Starting a 605 build

[Renegade04]

Well guys, I have not even finished up on my XM16E1 and M16A1 builds and I am already starting on getting parts together for a 605 build. I ordered the partial-fence lower from Harlan (Nodak Spud) the other day as well as some more parts from Slim at Indiana Army Surplus. Here is the stuff I ordered from him.

D stock
Receiver extension
Buttplate screw
Buffer
Buffer spring
Triangular handguards
Bolt catch
Magazine release, spring, and button
XM Grey trigger guard
Teardrop forward assist, spring, and roll pin
Takedown pin
Gas tube (current)

I also just won an auction on GB for a Colt 604 upper receiver for this build. I have also contacted one of my sources and scored an original chrome slickside M16 bolt carrier and bolt for the build. I still have a few months before I have the NDS XM lower, so I have time to source a barrel and get it done by John Thomas at Retro Arms Works.

For those not familiar with a 605, here is a picture.

[Renegade04]

Here is a little update on the progress. I received all of the stuff I ordered from Indiana Army Surplus a few days ago. The Colt 604 upper is on its way. It will be here Monday. I have a chrome slickside bolt carrier with a chrome bolt that is scheduled to be here Monday as well. I ordered another set of handguards, a couple M16 selectors and a couple takedown pins from Indiana Army Surplus and they will be here Monday too. When I got the first set of handguards, the left side was the newer matte black finish and the right side was the older shiny mottled finish. The handguards I have coming will have a left side with the shiny mottled finish and the right side with the matte black finish. Next, to get a barrel and 3-prong FH ordered.

[H Wyman]

Didn't the 605A/B have a 14.5 inch barrel?

[Renegade04]

Didn't the 605A/B have a 14.5 inch barrel?

15"

I think I am going to buy the Brownells M16A1 pencil barrel as it is a 1/12 twist. I am going to have John Tomas (Retro Arms Works) cut down the barrel to 15" and pin and weld the 3-prong FH on. It will also have the gas port opened up to .110" and the forge flashing will be removed from the FSB to mimic a cast FSB.

[H Wyman]

I asked because the barrel in the photo you posted looks like a 20" cut to 16". I didn't think you get a 15" barrel out of a rifle length gas system.

[Renegade04]

I asked because the barrel in the photo you posted looks like a 20" cut to 16". I didn't think you get a 15" barrel out of a rifle length gas system.

The 605s were more or less an experiment in developing a carbine. That is why they never made too many of them. They could not get them to work very well. The gas cycling was the big issue. Fortunately today, we know the cure to the gas cycling problem.

[Renegade04]

I just had a message from a member on AR15.COM telling me about a Colt USGI NOS barrel he already had done for a 605 he was going to do, but has decided not to. He gave me a good price on it. Looks like I have the barrel issue solved. All I will have to do to this barrel is have the 3-prong FH pinned and welded.

[Renegade04]

I got my Colt 604 upper this afternoon. It looks great. When I bought it, the seller told me that the port door spring was broken. Well, I fixed that in less than a minute. It works great and I still have an original spring. I also got in the chrome 601 carrier and bolt from boywonder777.

[Renegade04]

I managed to get a barrel already done from a fellow ARFCOM member. It came in yesterday. Here is a mock up of the upper assembly (minus CH and gas tube). I still have to have the FH pinned and welded to bring the barrel to legal non-NFA length. Next week, I should have the charging handle and gas tube for it.

[Junkie]

I like your build. I'm planning on building something loosely based on a 605 before too long, but probably a 16" barrel and nitrided. Might also go for a shorter stock. What's a reasonable price for an upper? I want no FA or deflector, just like yours.

I know what you mean about handguards... I bought a furniture set and the two sides don't match very well, they're even significantly different weight.