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Posted: 3/8/2014 12:37:30 PM EDT
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Greetings,
I need to do some minor fitting/modification to a 9mm AR bolt. I do not have a milling machine or lathe; only typical hand tools, dremel, die grinder, stones and files. I need to radius over a sharp edge, so not too much material needs to come off. What would be the optimum tool suggested to do this within these limitations? Suggestion for either types of bits to use with either the dremel or die grinder or types of stones/files? Thanks much! Regards, Jim |
| I like to use ceramic stones because they stay flat or keep there shape. I bought mine as a set from Brownells years ago. It had a round, triangle, and square in the kit. I also found a cheap knife sharpener that uses two tiny round ceramic stones that just snapped in the plastic holder. They pop out easily and for about 5 bucks I have small rounds files for tight spots. For use on a Dremel tool I use "Cratex" bits. If you're not familiar with them it is kind of a rubber with abrasives in different grits embedded. They can remove a fair amount of metal fast as well as polish to a mirror shine. They are much safer than the stone type of bits if it jumps on you. You should be able to find these at Midway and Brownells as well. |
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What edge are we going to play with???
If the back bottom of the bolt where it lowers the hammer down, that edge is supposed to be square. Since the bolt does not lock up, the hammer against that edge, and the edge having to lower back the hammer, it helps to keep the bolt forward at ignition of the round. As for ramped 9mm bolts that are a little kinder to hammers pins, what the guys don't realize on them, that the trade off is you have to add buffer mass, or spring tension to bring the bolt back into check during the cycle when the bolt is ramped. |
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Greetings, I had started a thread about my specific problem over at the "pistol cal." section. Here is the thread, it contains some pix and info. Thanks to everyone that responded! http://www.ar15.com/forums/t_3_15/637402_DDLES_9mm_bolt__bullet_guide_problem.html Regards, Jim |
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Greetings,
Dano523, I hadn't seen your reply in the original thread when I started this one; but thanks! Anyway, all of the various stones I had were too large to fit into the relatively small area on the bolt that I wanted to radius. Looking through all my tools, I found a Brownells file from a 1911 set that I had. It just made dimensionally with enough clearance to do the job. I took my time, filed a couple stokes, checked work, etc. till I had just a small relief/radius cut on the sharp corner of the 90 degree edge. As for my idea of rotating the cartridge guide 180 degrees, didn't work out. I removed it, but the way it mounts in the lower with a roll pin holding it in, the design is NOT symmetrical as it initially appeared from the top. So, put it all back together and coated the nicked area of the guide with some black permanent marker. Today I put about 80 rounds through with no firing issues at all. Just got back in and will take down the rifle to see if there is still an indication of the guide being hit by the bolt. I'll report back after I get it cleaned up and take photos (if any show areas of interest). Thanks again for every ones input! Regards, Jim EDIT TO ADD: Just finished cleaning up the carbine and checking everything. Though 80'ish rounds isn't really an extensive test, there does not appear to be any further damage to the cartridge guide. I may install the new spare guide I got from DDLES to verify that it holds up for a few hundred rounds before calling it a fix. Although, the initial damage did start to appear within the first two or so hundred (at least that's when I noticed). On a side note, I was pretty surprised the bolt was able to be cut with just the file (it was a "two side safe" version, which was a good thing due to the very limited clearance). My concern was whatever surface hardening treatment was on the bolt would have prevented any file from making progress beyond the parkerizing. But, it did work. FWIW, I may send all my findings and photos to ADCO to get their opinion and perhaps alter the method they use for future DDLES Glock lower bolts. May end up preventing others from having to figure this out. Thanks again to all. Quoted:
Did input to you topic over at the other listed locations. |
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