I was wasting time at the gun shop and asked about an AR pistol. Out from behind the counter comes a gently used 10.5 inch 1 in 7 AR pistol with a tacticool paint job (I don't care!). I am wanting to play with it using a Sig brace and save the time on SBR paper work. The little thing has some pretty nice parts in it: a carbine length gas system, a Fail Zero M-16 BCG and hammer, KNS anti-walk pins, MBUIS, quad rail forend with a mount and light, a little Weaver red dot (it won't be staying), a tacticool looking muzzle break with sawtooth design on muzzle. The price is right and with the upgrades and extras is far cheaper than what I could build it for and it shows little to no wear. I am a little suspicious about what caused it to be sitting in the gun shop but I figure I have time to experiment now that I am retired. Off to the range and load it up with a known good 30rd Magpul magazine of Win 64gr Ranger PP. Bang stovepipe. Clear, bang, stovepipe, clear, bang, stovepipe. Now I know why it was at the gun shop. The compensator works well at least but the side blast is pretty formidable.
I head to the house strip it down and wipe the dripping oil out of it. Why do gun plumbers think if it is not running put more oil on it? I start with looking over the bolt and I notice that I can open and close the extractor with moderate thumb pressure. I am not an expert but I am pretty sure this is a problem. I check the extractors on a couple of other bolts and they cannot be moved by squeezing them at all. I remove the extractor and find it has only a 4 coil spring (very weak), rubber buffer, no o-ring. I replace the extractor spring with a BCM extractor upgrade kit: new 4 coil CS spring, rubber buffer and mil spec o-ring. I was going to be very scientific and only make one change at a time and test to see exactly what it takes to get it running reliably but I broke my rule and pulled the ejector and found that spring was about an 1/8" shorter than a new CS ejector spring so I changed that also. I check the buffer and spring and find a standard carbine buffer (2.95 oz) and spring that is 1 1/2" short and suspiciously weak but I leave them for now. A little bit of TW25B on the right parts and it is ready to go again.
I am back to the range the next day and start with the same magazine and ammunition: bang.......bang...bang, bang bang bang....bang bang. It is running right now. I try a magazine loaded with the cheapest 55 gr FMJs I could find at Academy and it runs fine fast or slow. Both magazines lock back on last round fired. The action spring is pinging away so I replace it with a Wolff extra power action spring with the stock buffer and it runs fine with a bit less noise from the action spring but still a noticeable ping. I put in a BCM H2 buffer (the heaviest I have) and test some more. It runs fine the bolt locks back on an empty magazine with all the ammunition I feed it. The muzzle seems to come up less and the spring is not pinging anymore. I try another 200 rounds made up of all the odd bits of .223 and 5.56 ammunition I could find laying around the bench and this little pistol is running perfectly. I know the guy who originally built this rig and he builds pretty nice stuff. I am pretty sure he is not responsible for the weak and or cut springs I found in this pistol. I cannot for the life of me figure out why some nimrod would think using a weak extractor and ejector spring on the bolt would be a good idea or improve anything let alone cutting the action spring.
I am no expert on short barreled ARs so do I leave it alone or would I gain more recoil reduction and reliability by going to an H3 buffer or one of Slash's heavy 5.5 oz. buffers? I kind of like the little thing and I have to admit it looks pretty good. The function and reliability is most important. From what I have heard and read the heavier buffers and or adding weight to the BCG improves function and reliability with the short barrels. I am going to keep it and I will be switching out the compensator for a Noveske KX3 to make it a bit easier to be around and to stop the dust storm in my face when firing prone. I appreciate your input.
I head to the house strip it down and wipe the dripping oil out of it. Why do gun plumbers think if it is not running put more oil on it? I start with looking over the bolt and I notice that I can open and close the extractor with moderate thumb pressure. I am not an expert but I am pretty sure this is a problem. I check the extractors on a couple of other bolts and they cannot be moved by squeezing them at all. I remove the extractor and find it has only a 4 coil spring (very weak), rubber buffer, no o-ring. I replace the extractor spring with a BCM extractor upgrade kit: new 4 coil CS spring, rubber buffer and mil spec o-ring. I was going to be very scientific and only make one change at a time and test to see exactly what it takes to get it running reliably but I broke my rule and pulled the ejector and found that spring was about an 1/8" shorter than a new CS ejector spring so I changed that also. I check the buffer and spring and find a standard carbine buffer (2.95 oz) and spring that is 1 1/2" short and suspiciously weak but I leave them for now. A little bit of TW25B on the right parts and it is ready to go again.
I am back to the range the next day and start with the same magazine and ammunition: bang.......bang...bang, bang bang bang....bang bang. It is running right now. I try a magazine loaded with the cheapest 55 gr FMJs I could find at Academy and it runs fine fast or slow. Both magazines lock back on last round fired. The action spring is pinging away so I replace it with a Wolff extra power action spring with the stock buffer and it runs fine with a bit less noise from the action spring but still a noticeable ping. I put in a BCM H2 buffer (the heaviest I have) and test some more. It runs fine the bolt locks back on an empty magazine with all the ammunition I feed it. The muzzle seems to come up less and the spring is not pinging anymore. I try another 200 rounds made up of all the odd bits of .223 and 5.56 ammunition I could find laying around the bench and this little pistol is running perfectly. I know the guy who originally built this rig and he builds pretty nice stuff. I am pretty sure he is not responsible for the weak and or cut springs I found in this pistol. I cannot for the life of me figure out why some nimrod would think using a weak extractor and ejector spring on the bolt would be a good idea or improve anything let alone cutting the action spring.
I am no expert on short barreled ARs so do I leave it alone or would I gain more recoil reduction and reliability by going to an H3 buffer or one of Slash's heavy 5.5 oz. buffers? I kind of like the little thing and I have to admit it looks pretty good. The function and reliability is most important. From what I have heard and read the heavier buffers and or adding weight to the BCG improves function and reliability with the short barrels. I am going to keep it and I will be switching out the compensator for a Noveske KX3 to make it a bit easier to be around and to stop the dust storm in my face when firing prone. I appreciate your input.
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