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Posted: 5/4/2009 8:12:18 PM EDT
| I am have a problem intalling a caslte nut on my mil spec reciever extention from my comercial reciever extention. Has anyone had this problem? Also I can no fit any end plates on this extention either. I boght it from PK and never had problems with there products before. I just ordered another complete set from AIM to solve the problem but don't want to lose out on these. |
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Quoted:
I am have a problem intalling a caslte nut on my mil spec reciever extention from my comercial reciever extention. Has anyone had this problem? Also I can no fit any end plates on this extention either. I boght it from PK and never had problems with there products before. I just ordered another complete set from AIM to solve the problem but don't want to lose out on these. sounds like it is out of spec...i just got one from them as well, it installed perfectly, but when i charge the gun i can hear the bolt carier rubbing on the inside of the tube...i tryed 2 different carriers, they bother od it...then i looked inside the tube, its not very smooth, you can see the milling lines spiral cut all the way thru the tube, its not rubbing SUPER bad, but its a little rough, i figure aluminum is much weaker then the carrier so ima just shoot the shit out of it and it should smooth out the inside and be good to go. but as far as your problem, looks like you dont have any options. |
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You never said what the problem with the Castle Nut was, we're assuming its just to tight and won't thread on the new receiver extension properly.
A tap & die to chase the threads would cost way more than a new castle nut or receiver extension. Inspect the threads of both, if there is some damage to the threads that you can file down to the intended thread shape, you can try that, but you might as well just get new items if you need a tap & die, it would be cheaper. OR just return it, if it doesn't fit the parts like it should, then something is wrong with it. What is preventing the end plates from fitting on this extension? The outside diameter is too great? The slot cut into the 6 O'Clock position of the extension is NOT deep enough? If the outside diameter of the threads is too big, that could cause it NOT to fit castle nut, end plate and receiver. The milspec outside diameter of the threads is slightly larger than the commercial version, like 0.015". The best I can tell, the threads are rolled/cut to the same specs, the commercial tube just starts at a smaller diameter than the Milspec Tube AT THE THREADS. If that's true, then you would just end up with the peaks of the threads truncated a bit on the commercial tube, while the milspec tube threads would be the full height. The same castle NUT would fit both threads just as well, arguably the milspec threads would take more torque and abuse because there is more metal in the threads. |
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When I switched out my commercial extension for a mil-spec extension, the castle nut fit fine (as expected the threads are the same). But the end plate was too tight to slip over the threads of the mil-spec extension. And I followed the rule of firearms and filed the least expensive part... I took a curved file to the inside of the end plate, took out enough material for it to slip over the threads and not it fits fine. It may have been just enough material from the stamping process that was getting hung up.
I only had to take a little material about 3/8" up from the indexing peg (on both sides) that rides in the groove in the extension. |
| i had the same problem with an end plate that (i think) i recently bought from pk firearms (i'm not blaming them - they can't control all the parts they buy). the endplate would not fit over the threads of a mil-spec buffer tube. i used a dremel on the inside of the end plate until it fit over the tube's threads, then cold-blued it. the castle nut i bought at the same time worked fine. |
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My castle nut seems to have some marks in the threads to create an interference fit, it does NOT spin onto the threads of my milspec tube easily, but I can thread it on by hand. I think the idea is to help prevent the nut from loosening easily. Like mentioned, the commercial tube threads are slightly truncated (overall diameter at the threads is slightly less), so it shouldn't be surprising if the castle nut is a little tighter on a milspec tube. If its just a matter of it being a little tighter than the commercial tube, I wouldn't worry about it. BUT, I doubt you would have posted if it was just a little tighter, its probably NOT working.
A castle nut is usually about $6, I'd get a new one and see if it fits better, maybe the old got messed up during disassembly. Do like the others recommend for the end plate, take dremel or file to it and widen the hole to fit the threads. If the new castle nut doesn't fit, then contact the supplier of the milspec tube and let them know something is wrong, they should replace it. |
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