Barrel Options for CMMG Bolts

2733 Views 55 Replies 14 Participants Last post by colonelhogan44, 4 h ago

Kevin_K

Discussion Starter · 9 mo ago

For my next 22LR project, I am thinking of making a dedicated upper for my Colt lower. I trained and qualified with a M4A1 SOPMOD Block 1 around 10 years ago. Things have definitely changed since then and the USASOC URG-Is (Block IIIs) are very interesting for modernizing what is otherwise and old platform. I live in a slave state, so converting this to 22LR is abut the only thing I can do to retain controls familiarity.

After some preliminary research, I think I've decided on going with a dedicated CMMG bolt due to parts availability and aftermarket support.

So with that, what is the best recommended barrel for a build like this?

It looks like CMMG has two 16"+ options:
1. 16.1" M4 4140CM SBN, 22LR
2. 17" MT 4140CM SBN, 22LR

The 17" MT looks new. Anyone running one of those yet?

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Artd

· #2 · 9 mo ago

I made an upper using the CMMG 20" barrel years ago and although it functioned great, its accuracy was questionable. The upper was built as a NM training rifle and was quite sufficient for off-hand practice, more accurate then my hold, but poor for prone practice. I eventually sold it and bought a barrel from Keystone Accuracy.

Art

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zukiphile

· #3 · 9 mo ago

Kevin_K said:
The 17" MT looks new. Anyone running one of those yet?

I have not, but I have a couple of 16.1" heavy taper barrels that shoot very well.

As much as I dislike the M4 profile, it does have the advantage of a lot of gas block compatible surfaces. For me that means I was able to make a 16.1 inch iron sight rifle with a gas block front sight set all the way at the end of the barrel.

My guess is that the 17 inch medium taper would be more accurate though.

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BigEd63

· #4 · 8 mo ago (Edited)

I've had good luck with the Lothar Walther 16" barrel I used for my franken AR build.
I have a feeling if I had as better trigger group it'd be in the running with some match rifles.
It's original purpose was to match my MK-12: Wannabe build rifle someone else put together.
But currently it's being reworked as a understudy for my 16" barrel "Traveling Rifle"as I call it
The .22 I call a franken build because it's got a lower made from spare and changed out parts.
I don't have many pics of it this was at the Hobbs public range near Beaver Lake in NW Arkansas.

I apologize nix Lothar Walther ☹ they apparently stopped making .22lr barrels during the pandemic.😑 And after I moved I was going to do a pistol build in .22lr, ☹

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zukiphile

· #5 · 8 mo ago (Edited)

BigEd63 said:
I've had good luck with the Lothar Walther 16" barrel I used for my franken AR build.

My 16.5" LW is the most accurate barrel I own and shows why one should never give up on an ammunition type.

I shot Aguila SV and subsonic from my CMMG heavy taper barrel for a couple of years after testing a dozen different types and finding those worked very best. Nothing by Federal gave promising results, so I assumed Federal was rubbish.

Vascar2 wrote good things about LW barrels in Spike's builds, so I bought one.

I tested at 50 yards with a Barska 1.5-6x euro. The rubbish Federal Gold Match Target put five rounds into a dime sized hole, then did it again. Always looking for something cheaper, I wondered if Federal Automatch would work well enough to be the regular stuff for this rifle. It threw some fliers, but also sometimes printed that same dime sized group. Weirdly, some old American Eagle HV, the stuff that was put in 40 round boxes back in the 90s to frustrate the innumerate like me, also did very well in offhand use.

The LW 10.5" shows the same preferences, but I've yet to put it on a bag with the big scope.

Lothar Walther left the market after CMMG changed the shank and collar depth. The fix is trivially simple for customers, but my sense is that they didn't want to sell a barrel that comes with an explanation.

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colonelhogan44

· #6 · 8 mo ago

Shameless plug -- BoreBuddy is set to release a run of 4.5" barrels in the next couple weeks, and we'll immediately start work on the next run which includes 12.1" and 16.1" barrels assuming sales are decent on the first run. They'll be a straight 0.625" profile for weight savings and to allow gas block sights at any position.

Reactions: 1

12Bravo

· #7 · 8 mo ago

colonelhogan44 said:
Shameless plug -- BoreBuddy is set to release a run of 4.5" barrels in the next couple weeks, and we'll immediately start work on the next run which includes 12.1" and 16.1" barrels assuming sales are decent on the first run. They'll be a straight 0.625" profile for weight savings and to allow gas block sights at any position.

I'm willing to bet that the 4.5" barrels will sell just fine. I am going to put in a request for you for some 20" barrels. There are a few of us over on ARFCOM waiting for 20" barrels to build A2 clones with.

Reactions: 1

zukiphile

· #8 · 8 mo ago

colonelhogan44 said:
Shameless plug -- BoreBuddy is set to release a run of 4.5" barrels in the next couple weeks, and we'll immediately start work on the next run which includes 12.1"...

I have the upper receiver, handguard and thread protector. I'm a 12.1" 1:12 barrel away from an exciting trip to the range.

Kevin_K

Discussion Starter · #9 · 8 mo ago

Well, that explains why I couldn't find a LW barrel, good to know thanks!

I'm interested in how the 16.1" BoreBuddy barrels turn out. I was planning on buying a bunch of BB parts and the AR22 Catch anyway to get my rifle functioning in the same configuration as what I trained with.

Off topic: I'd be interested in a 22LR MCX LT barrel one day. Those look to be like the most serious contender for actually replacing the venerable M4. There's a charging handle adapter that allows one to use the CMMG bolt in an MCX.

colonelhogan44

· #10 · 8 mo ago

12Bravo said:
I'm willing to bet that the 4.5" barrels will sell just fine. I am going to put in a request for you for some 20" barrels. There are a few of us over on ARFCOM waiting for 20" barrels to build A2 clones with.

Noted -- I'll add that to the list for run 3, probably around the end of Q1 of 2023 if things go (relatively) smoothly from this point forward. So far they have been pretty rough with all the logistics of barrel production and the added strain of the ongoing supply chain issues. We had to reject the entirety of the original run of 4.5" barrels for some QC issues on the profile turning operations...which set everything back by about 6 weeks, but I'm not about to let anything we have knowledge of not being perfect hit the market with the BoreBuddy name on it.

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Erik72

· #11 · 8 mo ago

22lr match/precision upper build recommendations - AR15.COM

Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.

www.ar15.com

the user “Big-Bore” speaks very highly of Paladin Machine. He sent them his CMMG bolt/collar and he custom machined a barrel for him.
I’ve been wanting to have my brother do this for me but he works on a “gubmit” installation and really can’t work on firearms parts. It may not be sub $200 like you can get from CMMG/RTB but I bet any smith could turn one out of ant blank you provide. I feel like there’s a few guys on here that have done it themselves with great results.

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zukiphile

· #12 · 8 mo ago

Triggershoe rolled his own. A Green Mountain barrel blank turned to one's own specifications might scratch the itch for a lot of people.

The nice thing about the barrels I already have is that they are nitrided, and that could be hard to get with a one-off barrel.

Bore Buddy is teasing some creative tighter twists, and I'm curious to see how those work out. (I have serious inaccuracy issues with 45gr bullets and all my 1:16 barrels). I think the BB barrels will be in stainless.

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colonelhogan44

· #13 · 8 mo ago

zukiphile said:
Triggershoe rolled his own. A Green Mountain barrel blank turned to one's own specifications might scratch the itch for a lot of people.

The nice thing about the barrels I already have is that they are nitrided, and that could be hard to get with a one-off barrel.

Bore Buddy is teasing some creative tighter twists, and I'm curious to see how those work out. (I have serious inaccuracy issues with 45gr bullets and all my 1:16 barrels). I think the BB barrels will be in stainless.

Yep, all stainless. We're considering doing a nitride over the stainless on some of them as a "black label" line as well and we're planning to custom order 1-12" tooling for the second run of barrels.

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zukiphile

· #14 · 8 mo ago

colonelhogan44 said:
Yep, all stainless. We're considering doing a nitride over the stainless on some of them as a "black label" line as well and we're planning to custom order 1-12" tooling for the second run of barrels.

This may be my own phobia, but I offer it as one potential data point in the spirit of FWIW.

I don't prefer stainless barrels. My second pistol was a Ruger 22/45. In taking it apart for cleaning, I dropped the barrel onto the metal edge of a card table and onto carpet. When I picked up the barrel, I saw that the cheap metal of the card table had dinged the barrel. I was appalled at how soft the barrel metal must have been.

I doesn't bother me that a barrel is shiny or blued or black. If a barrel has the surface hardening treatment of nitriding or carburizing, I would prefer it over untreated SS.

I don't know if this sentiment is widely held or idiopathic.

Triggershoe

· #15 · 8 mo ago

2

zukiphile said:
Triggershoe rolled his own. A Green Mountain barrel blank turned to one's own specifications might scratch the itch for a lot of people.

The nice thing about the barrels I already have is that they are nitrided, and that could be hard to get with a one-off barrel.

Bore Buddy is teasing some creative tighter twists, and I'm curious to see how those work out. (I have serious inaccuracy issues with 45gr bullets and all my 1:16 barrels). I think the BB barrels will be in stainless.

I did indeed (pics attached)... Like Zuk, I will be watching BoreBuddy's progress with his barrels, and could probably be talked into buying a heavier profile 20" or so barrel when available. I'm really not looking forward to machining another, as it was a labor of love and very time consuming to do on the equipment (a little South Bend 9" swing bench lathe) I have available. Contouring, chambering, and crowning operations all needed a different set-up, each time dialing everything in to sub .001" TIR ("runout"). The one I made finished out at about 23" (from a 25" blank), .920" muzzle diameter. It IS a heavy beast for an AR-22.

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BigEd63

· #16 · 8 mo ago

zukiphile said:
..........
Lothar Walther left the market after CMMG changed the shank and collar depth. The fix is trivially simple for customers, but my sense is that they didn't want to sell a barrel that comes with an explanation.

Well that figures on at least two counts then. The change by CMMG themselves. And Lothar Walther's not wanting to hold the hands of people who aren't mechanically inclined at all.
I remember my correspondence with them before they'd "allow me" to place my order. So they probably were concerned about bubba botching a fitting job.

zukiphile

· #17 · 8 mo ago

BigEd63 said:
Well that figures on at least two counts then. The change by CMMG themselves. And Lothar Walther's not wanting to hold the hands of people who aren't mechanically inclined at all.
I remember my correspondence with them before they'd "allow me" to place my order. So they probably were concerned about bubba botching a fitting job.

They were like that before CMMG changed the shank length. They wanted to know who they were selling the barrel to; I've never had that experience before and I imagine some would find it off putting.

I am not mechanically inclined. Even I could figure out how to grind a bit off the front of a collar.

After the CMMG change, the girl who sold it to me wanted to be absolutely sure I had the old kind of collar. The barrels are so good, I forgive it all.

carbineone

· #18 · 8 mo ago

I really like the 20 Inch A2 Clone I built more than my others..

They are just cool in my opinion..My Barrel is a CMMG and is reasonably accurate and serves my puposes well..Not sure if CMMG is even making them anymore..

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12Bravo

· #19 · 8 mo ago

carbineone said:
Not sure if CMMG is even making them anymore..

I haven't seen any 20" 22lr barrels in stock for two years or more. I've been looking and also signed up for back in stock notifications on as many websites as I can.

I have my 4.5" pistol that runs well and my 16" heavy barrel that is pretty accurate. Both are CMMG barrels and I am using the Bore Buddy bolt weights and firing pins in both. So yes I would love to get a 20" barrel so I can make a 22lr clone to match my M16A2 clone.

zukiphile

· #20 · 8 mo ago

12Bravo said:
I have my 4.5" pistol that runs well and my 16" heavy barrel that is pretty accurate.

I don't know if this is any consolation, but my 20" isn't as accurate as my 16" HT. That A2 profile can't be good for rigidity. I use mine as a dedicated iron sight rifle, so pinpoint accuracy isn't necessary for me. I've considered a bloop tube for the 16" HT to get the outstanding accuracy and longer sight radius in one rifle, but it's vanity to pursue accuracy I could never use in its intended role.

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