Airsoft M16 SDMR?

[Groombug]

I'm looking to build an M16 SDMR: http://en.wikipedia.org/wiki/United_...Marksman_Rifle

I have only one problem with assembling the parts - I can't seem to decide on the best-fitting and best-looking RAS assembly to use in conjunction with a one-piece M16 outer barrel.

I'm looking at RAS assemblies similar to these two examples:

King Arms free floating RAS
http://www.uncompany.com/pageproduct...sp?prodid=6817

G&P RAS
http://www.wgcshop.com/pcart/shopper...AS-300_cat_RIS and RAS

I plan on taking the RAS assembly and using it over the one-piece barrel. What I want to know is if these assemblies are the right length and whether or not the barrel will fit properly. Essentially I'm wondering if these RAS assemblies are the same length as the Daniel Defense 12.0 rail system used on the real steel SDMR.

I'm aware that the Daniel Defense octagonal delta ring is not available as an airsoft part. I'm going to overlook that until a suitable replacement is available.

[pugs144]

I've got a similar setup using a GB-Tech long RAS. The G&P long RAS you've shown should fit as well with no interference from the M16-typ front sight.

[Groombug]

Originally Posted by pugs144

I've got a similar setup using a GB-Tech long RAS. The G&P long RAS you've shown should fit as well with no interference from the M16-typ front sight.

Which GB-Tech kit did you get? Did you also butcher the RAS and mate it with an M16 barrel with triangle sight?

[pugs144]

I have the 300mm RAS kit. No butchering is required. Instead of using the heavy barrel included in the kit you simply use your regular M16 barrel.

Forgot to add. In order to properly tighten down the big barrel nut you'll need an M16/M4/Armalite armorers wrench. The barrel nut is the piece with the little holes along the circumference. It's what mates the barrel to the upper receiver. The shims are so you can properly align a hole for the gas tube to pass through.

[Groombug]

Speaking of the gas tube.... did you have to get a M16 triangle sight with the gas tube hole, to accomodate the gas tube? Likewise, did you have to accomodations for the gas tube on the upper receiver? I have a metal body, if that makes a difference.

Strong-arming the barrel nut won't work, right? I 100% need that armourer's wrench?

[pugs144]

I drilled out a hole in the triangle sight to accomodate the gas tube. I have a CA one-piece barrel BTW. 100% you'll need the armorers wrench because there's no way to strong arm the nut. If you look at the pic above, the other nut that secures the RAS to the receiver goes over the barrel nut. Anything less than the armorers wrench and the barrel will not be tight enough and you'll eventually get some barrel slop.

If your upper receiver doesn't have a hole to accomodate the gas tube, just drill one.

[Groombug]

Thanks Pugs...

Couple more questions...

Will this substitute for the barrel nut wrench?


Also, I'm thinking of using a Specter Gear SOP sling for M16A2 - it'll require me to use the sling mount under the triangle sight and also wrap around the collar on the frontmost part of the RAS. Will this put undue stress on the barrel or the RAS?

[pugs144]

That's the wrench you need. You see those nub-like protrusions facing away from the camera? Those nubs are what go into the little holes of the barrel nut and allows you to tighten it.

I don't have experience with that Specter Gear sling though, so I don't know how collar will interact with the the sling mount and how much stress it'll put on the barrel.

After all is said and done your rifle should look like this:

[nutboi]

or something close to my rifle but with a longer ras and barrel. i have a tri rail mount on the outer barrel that i mount my sling onto. i don't notice any stress on my g&p one piece barrel when we're standing around and i don't really let go of the gun during a game either. if ur worried about stress on the barrel then u can get a ras/ris sling mount.....like this one
http://elitetacticalsources.com/clie...s.php?pid=2999

[ILLusion]

I've helped install triangle front sights on to G&P and KA RAS' with other outer barrels, and it's a pain in the ass. A good amount of fitment is required to get it right. The pin slots on the outer barrel for the triangle sight won't line up right because the RAS is a bit longer and ends up pushing the triangle sight forward. You would either need to file new pinholes, or file down the back of the triangle sight to get it to sit closer to the handguard.


That armourer's wrench you have there is overkill and pricy. Here's a cheaper alternative that gets the job done just as well:
http://www.wgcshop.com/pcart/shopper...=GP-TOOL-GP266

I have one here that you can borrow, Ernest... rather than buying one.




pugs: it wouldn't look like the gun in your picture. That's a Long-SIR. That's a totally different rail system.





Actually, your best bet would be to get either the GB-Tech, G&P or King Arms RAS kits (they're all manufactured by the same factory... they're just finished individually, so the final "look" will be different, although all mountings and fitment will be the same) and get the Guarder steel M16 outer barrel WITH VARI-LENGTH.

MAKE SURE IT HAS VARI-LENGTH. That will allow you to extend the outer barrel as required to fit with the RAS kit.

[nutboi]

as for the tool.....i used one of these
http://www.canadiantire.ca/assortmen...romSearch=true
:tup: it worked great and no damage to anything.

[integratyperx]

I'm a little confused, as far as airsoft is concerned, replicating the SDMR just requires an m16 w/ an RAS kit and a barrel?

[nutboi]

Upper & Lower Receivers: From most reports the rifles appear to have been built up using existing lower receivers in inventory. What this means is the rifles are completed using A2/A4 lowers previously supplied by either Colt or Fabrique National, with a fixed A2 stock. The upper receivers are flat top style. Unlike the SAM-R and SPR, it does not have extended feed ramps. The trigger has been replaced with a Knight's Armament Company 2-stage match trigger capable of only semiautomatic fire.
Barrel: The traditional 1:7 twist 20-inch barrel has been replaced with a stainless steel Douglas 1:8 twist 20" barrel, with 12 flutes cut into the barrel to reduce weight. The front sight block is installed with 4 set screws instead of two taper pins. The A2 style flash hider is retained.
Handguard: The SDM-R uses a Daniel Defense M4Rail 12.0 handguard, with an octagonal steel collar locking it to the receiver block. The Daniel Defense handguard provides a free-floating MIL-STD-1913 rail forend.
The 82nd Airborne Division uses an alternate version, based on the M4 Carbine. The barrel is an 18"-long fluted Douglas barrel with 1:8 twist. A mid-length gas system is used, along with the Daniel Defense M4Rail 9.0 handguard