obsessiveshooter Posted February 8, 2015 Share Posted February 8, 2015 Please AR gurus, does the streaking around my gas block look like a normal amount or an excessive amount? This is from 80 rounds of PMC bronze. I am seriously short stroking with this rifle, which is my first AR build. Another possible source might be my buffer spring. It seems to take a lot of force to pull back the charging handle, compared to an M&P15 I yanked on in a gun store. The buffer moves freely in the tube w/o the spring. These are no-name parts (buffer assembly and gas block). Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 8, 2015 Author Share Posted February 8, 2015 Okay, I thought I had attached pictures. Sorry. Let me work on this, I've never posted a picture before. Link to comment Share on other sites More sharing options...
TonytheTiger Posted February 8, 2015 Share Posted February 8, 2015 Pictures of the leaking? Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 8, 2015 Author Share Posted February 8, 2015 Yes, pictures of the leaking. I did verify that the GB wasn't partially covering the hole in the barrel. Can someone please guide me on how to post pictures? I'm sure it's right in front of me but I'm just not seeing it. Link to comment Share on other sites More sharing options...
BOOM Posted February 8, 2015 Share Posted February 8, 2015 Have you tried another brand of ammo ? PMC gold. its very soft shooting ammo, and short strokes with heavy Buffers Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 8, 2015 Author Share Posted February 8, 2015 Thanks for the tip. I'll remove some weights and see what happens. I'd be elated if that was all I needed to change up. Still haven't figured out how to post pics here, but I did post some pictures on a Facebook gun page and the responses I got were that the leakage looked completely normal. One person suggested trying to seal the GB with blue Loctite. Is this an insider trick or a really dumb idea? Link to comment Share on other sites More sharing options...
LikesToShoot Posted February 8, 2015 Share Posted February 8, 2015 Have you tried another brand of ammo ? PMC gold. its very soft shooting ammo, and short strokes with heavy Buffers+1 on trying different ammo. Check out this leak for posting pics. http://www.brianenos.com/forums/index.php?s=17e3187a9a5826978b2731c5509acce1&showtopic=103674 Have you inspected the gas rings in your bolt? Link to comment Share on other sites More sharing options...
OPENB Posted February 8, 2015 Share Posted February 8, 2015 If its a gas block leak, they usually go away after some rounds. The carbon will seal it up. If yours continues to streak and not seal, you may have to swap gas blocks. Try changing one thing at a time, so you aren't chasing fixes. All of the suggestions are good, hopefully only one thing is wrong and not all of them! For photos, host them to photobucket or similar, then put the img link in the post. Magically the photo will be there when you post it. Link to comment Share on other sites More sharing options...
dauntedfuture Posted February 9, 2015 Share Posted February 9, 2015 Is your rifle properly lubricated? Are you running quality magazines? These are the most common causes of AR issues. Most of the time you can have lots of gas leaking around the barrel and things work fine. This is provided you have a .750 ish OD barrel and .750 ish ID gas block. I would think about pulling the gas block and making sure everything is all lined up. If your buffer and some parts are no name there is a chance that you have some part incompatibility. I once bought a gun-show put together AR...I ended up having to replace most all parts and re-chamber the barrel to get things to work. I cant see the pics, what are the stats on the parts in the rest of the rifle. Define short stroke: Does it eject completely and then fail to chamber a new round, does it chamber some times. You say its hard to charge: if its a carbine buffer are you sure you are running a carbine spring? There is a difference between Hard and rough and hard but smooth (phrasing I know) which is it. Hard and rough can indicate parts not matched as well as they could be; look for unusual wear. ARs should run, they don't need to be "broke in" Link to comment Share on other sites More sharing options...
gng4life Posted February 9, 2015 Share Posted February 9, 2015 There is a gauge for checking your gas block, I think it is called a GBA Gas Aligner. That is normally the problem on a gas impingement system when it short-strokes. Search for posts from KurtM and he has made countless predictions about this problem with short-stroking and he's right about every time. Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 9, 2015 Author Share Posted February 9, 2015 The gas block is definitely lined up correctly- I removed it and the carbon circle is perfectly centered with the gas hole. The gun only has 80 rounds through it. The first 40 rounds it didn't eject a single case. The second time out with it, I fired another 40 rounds and maybe 20 of those casings ejected, but the bolt never got far enough back to load up another round. I really think that most of the problem is my BCG. The gas rings are really tight on the carrier and it takes a few pounds of force to push the bolt back and forth in the carrier. If I ease the charging handle forward, the bolt will not lock up on it's own. I'll need to assist it forward to get the final lockup. I'm pretty sure that's a big problem, right? Link to comment Share on other sites More sharing options...
TonytheTiger Posted February 10, 2015 Share Posted February 10, 2015 Sounds like a problem to me, I've got a JP carrier and a Nickel Boron bolt and it doesn't matter how slow I ease the bolt home on an empty chamber it always goes into battery. I can't even feel when the bolt starts rotating. Link to comment Share on other sites More sharing options...
WhiteDingo Posted February 10, 2015 Share Posted February 10, 2015 The gas block is definitely lined up correctly- I removed it and the carbon circle is perfectly centered with the gas hole. The gun only has 80 rounds through it. The first 40 rounds it didn't eject a single case. The second time out with it, I fired another 40 rounds and maybe 20 of those casings ejected, but the bolt never got far enough back to load up another round. I really think that most of the problem is my BCG. The gas rings are really tight on the carrier and it takes a few pounds of force to push the bolt back and forth in the carrier. If I ease the charging handle forward, the bolt will not lock up on it's own. I'll need to assist it forward to get the final lockup. I'm pretty sure that's a big problem, right? Standard gas rings, or something unusual? That does sound like a probable culprit Link to comment Share on other sites More sharing options...
Steve RA Posted February 10, 2015 Share Posted February 10, 2015 Look on the bolt carrier and see if there are any marks from rubbing, if so, you might relieve that area slightly and see if it works more freely. Link to comment Share on other sites More sharing options...
Dan Sierpina Posted February 10, 2015 Share Posted February 10, 2015 Have you lubed the gas rings? Yes, they should be lubed. Link to comment Share on other sites More sharing options...
Dannybot Posted February 12, 2015 Share Posted February 12, 2015 Are you sure your gas tube is properly installed, open and not kinked/bent. Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 13, 2015 Author Share Posted February 13, 2015 Everything is lubed, including the gas rings. The gas tube went on easily and isn't kinked or under any stress. I touched the gas rings with some 600 grit paper because they felt like there was a burr on them. The bolt doesn't feel so gritty now. the Rings were not all aligned either. a buddy just lent me this new unfired Colt light carbine so that I can try a few different parts in mine and for general comparison. His bolt has a little resistance just before lockup, similar to mine. His buffer spring is just a tiny bit less stiff than mine. So, assuming that his rifle fires and functions perfectly, I may start looking at my gas system. The one thing I haven't looked at yet is the gas hole in my barrel. Sunday I'll be shooting and It should tell me something. BTW, can anyone tell me what the proper size gas hole is for an 18" mid length gas barrel? Even though I only shoot USPSA for now, the entire competitive shooting crowd is just amazingly helpful and I'm really appreciating all the advice I'm getting from everyone here. Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 16, 2015 Author Share Posted February 16, 2015 Today I shot my rifle with parts from other working rifles, supplied by two friends. With the BCG swapped out, it short stroked every time still. With the spring and buffer swapped out, it short stroked every time. So, I think I'm back to the original assumption: not enough gas. The GB is properly aligned, so I need to check my gas hole size. Can anyone tell me the proper gas hole diameter for an 18" mid length gas barrel? Link to comment Share on other sites More sharing options...
mpom Posted February 16, 2015 Share Posted February 16, 2015 What barrel; brand, gas length? Some companies are known for small ports, others for large. appropriate size depends on gas length, as pressure diminishes further down the barrel, so ports need to increase in size the further they are from chamber. Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 16, 2015 Author Share Posted February 16, 2015 It's mid length, 18". Made by Bear Creek Arsenal. I don't expect anyone to have specs on that brand, it's just something I got such a great deal on that I thought it would be worth trying. Link to comment Share on other sites More sharing options...
mpom Posted February 16, 2015 Share Posted February 16, 2015 Believe port should be .075 to .085. Would check to see what yours is, using drill bits or pin gauges, if you can find them. Hope its undersized, as that is easy to fix. If port size is within range, then either a gas restriction, or too much friction somewhere. Link to comment Share on other sites More sharing options...
gdcguns Posted February 17, 2015 Share Posted February 17, 2015 I'm no expert but my thoughts are that it could be your chamber or barrel extension are out of spec. Any odd markings on the brass? Have you checked headspace with gauges? Link to comment Share on other sites More sharing options...
obsessiveshooter Posted February 17, 2015 Author Share Posted February 17, 2015 I have not checked headspace; I don't have a gauge. The brass looks normal to me, the guy with his first AR who doesn't know what to look for. The chamber being out of spec is certainly a possibility. It looks like the gas port in the barrel is correct. A 5/64" ( .078") drill bit fit in with a little extra room, so I can rule that out. The carbon circle around the gas port wasn't perfectly centered, but the gas port was in the circle. I think I have it dead-center now and I'll see if maybe that will make a difference. If not, then I think I may have a chamber issue. Link to comment Share on other sites More sharing options...
ac4wordplay Posted February 17, 2015 Share Posted February 17, 2015 (edited) Is this the "ultra cheap rifle" (your words, not mine - post 11 here: http://www.brianenos.com/forums/index.php?showtopic=206474&hl=) that included a barrel that nobody was familiar with, and at least one person was suspicious of? I hope it all works out for you and I look forward to long-term follow up information of your experience. If I had plenty of money, time, and already had a few good/reliable ARs I might consider an experiment like this. Or maybe not. Edited February 18, 2015 by ac4wordplay Link to comment Share on other sites More sharing options...
WCK Posted February 17, 2015 Share Posted February 17, 2015 I read your other post and you said you have a bunch of cheap no name parts, one of these parts might be the problem. Something's to look at are: What type of gas block do you have, is it a clamp on or set screw gas block? What is the outside diameter of your barrel were the gas block attaches? Measure the barrel with a caliper. When you installed your gas block on the barrel, did it slide on tight or was it a loose fit? I suspect you might have a barrel with an undersized outside diameter of where your gas block attaches or you have cheap gas block that doesn't fit tight to your barrel. One other thing to look at is your gas tube, if it is a cheap no name gas tube and the outside diameter is undersized you maybe loosing gas pressure there. Your gas tube might have an undersized outside diameter at either end of the gas tube. If the gas tube doesn't seal well in the carrier gas key you might be loosing gas there. Did your gas tube fit loose in the gas block? Link to comment Share on other sites More sharing options...
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