phantom01231 Posted February 20, 2012 Report Share Posted February 20, 2012 Ok new here. I just finished my first .308 build and have an issue with cycling. With one round in the mag I can load and fire. When the BCG cycles it goes far enough to eject the brass but not lock back or feed a new round (if more ammo is in the mag).This is my setup.Mega Ma Ten setJP adjustable gas blockSJC brakeFulton:Gas tube22 inch barrelChrome BCG & boltBuffer, spring, tube, and Magpul PRE Stock combo The overall performance is more than i even hoped for. Rounds stack on rounds down range. I found no signs of gas bypassing or leaking around anything. Not sure whats going on. I know the block and gas hole on the barrel are lined updead on. Quote Link to comment Share on other sites More sharing options...
imschur Posted February 20, 2012 Report Share Posted February 20, 2012 Did you you run it wet...dripping with oil? Quote Link to comment Share on other sites More sharing options...
edgecrusher Posted February 20, 2012 Report Share Posted February 20, 2012 And by wet we mean dripping with oil. Break in is much more dependent on this with big ars Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 20, 2012 Report Share Posted February 20, 2012 Ok new here. I just finished my first .308 build and have an issue with cycling. With one round in the mag I can load and fire. When the BCG cycles it goes far enough to eject the brass but not lock back or feed a new round (if more ammo is in the mag).This is my setup.Mega Ma Ten setJP adjustable gas blockGive it more gas. Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 20, 2012 Author Report Share Posted February 20, 2012 Yes it was wet! Like a virgin on prom night! I had ultra bore dripping down the mag. The gas block was opened up all the way. only things I can figure is gas is leaking around the tube at the BCG Key but the fit there seems good. I also thought maybe the gas hole on the barrel might be under drilled. Any thoughts? Is there a standard size they should be drilled to? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 20, 2012 Report Share Posted February 20, 2012 The gas block was opened up all the way. Start closing it down then, little by little, and see if things improve. It's possible that it's overgassed, then, and running so fast that the BCG has already overrun the bolt stop (single-round mags), and cycling so fast that the bolt is jumping right over the next round in the mag before the mag spring can get it up there. Quote Link to comment Share on other sites More sharing options...
Dusty44 Posted February 20, 2012 Report Share Posted February 20, 2012 Note has been made in this forum about buffer and buffer tube drag if the tube/buffer is dry. I do not know if a dry buffer & buffer tube could create enough resistance to prevent the BCG from full travel, but being sure the buffer assembly is also lubed and sliding easily won't hurt? Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 20, 2012 Author Report Share Posted February 20, 2012 the buffer and all had lube as well. When I say the thing was wet I mean it was wet. Now I did try the gas block at diffrent adjustments. I started all the way in to all the way out. I didn't have any thread lock/seal on the set screw. That wouldn't be the issue would it (gas leaking around the screw)? Quote Link to comment Share on other sites More sharing options...
mrraley Posted February 20, 2012 Report Share Posted February 20, 2012 When manualy pulling the charging handle back to lock the bolt back, how much room is in front of the bolt itself when you push the bolt catch/stop in to hold it back? Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 20, 2012 Author Report Share Posted February 20, 2012 I can't get a ruler in to measure but I would say it has about a good 1/4 inch. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted February 20, 2012 Report Share Posted February 20, 2012 What size bullets are you shooting? It sounds like you need more pressure. At least until things are broken in. Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 20, 2012 Author Report Share Posted February 20, 2012 145 gr FMJ BT Privi Parzatain Quote Link to comment Share on other sites More sharing options...
unforgiven Posted February 21, 2012 Report Share Posted February 21, 2012 Welcome from Indiana brother phantom,your at the right place for answers to your questions lot of sharp guys here. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted February 21, 2012 Report Share Posted February 21, 2012 145 gr FMJ BT Privi ParzatainThat's the problem. You need to try out a box of factory .308, and it should be over 160 gr. 7.62 NATO, especially surplus foreign stuff, is not as powerful as good old American .308 Winchester. You might need to run some high octane stuff till your gun breaks in. After the parts settle you can try the surplus stuff again. You may also want to try different brands of mags. Although, you should be able to test mags by cycling the action with your hand. Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 21, 2012 Author Report Share Posted February 21, 2012 Ill give that a shot and see how it turns out. So far it seems to be breaking in good. The bolt and all has loosened up pretty good. At first it was real hard to charge it even soaking wet but not so much now. It kind of puzzles me because the DPMS LR-308 I had shot this same ammo right out of the box like it was cool. I have mags from Fulton. I didn’t see or notice any issues with them. The BCG Locks back just fine with them by hand. That was one of the first things I thought of. With the time I spent in the Corps I’ve had my share of mag issues lol. As I mentioned above though, is there a standard size for the gas port in the barrel for .308. Just looking at it and thinking about the mass that gas has to push back it does seem a little small. It was drilled between 5/64 - 3/32. Just seems a little small to me. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 21, 2012 Report Share Posted February 21, 2012 As I mentioned above though, is there a standard size for the gas port in the barrel for .308. Just looking at it and thinking about the mass that gas has to push back it does seem a little small. It was drilled between 5/64 - 3/32. Just seems a little small to me.Is there a standard size for the gas port - No. That all depends on barrel length, barrel diameter, and gas port position. That stuff is barely standardized for the 5.56 guns - even that is not a science - and it's nowhere close to being standardized for the .308 ARs. "drilled between 5/64 - 3/32" - you need to stick a numbered drill bit in there to determine the exact size. Giving the dimensions that you did, that's a pretty wide varience. That's somewhere between 0.0781" to 0.0938". Quote Link to comment Share on other sites More sharing options...
Dusty44 Posted February 21, 2012 Report Share Posted February 21, 2012 Don't mess with that gas port. Buy and shoot some US commercial factory ammo like Robocop says. When the rifle is looser after 50 to 200 rounds the Privi Partizan will most likely work OK. Somewhere in this forum is a bunch of noise about foreign made and especially 'surplus' military ammo. You seem to be having a classic experience. Quote Link to comment Share on other sites More sharing options...
mrraley Posted February 21, 2012 Report Share Posted February 21, 2012 Like mentioned above, you might want to try a little heavier type of ammo. But it looks like you have enough room for cycle of operation.Even going through the ArmaLite manual, they recomend a minimum of 150gr because the 147gr are usually underpowered and wont cycle the action properly. Quote Link to comment Share on other sites More sharing options...
tlcoy1911 Posted February 21, 2012 Report Share Posted February 21, 2012 Gas port size on a 308 20" rifle length is .0935" or a # 42 drillSo I would (guess) that a 22" may be slightly smaller, something like.086 or # 44 drill5/64 is .0781 which I think would be too small, and 3/32 is .0938 which would be the closesed fractional size drill.But if you drill the port out, you may be stuck to using an adjustable gas block, so rule out everything else first Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 22, 2012 Author Report Share Posted February 22, 2012 Adjustable block wouldn’t be a problem being as I’m running one now. I am going to try a bit heavier load first. Ill run 50-100 rounds of that first. If that don’t cut it then Ill drill it out a small bit. My problem is I’m not or really don’t want to go out and spend 20 to 30 bucks for a box of ammo for practice when I get USA Surplus 7.62 for next to nothing. For a match or hunting then Ill spend it but other then that. When I start reloading that will be a different story. The better stuff I prefer to get a little at a time when I have a couple of extra bucks and stash it. Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 22, 2012 Author Report Share Posted February 22, 2012 Here is the rifle. Thought ya'll might like to see it. Quote Link to comment Share on other sites More sharing options...
imschur Posted February 22, 2012 Report Share Posted February 22, 2012 Whats with the long filename on the pictures? Quote Link to comment Share on other sites More sharing options...
phantom01231 Posted February 22, 2012 Author Report Share Posted February 22, 2012 They have gone from my phone to my facebook and now to my company computer and ive never bothered to change the file name. Quote Link to comment Share on other sites More sharing options...
imschur Posted February 22, 2012 Report Share Posted February 22, 2012 They have gone from my phone to my facebook and now to my company computer and ive never bothered to change the file name.Well just an FYI that can cause problems on some computer systems Quote Link to comment Share on other sites More sharing options...
robtmc Posted February 28, 2012 Report Share Posted February 28, 2012 Tacking on for replies. I have the same issue with my DPMS AP4 build. Using a JP adjustable GB and went through the 1.5 turns out and more. With it in too far, failure to eject. Further out ejected great, but no feed, and no lock back on empty. Two DPMS mags and a Magpul all the same. Locked back and fed manually just fine.Took the gas block off yesterday, carbon pattern perfectly centered on the gas port, so that is not it. Decided to measure the port hole size, .063". What was interesting was the drill bit did not just slide into the barrel, but hit an obstruction. Maybe a burr from the drilling? Pushed it through the obstruction and checked the bore. Looks fine.What is odd is the port size vs. a Fulton 18.5" barrel with rifle length gas system. That has a .093" hole. I find the hole size thing rather confusing. Lubed the heck out of things and will try again, after making sure the gas tube is clear. Quote Link to comment Share on other sites More sharing options...
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