View Full Version : Range report : Colt CM 308 gas gun
I recently purchased a Colt CM 6.5 CM. It has a 18 inch SS rifle length gas Sytem. Has a 17 inch very sturdy Mlok rail. The rail has a notch into the upper so it cant rotate. Full ambi controls. Colt Defense built rifle.
My two primary concerns were, is it going to be hugely over gassed ? Is it going to be accurate?
Mark started out on the gun, first round short stroked. It kept short stroking. Doing this while we are sighting in the gun. We popped on the Sig 762 can and the brass floated out to 3- 3:30 and shot like a pretty soft. We got the gun sighted in.
We shot the first group with S&B $11/box ammo and shot a clean Sub Moa group. Now I did this with a $179 Primary Arms 1-8 cheapo scope. Then we loaded up some Hornady 140grain match ammo and shot .5 Moa group.
I paid $1,400 for this gun and it impressed me beyond measure. If your looking for a price sensitive AR10, might want to give them a look. Mark may have pics to post.
PB
Nice, and congrats on your new rifle.
That's a fun rifle to have out west.
That sounds like exactly what I want in a 6.5CM. And awesome price. Congrats.
gunnerblue
06-09-19, 09:51
I've been thinking about picking up a 6.5 upper to go with the .308 which I already own. Glad to hear about your results concerning accuracy, thanks
Thanks for the review. I've been wanting one of these for a while, it sounds like I need to hurry up and buy one.
I've been thinking about picking up a 6.5 upper to go with the .308 which I already own. Glad to hear about your results concerning accuracy, thanks
Gunner, be aware the Colts configuration is somewhat proprietary, soil you go Cut, it needs to be the whole gun. Best of luck.
We were shooting off the concrete benches with mongoloids with body odor all around, yet we managed to get some impressive results out of this gun and the Bergara bolt gun.
The Colt shoots damned near as soft as a 5.56 AR. It's a cool gun.
https://i.imgur.com/2TWf4qy.jpg
gunnerblue
06-09-19, 12:59
Gunner, be aware the Colts configuration is somewhat proprietary, soil you go Cut, it needs to be the whole gun. Best of luck.
Should’ve mentioned that the .308 is a Colt 901. I believe that it will work but will certainly confirm
I think so because I read somewhere it has those same capabilities as the 901 to convert to a 556 dealio.
PB
Thanks for your report. Congrats, it sounds like it’ll be a shooter.
Here's a 3 round effort with that low magnification scope.
https://i.imgur.com/8aTkqLT.jpg
Eurodriver
06-10-19, 19:37
If this thread existed a few weeks ago I would’ve bought one over my Havak bravo. I really wanted one but had the same reservations.
What caused the short stroking? Did you chrono it?
If this thread existed a few weeks ago I would’ve bought one over my Havak bravo. I really wanted one but had the same reservations.
What caused the short stroking? Did you chrono it?
No idea why it short stroked. I cant imagine Colt planned this. I wouldn't trust the next would be the same. I'd buy a 308 tomorrow if I knew it would be gassed the same. We, of course, expected to be way over gassed then it short stroked multiple times. Because we started without a can to see if it would run. Then after scratching our heads, we screwed on the Sig 762 can and it ran like a top. 3 to 3:30 ejecting and soft. Still scratching my head. We didn't Chrono because my back is out, my knee is out, my leg is jacked up , I didn't have a ranch run in me, ....so we went to a local range to at least sight it in and check vague accuracy.
PB
coachjenorris
07-05-19, 15:23
Nice setup. My gas block was not "pushed" in as far as it should be and it caused some bad short stroking. Readjusted it and bam, no more short strokes.
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Have you looked into this cycling further?
Checked gas block alignment / measured gas port?
No idea why it short stroked. I cant imagine Colt planned this. I wouldn't trust the next would be the same. I'd buy a 308 tomorrow if I knew it would be gassed the same. We, of course, expected to be way over gassed then it short stroked multiple times. Because we started without a can to see if it would run. Then after scratching our heads, we screwed on the Sig 762 can and it ran like a top. 3 to 3:30 ejecting and soft. Still scratching my head. We didn't Chrono because my back is out, my knee is out, my leg is jacked up , I didn't have a ranch run in me, ....so we went to a local range to at least sight it in and check vague accuracy.
PB
So, if I was going to get into long range shooting down the road, do you see a benefit to a $1400 bergara bolt gun vs this?
I was pretty much sold on the Bergara, but this thread has me 2nd guessing.
We haven't dug into the gassing on this gun at all. I'm reluctant to tear a gun apart if I don't need to.
As far as Bergara vs. this Gun? Hard to say. Both are nice. The longer barrel on the bolt gun will give you more reach, but the capacity/rate of fire on the Colt is greater. Depends on the kind of shooting you see yourself doing. I like a suppressed bolt gun (personally) over a gas gun... but it is nice to load up a mag and see how few rounds it takes to hit every target in the range. "walk it out" as we call it.
Gunner, be aware the Colts configuration is somewhat proprietary, soil you go Cut, it needs to be the whole gun. Best of luck.
PB, great looking rifle. Checking out the 6.5 CM version.
Have you seen anywhere a list of the proprietary colt-only components in this rifle? Haven't been able to find that for this new version. I'm assuming all the usual suspects are standard: stock interface, pistol grip, triggers, etc. And no doubt, a proprietary BCG. Wonder what the barrel upgrade options would be?
Have you seen anywhere a list of the proprietary colt-only components in this rifle? Haven't been able to find that for this new version. I'm assuming all the usual suspects are standard: stock interface, pistol grip, triggers, etc. And no doubt, a proprietary BCG. Wonder what the barrel upgrade options would be?
The BCG was the most noteworthy. The trigger group is standard except for the longer pins that fit the forging. I still installed a Geissele for Pappabear using the shorter pins though.
The BCG was the most noteworthy. The trigger group is standard except for the longer pins that fit the forging. I still installed a Geissele for Pappabear using the shorter pins though.
Thx Mark. Have you by chance checked out the barrel or know what the upgrade options are? If I get one I'd probably stick with the 18" for a while, but I'd probably want to upgrade to something longer, maybe a proof.
Longer pins here.
https://geissele.com/large-pin-colt-901-replacement-trigger-hammer-pins.html
The trigger group is standard except for the longer pins that fit the forging. I still installed a Geissele for Pappabear using the shorter pins though.
thanks Clint, I just grabbed a set. Mark made mine work even though they were less than ideal. They didn't walk out yet but I don't want them to and have my trigger take a crapper on me.
PB
Does it still short stroke without the suppressor?
We haven't dug into the gassing on this gun at all. I'm reluctant to tear a gun apart if I don't need to.
We haven't pulled the can off. We may give that a try next shoot.
noonesshowmonkey
07-17-19, 00:27
6.5 in an 18" barrel makes me cringe a bit... But even when you lose ~100 (or more!) FPS, the 6.5 round really still performs. Even out at 1000m, you're only looking at a little over 1 mil elevation and under a half mil of windage in 10 mph full value cross winds. Even when seeking to optimize the barrel length, the reality is that the external ballistics on secant ogive 6.5 projectiles are just... good.
I am really very interested in seeing what you guys can squeeze out of this particular rifle, especially when you stretch the range out a bit. I'd love to see that data set along side a .308 semi , if you have one in inventory between the two of you (which, somehow, I am sure you do).
I hope we can get back out in a few weeks. The weather is too hot, and Pappabear is healing up.
6.5 in an 18" barrel makes me cringe a bit... But even when you lose ~100 (or more!) FPS, the 6.5 round really still performs. Even out at 1000m, you're only looking at a little over 1 mil elevation and under a half mil of windage in 10 mph full value cross winds. Even when seeking to optimize the barrel length, the reality is that the external ballistics on secant ogive 6.5 projectiles are just... good.
I am really very interested in seeing what you guys can squeeze out of this particular rifle, especially when you stretch the range out a bit. I'd love to see that data set along side a .308 semi , if you have one in inventory between the two of you (which, somehow, I am sure you do).
We can swing that I have a 16 inch LMT MWS in 308, and the 6.5 in both 18 inch and 20 inch (20 being MWS). Might have to do full scale trial. But need to toss a NF on the Colt for a day.
And just like many folks would argue its stupid to have a 16 inch gas gun in 308, but it works.
PB
Kansaswoodguy
07-18-19, 22:17
6.5 creedmoor has a different pressure curve and likes to pierce primers in AR-10's just make sure the gun your getting in 6.5 has a high pressure bolt. I just finally threw in the towel on mine and ordered a JP high pressure bolt because I was tired of that issue.
Which gun and gas system?
6.5 creedmoor has a different pressure curve and likes to pierce primers in AR-10's just make sure the gun your getting in 6.5 has a high pressure bolt. I just finally threw in the towel on mine and ordered a JP high pressure bolt because I was tired of that issue.
I hope we can get back out in a few weeks. The weather is too hot
That's no MFing joke! I looked at my round count books and always seen a YUGE drop off to nearly nothing from late May through mid-Sept. Only time I really go is to do something specific like zero a new scope, then I'm there for the minimum time required. Handgun practice moves to the indoor range.
Kansaswoodguy
07-19-19, 23:58
Mine is a home brew DPMS upper/lower Krieger 26" barrel the bolt is the typical DPMS .080" firing pin opening and it causes me issues with pierced primers which is very common with 6.5 Creedmoor AR's my gas system is maybe a 1/4" longer than a standard AR-15 rifle length system barrel bolt and gas tube all came from Fulton Armory I don't believe they will even sell the .080" bolt with AR 6.5 barrels any longer it was so common of issue.
Kansaswoodguy
07-20-19, 00:04
My neighbor finally cut his native grass hay field where my 1000yd target is so the range is ready for shooting this summer and this African heat wave hit I think I saw zebra run across the lawn this morning there may have been a lion chasing it or maybe the heat is just effecting my vision.
A quick follow up on the gassing of my particular 6.5CM Colt. I reported the first outing the gun would not cycle because of this undergassing. Well on Sunday I forgot my bag of suppressors, tragic right? Initially I honestly felt like it might have been a needing of breaking in causing gun to not cycle.
Several months later, and many rounds, it does not cycle without a can. It’s a dream to shoot with can but won’t pick up next round and shoot without. I’m still thrilled as I run a can always.
Anyone else get this lucky or unlucky ?
PB
Be interesting to find out if folks with the .308's are having the same issue with running unsuppressed.
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