Need some valued opinions-AR15

[AdamMO]

Buying an AR soon. I like DPMS and have heard good things about RRA. I am wanting a varmint AR, 20 or 24 inch bull barrel. Can I get some advice? What twist do I need? Looking to spend around 1000 or so. Thank you so much for the help. O and it needs to be a 556 chamber.

[Daric]

I just want to mention olympic arms. I have a K8 20'' bull barrel target match model. it shoots sub moa all day long. Best was .6 but all I have shot are cheap factory loads. They also make a UM-1 model that cost a little more. Mine Cost $725 free shipping and no taxes from buds gun shop .com . If you haven't looked around there take a serious look at all their prices before you buy because when you add tax and possibly even shipping with someone else buds become very hard to beat. The K8 is a 556 chamber. "if you live in KY you do have to pay taxes" Good luck with your gun hunting!

[LDBennett]

The barrel twist longer than about 9 inches are for the earlier standard bullets in the 55 grain and lighter category. Those barrels MAY NOT stabilize the new Mil standard of 69 grains. For those and heavier bullets you need a twist shorter than 9 inches. If you try and shoot light bullets in those fast (short) twist barrels the bullets spin at such a high rate that some lesser bullets actually disintegrate from the rotational speed. I had this very problem when I attempted to use hunting 52 grain bullets in my fast twist barrel. I could get premium light bullet to not disintegrate but the accuracy was compromised using them.

So you have to decide up front if it is the heavy bullets or the light varmint weight bullets that you intend to use and match the twist to the chosen bullets.

All that being said it is not the bullet weight that counts towards which twist rate that is needed but the length of the bullet. Since heavy bullets are typically longer, most heavy bullets need the faster (shorter twist). It is the Greenhill formula that gives guidance as to the correct twist rate. The correct twist rate is 150 times the diameter of the bullet squared divided by the length of the bullet (all in inches) according to Greenhill's formula.

LDBennett

[jlloyd73]

I always recommend building your own stripped lower and buying a upper if you are mechanically inclined. I figure I saved about $200-$300 or so doing mine that way. I bought a RRA stripped lower $125 and a Del-Ton upper kit for around $450. Chrome lined barrel, chrome bolt assembly, M4 feed ramps......good deal. Just do some research and look to see if there are any sales going on.

[LDBennett]

Today there are many AR manufacturers. If you stay with a Mil Spec gun you can get stripped lowers for in the $125 range. Most are forged aircraft aluminum. Strength in the lower is not all that important as all it does is hold the magazine and the fire control system. There are many options for trigger systems that can give excellent single stage or two stage trigger pulls. For a Varmint gun you would not be happy with the military trigger that comes with almost any complete gun. You also need a operating handle with an extension because the scope keeps you from getting good access to the Mil version. For a Varmint gun you might also like a more Ergonomic grip as well. The Mil one is only OK for a varmint gun.

When it comes to the upper, it is the magic for accuracy. Buy the most you can with a Match barrel, floating hand guard, and a reputation for accuracy. Again, if you stay with Mil Spec parts then the uppers and lowers all interchange between manufacturers.

My varmint AR uses a Double Star lower with a two stage trigger and an American Spirit Arms flat top upper with a floating hand guard and a Lother Walther 24 inch barrel in a 1 in 8 twist. To meet CA requirements it at one point had a magazine-less lower made to circumvent CA Assault Weapons ban but the recent rulings on mag buttons that require a tool to use (a bullet point is a tool) allowed me to put a regular Mil Spec lower on it and use 10 round mags.

There is nothing to building an AR if you buy the upper complete (barrel already fitted on the receiver). There are videos that show you exactly how. Gun shows in my area of CA have guys there that specialize in the parts and pieces for building up AR's. I think you can get more gun for the same money if you build it up yourself. I have less than $1000 in mine and it is superb.

LDBennett

[AdamMO]

Thank you all for the help, esp Bennett. I will probably just stick to buying one. I will be shooting 50-62 grain bullets, what twist is best for that?

[LDBennett]

According to the Greenhill formula the minimum twist is as listed below:

WT./LEN./DIA./TWIST-IN.
50/0.650/0.224/11.6
53/0.710/0.224/10.6
55/0.680/0.224/11.1
60/0.750/0.224/10.0
62/0.930/0.224/8.1

The lengths shown are typical bullets of the corresponding weights but to do it right you need the exact lengths:

The correct minimum twist rate is 150 times the diameter of the bullet squared divided by the length of the bullet (all in inches) according to Greenhill's formula.

If you get it too fast it may disintegrate hunting bullets. Get it too slow and it may cause heavier bullets to wobble in flight effecting accuracy. But you can use a faster twist with some lighter bullet if they are premium bullets rather than hunting bullets and/or you reduce the velocity significantly, in my experience. You have to test to be sure.

Here's an example: a bullet traveling at 3200 FPS in a 1 in 8 twist has the bullet revolving at 288,000 RPM !!!!

LDBennett

[permafrost]

Originally Posted by Daric

I just want to mention olympic arms. I have a K8 20'' bull barrel target match model. it shoots sub moa all day long. Best was .6 but all I have shot are cheap factory loads. They also make a UM-1 model that cost a little more. Mine Cost $725 free shipping and no taxes from buds gun shop .com . If you haven't looked around there take a serious look at all their prices before you buy because when you add tax and possibly even shipping with someone else buds become very hard to beat. The K8 is a 556 chamber. "if you live in KY you do have to pay taxes" Good luck with your gun hunting!

I concur, Daric, I have the K16 w/SS bull barrel. It has a 1 in 9 twist and is superbly accurate with 55 and 62 grain bullets out to 200yards(that's all our range goes to). It is multi chamber(223 and 5.56)

[Zhurh]

I have 3 Ar's in 556. a colt preban I bought new for $440 in late 80's and two stags I picked up couple years back. I also got a stag 6.8 spc last year; it's all I shoot anymore. Seriously look at the 6.8 spc; several companies make them. We shot a few caribou last fall, one at over 500 yards with the 6.8 and my kids killed several 200-300 lb blk bear this spring with same gun. Luv the 6.8 spc.

[Juker]

Ditto on Stag.

http://www.stagarms.com/index.php?cPath=13_22

[Daric]

I just want to thank LDBennett for the data and info about greenhills. I'm fresh in to reloading and can't wait to see what my free floated AR I mentioned above will do once I figure out what ammo it likes best. My gun is a 1 in 9 twist and cheap 55 gr. have shot really good but there is a improvement when I go to say Hornady match boattails in 62 grains. Best of luck adamMo!
Thefirearmsforum Rocks !!!!!!!!!!!!!!

[Tony22-250]

Spikes tactical makes some fine rifles. Look into them.

http://www.spikestactical.com/new/z/...les-c-113.html

[Snakedriver]

Originally Posted by jlloyd73

I always recommend building your own stripped lower and buying a upper if you are mechanically inclined. I figure I saved about $200-$300 or so doing mine that way. I bought a RRA stripped lower $125 and a Del-Ton upper kit for around $450. Chrome lined barrel, chrome bolt assembly, M4 feed ramps......good deal. Just do some research and look to see if there are any sales going on.

Along the same line, I'm starting my first build of an AR in 5.56 beginning with a stripped lower. What stripped lowers are the best value? Are there any significant differences between all the various manufacturers or is it more important about what parts you put inside when you assemble the lower? It's all very confusing

[LDBennett]

Snakedriver:

I bought a Double Star bare lower at the local gun show. All the internals fit just fine. The one thing that makes or breaks the lower is the trigger. Stock AR triggers are OK for a tactical gun but not very good for a varmint rifle. There are several premium trigger systems on the market, both single stage and dual stage. I have come to prefer a good adjustable dual stage trigger. Brownells has everything you might need for AR's They have a dedicated printed catalog that has it all.

My original lower was a FAB-10 which was a internal magazine lower to circumvent the CA assault weapons ban. Today there is a very strict set of rules for CA that allow regular lowers if you use a "bullet button mag release" and exclude some of the assault weapon common features like flash hiders and collapsing stocks. But this lower also took MIL Std internals just fine. Today it is the lower used on our 50DTC (50BMG case modified slightly to be CA legal as 50BMG is outlawed here). The FAB-10 lower is perfect for this bolt action, magazine-less AR conversion.

Hook up with a gun dealer that stocks all these parts and use his recommendations for the lower. The most important part of any AR is the upper. Get the best one you can afford. My American Spirit flat top varmint upper with a Lothar-Walther match barrel is superb.

LDBennett

[zkovach]

I have a dpms oracle in 308 which shoots extremly well . It definatley needed a aftermarket trigger and I installed a chip mckormick tactical trigger

[JLA]

Originally Posted by LDBennett

According to the Greenhill formula the minimum twist is as listed below:

WT./LEN./DIA./TWIST-IN.
50/0.650/0.224/11.6
53/0.710/0.224/10.6
55/0.680/0.224/11.1
60/0.750/0.224/10.0
62/0.930/0.224/8.1

The lengths shown are typical bullets of the corresponding weights but to do it right you need the exact lengths:

The correct minimum twist rate is 150 times the diameter of the bullet squared divided by the length of the bullet (all in inches) according to Greenhill's formula.

If you get it too fast it may disintegrate hunting bullets. Get it too slow and it may cause heavier bullets to wobble in flight effecting accuracy. But you can use a faster twist with some lighter bullet if they are premium bullets rather than hunting bullets and/or you reduce the velocity significantly, in my experience. You have to test to be sure.

Here's an example: a bullet traveling at 3200 FPS in a 1 in 8 twist has the bullet revolving at 288,000 RPM !!!!

LDBennett

It goes a little further than this LD..

Bullets require a specific minimum RPM to stabilize, the twist rate is what determines what RPM the bullet gets at whatever velocity. This is exactly why .22-250 rem rifles usually bear slower twist barrels than the .223 but they still can shoot accurately with the same bullet weights. If you are running a 55 gr .224 bullet at 2500 fps it will be better served in a 9 twist tube. If you are runing one at 3500 fps, the 12 twist tube will serve better. There is a such thing as overstabilization, I know it sounds like an oxymoron, but over spun bullets usually either break up in flight or yaw uncontrollably throughout their pointblank range. it is best, when deciding on twist rate to consider what the nominal velocity of the cartridge of your selection is with the bullet you intend to use and select a twist rate that will give you the ideal RPM for that bullet at that velocity level.

[D.Mathews]

Originally Posted by permafrost

I concur, Daric, I have the K16 w/SS bull barrel. It has a 1 in 9 twist and is superbly accurate with 55 and 62 grain bullets out to 200yards(that's all our range goes to). It is multi chamber(223 and 5.56)

same here love the k 16 its my first ar 15 wouldnt ever get rid of it

[TheGunClinger]

Originally Posted by grimreefer

Don't buy an AR its horrible, go big or go home ... get those varmints with an AK LOL

I have the only AK-47 in the world that jams at least 2-3 times per mag. Love my AR'S.