I have a Colt 6920 SOCOM with the 16" barrel that I will be SBRing to the MK18 configuration. Should I purchase the complete upper or just the barrel? Aside from the cost factor, is there an advantage to doing one over the other?
1- If you have the tools, a new barrel replace is easy and fast.
2- if not, and you know a GOOD smith who can chop/thread barrel, and redrill gas port, it’d be much cheaper. (IMO likely-hood of finding competence locally is nill)
3- any smith should be able to put on a barrel w/o issue
4- no tools/no experience maybe buying a complete upper, from a respected vendor, a more sound choice. It can be hard to resolve an issue… when a cobbled together pile o poo doesn’t work.
Generally, the shorter one goes the better ammo will be required.
If the only thing you’re changing is barrel length, chopping your barrel will be the most cost effective way to go about it, for sure.
Are you happy with the Colt handguard and fixed FSB?
I would rather not cut my Colt barrel down. I saw that Specialized Armanment has the Mk18 barrel assembly with the fixed FSB for $495 and the complete upper for $895 minus the BCG and CH.
Are the uppers from Specialized Armanment factory Colt assembled uppers or are they put together from Specialized Armanment?
I’m not 100% on this but I’m under the impression that Specialized Armament puts all their stuff together.
Also, if you go the route of cutting the barrel + 1 for ADCO. They do great work.
Keep your stock upper and buy a complete upper. Then you can use your stock one till the stamp comes back and then sell it, or just have 2 uppers to choose from… Cough Block II upper, and a Mk18 upper Cough
I would buy the upper assembly.
If cost isn’t an issue, the upper would be the straight forward, no hassle thing to do. However, $895 would go a looong way if you were to just get the barrel and shop for parts, esp. if you have the luxury of time, waiting for your stamp.
That $900 doesn’t even include the bolt group… Extra $300 if you get it from them.
$1,200 is very steep for a plastic hand guard chrome lined upper. But it’s definitely your money.
Ok stupid question. Do I need to get a new BCG for the 10.3" Mk18? Can’t I use my existing BCG from my 16" SOCOM upper?
You can use your existing BCG, but make sure your bolt headspaces ok with your new barrel…accuracy can suffer if it does not.
Also, if you go the cut down, or chopped and channeled route with your existing barrel…make sure you do not forget to upgrade your extractor spring and recoil buffer…not forgetting that you have to have your gas port in the barrel opened up to MILSPEC to work properly…seems like a lot of work, but when he was not backed up…John Norrel out of N Little Rock used to do that service with ease…Ken Elmore knows what he is doing…but he costs a lot compared to a shop like ADCO…
Just my 2 cents.
Good luck on your Mk 18…I used one for 5 years…great little rattle gun…don’t shoot cheap crap ammo through it though…Mk 18’s like 3 things more than anything else…good ammo (green tip ball), a good muzzle suppressor and a good cleaning after firing…
You can but it’s not ideal. To be safe, check your headspace… And certainly dont go switching back and forth between uppers.
I recommend just getting a new bolt or bcg to go with your new barrel or upper, whichever it may be.
My Mk18 eats everything. Esp. cheap russian steel. Actually that is all it gets fed.
I’ve recently seen this statement (that 10.5s require “good” ammo) a couple of times, now. I’ve also been able to shoot ammo from across the pressure spectrum in the several 10.x" uppers that I have had. Though we have to accept that this configuration will overall be a bit more likely to be finicky than others, the margin of reliability should still be wide enough to shoot any ammo. If it shorts, drop to the next lighter buffer.
Mine has been shot both suppressed and unsuppressed I might add, but the can is always on it now.