Gunsmithing 260, 284, 7mm08 into semi auto or AR10 7mm

roblewis999

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The 260 rem, 7mm08, 284 win are all limited by length constraints and case capacity in the AR10 platform and SA bolt rifles. Bolt rifles overcome this with LA frames, custom chambers, and other voodoo.

I base that statement on the fact that they all have a listed cartridge length of 2.8. This also seems to be teh maximum length of the AR10 magazines.

http://www.6mmbr.com/index.html has a list of cartridge dimensions that I used as the basis of my research for this post.

What has to be done to an AR10 or other semi-auto platform to allow the 260 rem, 7mm08, and 284 win to perform to their fullest potential?

Specifically I am interested in adapting an AR10 platform to fully utilize the 284, with the 7mm08 being my second choice. If the AR10 is unusable- which seems to be the case -what act of god would it take to adapt any of the other semi auto rifles to shoot the long heavy high BC 7mm bullets?

On 6mmbr.com the cartridge dimensions show that the 30-06 uses the same .4728 bolt face, and the nominal cartridge length is ~ 3.3402. Is there any way to turn this into a 7mm sniping platform? It also seems that a 7.62*54 dragunov platform might work with a length of ~ 3.02

Any thoughts or is it just not possible to get the big 7mm bullets into a semi auto?
 

BOLTRIPPER

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

one must be able to drive a gasser well to enjoy the just rewards..........grasshopper.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body">one must be able to drive a gasser well to enjoy the just rewards..........grasshopper. </div></div>

Thanks - that is the most insightful and well researched reply I've ever received. I can't even begin to comprehend how you ever came to that conclusion...useless

In what way did you think that would be helpful? You questioning my shooting skills on a post specifically related to altering and machining parts is absolute idiocy.

I want the three seconds it took me to read that back so I can go bash my head into a wall instead and have something to show for it.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

So you think the M1 garand would be a good firearm to start examining as a potential platform for the 7mm?

I have not used an M1 before - could you tell me why you suggest it in particular?

(availibility of parts, number of good gunsmiths, etc)
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jasonk</div><div class="ubbcode-body">How about the 6.5 Creedmore?

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1977268#Post1977268 </div></div>

Well it isnt a 7mm08 or a 284, but I do appreciate the offer to get in on the group buy.

Will you make me one in 284 that chambers 180gr Berger VLD if I buy a 6.5?
 

DMann

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

You seem to be concerned with cartridge overall length. The Garand was designed for the .30-06, which is the benchmark round for what are traditionally referred to as "long" actions. With cartridges in the .308 family, to be able to load the heavier VLD bullets out far enough to not encroach upon case capacity by seating bullets below the case neck/shoulder joint, you have to go to a long action so that you are not hampered by the magazines and their restrictive length, for a short action - i.e., if you want to shoot say a Berger 180 VLD in a 7-08 or a .284 and not push the bullet back into the case, but still feed from a magazine, in a bolt gun you have to go to say a Rem M700 long action as your COAL will exceed the mag length of a M700 short action.

The AR-10 family is basically a short action (nominal 2.8 inch mag length/COAL). The Garand is a long action. Many Garands have been modified to .308 with no problems. I would think any other chambering on that same case would still work. The .284 could prove problematic since the case body is "fatter" but I seem to remember somewhere seeing Garands that had been converted to belted magnum rounds.

All it takes is money. Somebody will build you what you want.
 

deadly0311

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

you arent going to be making friends well around here. The biggest problem you will run into with the AR platform is not the rifle itself it will be the magazine. Theoretically you could have some mags that are "one offs" and have a lower and upper that are one offs that had a "longer" mag well and alter the feeding angles and ramps. Now given your track record on this thread, i doubt anyone would want to undertake this job by your politeness. Most semis wont work with those cartridges that need a long OAL to get the most out of.
 

Brain

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

284 has been done in the AR10-type rifles. But, I just don't have three seconds to spoon-feed for fear of it being the wrong answer.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

So as long as I pick a "long action" semi-auto and throw money at it its a possiblity then?

OAL= Over All Length?
COAL= Cartridge over all length?

So a 7mm08 should be easier then the 284 in a 30-06 garand?

Know any good smiths that need an odd project?

Do you forsee any reason why this rifle would suffer accuracy problems?

Your answer was exactly what I was looking for, thank you.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Hmm - someone chooses to read a thread, chooses to insult the poster, chooses not to answer the question and thats cool.

The poster gives it back and gets told he's rude and wont make friends.

What am I mising here?
 

deadly0311

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

you are gonna have a tough time here if Boltrippers comment made you that twisted up....just sayin...grow some thicker skin
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadly0311</div><div class="ubbcode-body">you arent going to be making friends well around here. The biggest problem you will run into with the AR platform is not the rifle itself it will be the magazine. Theoretically you could have some mags that are "one offs" and have a lower and upper that are one offs that had a "longer" mag well and alter the feeding angles and ramps. Now given your track record on this thread, i doubt anyone would want to undertake this job by your politeness. Most semis wont work with those cartridges that need a long OAL to get the most out of. </div></div>

I saw a post by 284 win that showed his solution to this problem (albeit with a bolt gun). I looked at my ar and didnt think that this would be something I could duplicate.



Perhaps I was rude yes, but I don't think I should just let people I don't know insult me with no provacation and add nothing to my post.
 

DMann

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Personal opinion here, but converting a Garand to either a 7-08 or 260 or 243 should cause you no problems, and you should be able to shoot just about any bullet available - depending on the twist you choose for your barrel. Staying in the 308 case family means less alteration to the basic action and they will work with the Garand's en bloc clips.

Clint Fowler is a Garand builder, but I cannot find my bookmark for him and Google is being obstinate. Also check out Shuff's Restorations and Dean's Gun Repair (or Restoration). Those are the Garand smiths that come to mind.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Actually the only thing that bothered me is that you seem to think I'm wrong. What did I do to him to make him jump in my shit? Enough of this though - I am interested in rifles, not being a keyboard ninja.

Having a rifle that is a one-off is not a game I want to get into.
 

deadly0311

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

If having a 1 off isnt your goal, then you arent going to get it in an AR platform.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Yeah - I'm a little disappointed about this.

I contacted accuracy systems inc yesterday and they do build 7mm08 and 284 chambered AR10's. And I'm right back to the 2.8 mag limit again.

So I stay with 162/168gr bullets or get into a whole different problem with a completly custom gun. Argh.
 

TEAMSENDIT

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

now get all crazy on me but if you are willing to consider the garand i bet you could rebarrel one into a 280 and it would feed great since it is based on the 3006 cartridge. its not a 284 or 7mm-08 but should give you the same performance, not sure if you would have to do any other mods. honestly i am a bolt guy but it seems like it is doable. also i think cobb or somebody else made a 30-06 based on a ar a few years ago. here is a link to an article on one maybe give them a call see what you can get going.

link http://findarticles.com/p/articles/mi_m0BQY/is_5_53/ai_n27176809/
 

DMann

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Go to Robert Whitley's site, 6mmar.com, and read up on the 6mmSuperLR - basically a 243 with the shoulder shoved back to give a longer neck and less throat burning. Even with 115's you should have no problem staying in a short mag.
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Excellent - I will research these ideas

I wanted to stay with 7mm for the retained energy at range, and reading various threads here lead me to believe that the 243 and 260 were less capable in that regard compared to the 7mm bullets.

This may be a silly question - how much of a difference is there between the 280rem and the 284win? They both shoot 7mm bullets right?
 

roblewis999

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

The Cobb looks cool but I haven't seen them produce anything (other than the 50) since bushmaster bought them a few years ago.

I was only able to find a few for sale after mucho google scouring. It's to bad - that was almost exactly what I wanted.
 

flyboy

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadly0311</div><div class="ubbcode-body">you are gonna have a tough time here if Boltrippers comment made you that twisted up....just sayin...grow some thicker skin </div></div>

My "Tactically Thicker Skin" should be here in a week along with my Counter Sniper Super duper Scope. Then I'll be a real Internet SNIPER.
 

deadly0311

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: flyboy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadly0311</div><div class="ubbcode-body">you are gonna have a tough time here if Boltrippers comment made you that twisted up....just sayin...grow some thicker skin </div></div>

My "Tactically Thicker Skin" should be here in a week along with my Counter Sniper Super duper Scope. Then I'll be a real Internet SNIPER. </div></div>

you always a tool too?
 

flyboy

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

Guess a guy can't be funny these days without offending somebody.
 

BOLTRIPPER

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

well it seems now all one got to do is paint the rifle and all is then well with the world......you do know roblewis999 that then will make you a sniper....right sport ?
 

9H_Cracka

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadly0311</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: flyboy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadly0311</div><div class="ubbcode-body">you are gonna have a tough time here if Boltrippers comment made you that twisted up....just sayin...grow some thicker skin </div></div>

My "Tactically Thicker Skin" should be here in a week along with my Counter Sniper Super duper Scope. Then I'll be a real Internet SNIPER. </div></div>

you always a tool too? </div></div>

I thought that was funnier than shit.

Is the tactical skin in gucciflauge?
 

Veer_G

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Re: 260, 284, 7mm08 into semi auto or AR10 7mm

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: flyboy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: deadly0311</div><div class="ubbcode-body">you are gonna have a tough time here if Boltrippers comment made you that twisted up....just sayin...grow some thicker skin </div></div>

My "Tactically Thicker Skin" should be here in a week along with my Counter Sniper Super duper Scope. Then I'll be a real Internet SNIPER. </div></div>

Be careful, or you'll have Maser trying to hitch a ride on your jock strap.