300 Whisper SBR AR

[gotgraham]

I tested it out last night - worked awesome. I will get some video / audio this weekend to share.

[gotgraham]

Ok. Range report time...

Accuracy was great - about 1 moa with the super sonic load I tested. After drilling out my gas port to 0.093", function was flawless. Bolt speed was just right, the brass didn't get beat up. Here's a video of it in action. There's a .223 AR in the background about 100 yards away that you can hear at the same time, unfortunately. You'll get the idea.

Here's the video - suppressed with supersonic loads (~1250 fps). Ignore me jerking the trigger, i was just popping off some rounds for the video :) It was very much hearing safe. http://tinypic.com/player.php?v=2lihk6d&s=5

My wife posing with the whisper...

[Casey]

That is possibly the nicest SBR setup i have seen. Nice work.

[lovdasnow]

very nice, thanks for posting the follow up.
what are the specs of the subsonic load are you using?

[gotgraham]

Thanks guys!

Bullet: 190gr. HPBT-M
Primer: WSR
Case: LC brass mixed year
Powder: Hodgdon's Lil'gun
Weight: 7.7 gr. @ 920 fps
7.5 gr. @ 875 fps
7.4 gr. @ 800 fps

Test elevation: 3200 ft.

Brass
Trim: 1.385"
Max: 1.395"

C.O.A.L.: average 2.080" perfect depth for PMAG

[Keith1863]

Very nice. If I wasn't totally invested in my current build I probably would have gone with your setup.

I have been working on a Daewoo DR200 SBR upper in 300 Whisper. I am getting ready to drill the gas port but I don't know what size to go with. It has an adjustable gas system (via rotating a gas plug in the gas block), so it really shouldn't matter too much? As long as it is not too small right?

The Daewoo DR200's in stock config with a 223 barrel have a gas port diameter of 0.102".

I figured if I stick with this diameter and hang a suppressor on the end of the 2 inches of barrel that sits past the gas port, I should be able to cycle the gas piston with subsonic loads.

Any suggestions as to making the hole bigger or smaller would be appreciated.

Sorry for hijacking the thread.

Thanks,
Keith

[gotgraham]

No problem. If you're going to have an adjustable gas block, I would suggest drilling the port out to the full inside diameter of your gas tube. Others can probably chime in. I think its not much beyond the 0.102". Is your gas system carbine length? As far as drilling the hole, I picked up an assortment of cobalt steel drill bits from local tool supplier. Pick the one closest to your desired final measurement. To prevent drilling through your barrel, you should insert a rod of sorts (or drive a bullet) down the barrel to drill down to. In my case, I used an old cleaning rod. Slowly drill through the existing hole, taking a small amount of material at a time. Eventually you will drill completely through the gas port. Knock out any excess 'flashing' from the drilling with a cleaning brush. You're done. Test it out.