.308 DPMS SASS "follow-up shot" Build

7disciple7

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Hi guys,

So here it is Xmas day and Santa just gave me the "green light" on a .308 SASS build...Yes, I've been very good this year. I am new to SH and this will be my first build. I have been pondering this build for about a year and would like to submit it to you guys for advice.

I maintain the purpose of a Semi-Auto Sniper System (SASS) is based on the "follow-up shot" or "rapid target engagement." I don't think too many would argue that a bolt action rifle, albeit slower, is far more accurate than a SASS. If I am going to sacrifice accuracy, it had better be for a damn good reason. I want to base this rifle around:

1. Accuracy. (just because I have to give some up to an Auto doesn't mean it still isn't #1)

2. Recoil/Barrel Climb

3. Reliability

3. Keeping it CA Legal (Let's not turn this into how bad CA sucks...we all know it, I am here, and I cannot leave.)

4. Aethestics

With these points in mind I'd to start with the ammo I intend to use. The .308 can be a fickle beast. It is easily effected by weather/wind. A 145gr projectile may recoil marginally less and will travel further but will be swayed by the wind. A 173gr FMJ will do a better job of staying true. I am open to debate which path to go as both have pros/cons. As of now I am leaning towards a heavier projectile like the M110.

I have combed the market for stripped lowers and have settled on a Iron Ridge Armory matched upper and lower.

http://www.ironridgeguns.com/the-ira-x-matched-receiver#sf

with JD Enterprise, Mega Arms, and SI Defence as runner ups.

I am going to request that the take down pins be installed upon shipment (to ensure a good fit). I would also like the "Safe" and "Fire" be filled with red and white paint respectively.

I am leaning towards a 2 Stage Trigger that breaks crisply at 4#s.
http://geissele.com/supersemi-automaticenhancedssa-etrigger-1.aspx

Falcon Industries Ergo Tactical Deluxe with Palm Shelf is the grip I think I want to go with. Sort of a throw back to the HK-PSG1
http://www.midwayusa.com/product/1949223...olded-rubber#sf

and, of course, a Magpul Precision Adjustable Stock.
http://store.magpul.com/product/MAG308/84

I want to run a Hydraulic Buffer and heavy spring.
http://www.nokick.com/Buffer_for_308_AR_w_collapsible_stock_2_5_p/earr-10s.htm#sf

and

http://www.brownells.com/.aspx/pid=...UFFERS/Product/MODIFIED-AR10-BUFFER-SPRING#sf

It seems quite logical that the mass of the Bolt Carrier Group greatly affects felt recoil. Using a reduced weight BCG sounds good but it ties you into an adjustable gas block to maintain reliability. In my research I have found that JP Enterprise comes out on top.

http://www.jprifles.com/buy.php?item=JPBC-4A#sf

I would be interested in sending this BCG to get slick coated to reduce friction and the amount of lubrication needed.

I have yet to find the barrel. Based on the 173gr projectile, I would like a 20" bull barrel (fluted) with a 1:11 inch twist. Adding a heat dissipator makes sense to me. This setup would match the M110.

I like the JP Enterprise "Recoil Eliminator"
http://www.jprifles.com/1.4.2_re.php

or the Alumalite (not sure of it's legality)
http://www.alumaliteusa.com/servlet/the-5-fdsh-8-dsh-24/Categories#sf

A Harris bi-pod.

I am not sure of the handgaurd and optics at this time. I just wanted to put this out there and see what people think. I am positive I am not the first to come up with this so Id like to hear of any similar builds. Thank you guys and Merry Xmas!
 

KillShot

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May 25, 2010
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Re: .308 DPMS SASS "follow-up shot" Build

Lose the hydraulic buffer and get a Slash heavy buffer. If you're wanting to reduce recoil, get a good compensator or brake such as the PWS FSC30. Lose the Harris and get an Atlas V8.

If you're wanting to get a bull barrel to improve accuracy, it isn't needed and it will be a pain in the ass to carry around. Look at barrels from Krieger, Bartlein, etc. as they will give you the accuracy you want without adding a lot of weight.
 

7disciple7

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Dec 22, 2011
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Re: .308 DPMS SASS "follow-up shot" Build

Thank you for the advice. BTW that is a gorgeous rifle you got. What kind of scope is that?
 

KillShot

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Re: .308 DPMS SASS "follow-up shot" Build

It's a NightForce NXS 5.5-22x50 NP-R1 zero stop in the quick detach American Defense AD-Recon mount.
 

7disciple7

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Re: .308 DPMS SASS "follow-up shot" Build

That is what I thought it was and what I was thinking about getting for this build. It is a pretty penny, would you recomend it?
 

SSSamurai

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Re: .308 DPMS SASS "follow-up shot" Build

+1 to Killshot's comments, Slash's buffers are good stuff and I love my Atlas

The 173gr FMJ is old technology, but your logic is sound. The heavier projectiles will fight the wind better. 175gr Sierra MatchKing BTHP is the current M118LR bullet. Another option is the 178gr A-max or 178 BTHP from Hornady. I've had good results with the A-max and will be trying the BTHP soon.
There are a lot of good AR 308 barrel makers to choose from, Noveske, Kreiger, Rainier Arms, etc...
 

KillShot

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Re: .308 DPMS SASS "follow-up shot" Build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SSSamurai</div><div class="ubbcode-body">+1 to Killshot's comments, Slash's buffers are good stuff and I love my Atlas

The 173gr FMJ is old technology, but your logic is sound. The heavier projectiles will fight the wind better. 175gr Sierra MatchKing BTHP is the current M118LR bullet. <span style="font-weight: bold">Another option is the 178gr A-max or 178 BTHP from Hornady. I've had good results with the A-max and will be trying the BTHP soon.</span>
There are a lot of good AR 308 barrel makers to choose from, Noveske, Kreiger, Rainier Arms, etc...</div></div>

The Hornady 178gr isn't recommended for the AR platform but if you're reloading with the projectiles then there won't be an issue.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Disciple</div><div class="ubbcode-body">That is what I thought it was and what I was thinking about getting for this build. It is a pretty penny, would you recomend it?</div></div>

Would I recommend it? Yes, I do but you'll talk to other people who will recommend something lesser priced or higher priced from Vortex, Sightron S3, and SWFA to Premier, USO, Hensoldt, and Schmidt & Bender.

It all comes down to what you're comfortable spending and what you feel will suit your needs the best. I chose the NightForce NXS because they're tough as nails (reliable), have a great reputation in the industry, and have good glass.

With all of the other optic choices I've mentioned and even those I haven't, the NightForce on my rifle is the third one I've purchased. I'm sold on NightForce for all of the previously mentioned reasons and because I feel they offer the best value for the money.

The link that ScottishTornado posted above is linked to the topic for the GAP-10 and it's revered as probably the best AR-10 platform being produced at the moment with a 3/4 moa guarantee and the guys at G.A. Precision will do you right.
 

7disciple7

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Re: .308 DPMS SASS "follow-up shot" Build

The problem I seem to be having is finding a maker that does 20" @ 1:11 twist. You can find 1:10 all day long at that length. Is it really needed if I step up to the 175gr (which is far more cheaper) than the M118 "special ball."
 

KillShot

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Re: .308 DPMS SASS "follow-up shot" Build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Disciple</div><div class="ubbcode-body">The problem I seem to be having is finding a maker that does 20" @ 1:11 twist. You can find 1:10 all day long at that length. Is it really needed if I step up to the 175gr (which is far more cheaper) than the M118 "special ball." </div></div>

A barrel with a 1-10 twist will handle the heavier grain bullets and I'm sure you'll find that it's pretty much the standard for .30 cal barrels in the AR platform.
 

SSSamurai

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Re: .308 DPMS SASS "follow-up shot" Build

1:10 twist would be fine for that whole range of bullets. I've shot M118LR (175gr) out of 1:10, 1:11 and 1:12 and not had any problems stabilizing and getting good accuracy. Is there a reason you keep mentioning the 173gr? That's the old M118 bullet, which has been replaced.
 

7disciple7

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Re: .308 DPMS SASS "follow-up shot" Build

I was basing the barrel length, twist, and projectile weight around the M110. I figured at $20,000 a rifle a lot of research went into this configuration. I misread the 173gr, it fires the M118LR.
 

josie6637

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Re: .308 DPMS SASS "follow-up shot" Build

Maybe a light contoured barrel? Gives you a little more mass w/out all the weight. As commonly seen in spr's
 

Chris K

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Re: .308 DPMS SASS "follow-up shot" Build

The M110 although a very nice rifle, may not be the template to follow as far as accuracy as a first priority. I AM NOT starting a KAC thread, but want to add that there a lot of very accurate AR10's out there, and to use only one as a template may be narrowing your scope too far.

Our 110s shoot very well with M118LR and my 18" DPMS does as well. I would, if I were in your boat, look at as many different platforms as possible, and pick and choose from the crowd.

I think 1:10 is what you will likely find for barrels and they should work very well for you with a number of different projectiles. In fact, CS Tactical may have bartliens on sale right now. IIRC.

Good luck with your build, keep your mind open to new things, and other options, but most of all build what you want, and have a LOT of fun with it.

As a side thought, your requirements in the original post I might swap 2 for 3, to me reliability should trump your recoil management. Recoil can be mitigated by position and equipment (brakes, comps, buffers, etc) reliability to me is paramount, because who wants a gun that fails to fire/eject? Its a frustrating deal...

C_K