CMMG 18" SPR upper

[SoCalAR]

Shot an AR yesterday for the first time and now I think I might be coming down with the disease even more!

Anyway, I put some money down at 10% and Wes agreed to hold the CMMG 18" mid-length he had in stock. I'm gonna go pick it up this weekend and I'm pumped.

My question: What exactly is the Special Purpose upper for? Is there any advantage over a 16"? I've read the mid-length gas system is better for a few reasons. I get a longer sight radius with it (though at this point in my young shooting career I don't think that's going to matter too much for me) which some folks seem to prefer. I'm more curious about the 18" barrel. I suppose I'm going to get more velocity out the muzzle...

Can anyone throw a little info my way on the benefits of an 18" vs. a 16"?

Thanks.

[Jicko]

mk12 mod0/1 spr

Wikipedia.... not everything is correct.... but this is a good overview...

http://en.wikipedia.org/wiki/United_States_Navy_Mark_12_Mod_X_Special_Purpose_Rifle

[aplinker]

Well... the 18" SPR actually is a rifle length gas system. With a mid-length the only advantage to 16" vs. 18" is velocity.

I wouldn't get a mid-length 18" upper, personally. I'd always get the longest gas system feasible.

Shot an AR yesterday for the first time and now I think I might be coming down with the disease even more!

Anyway, I put some money down at 10% and Wes agreed to hold the CMMG 18" mid-length he had in stock. I'm gonna go pick it up this weekend and I'm pumped.

My question: What exactly is the Special Purpose upper for? Is there any advantage over a 16"? I've read the mid-length gas system is better for a few reasons. I get a longer sight radius with it (though at this point in my young shooting career I don't think that's going to matter too much for me) which some folks seem to prefer. I'm more curious about the 18" barrel. I suppose I'm going to get more velocity out the muzzle...

Can anyone throw a little info my way on the benefits of an 18" vs. a 16"?

Thanks.

[SoCalAR]

Well... the 18" SPR actually is a rifle length gas system. With a mid-length the only advantage to 16" vs. 18" is velocity.

I wouldn't get a mid-length 18" upper, personally. I'd always get the longest gas system feasible.

This is what the description from the CMMG website states:

So maybe it's a CMMG spin on an actual SPR, not knowing much AR/M16/SPR history I'm not really sure. I was deciding between this 18" and a Stag 3H upper, Wes just happened to have the CMMG in stock. The description says "chrome-lined 5.56 chamber and bore" and I've heard chrome-lined is better than chrome-moly and CMMG seems to have a fairly good reputation for quality.

Hopefully I made a good choice! Either way, it's my first build so I'm sure I'll find things I wish I had done differently. That's what first builds are for, right?!

I'm already planning my second and third builds though...I need a second job!

[aplinker]

This is what the description from the CMMG website states:

So maybe it's a CMMG spin on an actual SPR, not knowing much AR/M16/SPR history I'm not really sure. I was deciding between this 18" and a Stag 3H upper, Wes just happened to have the CMMG in stock. The description says "chrome-lined 5.56 chamber and bore" and I've heard chrome-lined is better than chrome-moly and CMMG seems to have a fairly good reputation for quality.

Hopefully I made a good choice! Either way, it's my first build so I'm sure I'll find things I wish I had done differently. That's what first builds are for, right?!

I'm already planning my second and third builds though...I need a second job!

Yes, it's CMMGs version.

I think you'll be perfectly happy with that upper. CMMG is good. Chrome lining prevents things from sticking to the bore. You can still have a chrome-moly barrel. but then chrome lined.

Just shoot it like crazy and enjoy.

[SoCalAR]

Just shoot it like crazy and enjoy.

Thanks for the replies.

And I intend to! Can't wait!

[bwiese]

My CMMG 18" SPR (chrome-lined, middy gas, Troy-rail freefloated) like the Black Hills 69gr SMKs - really tight groups.

[ar15barrels]

My CMMG 18" SPR (chrome-lined, middy gas, Troy-rail freefloated) like the Black Hills 69gr SMKs - really tight groups.

Bill shooting a chrome lined barrel.
What's the world coming to?

[J_Rock]

Since you are getting a SPR, I assume you are going for maximum accuracy. You'll want a stainless steel barrel for that not chromed lined

[tenpercentfirearms]

Anyway, I put some money down at 10% and Wes agreed to hold the CMMG 18" mid-length he had in stock. I'm gonna go pick it up this weekend and I'm pumped.

We might have had a communication error. I do believe I sold both of those. Please e-mail me ASAP so we can get this cleared up.

Just in case I will order some more today. They come pretty quick.

[tenpercentfirearms]

Anyway, I put some money down at 10% and Wes agreed to hold the CMMG 18" mid-length he had in stock. I'm gonna go pick it up this weekend and I'm pumped.

Crap, it wasn't miscommunication. It was straight up my error. I forgot to take that other one out of stock on the website and didn't notice the inventory said I didn't have any available when I sold it to a guy online this weekend.

DOH! I will order more today and you can most certainly get a full refund if you choose not to wait. Trying to balance an online and in shop inventory does not always go well.

[tenpercentfirearms]

I just ordered 4 more. It might be...two weeks.

However, I have 4 floor model uppers in the shop (2 CMMG lightweight 16" with muzzle brakes or cans, 3 Stag 16"ers with FH, and 1 Stag 20") that I would be more than happy to loan you that you can shoot and enjoy until your CMMG that you paid for comes in. Then bring me back my upper and I will give you yours. I don't care how many rounds you shoot out of it, I just want you to shoot a gun this weekend if you were planning on finishing a build.

My apologies for the screw up and I will do what it takes to make it right.

[redcliff]

This might actually work out to the OP's benefit to try another barrel length; I personally like the 16" lightweights for their fast handling.

I know the mid-length gas system is better, (my last build was one) but out of the 10 or so carbines I've owned I've not had one that wasn't 100% with good ammo.

[monkey]

Few things:

The SPR should be considered an lengthened carbine rather than a shortened rifle as this was the intent. None of the original SPRs were anything other than rifle-length gas systems with 18" barrels. The 18" barrel was an attempt to increase the muzzle velocity and effective range of a carbine while still maintaining a compact package.

Gas pressures in a carbine-length gas system are horribly excessive and result in dramatically accelerated wear over a rifle-length system. The mid-length was an attempt to improve this, to reduce gas pressures while maintaining the other qualities desirable in a carbine.

If using a mid-length handguard, then yes, the sight radius is increased over a carbine, but still does not match a rifle's sight radius.

A standard 20" barrel with rifle-length gas system will give you higher muzzle velocity and longer range than an 18" barrel and lower gas pressures than anything in middie or carbine length.

The 20" barrel and rifle-length gas system is more desirable in just about every category unless you simply need/want a more compact weapon. Now that you have a change to change your order, I would make sure you get a rifle rather than a middie or carbine especially since you want an 18" barrel.

[Jicko]

How much is a CMMG 18" SPR upper!?

I just found out that Troy do complete uppers.... I don't know how long you have to wait, but prices are GOOD... and you can get a complete FDE upper too!! An 18" SPR is only $1145!! Comes with Troys BUIS set, just that is $250!! And Troy's FF rail, continuous rail.... I think it is a GREAT deal....

http://www.troyind.com/upper.html