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BurningOrange
04-20-12, 12:25
I am in the planning stages of an SPR build that I have had in the back of my mind for some time and would like a little advice. I am somewhat new to the "custom" AR game but I have been doing some research and think that I have come up with my* build components. My goal is a good all around rifle with above-average mid/long range capabilities and while I'm not trying to throw as much money as possible at it, I don't mind spending extra the first time around for quality parts or to get it done how I want it. Please take a look at what I've come up with so far and let me know if you see any glaring mistakes that I may have missed.

*As this would be my first AR build, I will probably be having someone much more qualified do the actual assembly.





Upper: Bravo Company BCM SPR Mk 12 Mod 0 Bravo (Natural) w/: BCMGUNFIGHTER Mod 4 (med), Ops Inc 12th model brake & collar, ARMS #38 Rail & #40 BUIS (http://www.bravocompanyusa.com/BCM-SPR-Mk-12-Mod-0-Bravo-Natural-p/bcm-urg-mk12-0%20pri%20nat.htm)

Lower Assy: BCM Lower w/: BCM Mod 1 Blk Grip, Noveske QD receiver plate, Geissele SSA-E trigger group. (http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=LWR-BCM)

Stock: Magpul PRS PRECISION-ADJUSTABLE STOCK AR15/M16 (5.56X45) MODEL

Optics (Long Range): NightForce NXS 3.5-15x50 F1 w/ H-58 Reticle, Mil-Rad, Zero Stop and LT104-30 QD Mount (http://www.laruetactical.com/nightforce-nxs-35-15x50-f1-w-h-58-reticle-mil-rad-zero-stop-and-lt104-30-qd-mount)





A few notes:

I have not made a final decision on which BUIS or muzzle brake that I want to go with (only that I would like it to be suppressor compatible) so I add those listed as place holders for now.

As for the NightForce optic: It may be overkill for this build but I view it as a quality optic that can be moved to a higher caliber (longer range) gun if I choose so I count it as more of an investment than a necessity for this build.


Any constructive input is appreciated

a0cake
04-20-12, 13:30
Let's ditch the term SPR, since we're not talking about an actual MK12, and call this genre a "precision AR."

Those PRI tubes / ARMS Rails / Folding front sight gas blocks are really not the greatest. They're relics and unless you want that configuration for so called "clone" or nostalgic, or historical purposes, there are better options. Go with a pinned gas block and a rail that covers it. A 14'' DD Lite Rail is a great solution for an 18'' barrel with rifle gas, and is what I use on mine. A 15'' Troy Alpha rail is another (although there are sometimes GB contact issues), if you prefer the tubular style.

As far as the lower, the Magpul PRS is designed for a rifle buffer system, and will not fit on the complete lower you have selected. IMO, the PRS is a clunker and doesn't do anything for me anyway. BCM recommends an H3 buffer if you're using a carbine buffer system with their 18'' rifle length gas system SS410 barrels. But what you should do is look into a VLTOR A5 buffer system. This will allow you to retain the soft shooting nature of the rifle gas / rifle buffer without fixing you into a certain length of pull. Top it off with a heavier stock to keep the rifle balanced and you're in business. With front heavy rifles, a lighter rear end doesn't balance quite as well, and for handling, balance can be just as important as weight.

So, in the end, here's the direction I think you should be moving:

- Rail that covers a pinned GB.
- VLTOR A5 buffer with ACS stock or similar.
- Geissele SSA-E or SD-E.

BurningOrange
04-20-12, 15:06
Thank you, I much prefer the term "precision AR" to SRP in this case.

Also, thank you for the info, a0cake! You have given me a lot to think about. I'm not completely familiar with pinned gas blocks (just heard the term here and there) so it looks like I have a little more research to do. I will certainly look into the VLTOR A5 buffer system and the ACS was actually my initial choice so I have no problem substituting that.

As far as the tube/rails, I was hoping to retain the PRI tube as I am just a little nostalgic to it's look and feel. However, I hear what you are saying and I am now starting to look into ditching the folding front sight GB and going with a pinned GB as you recommended (as stated, I need to do more research on pinned GBs). With that in mind, I noticed that PRI offers a Gen III 15" Free Float Carbon Fiber Forearm. Do you know if that would cover a pinned GB adequately?

caelumatra
04-20-12, 15:52
If you're wanting a higher cheek weld I'd go the MOE or ACS + larue risr. The PRS is mightily heavy compared to the alternatives out there

I took mine off of my AR308 without even firing it. Too damn heavy lol. The lower alone with the prs weighed over 5 lbs

Pappabear
04-21-12, 03:53
I like the PRS stock, but it is heavy. And you might need it if you get that NF scope. That rail looks fugly to me and cheap. But to each his own and it might be nice.

I went 18 inch white oak barrel and 12 inch DD rail. Change that rail and front sight and I think your GTG.

Sticks
04-21-12, 04:39
You could also go with a Centurion Arms Mk12 Mod1 or DMR (MK12 with the MK262 chamber) and have your SPR upper.

Ditto on the Vltor A5 receiver extension.

If money is not a factor, lots of top quality uppers out there to choose from.

zombie killer
04-21-12, 12:46
With the LT 104 you may need a stock that allows for a higher cheek weld. I initially had a UBR but traded it for a PRS to meet my needs.
I built a similar set up with and was considering a DD 14 inch rail and a Vtac tube. I went with the DD but think a tube would be just as good.

The_War_Wagon
04-21-12, 13:09
I'll second the VTAC tube (15" on mine), but that UBR stock is largely overkill. I actually went ACS on mine.

http://i212.photobucket.com/albums/cc305/The_War_Wagon/New%20build/T-1.jpg

BTL BRN
04-21-12, 20:33
I decided on something similar to you for my modified RECCE build, it's a DD 16" middy with a MFR 12.0 rail, MTAC in a Bobro mount, Geissele SSA-E trigger and ACS-L; really soft shooting, and incredibly accurate.

http://i41.tinypic.com/34p0vmd.jpg

I may eventually go with something more than a 1x4 optic, but for now I really like it; you seem to have some really nice parts picked out, but I agree about ditching the UBR in favor of something lighter.

clmarshall21
04-29-12, 09:15
War Wagon, what mount is holding your RDS? From that angle it almost looks like it is integrated into your scope mount (which appears to be LaRue) but I have never seen that before. I would have guessed that it is a separate mount that fits under the LaRue but it does look convincing in that pic! Nice rifle

OP, I am in the middle of a "precision" build myself. The upper is very similar to War Wagon's (MUR receiver and Alpha 15" handguard). The build is mostly Rainier Arms parts including their 18" Match SPR barrel. They can assemble the upper for you and ship it as a complete upper. They have been very helpful so far and hopefully I can give a review on that build soon. Out of stock parts are the only delay at this point. Check out RainierArms.com if you are interested. Good luck

Scoby
04-29-12, 09:51
Let's ditch the term SPR, since we're not talking about an actual MK12, and call this genre a "precision AR."

Those PRI tubes / ARMS Rails / Folding front sight gas blocks are really not the greatest. They're relics and unless you want that configuration for so called "clone" or nostalgic, or historical purposes, there are better options. Go with a pinned gas block and a rail that covers it. A 14'' DD Lite Rail is a great solution for an 18'' barrel with rifle gas, and is what I use on mine. A 15'' Troy Alpha rail is another (although there are sometimes GB contact issues), if you prefer the tubular style.

As far as the lower, the Magpul PRS is designed for a rifle buffer system, and will not fit on the complete lower you have selected. IMO, the PRS is a clunker and doesn't do anything for me anyway. BCM recommends an H3 buffer if you're using a carbine buffer system with their 18'' rifle length gas system SS410 barrels. But what you should do is look into a VLTOR A5 buffer system. This will allow you to retain the soft shooting nature of the rifle gas / rifle buffer without fixing you into a certain length of pull. Top it off with a heavier stock to keep the rifle balanced and you're in business. With front heavy rifles, a lighter rear end doesn't balance quite as well, and for handling, balance can be just as important as weight.

So, in the end, here's the direction I think you should be moving:

- Rail that covers a pinned GB.
- VLTOR A5 buffer with ACS stock or similar.
- Geissele SSA-E or SD-E.


Solid advice.

For the rail, I be looking at one of the Troy options if you like the circular type rails.

LawTac
04-29-12, 10:45
+1 on White Oak, they built my SPR (I am calling it an "SPR" and not a "precision ar" because it was built as a MK12 clone). Its the best shooter I own, I don't consider the mk12 builds relics, but yes you have many many more options available today. +1 on the 18" barrels for this type of built.
https://www.m4carbine.net/attachment.php?attachmentid=11999&d=1335710688
https://www.m4carbine.net/attachment.php?attachmentid=12000&d=1335710707

TehLlama
04-29-12, 16:28
Mine is a Centurion DMR (Mk12 Barreled) upper that I installed a 14" Lite Rail on - it's as heavy as you'd need to go, and a tack driver at that.

If you don't need to reach beyond 600m often, I'd really look at a 16" barrel instead (again, great options abound from Centurion, HCS, BCM, Noveske) at that length, and more common handguards work.

Handguard will be at your preference - DD Lite, KAC URX-II, LT, TROY/VTAC Extreme, DD RIS-II, DD V7, or Centurion C4 are ALL rails I'd consider before the PRI unit.
Stock - if it's for bench or static only use, then the PRS is great. For anything else, a collapsing stock (UBR is still heavy, otherwise an A5/EMOD or A5/ACS would be my suggestion).

I think the GSSA is enough trigger for a precision setup, but my one SSA-E is just a touch lighter, and especially if you stick with a heavier 18" with a full stock you'll be even happier with that lighter pull.

AoC had it absolutely correct - spend cash on the barrel, trigger and optic, you'll get great results.

I have that scope (but with MLR Reticle), and it's brilliant, but big and heavy on a 5.56 rifle. Makes sense for this if you're working past 500m a fair bit, or wringing out accuracy closer, but that with a PRS pretty much negates any handiness in favor of being able to make small groups at range.
I'm looking at the 2.5-10x32 NxS-C for that 18" upper I have for that reason, and moving the 3.5-15x up to my 7.62 rig.

BlahBlah
04-29-12, 21:38
First off, buying a complete upper and a complete lower and swapping out the stock is not a "build". That is an "assembly". If you can't handle that much on your own, there is something wrong. ;)

Now that I'm done busting your balls a bit...

I like the long tubes, covering the gas block on the longer barrels. Hell, I like them on shorter barrels too! A 14-15" rail on an 18" barreled upper is perfect.

I have the DD Lite rails and Troy/VTAC tubes on various builds, but for a "precision" rig, there really is no need for the bulk and weight of a 4-rail setup. I'd recommend the 15" Troy/VTAC tubes. They give you the top rail for optics/sights/NV/etc, and you can put the small rails where you need them for bipod mounts and the like. The TRX/VTAC Extreme rails are nice, but skip them and make sure you get the newer Alpha version. The mounting method is MUCH nicer.

I'll echo what most people have said about the PRS. Unless you absolutely need the adjustable cheekpice or want to use a monopod on the bottom rail, they are too heavy and clunky to bother with. The UBR is a good option. It's heavy enough to balance an 18" build, but still lighter than the PRS. I'm currently playing with an Ergo F93 stock (based on the original Magpul M93 stock). It has most of the same advantages of the UBR while being even lighter (and almost $100 cheaper).

If you're serious about precision... Make sure you buy a good trigger! I can't stress that enough. Don't spend a bunch of money on a "precision" rifle with a regular "milspec" trigger! The Geissele one you specified is a VERY nice trigger, so you're good there.

I'm currently building a very similar configuration to what you're talking about (mine is a 6.5 Grendel, though), so I've been debating much of the same things you are. I'm doing things a little different on this one, but only because I have a couple ARs in similar, SPR-ish configurations already.