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Posted: 12/27/2015 5:05:36 PM EDT
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I am building a .40 cal AR on a Glock magazine lower using the setup below and am trying to figure out the appropriate buffer and spring combination. There are so many buffer weights out there now for 9mm ARs, I figured one of these on the heavier side would be appropriate for a .40 cal, but the carbine H3, carbine spring and a spacer might be too light. Any help, particularly if you have experience (Rudy) with .40 cal blowback ARs would be greatly appreciated!
- QC10 7.5" barrel - QC10 .40 Cal bolt - Pistol length buffer tuber - CMT billet upper - Spartan/RRG/JBO type lower Thanks! |
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I hate to point out the obvious, but this is from Quarter Circle 10's own FAQ's on the website. Our test rifles use a 5.3-5.6oz buffer for both 9mm and .40 S&W builds, but have had success with a wide variety of buffer weights, ranging from 4 oz to 8 oz, depending on spring strength. Our .45 ACP builds use a 7.3 oz buffer. If given a range of buffers to try, start heavy and move down in weight until ideal performance is reached. |
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I am running one of the heavy buffers we did for the 45 with a standard carbine spring.....smooth as silk.........have a batch going for coating after the first....(all the plants I use are closed) I have plenty in the white if you want me to box one up and ship it.
It is also extended length so no spacers required....... 
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