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Posted: 9/9/2012 10:49:51 AM EDT
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Hi All,
I just completed my first AR build. Spikes lower and lower parts PSA Mid length upper with chrome lined barrel. Standard buffer tube and spring. On my first day at the range I experienced 50% short cycle. Basically it would fire and extract, but not peel a round off the magazine. If I cycled the charging handle, I can get another round but the same problem after that. Also, I have had some instances where the new round partially fed and got stuck. From what I have read, this sounds to me like a short cycle issue. Let me know if I'm off base here. Now, here is the kicker, I am using cheap ammo(Wolf and TulAmmo). My intent is to adjust my rifle so that it can work reliably with the cheap ammo, as that is what the budget requires. I'm looking for useful solutions, not a recommendation to stay away from cheap ammo. From what I have read, some recommend a lighter spring and/or buffer. Yet others recommend a heavier buffer. Light buffer or light spring seems to make sense to me but I need some clarification. Do I just need to get through a break in period? Any help is appreciated. Thank you. |
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Since you are determined to run underpowered ammunition through your rifle:
Have the gas port slightly opened up. This will increase the flow of gas pressure to force your rifle to cycle. This wash of gas will increase the wear and filth of your rifle, so get ready to clean and replace parts more frequently. 
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| There have been many cases of this. First it is a new rifle. Parts need time to wear in. It is always recommended to shoot brass cased normal ammo the first 500 rounds or so through any new gun. After that it should run tula just fine. I just shot 100 rounds of tula through mine today with the gun having minimal lube just to see if it would do it. After it was first built it had to be soaking wet with lube to shoot 193. Now it shoots Tula with just the lube left over from the previous cleaning. |
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Thanks Baxsom,
That makes sense. I'll cycle some quality ammo through it next weekend to see how it behaves. I also have an old Colt AR that cycles the cheap stuff just fine. I might swap the uppers to see if the problem follows the upper or stays with the receiver/buffer tube and spring. |
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Quoted:
Thanks Baxsom, That makes sense. I'll cycle some quality ammo through it next weekend to see how it behaves. I also have an old Colt AR that cycles the cheap stuff just fine. I might swap the uppers to see if the problem follows the upper or stays with the receiver/buffer tube and spring. A lot of it has to do with the locking lugs both on the bolt and in the chamber. When they are brand new they are very tight. As they wear they wear together and there is less friction to unlock the bolt so not as much energy is wasted just in the unlock cycle. At first a lot of the gas is used just to unlock the bolt from the barrel so if the rounds are underpowered already then there just isnt much left to get the bolt back. |
| I have a Bravo Company upper that would not cycle with Wolf ammo. It would run Nato ball and heavy handloads fine. I removed the heavy duty spring and H buffer and replaced it with a standard buffer and a Wollfe reduced power spring. It functions flawlessly now with cheap steel case ammo and I don't notice any damage to the rims on hot ammo. Also if you are running a full auto bolt carrier try a semi auto carrier because it is a little lighter than a full auto carrier. I was even prepared to machine aluminum counter weights and use them to replace one or two of the steel counter weights in a standard buffer. The reduced mass and lighter spring may allow the rifle to run with the lower power ammo before you drill the gas port out which is permanent. A break in period with brass case ammo will work wonders too. |
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Interesting info.
Yes, I have a full auto bolt carrier. It is from PSA and it is heavier than the carrier in my Colt. Here is what I'll try to fix the problem: I have been working that bolt carrier loose by just pushing and pulling on it. It has loosened up quite a bit. I ordered the reduced powered spring from Wolff. I'll run some brass through it to see if the failures start to reduce after time with the cheap steel ammo. I will also simply swap carriers with the lighter Colt to see if my AR cycles correctly. Thanks for all the help, it looks like I have a lot of options and one of them should fix the problem. |
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Just an update:
I've been to the range twice since and it is loosening up a bit. My rifle now does shoot Tulammo just fine without any issue. The Wolf WPA is still giving me a short cycle 1 out of 4 rounds. I think it just needs to break in some more and it should cycle through the cheap stuff reliably. I also did install the BCG from my Colt Lightweight Sporter and my rifle cycled through both WPA and Tulammo without a single malfunction. |
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Quoted:
Have you checked to make sure the gas rings are offset properly. I once had the exact same problems you described and the misalignment of the gas rings were the culprit. Gas ring alignment is a fallacy. First, when installed into the BC the gaps between the rings compresses to virtually nothing. Second, an AR will run with only one ring. Post a pic of your rifle OP or else answer all the questions about rifle configuration... gas block, handguards, BCG, etc etc. Main thing is to just check the entire gas path to make sure you don't have leakage or obstruction. Most common places are at the gas block and the gas key on the BCG. Although most companies are attaching gas keys better these days. |
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