View Full Version : 18"bbl mission?
I've read some about the genesis of the SPR as a type-designated rifle, but I'm curious if anybody know what requirement (figuring there was something specific) mandated an 18 inch barrel? I'm in the market for a new precision-oriented upper and a PM conversation with another member last night has me wondering if I'd really be giving up all that much by going with a "Recce" upper vs an 18" DMR upper from the same manufacturer. Since they would come from the same shop and all other factors would be identical (bbl maker, rail maker/length, sight radius, Mk262 clone ammo, etc) I realize the shorter tube would yield a velocity drop-off but is there any other disadvantage I'm not seeing? With my hunting rifle (until I accidentally shot my chronograph) I saw an increase in muzzle velocity of ~25fps per inch of bbl length so if the 5.56 round is approximately similar, the 18" tube would add an almost negligeable increase in muzzle velocity/fragmentation threshold.
For a 50fps or so drop, you end up with a much handier rifle, and if you forsee any use up close that will take precedence.
I chose to go with an 18" for my precision rifle to match the Mk12 silhoette, and be able to use a rifle length gas system and run it suppressed. With a middy or intermediate gassed 16" Recce, this isn't a problem, so unless you're building it to hit stuff at or beyond 600yd, then 16" is smarter in my book.
... unless you're building it to hit stuff at or beyond 600yd, then 16" is smarter in my book.
That makes sense--thanks. When I set up a rifle for 600+, I'm going to step in caliber as well so for <600, it sounds like a 16" tube would be perfectly acceptable.
Having both, I think it is more optic that determines the use, rather than the 2" in barrel length.
If I only had one I would get a Recce over an SPR.
Here are both of mine.
http://farm2.static.flickr.com/1132/5134174023_5f8436c7e2_b.jpg
Cameron
Belmont31R
11-28-10, 14:46
To me what differentiates the two barrel lengths is the "mission" of the gun. The SPR is basically a light sniper rifle. The recce type guns can be used for faster close in work. Basically an accurirzed carbine. The SPR is an accurized rifle.
A larger scope on a 16" barrel would feel pretty out of place to me. A 1-4X or ACOG goes well on a 16" gun balance wise.
Heres my two to illustrate the differences in setup:
http://i274.photobucket.com/albums/jj245/BM31R/2579c958.jpg
Heres my two to illustrate the differences in setup:
Love that pic.
Cameron
Belmont,
Nice set ups, and a question for you. I know there's lots of right ways to set them up but what would be the difference on a 16" gun with, say a 2.5-10 NF vs. a 1-4? Same body, weight, just more mannification. As I shoot more and more I've about came to the conclusion that is almost no reason for anything over 16" for me in a 5.56. Most of my precision AR experience comes from a 20" Kreiger barreled upper and a Noveske 16" Recce. I shot the 20" out to a thousand on a few occasions but have only shot the 16" to 580 (the longest easily accessible range for me). Is there a big difference with the extra 2-4 inches at longer ranges over 600?
Belmont31R
11-28-10, 16:08
Belmont,
Nice set ups, and a question for you. I know there's lots of right ways to set them up but what would be the difference on a 16" gun with, say a 2.5-10 NF vs. a 1-4? Same body, weight, just more mannification. As I shoot more and more I've about came to the conclusion that is almost no reason for anything over 16" for me in a 5.56. Most of my precision AR experience comes from a 20" Kreiger barreled upper and a Noveske 16" Recce. I shot the 20" out to a thousand on a few occasions but have only shot the 16" to 580 (the longest easily accessible range for me). Is there a big difference with the extra 2-4 inches at longer ranges over 600?
No not really. As long as you can know your dope its just a matter of dialing in or holding over depending on your setup. You are already way past the fragmentation range of 556 rounds anyways so the little loss of velocity doesnt mean a whole lot.
With my two setups above I do think its easier to hit at that range, and spot your own shots for corrections. Thats hard to do with a 4X top end optic. The NF 2.5-10X would do a similar job to my 3-12X in that regard. The rifle length gas is a bit smoother too so after the shot there is less gun movement. That would be more impacted by the type of muzzle device though. A 16" with a brake would be smooth enough to stay on target and quicker follow up shots.
With the Short-Dot I dial to 25MOA and whatever windage correction. The 3-12X is right around 6.5 mils (65 .10 clicks) so they are pretty close to each other with the same ammo. That is at 750 yards.
Less is more when holding the areas critical to precision accuracy constant like the said match grade barrel, trigger, optics, FF rail, etc. The Recce is where its at.
http://i55.tinypic.com/347zk46.jpg
FWIW, my 18" (SS) Noveske chronographs just over 100 FPS faster than my 16" (CL) N4 Light barrel with a 77 SMK reload.
Charge is 23.8 grains of TAC & Rem 7 1/2s; 2,700 fps VS just under 2,600.
For what it's worth I've recently faced the same decision.
Reece profiles are designed to be light, fast, and accurate.
SPR's are used for sniper / precision support.
Basically it comes down to your intended use and what use you may be pressed into with the rifle. It's a fully mission dependent choice
If you're only interested in accuracy and want a AR platform look at the longer Bull barrel rifles designed for varmint hunting, etc.
The SPR used by SF is an 18" bbl rifle. It is more at home on the rooftop of a cullot in Afghanistan providing overwatch than doing CQB. Could you use it to clear the house? Absolutely.
My choice was both an 18" Stealth and a 16" mid length. The Stealth is for the precision long range capability and very slight extra velocity. Since I'll never use this rifle for entry work I had no issue with the extra 2" of barrel length. The 16" BCM mid length lightweight with an Aimpoint for training and coyotes.
A 16" free float will have negligible difference in accuracy (especially with the same optics) with some people touting the shorter barrel is more rigid making it less susceptible to barrel whip. This would most likely serve the purpose as a all around platform. (optic dependent)
Belmont has the best answer: get one of each!!! That's what I ended up with.
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