What makes an "SPR"???

AR/M4 AR Technical Discussion
21

razorhunter,

If you are looking for “accuracy” and “precision”, a 16" barrel may be all you need… the 18" length of the SPR barrel is based on ammo testing to be the shortest barrel length that still gets full performance.

There has always been a discussion about what a “carbine” is… I subscribe to a definiton that seems to be popular in the industry currently, in that a carbine is a shortened or reduced size rifle that sacrifices ballistic performance when compared to the parent rifle – either by smaller cartridge or reduced efficency.

That said, the 16" does not give up that much to the 18"

With the AR, accuracy is the product of the barrel and how it is mounted, the effective range of that accuracy is dependent on the ballistics, the pratical range is based on the sights/optics and the precison is a product of all of the above.

A 16" carbine, with a good free floated barrel, a solid sight mounting platform and good glass will shoot right along side the longer rifles for a couple or few football fields just fine :wink:

22

Check this one out
https://www.m4carbine.net/showthread.php?t=4262

I’m still somewhat confused as to what you’re after. Are you:

  1. trying to learn about the “SPR”
  2. looking tobuild an exact replica
  3. looking to build a rifle that suits your purposes?

If it’s #1 or #2, the wikipedia link I provided gives you pretty much all the information you need.

If it’s #3, be specific and honest with us and yourself as to what role you are trying to fill with the rifle, or what task you would like to perform with the rifle.

Personally, I think everyone’s suggestion of a 16" barrel has alot of merit. If you don’t intend this rifle to be a people-killer (or even if you do and you don’t envision shots beyond about 200 yards) then the extra 2" of barrel won’t accomplish much. All the longer barrel does is give the rifle a little longer effective range, which may or may not be a requirement for you.

Personally, I’d buy one of these, mount one of these on it, and mount one of these on one of these and be done with it. Expensive? Absolutely, but I’ll betcha it would outshoot almost anyone who picked it up, and it would certainly not be the weak point in the system with my shooting skills.:smiley:

23

–what distances are you guys shooting with the 18in barrel lengths ?

I guess what I,m asking is with a High Quality 18in barrel ( Noveske )how Accurate are they to about 600yds ? I know a lot depends on the shooters skill…

I,m undecided between getting the 20in or 18in barrel for my next build …

24

Guys, at 400+ yards making hits with 556 comes down to wind estimation-- 556 blows around in the wind. Guess what, if you mis-judge the wind by 5mph at 600 yards, that’s 3 or 4 MOA windage error. On the other hand, I can make hits @ 700 yards on a 12x18 with my 12" SBR using a TA11, with a couple sighters.

556 is just not the right tool for the long-range job, so in my opinion, do not obsess over optimizing a 556 weapon for it.

25

Look above for the ADCO banner and check out Steve’s site (sorry for the plug.)

Steve’s got a lot of the parts. Maybe looking at the prices will set you straight! :stuck_out_tongue:

-note: just some of the PRI costs in general, not that Steve is high. I’ve never sought out the PRI parts but I always see that Steve has them. He also may have custom SPRish uppers that will suit your needs better but at that point it would be fair to look at other supporters of this site.

26

Yeah guys,
Noticed how I haven’t replied to this thread lately? I’ve seen the light, as Zak suggests, and I WILL be going with 7.62 of some sort.

My only thing now, is trying to decide WHAT 7.62 to buy. I like several, including Noveske stuff (does he custom build these with other manufacturers uppers and lowers?),
Also looking at POF’s P308 rifle - not sure which bbl length, LWRC (someone recommended), and a couple others.
Quite honestly, I would LOVE to find a damn STONER, but I just don’t know WHERE to get one, and IF I can even find one. I want a damn 7.62 Stoner so bad I can taste it…
If anyone can help, send me a private PM please. OR email direct at pc79@bellsouth.net. Please keep it private though…
Thanks guys, and I’m always open to 7.62 rifle suggestions! Not really looking for an AK47 type combat weapon (although some of the above would qualify as such).

I would really just like to build me a semi-sniper-type 7.62 weapon, with a high power typical scope up top. I’ve ruled the M1A out for now, as I’d really like an AR type platform… I’m telling you guys, I REALLY want a Stoner…!

27

Never mind…

28

I’m surprised Zak didn’t talk you into a 6.8- they seem ideal. Much more power than a 5.56 (I’m assuming again) and they fit into a rifle basically the same size in every respect as a regular 5.56 host weapon. No special parts besides the barrel and bolt I think… Mags too…

29

6.8 SPC has external ballistics basically identical to 75-77gr 556.

I personally gave up on 308 AR-10-pattern rifles due to extreme ammo and “setup” senstivity with regard to accuracy, reliability issues, and inertia events during recoil/cycling (which made it hard for me to spot hits).

If you want an SR25, you can find them for sale now and then.

30

Ok I’m confused. What did you suggest to him Zak? How about suggesting a 6.8mm now? How about repeating to some of us the major advantages to one. Aw hell. I just need to start another thread. I’d like a 12.5" 6.8mm I think. Good compromise, right?

31

Zak did not suggest ANYTHING specifically to me guys.
When I said that he has helped me to “see the light”, I just meant that he has stated that 5.56 is not a that much of a performer at longer ranges…
That is all. Let’s not look into any posts too deep.

I would still love to have a 5.56 SPR, but my funds are limited, and I have decided I’d like to step up to 7.62. Now I probably don’t have NEAR the range time that many of you have had, (especially you Zak), but I’ve shot a fair amount of 7.62 AR’s, and never a problem. Granted, this is mostly Stoner rifles setup as “match rifles” according to the owner. I’ve also had a fair amount of range time on said gentlemans Armalite AR10’s, and even a DPMS or two.
ALL have performed flawlessly, but as I said, I have not put thousands and thousands of rounds downrange. Probably only hundreds and hundreds.
I seriously doubt that the Noveske rifles are problematic in any way. This is not to doubt Zaks comments on the AR10 however. I am disappointed to read some of the posts regarding AR10’s, similar to Zaks post above, on different forums on the net.
So I’m basically stuck, trying to decide on something along the lines of a Noveske of some sort, Armalite, Stoner (my main desire as of now), Hk 417 (yeah right!), or maybe even something from POF.
Granted, the Noveske and Stoner are really the type that I think I would put a high power scope on. The POF seems more like an M4 type carbine to me, and I’m not sure if they are offer an SPR type 7.62 or not.
Many of the Noveskes are shorter carbine types too, but I think they have some longer bbl length rifles as well in 7.62.
Again, I’m no expert, but these are my desires, and I’m basically just trying to figure out what is the best 7.62 rifle for me right now… What a great choice to have to make…

32

I have personally witnessed about three of four AR-10 pattern rifles which ran flawlessly with a variety of ammo, and a whole bunch that choked, some early and often, some just “eventually.” I don’t mean to beat up on them, that’s just what I have experienced.

That said, if I were going to put another AR-10 style rifle together, there are two guys I’d consider going to to build me one that would be reliable and accurate: George Gardner, and John Noveske (in no particular order). I can honestly say that the 12" 556 SBR upper John built for me is the most reliable AR-15 I have ever ran.

.308 will perform at long range, but in the scheme of things, it’s close to the minimum (in terms of BC and MV) you can use and still hope for 1000-yard performance. Friends of mine who have carried sniper rifles into harm’s way have characterized 308 as an “800-yard” cartridge.

I shoot my AR-15’s from 0 to 425 yards regularly at small practical targets (at the Pueblo Rifle Match, Camp Guernsey MG, etc). I am familiar with how to use my sighting systems and ammo’s trajectory to make hits at those distances, and what kind of hit probability I can deliver from different improvised positions. If I need more terminal oomph than 556 can provide, I can swap uppers to a better caliber (my 18" 6.8 SPC upper uses the same holds in the ACOG as my 17" 556). Realistically, no normal cartridge that fits in an action 2.8" long is going to deliver decisive terminal effects at 500+ yards.

To make a quantum leap up in ability from what can be achieved with a light and “handy” carbine with low-power magnified optics, you need to upgrade both optics and ballistics. This basically nullifies “light and handy” and now you’re talking about a real rifle. And at this point, I would rather have a rifle system that can deliver fantastic long-range performance.

Decent LR cartridges start with a BC of 0.50 and a MV of 2700 (ie, 175SMK@2700fps), to draw an arbitrary line in the sand. “Good” LR cartridges have a BC of 0.60 and a MV of 2800fps (ie, right at 260REM). “Great” LR cartridges usually have a BC of 0.6 and a MV of 2900+fps, or 0.70+ BC and 2700+ MV.

That’s sort of rambling, but I wanted it to fit in with this thread… :smiley:

33

My brother had a suggestion for an AR10 that would work great. He suggested running one without a gas system:eek:

Hey, if Tubb can do it, so can you!

34

Not to be funny, but it is an SPR because Crane says it is!

The ones I have seen are really just ‘build’ rifles. They have new uppers on old M16A1 lowers (with all new KAC FCG) with an A1 buttstock.

I am pretty sure they also have a 1/8 twist.

35

1:7 Twist