AR cycling question??

bushmaster · March 11, 2010, 03:43:47 PM

How much pressure does it take to cycle a gas operated AR? I'm trying treading in rough water here as my cases are modified and the powder selection is unorthodox. Do any of you reloaders have a clue about what pressure level is the bare minimum?

bushmaster · March 16, 2010, 11:57:35 AM

Seriously? Nothing?

KySongDog · March 16, 2010, 01:23:13 PM

Quote from: bushmaster on March 11, 2010, 03:43:47 PM
How much pressure does it take to cycle a gas operated AR? I'm trying treading in rough water here as my cases are modified and the powder selection is unorthodox. Do any of you reloaders have a clue about what pressure level is the bare minimum?

Quote from: bushmaster on March 16, 2010, 11:57:35 AM
Seriously? Nothing?

Why screw around with what works? Federal, Remington, any number of quality manufacturers make ammo that WORKS in an AR. There are several reloading books on the market that give reloading data that WORK.

I guess I do not understand what you are trying to accomplish. Modified cases?? Unorthodox powder selection? Sounds like a recipe for disaster to me.

GunDog · March 16, 2010, 03:20:21 PM

sub - sonic .... whisper ....

QuoteSounds like a recipe for disaster to me.

^^^ I'm with these guys ^^^

Yotehntr · March 16, 2010, 04:01:56 PM

Quote from: Semp on March 16, 2010, 01:23:13 PM
Sounds like a recipe for disaster to me.

+1

slagmaker · March 16, 2010, 04:50:34 PM

The newest issue of Predator extreme "Feb 2010" has an article in the "from the bench" section on subsonic AR loads. His suggestion was don't do it unless you want a lot of problems or a special built rifle.

bushmaster · March 18, 2010, 05:08:03 PM

Well, my experience has been quite the opposite. The subsonic loads stabilize, the brass shows no sign of over stretching in the head region. Mouths are not cracking, wall density stays consistent, and the shots are silent.

I know all about the leading makers of commercial ammunition and what they offer has nothing to do with a subsonic 6.8spc (not .223)

I just wanted to know if you guys were familiar with the pressure levels that cycle the bolt carrier.

I've done my homework. Modified cases, calculated ballistic data, and unorthodox powder selection are precautions that PREVENT disaster!!

Thanks anyways

KySongDog · March 18, 2010, 09:25:04 PM

Sorry if I expressed concern for your safety. I'll try not to do that again.

slagmaker · March 18, 2010, 11:30:40 PM

I think you may be able to get in touch with the manufacturer of your particular AR and get the information you ae looking for. As for ever seeing the info printed somewhere, no I have not. But it is a good question in refrence to what makes your rifle tick.

pitw · March 19, 2010, 05:39:46 PM

Quote from: Semp on March 18, 2010, 09:25:04 PM
Sorry if I expressed concern for your safety. I'll try not to do that again.

You gotta watch that Semp, kinda like the daughters boyfriends some subjects are taboo

.

bushmaster · March 19, 2010, 09:30:46 PM

I'm sorry for getting hostile about the matter. seriously.

I spent a lot of time with a calculator, note pad, and broken down theory behind calculating load data for something that doesn't exist. Researching SEE (secondary explosive effect) was very alarming at first. Especially when it came time to fire the first round. Which i dissected and analyzed thoroughly. No one thought it would work, all of my friends and family said i was going to blow my face off; and guess what...it worked. and it has worked since the first round fired.

A 6.8 AR is only different from a .223 in the bolt, chamber, and barrel. The gas system, bolt carrier, and all other parts are interchangeable with a .223.

slagmaker · March 19, 2010, 11:02:19 PM

I know the secondary explosive effect was talked about in the predator extreme article. If you can find that article it may give you some of the info you need. It is a 3 part if I remember right. The newest article was the first in the series.

CCP · April 09, 2010, 12:25:17 PM

Over looked this post before.

bushmaster, dont think I can answer your question but here are 2 subsonic loads for the 6.8 ( use at your own risk)

1) 130 grain Nosler / combined Tech ballistic Silvertip, 130 grains, SSA brass, Wolf 5.56 Primer, 7.2 grains of Trail Boss, with COAL of 2.295" fired from WOA stainless 11 twist 6 groove, SPC II, 16" barrel, and velocity of 1065 FPS, subsonic.

2) 130 grain Sierra Game King, 130 grains, SSA Brass, Wolf 5.56 Primer, 7.2 grains Tail Boss, COAL of 2.30", fired from same barrel as #1, with velocity of 1090 FPS, subsonic.

I love shooting subsonic loads with heavy bullets one of the reasons I like my Whisper so much. I load subsonic for my 7.62x39 with 165gr bullets and in the past loaded 77g .223 subsonic s.

Keep us posted as I am really interested in this!!!!!!!!!!!!!!

bushmaster · April 16, 2010, 05:02:15 PM

rich, do any of your subsonic loads cycle in an automatic platform? I've loaded 130gr sierra game kings at 950fps. They grouped well. I'm more impressed with the 150 gr BTSP bullets. After some research, it looks like there are modified gas systems for suppressed weapons. I know nothing on the function but its the closest i've got on closing the gap.

By the way, the 150gr bullets at 1,000fps drop 6" at 100yards and hold 1MOA