jn_fsu Posted May 27, 2011 Share Posted May 27, 2011 I finally got out to the range and had a very nice time. Managed to zero my irons and do my break in as suggested by BCM. Put 100 rounds thru it with no FTFs or FTEs. The rifle appears to be more accurate then I. I was able to put some of my follow up shots thru the first hole at 50 yards but not on a constant bases. My primary concerns were function, getting used to the rifle, breaking it in and zeroing my irons. I have two concerns! First my BCG doesn't always lock back when the mag is empty. Second concern is my brass ejection. It appears to be ejecting some where in the area of 4:30-6:00 with some brass deflecting off the rifle it self. From the charts listed for ejection pattern it seems to suggest that either it's short stroking, my buffer and or my BCG is too heavy, or my my SSS spring needs tuning. This is my first rifle and I need help on where to start narrowing the problem down? Or is this a common when a rifle is first breaking in and all the new parts are learning to work together as they work out inperfections of machining or forming unions in order to function properly? Thanks- Jason Link to comment Share on other sites More sharing options...
MickB Posted May 27, 2011 Share Posted May 27, 2011 Try a standard weight buffer with standard recoil spring. Ejection should be in the 2-3 o'clock area. What ammo are you using? It could be underpowered? Mick Link to comment Share on other sites More sharing options...
cardiackid Posted May 27, 2011 Share Posted May 27, 2011 (edited) If the bolt doesn't lock back on an empty mag it's 99% of the time usually a worn follower or spring on the magazine. Mark/label your magazines and try it with all of them to identify if it repeatedly happens with a certain one or another. It's a factory assembled upper from BCM correct? Their stuff is pretty bomb proof out of the box. I highly doubt it's anything regarding their upper and I'd put more money on it being a problem related to your lower (buffer, spring, etc.) How much force is your brass coming out with/how far away is it landing? Carbines and mid-length gas systems can tend to be a hair overgassed by nature (especially the carbines) and if you couple that with a light buffer and spring it would explain a more violent ejection of the brass. For carbine and mid-length uppers I've always used and seen H buffers with standard carbine springs. I've never heard of/seen anyone "tune" a buffer spring. This isn't a top end custom shop 1911 - it's a carbine. I don't understand how it could be missing the brass deflector entirely and landing at the 5/6 o'clock area. If you said it was slamming into the deflector and then getting kicked way out to the side (anywhere from 2:30-4:30 o'clock) it would make sense. Edited May 27, 2011 by cardiackid Link to comment Share on other sites More sharing options...
double_r76 Posted May 27, 2011 Share Posted May 27, 2011 Yeah, we really need more details... Ammo? Barrel length? Gas system length? Buffer weight? Magazines? BCG maker? 14.5" barrels with mid-length gas systems may not fully cycle with weaker .223 ammo. Your buffer may be too heavy if you're running weaker ammo. Bad magazines is the primary cause of AR-15 malfunctions, in my experience. If you're not running a good BCG, the gas key may be loose and this could cause short stroking. There's more, but if you get us some additional details it's easier to diagnose. I would run some NATO-spec 5.56 ammo and see what happens. Thanks! -Randy Link to comment Share on other sites More sharing options...
jn_fsu Posted May 27, 2011 Author Share Posted May 27, 2011 Ammo Federal (100 round value pack) 55gr fmj BCM 16" SS410 (stainless steel) 1/8 twist Midlength gas system Spikes T2 buffer Superior Shooting Systems buffer spring PWS enhanced buffer tube (has a dampner in the tube) All MagPul mags brand new BCG JTR (Johnson Tactical Rifles) Link to comment Share on other sites More sharing options...
jn_fsu Posted May 27, 2011 Author Share Posted May 27, 2011 I built the lower and the BCM upper assembly was purchased whole from BCM. Link to comment Share on other sites More sharing options...
cardiackid Posted May 27, 2011 Share Posted May 27, 2011 I have absolutely zero experience with the PWS enhanced buffer tube and the Spike's T2 buffer, but I did try a Tubbs CS Spring (Superior Shooting Systems/same thing) and ended up swapping mine out for the JP. My guess right now is that it's a combination of the SSS spring, the enhanced buffer tube and that T2 buffer. Without seeing/feeling everything, I can't say for sure. I can't remember for sure if SSS offers a carbine and a rifle length spring, but I know the one I got from them was even longer than my JP rifle buffer spring. If that's the case, it sounds like there's definitely something not agreeing with the gas system with how you have your buffer, buffer tube and spring set up. If at all possible, try to get up to a range, call a buddy that has an AR, etc. and swap out the buffer and spring he has in his and give it a whirl. It will at least let you start to narrow the problem down. Link to comment Share on other sites More sharing options...
jn_fsu Posted May 27, 2011 Author Share Posted May 27, 2011 I have an extra milspec buffer tube ,spring and H buffer already in my possesion. I thought about doing a little mix and match. Or I could just install the basic milspec buffer assembly to see if I obtain proper ejection. That will either fix the problem or rule out the buffer tube, buffer and spring. Link to comment Share on other sites More sharing options...
jn_fsu Posted May 27, 2011 Author Share Posted May 27, 2011 Also is it possible the Federal value pack ammo was under powered for my set up? I have a few other brands and grains I didnt get to try. I was going to run them see how they do or should I start with swapping parts? Link to comment Share on other sites More sharing options...
Kevin Holman Posted May 27, 2011 Share Posted May 27, 2011 (edited) Federal valupack ammo is just fine. If it wont run on that - you dont want it. Failure to lock back on last round is short stroking 99% of the time. Mag related failures are rare - with today's common magazines and followers. 10 years ago... with a bunch of USA mags flooding the market, maybe. So - you are short stroking - find the cause. As you are already find out from above... some of your choices are very nonstandard, and therefore might require tweaking. Too many times people purchase "enhanced" products that add very little value, and sometimes are a detriment. Heavy buffers were needed to slow the cyclic rate down of very short barrels with carbine length gas systems with large gas ports, to allow the bolt to unlock a little less violently due to the large gas impulse created by that system. However - you are running a midlength gas system and a 16" barrel. Therefore you have NO need for a heavy (T2) buffer. Use a standard carbine buffer. I'd start there. I would not use an H buffer... as that was designed for the Colt M4 with a 14.5 barrel and carbine gas system. You have neither. Next - the SSS spring is a Chrome Silicon spring as opposed to piano wire. This isnt bad in itself - however, this spring is heavier (extra power) than a standard carbine spring - and is advertised to slow down the unlocking process. Therefore... this is also slowing your heavy buffer and potentially causing a short stroke when used in combinations. This particular spring - they only sell one - for both carbine AND Rifles. That's odd - because both have different and specific length requirements for minimum and maximum - to determine correct spec and service life. If it is one size fits all, its going to err on heavy for the carbine configuration. Which is also hurting you. To top it all off, you are using a specialized carbine receiver extension which was designed around using a short stroke piston system to hold the carrier in tighter alignment, but you arent using a short stroke piston. This extension has a poly buffer installed in it to lower the impact that the carrier can make in the case of using a short stroke piston system. This buffer could be contributing to your issue... as your heavy buffer and heavy spring are already slowing it down more than it should. Use standard parts. That's my advice. :-) I'd try the buffer first - its cheap and easy. Next, I'd ditch the PWS and use a standard receiver extension. Using the spring should be fine. However, having to replace a carbine spring after 5000 rounds is really not a big deal. :-) Edited May 27, 2011 by Kevin Holman Link to comment Share on other sites More sharing options...
cardiackid Posted May 27, 2011 Share Posted May 27, 2011 What Kevin said about the magazines is dead on. I'll buy everything else he said for a buck too (I really wondered what the advantage of the "advanced buffer tube" was and his explanation of everything makes sense). If you are using new pmags the bolt issues are not caused by them. On a gun that otherwise runs fine, the old USGI mags were the culprit like he said. Hopefully you can hock the parts you end up changing out and not lose too much money. Link to comment Share on other sites More sharing options...
jn_fsu Posted May 27, 2011 Author Share Posted May 27, 2011 Thanks! Ill order carbine buffer and go from there. But I'm thinking the PWS buffer tube is the problem. The Spikes buffer and SSS spring I didnt really find any problems linked to be used on mid length systems during my research. The PWS tube I knew very little about and missed the part about piston rifles when I ordered it. I had already bought it so I figured I'd give it a go... Link to comment Share on other sites More sharing options...
double_r76 Posted May 28, 2011 Share Posted May 28, 2011 I'm glad Kevin typed all that out so I didn't have to! Spot on assessment, in my opinion. I would throw on the mil-spec parts you already have (buffer tube, spring, and H buffer). That will likely get you running. However, I would go ahead and swap that out for a standard carbine buffer eventually. -Randy Link to comment Share on other sites More sharing options...
jn_fsu Posted May 28, 2011 Author Share Posted May 28, 2011 Thanks for all the input guys! Yea I'm going to try going with a Carbine buffer and see if that fixes the problem. If that doesn't do it I'll remove the PWS buffer tube and install my standard mil-spec buffer tube. If still no go I'll swap springs. If that doesn't do it I'll try a different BCG but I don't think thats the problem.I'm sure I've just slowed everything down too much by the add ons. Now it's more finding the balance. Unfortunately all the rifle ranges are atleast an hour away so it will be a week or two before I can get back. My buddy took a 18 sec video clip towards the end of my shooting and it looks like the shell is coming out at about 3-3:30ish but it still didn't lock back. It locked back sometimes and appeared to throw brass properly some of the time. Link to comment Share on other sites More sharing options...
mpeltier Posted May 28, 2011 Share Posted May 28, 2011 I would start with swapping the spring AND trying differant ammo. Every mid gas AR I have built liked the heavy buffers with a standard spring. Link to comment Share on other sites More sharing options...
jn_fsu Posted May 28, 2011 Author Share Posted May 28, 2011 As far as the carbine buffer is concerned are they all the same? I noticed the price for a standard carbine buffer ranges from $8.50-$17 depending on what site I get it from. Link to comment Share on other sites More sharing options...
Kevin Holman Posted May 28, 2011 Share Posted May 28, 2011 As far as the carbine buffer is concerned are they all the same? I noticed the price for a standard carbine buffer ranges from $8.50-$17 depending on what site I get it from. No. As long as they are in spec (weight) they are all the same, for the most part. Just best to get one that wasn't made in china from a Tapco style stock. However, you should try running with your H buffer to start... it should work with that... unless it is the tolerance stacking of heavy buffer, heavy spring, and specialized receiver extension. Link to comment Share on other sites More sharing options...
cardiackid Posted May 28, 2011 Share Posted May 28, 2011 If it's run of the mill mil-spec stuff it should be. It's kind of like buying a lower - lots of companies have their names stamped on them/on the packaging and in actuality there's only so many people manufacturing the unit. Link to comment Share on other sites More sharing options...
jn_fsu Posted May 29, 2011 Author Share Posted May 29, 2011 Thanks guys! I've got a carbine buffer shipping out on Tuesday. A member on another forum has a box full of spare carbine buffers and offered to send me one. I spoke with PWS and the enhanced buffer tube works fine on both piston and DI guns. The effects are greater on piston rifles then DI but it still reduces recoil for both. I'm fairly sure it's just over dampening with the combination I've chosen. I'm hoping the carbine buffer fixes the problem. I really like the PWS buffer tube it fits extremely well and helps balance the rifle out, being I'm running a stainless steel barrel. Both add a little weight but I'm comfortable with it. Link to comment Share on other sites More sharing options...
jn_fsu Posted June 23, 2011 Author Share Posted June 23, 2011 OK back from the range had a hell of a day! Besides shooting 3 different burst/full auto weapons I managed to fix my gas short stroking issue. I first tried the Carbine buffer with Superior Shooting Systems spring, the PWS Enhanced buffer tube and shots came out about 5 oclock. So I swapped out the Superior Shooting Systems spring for standard milspec spring with carbine buffer and PWS Enhanced buffer tube and shots came out at 2:30-3:00 oclock no slide lock. So I swapped out carbine buffer for the Spikes T2 and keep the standard milspec spring and PWS Enhanced buffer tube and first shot came out about 4 oclock then 3:30 for the remainder of the day with slide locking back every time. So my baby is running smoothly now! Thanks for all the information and help it paid off! Link to comment Share on other sites More sharing options...
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