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blacklab

Precision gun build

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Im going to give  precision shooting a try in the near future so I scavenged parts off my other rifles to put together a  precision rifle and was wondering if I’m headed down the right path. What I have is:

AR 10 upper/lower

18” 6.5 Creedmore Ballistic  advantage barrel with 875 non adjustable gas block and  carbine gas tube 

M4-72 muzzle break

Standard weight BCG

JMT single stage 3.5lb straight trigger (I know, not the best choice but I’m not willing to give up my ELF out of my 3 gun rifle)

magpul PRS stock

standard weight buffer

burris MTAC 4.5-14x42 scope in a waren mount (again I know there are far better scopes but I had this one and thought it would be a good starting point)

Any  suggestions on what/if things need to be changed would be appreciated. 

As of right now I don’t reload 6.5 so I’ll be using Hornady ELD match 140gr. 

 

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You'll want a longer barrel so you can increase the muzzle velocity, that way you'll have less bullet drop at longer distance.

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Oh, ok. I had a 18" off a hunting rifle. Should I go with the 24" right away or is that going to a problem for free hand shots with too much weight out front? Is there a happy medium or is longer just better?

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If your gonna get a diff barrel look at 6 creed jp barrel that's what I shoot its 22 in. With the factory ammo available you will get more speed with a shorter barrel. My ammo is no where near max I'm getting about 2930 fps so the barrel should last as little longer 

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My comment above had nothing to do with length. Ballistic Advantage barrels for large frame guns are notoriously meh in the accuracy department, plus if you really have a carbine length gas 18" 6.5 CM barrel you're likely to be blowing primers with factory ammo. BA usually overgasses barrels too, and you'll want an adjustable GB no matter what.

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41 minutes ago, TonytheTiger said:

 Ballistic Advantage barrels for large frame guns are notoriously meh in the accuracy department, 

Ugh, I thought they were fairly good barrels. But then again I was using it for a field gun.  Its a mid length tube I was thinking of another gun when I posted, my bad. 

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Their small frame barrels are usually accurate enough for what most people do with AR15's, but they're still budget barrels. Once you step up to large frame guns and the extra pressure that comes with them budget barrels are not what you want, and all the cost saving measures are magnified. And they still won't port them appropriately and are apparently the last people around to have noticed mid length gas is still too short for an 18" 6.5 CM. If you're not handloading you might not mind it, but there really is no reason to be beating up brass and the rest of your gun with a poorly engineered system.

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What’s a good make, length and twist barrel?  Obviously rifle length tube is best. Not too worried about price, buy once cry once. Is there still an advantage using a adjustable gas block and low mass system? I know with 3gun low mass is a huge advantage. 

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Off the top of my head, Rainier Ultramatch, Proof Camgas, Craddock Precision, Keystone Accuracy to name a few. All these places turn out great barrels and will have 18" rifle gas and then +1" and +2" gas systems on anything longer than 18". Low mass systems aren't critical but being able to tame the gun with an AGB and something like a JP SCS can mean the difference between a brass chewing, small part destroying, AK47 feeling, needlessly excessive recoiling rifle and a finely tuned smooth running machine.

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12 minutes ago, TonytheTiger said:

Off the top of my head, Rainier Ultramatch, Proof Camgas, Craddock Precision, Keystone Accuracy to name a few. All these places turn out great barrels and will have 18" rifle gas and then +1" and +2" gas systems on anything longer than 18". Low mass systems aren't critical but being able to tame the gun with an AGB and something like a JP SCS can mean the difference between a brass chewing, small part destroying, AK47 feeling, needlessly excessive recoiling rifle and a finely tuned smooth running machine.

Got it. Thanks, that's the info I was looking for.

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I'm doing a similar project. Have a Brownells 24" 6mm creedmoor with rifle gas. Would a +1 or +2 be much better?

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A lot of people have trouble with getting 22"+ rifle gas barrels to run right. Apparently they actually have too much dwell time and an AGB and super heavy buffer and possibly reduced power loads or powder burn rate experimentation are the only way to get things timed properly.

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3 hours ago, TonytheTiger said:

A lot of people have trouble with getting 22"+ rifle gas barrels to run right. Apparently they actually have too much dwell time and an AGB and super heavy buffer and possibly reduced power loads or powder burn rate experimentation are the only way to get things timed properly.

Seems like anything over 22" would be counter productive in a gas gun then. Heavy buffer would be more felt recoil and make it harder to call the shot, Right? Reduced power loads would drop velocity and cancel any advantage the longer barrel has, wouldn't it? Unless I'm looking at things wrong a 20" barrel with a AGB and JP SCS would be a good setup. Sorry to be a pain Tony the tiger and ask so many questions. But I've learned the hard way in the past that you should do your homework BEFORE you buy.?

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I'm not saying a 22-24" rifle gas barrel won't work, there's too many variables to make absolute statements like that. What I am saying is that you stack the odds in your favor and buy a wider operational window by getting the longest gas system possible. Things like reamers used, gas port size, the particular lot of ammo you have and even your atmospherics can all come into play and make a system that works for the next guy be a total failure for you. Most higher end manufacturers like JP or any I mentioned above have started standardizing longer gas systems and there's a reason for it, they spend less time on the phone troubleshooting for the guys whose component/ammo choices put them on the edge of functioning.

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There's too many things for me to wrap my head around for now. Its way more complicated then 3gun.  I think I'll shoot a match or two with the setup the way it is and see what happens. A friend told me the first match he shot he only engaged 17% of the targets so I don't think I'll be the first person ever to shoot badly. I'm not looking to be the next world champion but I would like some bragging rights. After I figure more things out I'll look into a better setup starting with a barrel and go from there.

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Yeah once you get into large frame guns and faster cartridges than 308 it's a whole new game. 

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You will want a rifle that will consistently shoot a honest 1 MOA or under for matches and many large frame semi autos struggle to deliver. With the heavier bolt carrier group I think fitment of parts, etc. may be more critical than in small frame AR. Semi autos have frustrated me more times than I can count. Bolt rifles not so much.

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