi.
*The 284 has a Winchester 1954 rebated case head [284 parent], and possibly should not go more than 54,000 psi.

 

[Keith Johns]

Re: 7-08 Project - to go Ackley or not.

Clark, not sure what you mean by "could have gone to 80,000psi."

Is that what quickload said?

 

[Clark]

Re: 7-08 Project - to go Ackley or not.

The real limit for most cartridges is a loose primer pocket.
But with some, it is a pierced primer.
The 6mmBR and it's variants are the highest pressure cartridges.
There is no SAAMI registered pressure for the Remington 6mmBR, but there is a registered pressure with CIP for the Norma 6mmBR.
The limit depends on the firing pin to firing pin hole fit.
Gre Tan offers a service to bush the firing pin hole for $65 on Rem700, and this allows the 6mmBR rifles to go even higher in pressure before the CCI450 magnum small rifle primer pierces.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> Bush firing pin hole and turn pin

$64.00 includes shipping</div></div>
http://www.gretanrifles.com/prices.asp

The reason for the high pressure is that weak spot in most cartridges is between the extractor groove and the primer pocket, but the 6mmBR is thick there with a small rifle primer pocket.

 

[aqualung]

Re: 7-08 Project - to go Ackley or not.

I'm betting that I shoot as much 7mm-08 as anybody, perhaps more! (I do not own a .308, just the 7-08).

Just go with the standard 7-08. No need to AI it. The gain in capacity would be minimal. Hornady has just developed a new range of ammo, higher velocity with the same pressure. If you want higher velocity, go with the straight 7-08 and shoot this new hornady stuff.
My 7-08? Most accurate rifle I own, hands down! Light recoil, it's a real pussycat to shoot.

Honestly, what do you think you are going to gain with AI?

Donuts? That's what cops eat isn't it? No such thing on my cases. Wouldn't even know what you're talking about.

DO NOT mess about fire-forming cases and all that crap, just get the standard 7mm-08 and start shooting!!

N