Help with AR15 Varmint Build

[Davew223]

My cousin has the RR PP and loves it. I use a RR 16" for 3Gun and hunting, it is plenty accurate and 100% reliable.

 

[ncwg2boatguy]

I have a RR 20in Varmint ss barrel that shoots lights out. 1.25 inch groups at 300 yards with Factory Hornady 55g VMAX ammo.

Yep. They are lasers. I had one a few years back and it was a tack driver too. Here is how my latest build turned out. Specs above in previous post.

 

[Deleted member 48126]

Yep. They are lasers. I had one a few years back and it was a tack driver too. Here is how my latest build turned out. Specs above in previous post.

**** what a rifle! I want to re barrel my SW MP 15. I will always love the heavy barrel over the lighter barrel.

 

[ncwg2boatguy]

Tried a few different loads and commercial loads and it seems to really like the American Eagle 50gr Ballistic tips. No issue with accuracy. Best group so far is a 3 Shot .33" Group. It turns varmints inside out. The 50gr AMAX bullets are 3450FPS.

 

[jonny002]

I'm running a bushmaster 24" upper and shooting 50 gr hornady v-max. loaded around 3100-3200 there's only an entrance hole. Get much over that and they start blowing holes on marginal hits. killed a coyote a couple years ago right at 400 yards with mine and had bullet holes on either side. This is all with v max reloads.

 

[budlight]

Nice groups. I am not looking for a ccomplete upper anymore. I decided to piece one together with the parts I like. The reason I chose to go with the WA barrel is i have read great reviews on multiple forums about their barrels being great and accurate.

On a side note how does everyone feel about breaks or flash hiders on coyote rifles? Can't decide if I wanna throw one on the end or just get the target crown.

I started out wrong taking some ones advice on my first build. 20 inch 1:7 5.56/.223 The twist is for heavier pills and read up on it your self. But 5.56/223 are the worst for accuracy. The Wylde barrels are an improvement. The best is .223 crowned barrels.

Shooting 55 gr bullets a 16 inch barrel is a 200 fps loss compared to a 20 inch and a 24 inch nearly gains 180 fps over a 20 inch.

I have brakes on my two 20 inch barrels and you will see the holes appear on the paper. No jump at all across a good rest. But the flash hider or brake adds length so my 20 is closer to 22.5 inches. So I just bought a DPMS 24 inch 1:9 SS bull barrel.

Get the 7076 T6 aluminum upper receiver. I have two with the heavier full auto bolts in my semi autos and the

https://www.primaryarms.com/JP_Silent_Captured_Spring_for_AR15_p/jpscs-15.htm


My 24 inch gets a nickel boron bolt group and tungsten mil spec buffer tube assembly.

Wylde 20 inch bull SS

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[budlight]

upper 7075 t6

SAA - AR15 Assembled T-Marked Flat Top Upper Receiver - Surplus Ammo

 

[reeloarknot]

I decided on the WOA 18 inch rifle SPR barrel. Just put this together over the holidays, so only a couple dozen rounds, but looks to be a tack driver. It is so far way above my expectation. I think you will be very happy with this selection. And customer service has been top notch. The 1:7 twist is only a concern if you want to shoot super light pills. I have multiple barrels in this twist and they do just fine with 55's. I would not discount BCM, prob one of the best AR companies out there. I have read a lot of great reviews of there stainless barrels.

Here is a list of parts I used.

Hughes Precision Lower with G&R Tactical LPK. (because made locally in Indian River, MI)
ALG ACT trigger.
BCM upper
WOA 18 in rifle gas SPR barrel with there fitted bolt
PSA bolt carrier
Larue 13.2 free float handguard.
Larue low profile gas block
VltorA5 Emod (basically get rifle length buffer and spring with a colapsible stock)
BCM gunfighter charge handle. (medium)

On order is the Nikon M223 Ar scope 3-12 with 600 BDC reticle.

Looking forward to culling some dogs with this rig.

Do your research and choose quality parts and it's hard to go wrong.

Good luck

 

[ncwg2boatguy]

I'm running a bushmaster 24" upper and shooting 50 gr hornady v-max. loaded around 3100-3200 there's only an entrance hole. Get much over that and they start blowing holes on marginal hits. killed a coyote a couple years ago right at 400 yards with mine and had bullet holes on either side. This is all with v max reloads.

Love the 50 gr VMAX. If you want to have a handy stash the American Eagle 50gr Ballistic tips are 7-9$ a box of 20. Surprisingly accurate and cheap enough to keep a couple hundred on hand.

 

[budlight]

The 1:7 twist is only a concern if you want to shoot super light pills. I have multiple barrels in this twist and they do just fine with 55's.

This is not entirely a true statement. Twist rates create a bullet RPM with velocity as a factor. The higher the velocity for a given twist rate the higher the RPM. Shorter length barrels attain lower velocity for a given combination. In testing with a chrono and 1:7 we found that 55 grain .223's when shot at sub 3000 fps could actually stabilize. So 14.5, 16, and possibly 18 inch barrels using factory low powered rounds.

Higher than 1:9 is really a dumb move if you intend to shoot 62 grains or less. The higher the twist rate the higher the resistance to a bullet traveling down a barrel. So 1:8 and 1:7 will have less velocity.

So don't lock yourself into using low velocity 55 and 62 grain bullets and or only heavier bullets. Spinning a bullet faster than necessary can amplify any inconsistency in the bullet.


Quote:

1-in-9 Inches
This is the beginning of the road for the shooter wanting to take advantage of the heavy bullet trend. The 1-in-9 is a great compromise twist rate—not too fast to cause problems with the 55-grain Bullets, but fast enough to stabilize all but the heaviest bullets under most circumstances. This twist will stabilize most traditional bullets up to 75-grains, and monolithics up to 70-grains—but they do so right at the edge of the envelope so not all rifles will do it. My personal 16-inch Rock River Arms carbine with a 1-in-9 twist does fine with ASYM's Tactical Match Grade 77-grain OTM load, but has shown signs of instability with handloads using the 70-grain Barnes TSX—unless the bullet is pushed to maximum velocity. With longer barrels and the commensurate faster velocities, this twist can be more forgiving.

1-in-8 Inches
For a 16-inch general-use carbine, the 1-in-8 twist is about as versatile as it gets. This twist rate will comfortably stabilize bullets up to 80-grains, and the excellent 75- and 77-grain bullets also work great at a wider spectrum of velocities—which means barrel length isn't critical. My 3-gun rifle, built by my friend Iain Harrison, wears an 18-inch, 1-in-8 twist White Oak Armament barrel and shoots just about anything well.

1-in-7 Inches
This is the twist chosen by the military since the switch was made to the M16A2—and the 62gr. M855 cartridge—in the 1980s. This twist is found on the M4 carbine, the M16A4, the Mk12 Special Purpose Rifle and even the HK416. Its ability to stabilize tracer rounds in-flight is one of the reasons that the military chose this twist rate.

This barrel will stabilize bullets of up to 90 grains, and can handle the 70- to 77-grain bullets at just about any velocity, which makes it well suited for carbines with very short barrels. If you want a Mil-Spec clone, the 1-in-7 twist is the way to go.

I currently own two AR-15s with 1-in-7 twist rates—a 10.3-inch Mk18 Mod. 1 and an 18-inch Mk12 Mod. 1—both made by Monty LeClair at Centurion Arms. To illustrate how velocity and twist rates can be the ying and the yang of bullet stability and accuracy, I fired a variety of loads side-by-side from the two rifles. The 10.3-inch SBR shoots anything from 55-grain FMJ to 77-grain OTM with excellent accuracy, while the 18-inch Mk12 is scary accurate with the 70-, 75- and 77-grain bullets—but won't shoot 55-grain or 62-grain FMJs worth a ****.

Matching the rifling twist in your rifle or carbine to the appropriate ammunition won't guarantee great accuracy, but it will ensure the bullet is properly stabilized in flight. On the other hand, using a bullet that's too heavy for your barrel's twist is a virtual promise of poor accuracy and ineffective terminal performance. If you're struggling with the accuracy of your modern sporting rifle, be sure you've properly matched your ammunition to the barrel's twist.

 

[Deleted member 48126]

You're on it, budlight. Thanks for sharing. I've learned a lot from your posts. gun)

 

[Ghostwolf308]

So far I think I have what I want figured out. I have been doing alot of research and talking to people but if someone sees something they think would be better off different please let me know.

I have a locally made 7075 t6 lower with a spikes tactical parts kit w/ JP trigger springs
a carbine length buffer tube currently with a spikes tactical st-t2 buffer and spring
Magpul STR stock

and am planning on adding the following
Vltor MUR 1A upper
WOA 18 in rifle gas SPR barrel with there fitted bolt (still deciding if I should custom order it 1:8 twist)
JP low profile adjustable gas block
VG6 EPSILON 556 muzzle break
Odin Works 15" Keymod free float handguard
La Rue Tactical scope mount
Vortex Viper PST 2.5-10 FFP scope
JP low mass bolt carrier
JP low mass or captured buffer/spring
Im thinking either the BCM ambi or the rainier Raptor ambi charging handle
ALG ACT trigger with JP springs

I have heard that the Vltor MUR upper helps increase accuracy over other uppers because of its tight tolerances and added mass in certain areas. I have heard this from guys with multiple ar's and have read that the Vltor and Mega uppers are best for accuracy. The reason I am choosing to go with the adjustable gas block and low mass components is I have been talking to a guy that shoots three gun and he suggested the low mass components and adjustable gas block with a brake to remove virtually all recoil for faster followup shots.

As for the barrel I have read nothing but positive reviews on the quality and accuracy of the WOA barrels. I have talked with them and I can special order the 18" spr barrel in a 1:8 twist if I decide the 1:7 is to fast.

 

[budlight]

I'm one for higher powered scopes. I have a Nikon p223 4X12 BDC and you can't even really see a hole open up on paper at 100 yards. So I went with a 6X24 56 mm I do both paper and hunting

 

[Ghostwolf308]

I plan on getting a 6-24 for my 308. I think this build will be fine with the 2.5-10. I have a fixed 10 on my 308 now and it works great for everything inside 600 yards. Can't see holes in paper to well but i use dirty bird targets and a spotting scope for that.