03-13-2018, 07:55 PM
(This post was last modified: 03-13-2018, 08:01 PM by wideglidejoe.)
To 98Z; my 5.56 pistol lower buffer spring is 10.5" with .072 wire and 39 coils. It runs fine with 5.56, both 55 gr and 62 gr green tip. That's the lower I'm going to run the 12.5" Gr upper on.
Sometime back, I found a chart elsewhere on the web, or AR15.com or somewhere, that shows a bracket of 10 1/16" to 11 1/4" for carbine springs, and 11.75" to 13.5" for rifle springs. I have a stock out-of-the-box 16" Colt LE6920, it's spring is 10.5", with .072 wire and 38 coils, and a 16" 7.62x39 that I built upper and lower from scratch, using a 10.5" with .072 wire and 38 coils. Both of them run fine with a 10.5" spring. I see on Slash's chart that he just lists 11.25" with .072" wire and 39 coils instead of a range of length. I'm open to trying a 11.25" spring if it could help my situation.
To All; as far as gas port size, that's what the Ballistic Advantage tech told me yesterday; .0595". He elaborated that they don't have any trouble running suppressed or unsuppressed with that size port.
This morning, I removed my gas block and gas tube from the 12.5" Gr barrel. The barrel gas port measures .0550" with my Dillon reloading calipers. The gas block port is obviously much larger than the port in the barrel. The barrel has a "stain", or residue from firing it, where the gas block port was over the barrel port. The barrel port is centered within that stained area. I blew on the gas tube at the bolt end, it is very clear, unobstructed thru the gas block port.
At this point, I'm thinking my barrel gas port is too small. I tried calling the BA tech back today, but didn't get an answer, I'll keep trying to talk to him again. I'm thinking the gas block & tube are OK, were originally installed OK, and the unmarked standard carbine buffer and 10.5" spring are OK.
I'm going back to look on the AR15.com forum, I'm thinking it was there that I saw a post with several comments that they were taking their barrel port from .060" (or my .0550" port that is supposed to be .0595") out to the upper .060's or even .070".
Thoughts? Opinions?
Thanks,
Joe
Edited for typo.
Sometime back, I found a chart elsewhere on the web, or AR15.com or somewhere, that shows a bracket of 10 1/16" to 11 1/4" for carbine springs, and 11.75" to 13.5" for rifle springs. I have a stock out-of-the-box 16" Colt LE6920, it's spring is 10.5", with .072 wire and 38 coils, and a 16" 7.62x39 that I built upper and lower from scratch, using a 10.5" with .072 wire and 38 coils. Both of them run fine with a 10.5" spring. I see on Slash's chart that he just lists 11.25" with .072" wire and 39 coils instead of a range of length. I'm open to trying a 11.25" spring if it could help my situation.
To All; as far as gas port size, that's what the Ballistic Advantage tech told me yesterday; .0595". He elaborated that they don't have any trouble running suppressed or unsuppressed with that size port.
This morning, I removed my gas block and gas tube from the 12.5" Gr barrel. The barrel gas port measures .0550" with my Dillon reloading calipers. The gas block port is obviously much larger than the port in the barrel. The barrel has a "stain", or residue from firing it, where the gas block port was over the barrel port. The barrel port is centered within that stained area. I blew on the gas tube at the bolt end, it is very clear, unobstructed thru the gas block port.
At this point, I'm thinking my barrel gas port is too small. I tried calling the BA tech back today, but didn't get an answer, I'll keep trying to talk to him again. I'm thinking the gas block & tube are OK, were originally installed OK, and the unmarked standard carbine buffer and 10.5" spring are OK.
I'm going back to look on the AR15.com forum, I'm thinking it was there that I saw a post with several comments that they were taking their barrel port from .060" (or my .0550" port that is supposed to be .0595") out to the upper .060's or even .070".
Thoughts? Opinions?
Thanks,
Joe
Edited for typo.