1st 300/221 build

[jjmcrowell]

I have been working on this for quite awhile, It is finally done, all that needs to be done is workout some loads for subsonic.

I have wanted to build a M16 with the look of an MP5SD and when I came across the 300 whisper It actually made it possible. Originally I was going to just make one in 5.56, however the 300 whisper is the perfect round for this.

About the rifle..

Colt M16A1 receiver, although I may go the SBR route shortly.

Bushmaster upper receiver

Gemtech TPR-S suppressor with bi-lock

Del-ton 300 fireball barrel that started at a 16" preban and was cut and threaded to 9" for the bi-lock

YHM rifle length free float quad rail

Aimpoint CompM with ARMS mount

Troy front folding sight and a GG&G folding rear sight

Ammo made from .223 Winchester brass sized with redding dies and loaded with 220 HPBTs

Using a trial loading of 10.0 grs of H110 and the 220 HPBTs the rifle cycles fine, just need to get ahold of a chronograph to get a final load.

[Colorado Osprey]

Cool SBR....PM sent

[WhisperFan]

Originally Posted by jjmcrowell

I have been working on this for quite awhile, It is finally done, all that needs to be done is workout some loads for subsonic.

I have wanted to build a M16 with the look of an MP5SD and when I came across the 300 whisper It actually made it possible. Originally I was going to just make one in 5.56, however the 300 whisper is the perfect round for this.

About the rifle..

Sounds like a cool project

Originally Posted by jjmcrowell

Colt M16A1 receiver, although I may go the SBR route shortly.

It is already a Short Barreled Rifle - since that the lower was once a rifle already, you cannot even make it into a pistol. I'd disassemble it until I got the stamp.

Originally Posted by jjmcrowell

This was a SBR as soon as the upper and the lower was put together - it needed a tax stamp before it was assembled.

I built an AR pistol in .223, before doing so, I spoke to the NFA branch of the BATF&E. They had me contact the Technology Branch. The word I got was that you may build an AR Pistol out of a receiver that has never been assembled into a rifle. I told them that I wanted to use a DPMS lower and that DPMS doesn't sell one marked specifically for a pistol. They advised that when the dealer or FFL holder logs the stripped receiver into their books, they should enter it as a "stripped lower receiver" and not as a "pistol" or a "rifle" Then - when they transfer it to you, follow all State laws in the State where you live to purchase a pistol and enter it in the book as a pistol.

I then asked if an AR pistol would be treated like a TC Contender in that you can change a TC pistol into a carbine provided that the short barrel was never on at the same time as the rifle stock. ie - put the longer than 16" barrel on while the pistol grip is still on, then change the butt stock. When going back to the pistol - change the butt first - then the barrel.

The Tech Branch BATF&E rep said that he thought it should work exactly that way, but AR pistols are not yet all that popular and this issue had not been addressed in writing to his knowledge. He suggested if I want to ever do that, to get a written opinion first from the ATF. I never wanted to do the swap - so I never followed through.

The most misunderstood area of firearms laws is in the arena of NFA regulations (Even among FFL holders) I even once was told by a gun dealer that my friend, who has a Type 07 (Manufacturer of Firearms other than Destructive Devices) with paid SOT could mess with SBR's and AOW's but even he couldn't make a machinegun. I just rolled my eyes and didn't argue with him -

In any event - it's a cool looking SBR

[jjmcrowell]

It's on an full auto M16 lower receiver...It is perfectly legal as it is now.

I was thinking about putting it on a semi auto SBR lower, since the M16 normally has a 5.56 upper with an 11" barrel and I don't care for always switching the uppers back and forth.

[WhisperFan]

Originally Posted by jjmcrowell

It's on an full auto M16 lower receiver...It is perfectly legal as it is now.

I was thinking about putting it on a semi auto SBR lower, since the M16 normally has a 5.56 upper with an 11" barrel and I don't care for always switching the uppers back and forth.

My bad -

I was under the impression that it was a semiauto lower

How does it run?

[jjmcrowell]

I have only tried it with one load, 10.0gr of H110 with a 220 HPBT. It cycles OK, however it is super-sonic. I'm going to try and work out a load that is about 1050fps or so. I have to borrow a chronograph from a buddy.

I haven't tried it on full auto, I haven't formed much brass, and I really don't want to tinker with it untill I get a sub-sonic load worked out, since once I get it sub-sonic, I may have to open up the gas port alittle.

I figured 10.0gr would be close to sub-sonic especially with a 9" barrel, but I hear a pretty loud crack. Where as when I shoot sub-sonic .308win it sounds more like a paintball gun.

I just need a chronograph.

[Spook]

Jim, my best Whisper load uses 9.5 g.of VVN 110 w/ 220 RN,using a 1/8" gas port .You might try 9 g with a barrel that short.

[kurtz]

Jim, don't know if this helps but down here at sea-level in about 60 degree weather, 9.6gr of H110 and 220 Matchkings goes through the chrony at a very consistant 1060fps.....also working with 9.2gr of H110 and 200 Matchkings at 1050fps....hope this helps

[jjmcrowell]

Originally Posted by kurtz

Jim, don't know if this helps but down here at sea-level in about 60 degree weather, 9.6gr of H110 and 220 Matchkings goes through the chrony at a very consistant 1060fps.....also working with 9.2gr of H110 and 200 Matchkings at 1050fps....hope this helps

Seems like everybody is around 9 or 10 grains with H110 for sub-sonic. What length barrel are you using?

[m21black]

Use 9.3 grains of H 110 with a CCI SR primer topped off with a 240 grain SMK... equals 1040 FPS and many dead deer.