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Posted: 10/30/2016 2:48:10 PM EDT
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My 9mm build is far enough along to test the action, which I did the other day. The Spinta bolt rode flawlessly over the Metalform mag in my PSA mag block. But it kept hanging up on my ASC mags until I dremelel the feed lips to look more like the Metalform mag.
By the time I was finished, my 7.2 oz MASDefense buffer and Spinco red spring had sheared the nub off the buffer retainer. Not sure what to do other than keep a bunch of extra retainers on hand. |
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I had a similar problem but with a CMMG or QC10 bolt (can't remember which one) and the Law Tactical folder. Some one pointed out to me that the bolt was probably too short allowing the buffer to slam against the buffer retainer pin when a round was fed. I was able to lengthen the bolt/carrier extension by adding a 1/16" spacer between the bolt and extension, making the whole assembly that much longer and preventing the buffer from hitting the retainer pin when it was in battery. I'm not sure if there is an easy way to make your bolt longer but I THINK (normally not a good thing in my case) that I read somewhere that people have been known to run their ARs without the buffer retaining pin. Not sure if that's a good idea or not, plus you probably need to be ready to catch flying parts when you separate the upper and lower.
The Spinta bolt looks like it has an removable weight, so you could conceivably replace it with a longer one that extends out the back of your bolt, but now you're getting into the added expense of finding a longer weight, if one even exists. One other option might be to machine a ring about 1/16" deep around the outer part of bolt face that would prevent it from contacting the buffer retainer pin. If you have a spare buffer that's the same length as your MAS one that you don't mind sacrificing, you could fire up your trusty AR 15 rotary destructo tool (AKA Dremel) and test fit to see it that would work. I know this is not much help but I hope this gives you some ideas on how to fix your problem. Pete |
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Quoted:
you'd need to cut a shoulder on the buffer....to avoid breaking the pin. In the past the biggest issues when building a 9mm AR were the potential for broken bolt catches and crap CP/ASC mags. It sure seems like there are a lot more problems now and a lot more "solutions" to said problems. |
| I hadn't read Rudy's comment but did what he suggested tonight on a friend's carbine... just lathe turn a shoulder on the front edge of the buffer wide enough to clear the retainer height, and deep enough that the bolt makes contact with the buffer, and pushes it slightly beyond the retainer into the buffer tube when you close the action |
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