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Posted: 5/20/2017 9:44:17 AM EDT
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I have a DD M4V7LW that I'm using as a project gun to make it an SPR... I switched out the DD LW barrel with a 18" Ballistic Advantage .223 wylde with a rifle length gas sysyem. Just got it out finally yesterday... but having issues with it short stroking. Checked lube, mags, gas block and all seems well... it has an H1 buffer in it... I'm thinking that's probably the culprit.
Any suggestions?? |
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What ammunition are you using? If it is full power new manufacturered ammo keep trouble shooting. If it's a reload or re manufactured round try some factory full power ammunition.
I have always found rifle length gas systems run best with rifle buffers and Springs. Vltor A5 buffer system works well with a rifle length gas systems and carbine length buffer tubes although the A5 is its own unique animal using a proprietary spring, buffer, tube that shouldn't be used with other buffers, springs and tubes. I bought an Aero M4e1 18" upper with a rifle length gas system with a .223 Wylde chamber recently. Barrel comes from BA. I mounted on a carbine lower with an H buffer and I had some intermittent short stroking using Federal M855. Tried different mags and same thing happened sometimes. I bit the bullet and installed a rifle length buffer, spring, tube and wrapped it in a Magpul PRS stock. Runs like a champ now with all ammunition I have tried including Wolf Gold. It all depends on your particular rifle and gas port size and how it's timed. Got this from another site: One of the common hiccups with the AR is short stroking… often you will not even know it is doing it, until your rifle starts to fail to pick up a new round. One early indication of problems is that the bolt does not lock back on an empty magazine. Let’s look at a few things that are common cause of the problem. All of this is assuming that you are running full power, good name ammunition. If you are shooting “Uncle Festers’ Bargain Brand Reloads”, get a box good ammo and see if you still are having problems. First, and with nearly any problem with the AR – try a new magazine! I will talk more about the US magazines and our fighting doctrine concerning them, but if you are having any problem with your gun, switching magazines is almost always the first troubleshooting step -- even if the mag you are using works fine in another gun, that does not mean that it is fine in every gun! If you identify a bad magazine, get rid of it. Period. Some magazines set too high in the well and cause the lips to rub against the bottom of the bolt. In some cases it is enough to slow the bolt down enough to short stroke, at times it can be enough to lock the bolt back from returning to battery. The next easy thing to look at is lubrication – check out Pat Roger’s thread on here about lubrication… do not be afraid to lubricate the rifle, it is a machine. With those easy things out of the way, let’s troubleshoot the rifle for some other common things – working from the front to the back. The gas block – The front sight, gas block assembly should be looked at to make sure that it has not moved and is not leaking. If you have a cross pin mounted setup, most likely it has not moved, but the set screw type blocks can move (usually forward) or twist and block off the gas port. Carefully check to see if it looks like the gas block has moved, you can usually see marks that indicate it has moved… it only takes an eighth inch to cause problems. Also check for leaking, the most common sign is a brownish, rust looking stain around the barrel where it passes through the gas block. Some people will tell you that this is normal and will “seal” with time – it may be normal, but it is not right. The TDP specs for the barrel to gas block fit are one of the most exact measurement on the gun, this is a zero tolerance fit and is not supposed to leak at all – if you are getting leaking here, I strongly suggest talking to the supplier or builder about making it right. The gas tube – Make sure the gas tube is tight in the gas block and again is not leaking. Double check the roll pin that locks the tube into the gas block, this is all that holds the gas tube and if it has worked out a little the ports will not line up. Check to make sure the tube is not bent or ruptured… The fit of the tube in the gas block is another very precise specification and there should be no leaking around the tube where it fits into the gas block. Moving back to the bolt assembly, first take a look at the bolt key – it must be tight. The two screws that hold it on should be torqued and locked by staking. If you can wiggle or move the gas key any at all, the key needs to be removed, the surface under it cleaned and then properly reinstalled. Pull the bolt and check the gas rings… these are much more forgiving than many people think, I have seen guns work fine with rings broken, missing, or the gaps all lined up -- but just to make sure, check that they are in good shape, not broken, worn or missing and stagger the gaps so that they are at 3, 6 and 9 o’clock. Moving further back, check the buffer to make sure it is the proper weight for your rifle, running too heavy of a buffer can cause short stroking, especially in a rifle length gas/barrel system – also check the recoil spring, an over length or “heavy” spring can cause problems at times. |
| All the Ballistic Advantage barrels we use are notorious for short stroking or FTE. We learned that BA undersizes their gas ports on their barrels so "the customer can adjust the size to their needs", which just sounds like them covering their asses due to a spec error. We just use a 3/32 drill bit to open up the port just a little and that fixes it 100% of the time in our experience and we've used many BA barrels for builds. |
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Quoted:
All the Ballistic Advantage barrels we use are notorious for short stroking or FTE. We learned that BA undersizes their gas ports on their barrels so "the customer can adjust the size to their needs", which just sounds like them covering their asses due to a spec error. We just use a 3/32 drill bit to open up the port just a little and that fixes it 100% of the time in our experience and we've used many BA barrels for builds. |
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my BA 16" middy is pretty over gassed. eneded up using a vltor a5h3 to tame it down.
as for drilling out the port, make sure you use machines bits. they come in smaller increments little .002-.003 jumps. hardware stores should have them. using fractional bits will result in too large of hole most likely. i'd try an H or carbine buffer before you punch out the port. i have a BCM 20" that i cut back to 18" and runs perfect with a carbine h buffer and #42 bit hole size i think it was. |
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Quoted:
All the Ballistic Advantage barrels we use are notorious for short stroking or FTE. We learned that BA undersizes their gas ports on their barrels so "the customer can adjust the size to their needs", which just sounds like them covering their asses due to a spec error. We just use a 3/32 drill bit to open up the port just a little and that fixes it 100% of the time in our experience and we've used many BA barrels for builds. |
| Most definitely change the buffer before you open up the gas port. With a semi auto the heavier buffers are good to soften up the cyclic force in an over gassed rifle. If you are on the low gas side anyway there is no benefit offered with a heavy buffer. Always change a part first. With time and use the system is going to break in and smooth out, decreasing resistance and this issue may resolve on it's own. The gas port will also enlarge on it's own with use. To fix the problem you decrease resistance to cycling or increase the force of cycling. Enlarging the gas port will fix the problem but it is much easier to change the buffer first. I would always recommend changing the gas port as the last resort. I am almost positive it will not be necessary in your case. Then with use down the road if your rifle becomes a little over gassed you can put the heavy buffer back in to smooth it out. KISS applies here. It takes 30 seconds to change the buffer without tools. |
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Quoted:
Most definitely change the buffer before you open up the gas port. With a semi auto the heavier buffers are good to soften up the cyclic force in an over gassed rifle. If you are on the low gas side anyway there is no benefit offered with a heavy buffer. Always change a part first. With time and use the system is going to break in and smooth out, decreasing resistance and this issue may resolve on it's own. The gas port will also enlarge on it's own with use. To fix the problem you decrease resistance to cycling or increase the force of cycling. Enlarging the gas port will fix the problem but it is much easier to change the buffer first. I would always recommend changing the gas port as the last resort. I am almost positive it will not be necessary in your case. Then with use down the road if your rifle becomes a little over gassed you can put the heavy buffer back in to smooth it out. KISS applies here. It takes 30 seconds to change the buffer without tools. So I'll grab a lighter buffer until it breaks in more and see how it does... it has roughly 400 rds through it now since I switched out the barrel and did the above. |
| So... earlier this morning I switched out buffers. Took from my spikes 10.5" sbr (which was the ST-T2) and put it in my DD and visa versa... shot another 200 rds only putting 1-2 in the first 10 or so mags... no issues... then loaded them up with 5 rds, 10 rounds, etc...again, no issues. Ran great! So it'll be a while before I can get it out again but I feel much better knowing it was functioning properly. |
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Yes. It is... and I have no idea why it's working now but it is. You might even be able to go up higher than that. I actually run a 9mm buffer in my M4gery. Only cuz it smooths out the recoil a lot and I had it on hand. I've been wanting to get an H3, but haven't done it yet. But having said that, that M4gery will run on a standard CAR buffer. But it just poops the brass out. They just dribble out typically. But it never choked. Ejection becomes more positive with the heavier buffer with most loads. So I feel more confident with the 9mm buffer that it's gonna run, and it makes it easier to shoot. |
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