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Posted: 1/23/2010 4:41:24 PM EDT
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I assembled a SBR rifle a few months ago. I have not been able to manually lock back the carrier, it stops just a millimeter before the bolt stop catch can engage it.
I tried switching out buffers, I tried switching out carriers, the buffer retention post is not damaged (i have shot the rifle a few hundred rounds). the bolt will lock back after last shot, but not manually. what can I check? on my other rifles there is at least 3 or 4 millimeters from the bolt face and the bolt catch when pulled fully to the rear. the lower is a registered SBR so I'm stuck with it. it's made by rock river. any help? thanks. |
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Quoted:
Do you have a carbine spring in it? Having a rifle spring in a carbine receiver extension might cause that. I don't think the lower being out of spec has anything to do with it. This is what I would check. Assuming you're using a carbine buffer, you need to check your spring. Out of the receiver extension it should have a length between 10 1/16" to no more than 11 1/4" |
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Quoted:
Quoted:
Do you have a carbine spring in it? Having a rifle spring in a carbine receiver extension might cause that. I don't think the lower being out of spec has anything to do with it. This is what I would check. Assuming you're using a carbine buffer, you need to check your spring. Out of the receiver extension it should have a length between 10 1/16" to no more than 11 1/4" This ^ and if that isn't it this V Do you have any other AR lowers and a micrometer? Take measurements of everything from front to back (thickness of the front of the magwell between the pivot lugs, length of the magwell opening, thickness of the magwell in front of the bolt catch, and the length of the area where the bolt catch is). It sounds like something was machined too far back. Is this happening only when you have a mag in the lower or empty? If it happens only with a mag in, the magwell may be too far back. Compare the measurements from front to back of the lowers that are functional and the RRA lower in question. If the lower is defective, you may be able to get RRA to machine you another one with the same serial number. Then you will just need to get it engraved. I really hate to hear your are having this problem with an SBR registered lower....  Don't play the lottery for a while as you are having a run of bad luck. If you don't have another lower to compare measurements or a micrometer, email me and I will give you some measurements off of a Colt and a Tactical Machining lower tomorrow. I hope this hepls you figure out what is going on.
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Quoted:
Quoted:
Do you have a carbine spring in it? Having a rifle spring in a carbine receiver extension might cause that. I don't think the lower being out of spec has anything to do with it. This is what I would check. Assuming you're using a carbine buffer, you need to check your spring. Out of the receiver extension it should have a length between 10 1/16" to no more than 11 1/4" HA! I love respect greatly, you guys, your fricken geniuses! that was it. <––––––––––––––––-off to buy a new buffer spring. 
Thanks. |
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Quoted:
Quoted:
Quoted:
Do you have a carbine spring in it? Having a rifle spring in a carbine receiver extension might cause that. I don't think the lower being out of spec has anything to do with it. This is what I would check. Assuming you're using a carbine buffer, you need to check your spring. Out of the receiver extension it should have a length between 10 1/16" to no more than 11 1/4" HA! I love respect greatly, you guys, your fricken geniuses! that was it. <––––––––––––––––-off to buy a new buffer spring.
Thanks. Go buy a lottery ticket, you luck just changed....
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