Build complete - Happy ending!

[rednek58]

First of all I want to thank Quarterbore for a great forum. Secondly, I want to thank everyone on this board for the valuable information that I have received. In return I would like to share the details on the build I have just completed using the 300 whisper cartridge on an AR platform. I hope this report will be helpful for any of you currently building or plan on building a rifle of this kind.
Since I already had a Gemtech TPR-S suppresor for a Rem 700 308cal. with bi-lock adapter, I wanted something subsonic to shoot it on. The 300 whisper seemed to be the perfect cartridge. Since I already have a RDIS for the AR and have many years experience with the AR platform, it was not long before I yearned for subsonic supressed full auto fire. I can say now, that I have a very quiet and 100% reliable weapon.
I started with a Model 1 Sales 16" barrel w/barrel extension, milled gas block and 1/8 twist. I coupled it to a bushie flat top receiver, and bushie free float forearm. I used a standard Colt full auto bolt, that I already had lying around, and installed an extra power Wolff extractor spring (which I do on all my ARs). I will note here that I at first had the not so uncommon feeding problems, but was able to remedy this fairly easily. It seems that the M1S barrel came with a standard .223 barrel extension. Trying to feed 30 cal bullets using 22 cal feed ramps was causing obvious problems. I took the trusty Dremel and a suitable grinding stone and reformed the feed ramps to better accept the 30 cal bullet. Feeding problems solved. Also be sure to use self leveling mag followers to keep the cartridges from tilting at the rear and allowing the bolt carriers to ride up over the next to feed round in the mag. The barrel already had a .125 dia gas port so nothing was done to this. I had Gemtech thread the barrel and install a bi-lock adapter.
I at first installed a Fulton Armory adjustable gas tube, but I was not impressed with it and ended up using a standard carbine length gas tube.
As far as the lower receiver goes I switch between a bushie with a JP Enterprise match trigger (sweet) for more accurate shooting and a bushie lower with all the full auto parts for good ole full auto mag dumping.
(To be continued......)

[rednek58]

Part 2.
As far as ammo goes, I reloaded with 10.9 gr. of AA 1680, using 220 gr.Sierra MK's and processed brass purchased for Mr. Davis that we know from this board. I have not encountered any problem what so ever using this load. It chronographed at an avg. of 1055 fps with no signs of over pressure and cycling was perfect with and without supressor attached. Accuracy was well under 1 moa. I have not tried using any super sonic loads to date, but I feel that this should not be any problem. I will say that you will probably want to use one of the gas buster charging handles on your AR. These are a little pricey but they do work well in keeping the tiny powder particles off of your face, especially when using the supressor.
I want to say that it took some hours of trial and error to get to this point. So if you are having problems getting your AR running, don't give up. I believe your patience will pay off and you will be rewarded with a wonderful shooting experience, as I have. Let me know if I can be of any assistance to any of you. And thanks again for this forum and all the fine contributors.
Happy shooting! Al Sheffer

[Cornholio]

What didn't you like about the Fulton adjustable gas tube?

[Artful]

Originally Posted by rednek58

I will say that you will probably want to use one of the gas buster charging handles on your AR. These are a little pricey but they do work well in keeping the tiny powder particles off of your face, especially when using the supressor.

Al how much gas are we talking here - are you Tatoo city? I'm curious as I don't like the sound of this....I wear glasses but don't want to flame my beard

[Quarterbore]

Do you have a way to take some photos? I would love to see you feed ramp mods as well as the entire system with the 16-inch BBL and that monster TPR-S can on her...

[rednek58]

I will try to answer the questions from the replies to my original post.

Cornholio: My original thoughts were to use an AGI for the obvious reason of having the ability to switch from a self loading mode to a single shot mode in order to eliminate the noise of the action, thus having the quietest one shot possible. But when the Fulton AGI was installed it seemed to be loose, never being quite as solid as the original tube. Secondly, it meant I needed to keep up with a hex wrench, counting turns, and adding more complications to the equations. As I stated, I have not done anything with supersonic loads, and it may be necessary for some sort of gas flow adjustment so as to not overwork the receiver with excessive recoil, but I doubt it would be necessary since this is not a hot cartridge even with supersonic loads and the AR is a very strong platform.

Artful: I would describe the gas and powder residue that makes is way back through the action into the shooter's face at worst as anoying. In my case it was not excessive or painful, but I always use eye protection, as I hope everyone does. This problem is not just associated with this cartridge but happens in most cases when you suppress an auto loader, especially the AR. The gas buster charging handle, in my case, eliminated the problem completely and I feel was worth the hefty pricetag.

Quarterbore: I will try and get some pics. While I am not too proficient with posting photos, I will get my son and digital camera and see what we can do. It does look pretty sexy if I do say so myself, especially with the night vison scope and supressor installed. Have gotten a lot of compliments at the range. Thanks again for the forum and the information on your site, couldn't have done it without you.

MALON LABE, Al Sheffer

[alpo]

It all sounds real nice. How about some pictures.