14.5" Build. I need some opinions as I gather parts

[SonOfAGunn]

I thought I had this all figured out, I didn't. I'm looking to build a new rifle and was going to use a 14.7" CHF FN M4 profile barrel, pin and weld a muzzle device (Surefire Close Tine), pin a gas block (Geissele), and use a RIS II rail. I originally wanted to use a stripped Colt M4 SOCOM barrel but those are kind of hard to find right now so I settled on the FN, and that arrived today. Earlier tonight I looked online and of course, I found a Colt SOCOM barrel on brownell's. I ordered it even though it wasn't stripped since they seem hard to find. The Colt came with an FSB mounted and a barrel nut.

It looks like the Colt SOCOM is a pretty accurate barrel, I'm not sure if the CHF 14.7 FN M4 is relatively close to the Colt as far as accuracy. Any one with experience with both, please let me know your thoughts. I imagine since the FN is CHF it will last longer.

My thoughts are sending my barrels to "Retro Arms" for the work. I imagine he can answer some of these questions, but I'm pretty sure there are guys on here that have crossed this bridge before.

After having the barrel nut removed, would you reuse the FSB and just have it shaved so that it fits under the RIS II rail? Would that work/fit? Do Either of the pin holes that exist on the Colt line up for the Geissele GB so that the barrel doesn't have to be drilled again if the FSB option won't work?

I'm wanting to use the Surefire SOCOM Close Tine Flash Hider for this build and it's slightly shorter than the 3prong. Does anyone know if spacers can be used to bring a 14.5" barrel to 16.1" using this muzzle device or would using that many spacers cause problems?

I look forward to hearing from you!




Parts on hand so far.

Stripped Mega Arms GTR-3H lower and Mega upper
14.7" FN Barrel (might use that for a spare SBR upper or this build)
14.5" Colt SOCOM
VLTOR Carbine Receiver Extension
Geissele Super 42 H
Geissele Super 42 H2 (Most likely this will be the one used)
VLTOR IMOD Stock (basic)
Daniel Defense M4A1 RIS II Rail (most likely will be used)
Geissele Nitride Super Gas Block
Magpul K2+ Grip
Scalarworks Front Sight
Geissele ACH
Geissele SD-E


Parts I'm waiting for, looking for, and undecided on.

Geissele MK16
Geissele MK8
Centurion Arms C4 M-LOK w/ FSB Cut
Geissele Ultra duty LPK
Daniel Defense Chrome BCG
Geissele REBCG
Colt BCG

Haven't picked a Rear Sight yet.

Not sure what I want for the BCG.

[m1a_scoutguy]

After having the barrel nut removed, would you reuse the FSB and just have it shaved so that it fits under the RIS II rail? Would that work/fit? Do Either of the pin holes that exist on the Colt line up for the Geissele GB so that the barrel doesn't have to be drilled again if the FSB option won't work?
Not sure what I want for the BCG.

Only thing I'm sure of is the Geissele gas block has one "through" pin if you want to use it & I'm pretty sure its bigger than the stock pins that hold the original FSB. At this time finding a BCG could be tough, there are what's considered "lesser" quality ones out there but I guess it depends on how soon you want to be up and running and if you can find the others parts needed to complete your build. Here is an example of how things are, I went to MidwayUSA today cuz I received an In Stock on a Faxon BCG,good stuff I feel but I didn't really need it but was going through the paces and had it in my cart, I went and looked at a couple other things and when I came back it was GONE !!! This all took place in about 5 min,LOL Didn't really need it so no Biggy, but it boils down to if you see something buy it and don't wait cuz it will be gone in short order !

[SonOfAGunn]

Yeah, I knew about the pin for the Geissele Block, but I wasn't sure it would line up with the existing hole. Looking at pics it doesn't look like it will. I've got other guns to shoot at this time so waiting for parts to come back into stock isn't a big deal. I just have to ready to buy as soon as I get alerts that they're in stock.

[GH41]

I would put more faith in the FN barrel myself. Colt quality is all over the place IMO. You don't say what you are building the rifle to do but if it isn't for range use only I wouldn't use the SD-E trigger.

[everready73]

I would guess that both barrels will deliver adequate accuracy. i have heard good things on both. Molon tested the Colt barrel and it was very accurate. Others report this as well. I have a 16'' FN CHF barrel and it shoots 1.5 moa with match ammo. If i had those 2 barrels i would probably lean towards the colt, but wouldn't hesitate to use the FN. You are choosing between good and good. Barrel life wouldn't be a huge concern (for me). Both barrels will last at leas 15k rounds most likely and you will spend way more on ammo. The barrel is consumable and i treat them as such.

I am not sold on the G super 42 buffer set up personally. I would go with VLTOR A% or just the VLtor carbine tube you plan on getting and a regular h2 buffer

Feel confident sending anything to John at Retro. He is awesome. You can shave the FSB to fit under most any rail.

I am pretty boring when it comes to BCGs and if you have access to a COLT that would be my first pick. The DD Chrome BCG is a good option as well as Sionics milspec or NP3, or SOLGW. Sionics and SOLGW use Ned's OCKS screws on the gas key and they are very high quality BCgs . I would def not buy the Young-They dont even stake and you are paying a premium for the unproven G REBCG IMO.

[SonOfAGunn]

Wow, I've never heard that about Colt barrels. I've known that the finish on Colts products aren't always the prettiest. To be honest I haven't been very active on the site for awhile.

I'm thinking I may use both barrels. Use the Colt for this gun that I'll pin and weld, and then use the FN to make a spare upper to use on an SBR.

This build is going to be a range gun pretty much, I have an 11.5 that is a Defense gun so the trigger will be fine. I don't own an SD-C though or that newish single stage. I can't remember the name of that one.

[MC_Oper8or]

Good choices.

IMO the ACH is too small in the wings and easy to miss in under duress. I prefer Radian.

A properly gassed rifle may find the G42 spring too strong. I’d go A5.

Geissele lpks don’t seem to be any better than the usual suspects.

I’d explore wedge lock rails and the above mentioned bcgs.


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[SonOfAGunn]

Too late on the 42 H2, already have that.

I'm the same way for most of my BCG's. The fanciest one would be the Chrome DD. I was kind of skeptical about it, but it does clean up easy. Thanks for reminding me about Sionics! They supply APD and do builds for the cops here for personal ownership. I'll check out the NP3 bcg they've got.

The fact that the FN is an M4 profile doesn't make it less than a shooter compared to the FN SOCOM profile?

[SonOfAGunn]

I have searching the earth for a Wedge lock. Zev isn't planning on selling them individually for a while. I'm absolutely certain that when I finish this build Zev is going to do a run of Mega Wedge locks. That's the type of luck I have.

I've never used the larger Geissele CH, I always liked the idea of having a more compact CH and use one on my SBR. I may give the larger one a try.

Have you used an LPK that has a safety that's similar to the "Posi Snap" that geissele has. I dig that pop.

[MistWolf]

I like the Colt 14.5 SOCOM barrel. It's gassed right, it's a sweet shooter and it balances well. Cutting the FSB is a better choice than installing a new gas block.

Compared to the M4 profile, the SOCOM profile handles heat better and I like the balance better.

A spacer would bother me, so I would pin & weld the 14.7 FN barrel and SBR the 14.5 SOCOM barrel.

I have no experience with FN barrels but they have a good rep and wouldn't hesitate to try one.

[SonOfAGunn]

I like the Colt 14.5 SOCOM barrel. It's gassed right, it's a sweet shooter and it balances well. Cutting the FSB is a better choice than installing a new gas block.

Compared to the M4 profile, the SOCOM profile handles heat better and I like the balance better.

A spacer would bother me, so I would pin & weld the 14.7 FN barrel and SBR the 14.5 SOCOM barrel.

I have no experience with FN barrels but they have a good rep and wouldn't hesitate to try one.



A spacer can be used along with shims for a pin and weld job can't they? I hope they can, lol. If not I need to rethink my adapter choice. If I go with the RIS II for the build I'll just have the FSB shaved, but I messed up and saw a thread on the site about the Centurion Arms rail that's new for 2020. I'm liking the M-Lok rail with the FSB cut out, if I can find one of those I won't have to cut the FSB at all. I have no doubts that the wait time for that will be a while.

[m1a_scoutguy]

A spacer can be used along with shims for a pin and weld job can't they? I hope they can, lol. If not I need to rethink my adapter choice. If I go with the RIS II for the build I'll just have the FSB shaved, but I messed up and saw a thread on the site about the Centurion Arms rail that's new for 2020. I'm liking the M-Lok rail with the FSB cut out, if I can find one of those I won't have to cut the FSB at all. I have no doubts that the wait time for that will be a while.

Whenever I did a 14.5 BBL I just always made sure that the MB/FH was of the longer version, some will specify that they are for use with 14.5 BBLs so they are out past or at least even with the 16inch minimum length. I would have to look and see if your 1st choice meets that requirements. But with that said I don't know why you couldn't use a shim for some added length but not sure if that would mess up things with it being extended out some or farther than it was designed for ? I just always use a crush washer and call it good & that puts my BBL out to the 16inch needed.
I have always liked and wanted one of the older Centurion rails myself,didn't know they had a "newer" one ! The older versions were pretty sweet lookin on there own.

[SonOfAGunn]

Whenever I did a 14.5 BBL I just always made sure that the MB/FH was of the longer version, some will specify that they are for use with 14.5 BBLs so they are out past or at least even with the 16inch minimum length. I would have to look and see if your 1st choice meets that requirements. But with that said I don't know why you couldn't use a shim for some added length but not sure if that would mess up things with it being extended out some or farther than it was designed for ? I just always use a crush washer and call it good & that puts my BBL out to the 16inch needed.
I have always liked and wanted one of the older Centurion rails myself,didn't know they had a "newer" one ! The older versions were pretty sweet lookin on there own.

https://centurionarms.com/rail-systems/new-c4-mlok-rails/

The link is to the one I'm interested in. I think other new 12" rail was out of stock about 30 min ago.

I like the older versions as well.

The Closed Tine Flash Hider is 2.33".

[munch520]

I'll be the weirdo who suggests something different. To date in 2020 I've used or assembled/tested 4 ballistic advantage barrels (one 16" SS, two 14.5 Hansons, and a 12.3 Hanson). Get one on sale for sub $200 and it's a great option IMO.

I've found their "MOA guarantee" to be legit (with good ammo obviously), although I don't stress about it as I usually shoot something with a 2MOA standard (like 193). I really like the Hanson profile, which is basically a continuous taper down to the muzzle and lacks any shoulders or right angles, which apparently helps with harmonics. A bonus is that they pin their barrels and send a compatible low pro gas block with that barrel. The Hanson series is also pretty lightly gassed and has that target crown.

Same with rails, I've gone to SLR after not being able to find the Geissele options in stock. The Ion is what I have used a few times and have been really happy with it...big barrel nut with wedgelock-type interface, made of 7075, 7-sided MLOK, and 4 integral QD points. I felt I was getting a lot more for $100 less when I went to one of these in lieu of the Geissele MK16. And this is coming from a "Geissele all the things" guy.

Here's one of my 14.5s with the 13.7 SLR rail. One of my demo guns for 2021, hope to get 8-10k through it minimum. We'll see how things hold up.
https://live.staticflickr.com/65535/50698892682_36b49e0b12_b.jpg

[SonOfAGunn]

I'll be the weirdo who suggests something different. To date in 2020 I've used or assembled/tested 4 ballistic advantage barrels (one 16" SS, two 14.5 Hansons, and a 12.3 Hanson). Get one on sale for sub $200 and it's a great option IMO.

I've found their "MOA guarantee" to be legit (with good ammo obviously), although I don't stress about it as I usually shoot something with a 2MOA standard (like 193). I really like the Hanson profile, which is basically a continuous taper down to the muzzle and lacks any shoulders or right angles, which apparently helps with harmonics. A bonus is that they pin their barrels and send a compatible low pro gas block with that barrel. The Hanson series is also pretty lightly gassed and has that target crown.

Same with rails, I've gone to SLR after not being able to find the Geissele options in stock. The Ion is what I have used a few times and have been really happy with it...big barrel nut with wedgelock-type interface, made of 7075, 7-sided MLOK, and 4 integral QD points. I felt I was getting a lot more for $100 less when I went to one of these in lieu of the Geissele MK16. And this is coming from a "Geissele all the things" guy.

Here's one of my 14.5s with the 13.7 SLR rail. One of my demo guns for 2021, hope to get 8-10k through it minimum. We'll see how things hold up.
https://live.staticflickr.com/65535/50698892682_36b49e0b12_b.jpgThank you for the info on the Hanson barrels, I've never researched that brand before. I'll keep them in mind for a future build. I've got two 14" barrels now that I've got to figure out what to do with.

I've got a Ballistic Advantage barrel in a pistol I built earlier this year, and it's been great.

I haven't purchased the Centurion Arms rail yet, I'm still waiting for those to come in so I'll check out the SLR rail you suggested. I like the idea of 7075 for a rail.

You're not weird friend, just different. Lol



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[SonOfAGunn]

Very nice rifle by the way!

[munch520]

Very nice rifle by the way!

Thank you

[MistWolf]

A spacer can be used along with shims for a pin and weld job can't they?
Yes, but in my opinion it's a less than ideal setup.
-A spacer reduces the number of threads the muzzle device engages
-A spacer one more thing that can cause suppressor misalignment
-A spacer looks like the installer couldn't be bothered with getting the parts needed to do the job right

None of the above may be important to you, nor do they have to be. But it does bother my CDO.

[SonOfAGunn]

Yes, but in my opinion it's a less than ideal setup.
-A spacer reduces the number of threads the muzzle device engages
-A spacer one more thing that can cause suppressor misalignment
-A spacer looks like the installer couldn't be bothered with getting the parts needed to do the job right

None of the above may be important to you, nor do they have to be. But it does bother my CDO.

I'm guessing you're talking about any additional spacers along with the spacer that comes with the Surefire adapters?

[MistWolf]

I'm talking about spacers used to ensure, for example, that a standard A2 birdcage installed on a 14.5 inch barrel will meet the 16 inch minimum. Not shims etc, used to time a muzzle device.

[Gatorgrizz27]

I know it’s not trendy, and obviously may not work if you need to run an IR/laser or similar up front, but I’m still a fan of the fixed FSB for an “old faithful” rifle. Midwest Industries makes a drop in aluminum handguard with QD sling mounts M-Lok slots on the sides and bottom. It doesn’t feel as nice as their free float guards but it’s better than plastic or 1913. Mine is mounted on a 14.5” FN mid-length gas barrel, so if yours is carbine length it might not be as handy. Pair that with a red dot and then set up the other upper with a 1-6 scope and free float rail.

Sionics is awesome, I highly recommend them.

Also, Midwest industries sells a low profile gas block designed to cover the taper pin holes from the fixed FSB. You’d have to figure out how to mark it to match the barrel notches as it’s not drilled, but I’m sure a machinist could handle it.

[SonOfAGunn]

I know it’s not trendy, and obviously may not work if you need to run an IR/laser or similar up front, but I’m still a fan of the fixed FSB for an “old faithful” rifle. Midwest Industries makes a drop in aluminum handguard with QD sling mounts M-Lok slots on the sides and bottom. It doesn’t feel as nice as their free float guards but it’s better than plastic or 1913. Mine is mounted on a 14.5” FN mid-length gas barrel, so if yours is carbine length it might not be as handy. Pair that with a red dot and then set up the other upper with a 1-6 scope and free float rail.

Sionics is awesome, I highly recommend them.

Also, Midwest industries sells a low profile gas block designed to cover the taper pin holes from the fixed FSB. You’d have to figure out how to mark it to match the barrel notches as it’s not drilled, but I’m sure a machinist could handle it.When I first got into these guns I wasn't interested in having an fsb or fixed sights. I wanted as clean a sight picture as possible when using my rds. That changed about a year and a half ago when I decided to build another one but use fixed sights. The sights always being up never bothered me like I had initially thought it would.

I won't be shaving down the sight on my colt barrel (that just arrived today). I'll be using it for this build and I've decided to go with the Centurion 12" C4 M-LOK FSB. I guess it's similar to the RIS II FSB in that if I decided to run a laser in front of the FSB that would be possible. Now I just have to wait to see when it comes back on stock. I just have to decide between the black version or the od green. I think the od green that they use is lighter than what I expected OD green to be. If somebody has an example of the OD green that Centurion uses and posts a pic, that would be greatly appreciated.

I'll use the FN barrel with my RIS II.

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[JoshNC]

When I first got into these guns I wasn't interested in having an fsb or fixed sights. I wanted as clean a sight picture as possible when using my rds. That changed about a year and a half ago when I decided to build another one but use fixed sights. The sights always being up never bothered me like I had initially thought it would.

I won't be shaving down the sight on my colt barrel (that just arrived today). I'll be using it for this build and I've decided to go with the Centurion 12" C4 M-LOK FSB. I guess it's similar to the RIS II FSB in that if I decided to run a laser in front of the FSB that would be possible. Now I just have to wait to see when it comes back on stock. I just have to decide between the black version or the od green. I think the od green that they use is lighter than what I expected OD green to be. If somebody has an example of the OD green that Centurion uses and posts a pic, that would be greatly appreciated.

I'll use the FN barrel with my RIS II.

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A solid build. C4 mlok is nice. Another option to consider is to shave the FSB and use a Geissele mk16, which is my favorite setup. The m4a1 barreled upper with mk16 is my personal favorite.

[SonOfAGunn]

The MK16/14 were what I was going to go with. I saw a picture of a green Geissele Rail HERE (https://www.m4carbine.net/showthread.php?642-AR-Picture-Thread/page3161) and I can't stop going back to look at it. If the Centurion green is similar it's a definite purchase, I just can't seem to find a picture of one.