Hello everyone, new member here with a question on converting from a 16.5" barrel to a 14.5" barrel on a Colt LE6920.

I'm buying a LE6920 and want to be able to properly mount a M9 Bayonet on it. I spent 23 years in the army and just want a M4 that will properly hold a bayonet, not like I'll ever need to use it, I just love the look. As I understand the standard barrel is too long and for the bayonet to fit properly, does the barrel needs to be a 14.5" barrel? I know a lot about the M16/M4's but not the problems or legal part of exchanging the barrel out. Will the length of the barrel effect the gas system?

Thanks for your help.

You can buy a 14.5 and pin and weld an extended compensator or purchase one already done. It will be the legal 16 inch length when pinned and welded into place and should fit your bayonet.

Send your upper to a place like ADCO and have then cut, thread and mount a extended compensator with a pin and weld for the legal 16 inch length. Same results as above.

You could do what some here have done and mount a piece of a cut A2 compensator the nut part behind a A2 compensator and pin and weld. It will achieve the length but to an untrained eye at a glance the weapon will appear normal. Really your just doing the same thing as a extended compensator except your not going to have longer flash slots your will have longer section of grooves where you would normally mount a BFA.

Will it look absolutely legit? No but it will be damn close.

BCM

If you get this and select the option for the permanently attached extended A2X ($45.00) you would be able to swap over all your Colt stuff (side sling mount, hand guards, etc) to this upper and be ready to rock and roll. I haven't tested the fit for a bayonet as far as diameter however with the back end of the A2X in the same position as the standard A2 I don't see why it would not work.

Other option is to purchase a Colt 6921 which is a M4 minus the auto sear, it has the same length barrel as the issued item. However you will have to pay your $200 to DOJ and wait for approval before you can take it home.

Wow, a very long post that doesn't actually answer the stated question.



No, cutting the barrel down to 14.5 will not effect the gas system. Carbine length systems have been used on barrels as short as 10.5 and as long as 16. Cutting it down will not be an issue

It's easy.... remove handguard and gas tube, take off barrel, remove delta ring. Sell barrel. Get a 14.5 M4 profile barrel off the EE, send to ADCO and have an extended A2 pinned on it. Install delta ring and screw onto receiver. Easy and legal.

A bayonet will fit on a 14.5 carbine or a 16 middy IIRC. It will not fit on a 16" carbine.

14.5 is the way to go.  It is actually desirable to have that length barrel with the carbine gas system.  You can have your cut by ADCO, or simply buy a Colt barrel.  They are actually for sale more often than you would think.

I bought a 14.5 Colt M4 barrel, and was going to get a 6920 and SBR it.  Then I came to my senses, and cut that barrel to 12.5 and made a cooler rifle

Thanks for all that info, some understood some not  Ya I think the 6921 would be the was to go. Here in Washington it is legal to own a SBR but it must be an originally manufactured SBR like the 6921, you can't just modify a barrel. I wonder if anyone ever made a barrel mountable bayonet lug???

So are you saying I can just switch a 16" barrel for a 14.5" barrel without any gas system issues?

Absolutely.

People are submitting form 1s and getting them approved, although there is still a big debate on legality. WCA has a good amount of SBR's on the wall right now. I went with a DD Mk 18