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Discussion Starter · #1 ·
So I am currently broke, which means it is the best time to start researching my next purchases-since I can't make impulse purchases, I actually have time time and patience to do real in depth research.

Anyway, I think my next purchase (after picking up a Glock 42 for my wife) will be a rifle length AR build, tuned for varmint hunting (particularly prairie dogs and the like). I have a 8" barrel 300 blackout AR pistol (eventual SBR?) and a 16" midlength 1:8" .223 Wylde AR already.

Anyway, I have some questions.
1) With lighter varmint bullets, is a 1:9 good or do I need to hunt down a 1:12?
2a) How much benefit am I going to see out to a 20" vs a 18"
2b) How much muzzle flash would I see out of 18/20 inch barrel if I get a crowned barrel?
3) are the ACE stocks still among the best fixed stocks for the money?
4) More out of curiosity, if I used a complete rifle upper with a carbine lower until I saved the money to build a rifle lower, what would happen with gas? Over or under? any chance in hell it functions?
 

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1) With lighter varmint bullets, is a 1:9 good or do I need to hunt down a 1:12?
2a) How much benefit am I going to see out to a 20" vs a 18"
2b) How much muzzle flash would I see out of 18/20 inch barrel if I get a crowned barrel?
3) are the ACE stocks still among the best fixed stocks for the money?
4) More out of curiosity, if I used a complete rifle upper with a carbine lower until I saved the money to build a rifle lower, what would happen with gas? Over or under? any chance in hell it functions?
1) 1:9 should be good. 55gr work well in 1:9s
2a) Not much difference, maybe 1/2MOA
2b) I've got a concave barrel on my build and the flash is pretty prominent. Flashes enough to cover the 100yd target for a split second.
3) I can't speak about ACE, but the magpul MOE rifle stock actually pretty darn good IMO. It's solid on a DPMS rifle tube and I like it a lot.
4) Not sure on this one - you run the risk of bottoming out your BCG. It should function, maybe an XP carbine spring from Wolff would ease your mind.
 

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Discussion Starter · #3 ·
4) Not sure on this one - you run the risk of bottoming out your BCG. It should function, maybe an XP carbine spring from Wolff would ease your mind.
Thanks for the response. I hadn't that about that side of it. I am not planning on it, I was more just curious on why it wouldn't work. That would explain why you don't see people doing it.
 

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Anyway, I have some questions.
1) With lighter varmint bullets, is a 1:9 good or do I need to hunt down a 1:12?
2a) How much benefit am I going to see out to a 20" vs a 18"
2b) How much muzzle flash would I see out of 18/20 inch barrel if I get a crowned barrel?
3) are the ACE stocks still among the best fixed stocks for the money?
4) More out of curiosity, if I used a complete rifle upper with a carbine lower until I saved the money to build a rifle lower, what would happen with gas? Over or under? any chance in hell it functions?
1: It depends on your barrel length, your cartridge velocity, and the bullet length and weight, and ultimately how far out you're shooting. A bullet's spin will slow down as it travels down range, and the length of the bullet, as well as it's weight, will determine it's gyroscopic stability factor. It's not a simple answer HOWEVER, general guidance on 24" .223 Rem varmint rifles using lead varmint bullets typically says you're good to go with a 1:12 or 1:9 for lead free as the velocities that the longer barrel produces will create enough RPM to keep the bullet stable out to range.

2a: about 100fps.

2b: 16" barrel

3: i donno...

4: when it comes to the lower, the only difference carbine vs. rifle makes is the length of the buffer tube and associated parts. it makes no difference when tuned for the dwell of the upper. none. my rifle length 18" has a very short dwell, and is under gassed with the mid length tuned carbine lower, but it is under gassed tuned due to a suppressor which increases system pressure under dwell, which equalizes it and make it work perfectly.
 

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2b: 16" barrel

4: when it comes to the lower, the only difference carbine vs. rifle makes is the length of the buffer tube and associated parts. it makes no difference when tuned for the dwell of the upper. none. my rifle length 18" has a very short dwell, and is under gassed with the mid length tuned carbine lower, but it is under gassed tuned due to a suppressor which increases system pressure under dwell, which equalizes it and make it work perfectly.
forgot about adjusting the gas system... is there a guide out there to tuning it?
 

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if there is, i haven't found a good one... if it's throwing brass at 2 o'clock, increase buffer weight, reduce barrel length after the gas port, or reduce size of the gas port. 3-4 o'clock, don't **** with it. 5 o'clock, decrease buffer weight, increase gas port size, or add length to the barrel after the gas port.

getting an adjustable gas block pretty much takes the guesswork out of tuning a system.
 

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The standard M16 type stock is the best stock for the money especially if you are going to build a Rifle for hunting. A dedicated varmit upper should have a 24 inch barrel and an aftermarket trigger Giessel? Exactly how light of a buller will you use? 40 gn ? 50gn? etc. Muzzle flash,it doesn't matter.
 

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Discussion Starter · #8 ·
Ok so I have been looking at M16 a1/a2 stocks. I think I want an A2 stock, as my 7' wingspan appreciates room to breath, so the extra 5/8" will probably help, not hurt like it does for most people. I found this RRA A2 stock kit (Rock River Arms: A2 Buttstock) for $65 (currently $60, but it will be a while before I buy). Is that about as good as I am going to get for new?

Also, If I wanted to go down to 40 gr (potentially--I would be loading at highest velocity I could safely push it to) and I go with a 20" barrel, will 1:9 twist be enough?
 

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Ok so I have been looking at M16 a1/a2 stocks. I think I want an A2 stock, as my 7' wingspan appreciates room to breath, so the extra 5/8" will probably help, not hurt like it does for most people. I found this RRA A2 stock kit (Rock River Arms: A2 Buttstock) for $65 (currently $60, but it will be a while before I buy). Is that about as good as I am going to get for new?

Also, If I wanted to go down to 40 gr (potentially--I would be loading at highest velocity I could safely push it to) and I go with a 20" barrel, will 1:9 twist be enough?
The A2 stock is a good deal - i got mine slightly used (although I believe it is actual military surplus) for $70 for the entire kit. If you were interested in just the stock and you could find a buffer tube kit for cheap, I could part with it for sure... I have a Magpul MOE rifle stock on my AR and its not going anywhere
 

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if there is, i haven't found a good one... if it's throwing brass at 2 o'clock, increase buffer weight, reduce barrel length after the gas port, or reduce size of the gas port. 3-4 o'clock, don't **** with it. 5 o'clock, decrease buffer weight, increase gas port size, or add length to the barrel after the gas port.

getting an adjustable gas block pretty much takes the guesswork out of tuning a system.
Also knight, would increasing spring power help if the brass is ejecting a 2 oclock?
 

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If you want to use a collapsible stock with a 20" rifle-gassed upper, consider the Vltor A5 system. It was developed to offer to the USMC to convert M16a4s to. Collapsible stocks. It uses a slightly longer receiver extension and a special length buffer and spring. I have this on a 16" middie and it shoots very smooth.

If you must use a regular receiver extension, try a Sprinco blue spring with an H3 buffer.

As far as your no. 2, barrel length won't really affect accuracy, but as already mention, should gain you 100-150 FPS in muzzle velocity.
 

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Also knight, would increasing spring power help if the brass is ejecting a 2 oclock?
Well, since nobody seems to have read the thread I posted.

No, a heavier spring will not help if your brass is ejecting at 2 o'clock, unless you'd rather the brass eject at 12 o'clock. Chances are you're over-gassed already, and the rebound bolt speed is fast enough to shove the empties forward before the ejector can fully roll them out the ejection port.

A heavier buffer will delay ejection slightly, and will also allow the bolt carrier to "pause" at the rear end of travel long enough for the brass to eject in the 3-4 o'clock range.

Reducing the gas volume will also limit the rebound action you're experiencing, and dial in the ejection in the 3-4 o'clock range.
 

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Well, since nobody seems to have read the thread I posted.

No, a heavier spring will not help if your brass is ejecting at 2 o'clock, unless you'd rather the brass eject at 12 o'clock. Chances are you're over-gassed already, and the rebound bolt speed is fast enough to shove the empties forward before the ejector can fully roll them out the ejection port.

A heavier buffer will delay ejection slightly, and will also allow the bolt carrier to "pause" at the rear end of travel long enough for the brass to eject in the 3-4 o'clock range.

Reducing the gas volume will also limit the rebound action you're experiencing, and dial in the ejection in the 3-4 o'clock range.
Maybe because I have a rifle spring, buffer, and tube...
 

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Maybe because I have a rifle spring, buffer, and tube...
Let's try this again.

A stiffer spring will make it worse.

A heavier buffer will make it better.

Reducing the gas volume well make it better.

Did I say anywhere in there you had to do all of that?

Contrary to popular belief, rifle buffers can be tuned as well, though your first step should be to have your buffer accurately weighed to make sure you are in the correct range.

An adjustable gas block will reduce the gas volume, and allow you to tune into the lower edge of reliability, which is the best option in order to minimize the stresses your rifle internals are seeing.

Buying and trying everything you possibly could won't solve your dislikes except by trial and error pure luck.
 

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Well lets see. Bought a new spring because the old one was under 12", was pretty obvious it had seen some use. I don't want to adjust the buffer, so I figured the Syrac block would be best. Not trying to be a dick but I have been going at this pretty methodically. Replacing parts that would have needed replacing anyways and changing one thing at a time.

Sorry my AR theory isn't up to snuff some days.

Edit: Also, I did read your thread. It's just hard for me to extrapolate carbine mechanics to a rifle system - you talked a lot about changing buffer weights, H2/H3, etc and all I've got is an old mil surp buffer in there.
 
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