Barrel length based fuzzy requirements

[muddywings]

I panic bought a Mega Arms upper/lower combo as it was on my to-do list anyway.
It will be a slow build, maybe one major component a month type of project. I have most of the lower parts available/on order. Next month will be a magpul PRS stock but after that I will probably get the barrel and need to figure out 18" vs 20" based on my fuzzy set of needs/wants what this build will be.
So with that, i'm building this to be a bench/prone shooter with the possibility of hunting with it (probably not me, but my step dad will probably borrow it). Not a run-n-gun 3 Gun/Heman type so 16" is out. I also need to keep in mind long term wants such as a suppressor for it, because, why the hell not!
From what I'm finding is 18" use mid-length gas system and 20" use rifle. Initially I was thinking 18" just due to the suppressor option and lugging it around hunting to save some length and weight but with the gas system, I'm back leaning towards 20" to get a softer shooter with a rifled gas system and accepting the longer length and weight.
(I will also be getting a bipod for it if that helps complete the picture of what I'm thinking about)

So instead of building it an asking how did I do, I figure I would get some opinions before I commit on the barrel length (and next the rail length).

any opinions will at least be read...thanks!

[CS1983]

caliber?

Unless the caliber demands 20" due to performance concerns, I'd lean 18".

[muddywings]

oops-good question.
standard .308
know there are better ballistics options for ar10 but i'm going vanilla with this one.

[Hoser]

Get an 18 with rifle length gas.

My OBR is an 18 and I wish I had ordered a 20.

[muddywings]

Get an 18 with rifle length gas.

My OBR is an 18 and I wish I had ordered a 20.

Come on...you know it is easy to confuse me!

[SA Friday]

http://bulletin.accurateshooter.com/2015/06/308-win-barrel-cut-down-test-velocity-vs-barrel-length/

http://www.guns.com/2012/02/16/the-myth-of-barrel-length-and-velocity-loss/

http://www.chuckhawks.com/rifle_barrel.htm

[muddywings]

^^^thanks but more concerned with gas system length as it pertains to a longer distance steel pinging/hunting setup. If 18" came in rifle gas length I think it would be a no brainer for me.

[CS1983]

you mean like this one?

http://aeroprecisionusa.com/308-18-cmv-rifle-barrel.html

[muddywings]

you mean like this one?

http://aeroprecisionusa.com/308-18-cmv-rifle-barrel.html

http://i.imgur.com/xDhqppv.jpg

very

ETA: my googlefu is weak lately

[ray1970]

Just my personal opinion based on nothing factual.

Personally, I wouldn't want a 308 with a barrel less than 20" long. No reason other than that is my personal minimum barrel length for that caliber.

[CobaltSkink]

Aero claims that that 18" tapered, rifle-length 308 barrel weighs 3.27lbs.
It sure as hell feels like it.
I built an Aero rifle with that barrel.
With an Aero 15" Keymod handguard, a rifle tube, and no optics/sights, the rifle weighs a porky 8.8lbs without a stock.

[CS1983]

Could always spend 200%+ more and shave a pound or so..

https://www.rainierarms.com/barrels/308-7-62/18-rifle

[muddywings]

Could always spend 200%+ more and shave a pound or so..

https://www.rainierarms.com/barrels/308-7-62/18-rifle


ohhhh shiny!!

[muddywings]

my googlefu seems to have gotten better

any thoughts on these guys: http://ballisticadvantage.com/18-inch-308-rifle-ss-premium-barrel.html

[Firehaus]

I've been using these on my Mega Maten builds. Rifle length gas, 18.5" barrel. Clover leaf targets at 100yds, if I'm doing what I'm suppose to. I've only had it out to 600yds, but was still happy with the performance.

http://www.fulton-armory.com/barrelfatitan185lwcm1x10750gasblockchrome-lined.aspx



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[muddywings]

I've been using these on my Mega Maten builds. Rifle length gas, 18.5" barrel. Clover leaf targets at 100yds, if I'm doing what I'm suppose to. I've only had it out to 600yds, but was still happy with the performance.

http://www.fulton-armory.com/barrelfatitan185lwcm1x10750gasblockchrome-lined.aspx



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thanks....add that to the 'hmmmmm' list

[SA Friday]

^^^thanks but more concerned with gas system length as it pertains to a longer distance steel pinging/hunting setup. If 18" came in rifle gas length I think it would be a no brainer for me.

Really it doesn't matter. They are all over gassed. Rifle length is just slightly less over gassed. Put a Syrac adjustable gas block on it and be done with the problem from the start.

[muddywings]

^^^ good point...hadn't gotten there with the through process but I get what you're saying. might just have to factor that in

[CobaltSkink]

Aero Precision owns Ballistic Advantage.
My barrel is a "Modern" steel barrel. Your link (from 10am) is the Premium stainless barrel that also has HP and MPI.
I bought my barrel from Schuyler Arms in Tucson.
Schuyler-labelled BA barrel: http://www.schuylerarmsco.com/catalog.php?category=109657

[Firehaus]

thanks....add that to the 'hmmmmm' list

Here is what it looks like.

http://uploads.tapatalk-cdn.com/20160715/533bfb86d8b8f33400945abff8a72492.jpg



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[muddywings]

Aero Precision owns Ballistic Advantage.
My barrel is a "Modern" steel barrel. Your link (from 10am) is the Premium stainless barrel that also has HP and MPI.
I bought my barrel from Schuyler Arms in Tucson.
Schuyler-labelled BA barrel: http://www.schuylerarmsco.com/catalog.php?category=109657

Wow that's a smoking deal



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[muddywings]

Here is what it looks like.

http://uploads.tapatalk-cdn.com/20160715/533bfb86d8b8f33400945abff8a72492.jpg



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Well crap now I need to ask how long of a rail do I need to cover a lopro gas block on rifle length gas? Was planning on 15" rail. I'll have to look at that tmrw. I am leaning your way though but that is a good price just above.


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[Great-Kazoo]

Wow that's a smoking deal



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Those are some nice shooting barrels. I'd go with an 18" lightweight mid-length gas unit, go with an adj gas block. For hand guards, have you considered a carbon fiber one?

Next question... where you at optic wise ;)

[DireWolf]

I've been using these on my Mega Maten builds. Rifle length gas, 18.5" barrel. Clover leaf targets at 100yds, if I'm doing what I'm suppose to. I've only had it out to 600yds, but was still happy with the performance.

http://www.fulton-armory.com/barrelfatitan185lwcm1x10750gasblockchrome-lined.aspx



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I've got one of these mounted on a Mega Maten platform and have no complaints with the barrel at all......

You can't see it from this pic, but with the extended rifle length (14") MKM, a normal lowpro block is completely covered by the rail, and a MicroMOA block (which is a little longer and heavier but freaking awesome for running tuned and switchable normal/off/supressed) just barely peeks out the front of the rail.....

http://uploads.tapatalk-cdn.com/20160715/53424eb55d1a867d38c3b3139662c72e.jpg

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[muddywings]

I've got one of these mounted on a Mega Maten platform and have no complaints with the barrel at all......

You can't see it from this pic, but with the extended rifle length (14") MKM, a normal lowpro block is completely covered by the rail, and a MicroMOA block (which is a little longer and heavier but freaking awesome for running tuned and switchable normal/off/supressed) just barely peeks out the front of the rail.....

http://uploads.tapatalk-cdn.com/20160715/53424eb55d1a867d38c3b3139662c72e.jpg

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purdy....just bring it over and leave her on my doorstep!
i'm leaning that way on the barrel
I don't have that MKM upper, just the standard one so I'm leaning a BCM KMR or a Samson Evolotion 15" I just need to double check that the 15" rail on the rifle gas will cover the lopro gas block. pretty sure but need to double check-I don't know these things off the top of my head.
forgot about the microMOA gas block but I'm leaning towards a 2A Armament RBCG to solve the problem but not committed yet.

[muddywings]

Those are some nice shooting barrels. I'd go with an 18" lightweight mid-length gas unit, go with an adj gas block. For hand guards, have you considered a carbon fiber one?

Next question... where you at optic wise ;)

was thinking BCM or Samson for the rail. I don't think I need CF for a rail.
As for optics...that's pretty far down. We're trying to throw as much at my wife's student loan as possible and I figure once the rifle is built, to get a quality optic it would be a 2-3 month savings to have enough for a quality one. I may consider going low end with a primary arms as a 'hold me over' just to start getting ammo through it but i dunno. It won't be a 1x4 or 3x9 type scope but other than that, I'll still need to do some research/study on those type of hunting precision rifle type optics. mildot, moa, bdc....kinda lost there

[DireWolf]

purdy....just bring it over and leave her on my doorstep!
i'm leaning that way on the barrel
I don't have that MKM upper, just the standard one so I'm leaning a BCM KMR or a Samson Evolotion 15" I just need to double check that the 15" rail on the rifle gas will cover the lopro gas block. pretty sure but need to double check-I don't know these things off the top of my head.
forgot about the microMOA gas block but I'm leaning towards a 2A Armament RBCG to solve the problem but not committed yet.

A 15" rail will cover the gas block (assuming you're not using some kind of funky extended-length block)....

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[SA Friday]

Aero Precision owns Ballistic Advantage.


only 49% of it.

[Rhino0427]

You might consider giving DangerLee a call or PM through the board. He was essential for the AR-10 build that I did with a lot of Ranier and Precision Aero parts. He does this all the time and can talk you through the questions just like he did me. This is what I ended up with:

PA upper and lower combo with BCG
Ranier ultra match 20" barrel
US Pro 4.5# drop in trigger
Odin foregrip (15" I think)
PRS stock
Vortex 6-24 PST scope

Its a lot better gun than I am marksman, but I'm working on it!

[muddywings]

Well, where I am today is not where i was yesterday and probably not where I will be tomorrow but as of now I'm firm on the following since I've already bought them:

Mega arms upper lower
Larue MBT
Magpul PRS stock

This will probably change tomorrow but as of now:
Fulton Armory 18.5 medium barrel in grey w/ threads
SLR Solo 15" rail, SLR block/tube
Atlas bipod on a larue mount

Are Ar10 builds harder than -15? seems like it!

[Grant H.]

You certainly won't regret buying one of the Rainier barrels.

600+ out of my 16" is not a question, and the 24" does great at 1000. When I find a place, I will let you know how the 24" does at 1200.

I really like the SLR Solo handguards. They are light, comfortable, and usable without being stupid looking.

[Grant H.]

Are Ar10 builds harder than -15? seems like it!

In a general sense, yes, because planning and sourcing parts is a bit more taxing without the standardization that exists in the 15.
In assembly? No, not at all.

[muddywings]

Don't want to start a new thread but not sure this will see much traction but here I am so far:

http://uploads.tapatalk-cdn.com/20160804/4091ccf601c5f9dfa3863c6d43542327.jpg

But I'm out of cash for now. Maybe enough for the muzzle brake.
So toss me some options. Long term plan would be for a can to sit out there so take that into account.


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[CS1983]

It's .308?

If so, I have an extra muzzle brake you can borrow for now if you want. I think it's an old AAC 51T. I only ever used it for a brake and not a can mount.

[muddywings]

Might be a good hold me over, temp option. Not a huge fan of borrowing though. I'll PM you....

[CS1983]

Looked again. It's an old 19T. replied to Pm

[osok-308]

Aero claims that that 18" tapered, rifle-length 308 barrel weighs 3.27lbs.
It sure as hell feels like it.
I built an Aero rifle with that barrel.
With an Aero 15" Keymod handguard, a rifle tube, and no optics/sights, the rifle weighs a porky 8.8lbs without a stock.

That's what's bothering me with trying to figure out which Aero upper to get. I'm looking at the 16" and 18" as well for a hunting application. I'm trying to determine whether or not the added velocity is enough to justify the additional weight, especially since most hunting shots aren't taken at distances far enough for the change in velocity to be THAT significant.

[Irving]

Well, I think you need something like 1,000 ft/lbs of energy, minimum, at impact for most big game right? Find a rough idea of the distance where that threshold is crossed for each barrel and decide if that extra weight is worth hauling around in the woods for the 99.99999999999999999999999999999999% of the time you aren't actually taking a shot.

[SA Friday]

Well, I think you need something like 1,000 ft/lbs of energy, minimum, at impact for most big game right? Find a rough idea of the distance where that threshold is crossed for each barrel and decide if that extra weight is worth hauling around in the woods for the 99.99999999999999999999999999999999% of the time you aren't actually taking a shot.
My 150gr SST out of my 8 1/2" barreled 300 Blk is just over 1000 ft/lbs at the muzzle. Not even an issue with 308 of any length. Get the lightest Aero/Ballistic Advantage in an 18" and get to shooting.

Edited to add a Surefire 7.62 break is $56. No can, this is tough to beat.

[osok-308]

My 150gr SST out of my 8 1/2" barreled 300 Blk is just over 1000 ft/lbs at the muzzle. Not even an issue with 308 of any length. Get the lightest Aero/Ballistic Advantage in an 18" and get to shooting.

Edited to add a Surefire 7.62 break is $56. No can, this is tough to beat.

If energy isn't going to be an issue with any length of 308, is there any reason to go with 18" over 16"? Going back to what Irving was saying, I was thinking of going 16" to save almost a pound and a half for walking through the woods.

[SA Friday]

If energy isn't going to be an issue with any length of 308, is there any reason to go with 18" over 16"? Going back to what Irving was saying, I was thinking of going 16" to save almost a pound and a half for walking through the woods.

Not really. It will add a touch more velocity. For a long time, 16" barrels were hard to find in anything other than battle rifle configs. Now there are some pretty good ones. Ballistic Advantage is a pretty decent for the price in 16"