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Post by HMC710 on Mar 15, 2014 21:50:47 GMT -5
Been doing a bit of 30 Carbine shooting and finding the sweet spot on the mag adapters, mags, and barrel interface. I have one US GI mag and that thing is like butter. Going to work over some of the Taiwan units to see if they can duplicate it. Would like to get Rev2 of the adapter going with a stock style mag release but just too busy with other things. In an AR Carbine, there is virtually zero recoil and the bulk 110 gr JRN are cheap to shoot.
Update: Went through about 100 rounds this weekend testing different set ups with the M1 Carbine AR. The mag has a major role in the set up but barrel extension and buffer / spring combo play a part also. Now to find the sweet spot!
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Post by spaceman on Oct 14, 2014 19:47:02 GMT -5
Tim, Have you given up on this idea, or just too busy with other things? I've had a few ideas lately that I would share if you're interested.
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Post by HMC710 on Oct 18, 2014 21:27:19 GMT -5
Busy yes, but have been making and running the 30 Carbine set ups for a few years now. Next step is to get the stock style mag release going.
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Post by spaceman on Oct 19, 2014 17:57:28 GMT -5
Sorry, I didn't make myself clear. I was referring to the extensive discussion that you and 22Boomer were having last year about feeding a necked-down 30C (such as the 19 Badger or the 20 Garin) out of the 30C mags using your mag adapter. Did that discussion get moved to a different thread, or did it just die a natural death? Anyway, that is what I was interested in discussing further.
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Post by HMC710 on Oct 22, 2014 21:18:51 GMT -5
Oh, I guess I didn't catch that one. Hey, we're always willing to talk about this stuff, fire away. I have not moved fwd with the necked down carbine, but open to suggestions.
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Post by spaceman on Oct 24, 2014 21:22:30 GMT -5
OK, here goes: The first question is – does it make sense to come up with a small-caliber, bottleneck cartridge that can feed out of an M1 carbine magazine and work in a semi-automatic rifle? I believe that the answer is obviously YES, and what follows is motivated by that conviction. What should the caliber be, 17, 19, 20, or 22? The answer depends on various factors, of course. I think the 22 is not really practical unless the shooter is satisfied with flat-nose or wide-mouth hollow-point bullets. Since I am not, I am going to rule out 22 caliber. One of the most important considerations is the max OAL that will fit in an M1 carbine mag. I filed down the tips on a couple of dummy 22 Garin cartridges until they slid in and out with a little room to spare. They were right around 1.68” so I think we should take that as the max OAL. By the way, I should mention that this topic was also discussed quite a bit two years ago over on another forum. It is probably worth reading that thread if you haven’t already. See www.saubier.com/forum/showthread.php?t=20151The 17 Garin will fit in the M1C mag, at least with most of the available bullets that are not heavier than 25 grains. But even Paul Garin himself isn’t too keen on that particular variant of the Garin series, saying “Compared with the 17 caliber offerings, the 20’s offer heavier available bullets with superior ballistic coefficients. I have found this cartridge to be very accurate as well as being flexible and easy to work with. Its cleaning regimen is less demanding than the 17 caliber, and cleaning equipment is less fragile.” I agree with his assessment, so I am also going to rule out the 17 caliber. OK, so what about the 20 Garin then? I think one of the participants on that other forum claimed that they would fit in the M1C mag. I have no doubt that some of the bullets that are in the range of 30 to 33 grains can be loaded so that the OAL is no more than 1.68”. But I would prefer to use even heavier spitzer bullets, say around 40 grains. And there is another issue with this cartridge, which is that the chamber has a lead that, although not terribly long, is just long enough that the OAL would prefer to be somewhere around 1.73” or so. (There was also some discussion about this issue on the Saubier thread.) Closely examining the photos of some 20 Garin cartridges suggests that indeed they are around 1.73” OAL. So without some modification, the 20 Garin doesn’t look very promising to me. What about the 19 Badger? Without getting too carried away with the details, the main problem with it turns out to be the same as for the 20 Garin. The cartridge OAL really wants to be 1.72” to 1.73”. Furthermore, I don’t think the selection of 19 caliber bullets is nearly as good as it is for 20 caliber bullets. There is also an interesting point made on James Calhoon’s website that may be relevant, however. He states “19 Calibers have rifling up to 50% thicker than the 17 and the long dormant 20 caliber (5 mm). Thicker rifling (comparable to that of the 22 and 6 mm) results in less cleaning and longer barrel life.” Right below that he shows drawings of the rifling grooves for 17, 19, and 20 caliber barrels, which show that the groove depth is 1.5 to 2 mils for the 17 and 20, but is 3 mils for the 19 caliber barrels. I did a little research and found that there doesn’t seem to be a standard for 20 caliber groove depth. Some of them are around 1.5 to 2 mils, but apparently there are also some that are 2.5 or 3 mils. The only barrel maker I found that actually tells you what the groove depth is was McGowan, and theirs are 2.5 mils. To me that seems plenty, but my point is that one needs to be careful when selecting a 20 caliber barrel to make sure that the groove depth is sufficient. While I was researching these two cartridges, I also noticed something very interesting. From the photos of the 19 Badger cartridge, it appeared to have a very thick neck, and this turns out to be correct. In fact, the neck diameter for the 19 Badger is 0.228” whereas for the 20 Garin it is 0.224”. That’s right, despite having a bullet that is 6 mils smaller in diameter, the O.D. of the neck is 4 mils larger! The neck is 15 mils thick for the 19 Badger and only 10 mils thick for the 20 Garin. This creates an interesting possibility: A brass case formed using a 19 Badger die set could then be inside-neck reamed to accommodate a 20 caliber bullet and still be plenty thick. And the 19 Badger reamer could be used to cut the chamber. Of course, some other reamer would be needed to cut the lead and throat, but I’m guessing something could be found. But we still have the problem of the cartridge being just a little too long. To try to get an estimate of just how much shorter it needs to be, I closely examined some photos of some of the different 39 and 40 grain bullets. It looked like the length of the ogive portion of the bullets were mostly all between 0.400” and 0.425”. But this should be considered to be just an estimate. To be sure, I need to actually procure some bullets and measure them. But if the ogive portion is say 0.420”, then in order to keep the ogive completely outside the mouth of the case and still fit the mag, the case length must be no greater than 1.260”. With the Garin case, I think you could get by with just trimming the case down a little. (The neck would still be long enough.) But the “official” 19 Badger cases are a little longer and the shoulder is a little higher up on the case, so I would worry that the neck might end up being just a little too short if the case was trimmed to 1.26”. Also, with a shorter neck, there would be a significant gap in the chamber between the end of the case and the end of the chamber (at least if the chamber were cut using the 19 Badger reamer), and that might create some problems also. And with either cartridge, the bullet wouldn’t be anywhere close to engaging the lands if the standard reamer were used. In order to make the Badger case work, I think the shoulder needs to be pushed down a little bit, implying that the die would need to be shortened a little bit (40 or 50 mils). This would mean that the case is about 0.0006” smaller in diameter, but I don’t see that as causing any problem. The virtue of this approach is that the standard Badger reamer could be used, and I think that is a big plus. So at this point, I would be interested in getting your reaction. If generally positive, I may want to pursue it further. -Spaceman
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Post by HMC710 on Oct 26, 2014 21:00:58 GMT -5
Great info there Spaceman, some I've seen before, some not, keep it coming! You could always shorten the 20 Garin case and short chamber the barrel. Cut the dies down and you are ready to go. Either way it would be a fun project. If you get a direction set and gather parts let us know and we would be glad to help with what we can. H
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Post by HMC710 on Nov 2, 2014 4:23:48 GMT -5
Got the M1 and AR carbines out the other day for some plinking and had cycling issues with the AR as it would not pick up another round. I was running my same practice load from the bucket of ammo I have so I assumed that was not it. I pulled the hand guard and I had changed gas blocks so I could get a FF tube on. The gas block was an ebay special and the gas tube hole had been drilled all the way through the block. I questioned it at the time but put it on anyway. I pulled the block to see if the port was lined up ok (which it was) and noticed the back end plug in the gas tube was gone. The opened end of the gas block allowed the plug to get pushed out the end of the tube which dropped system pressure which caused the short cycling. I welded up the back of the gas block / tube and put it back on. Hopefully I can find some daylight to get back out and try it again.
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Post by HMC710 on Nov 10, 2014 20:04:00 GMT -5
Had a chance to run the welded gas block AR the other day and do some plinking. The carbine position set up worked ok with a couple minor FTF that I am looking into. This set up has a rifle stock, buffer, and spring. I like the rifle set ups because of the length of pull is a bit longer and allows a bit more travel and smooths out the cycle a bit. Holding the bolt catch down the bolt would lock back every time, however the FTF would always be the right side shell in the mag and it looked like a short stroke or a weak mag spring because the bolt would ride over the case but still push it forward enough to jam. An interesting note is that three shot bursts worked every time. The mag was a worked over Korean 30 round. Loads were the 110gr JRN factory duplication rounds. And of course, recoil is very mild with the 30 Carbine round. Another thing that I've always said I was going to do is include a cost per round factor to these builds. Using the bulk 110 JRN, this is an economical gun to shoot. It would be nice to SBR one of these and come up with a Urban Defense load if a suitable bullet could be found. If not an SBR maybe and XM style barrel with pinned/welded muzzle device and collapsible stock..... Hmmmm
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Post by 22boomer on Feb 11, 2015 14:54:42 GMT -5
Tim, on another note I was reading a thread on another site (Saubier again) and the thought was brought up that maybe the 22 tcm could be used in an AR. I remembered that you have designed and built a magwell adapter for the M1 carbine magazine so I got out one of my mags and found that the 22 TCM cartridges do seem to fit in the M1 mag pretty well and the fact that the 22 CTM cartridge case could be loaded to a longer length using the carbine magazine made me wonder if a nice little varmint rifle could be built using your magwell adapter, a carbine magazine and a barrel chambered for the round with one of your short gas systems. I have an AR in the 22 Reed Express but it uses the longer pistol gas system and it shoots great with the original published loads that Ron came up with for the 22RE so maybe the longer gas system might work fine with the 22TCM also. The velocities that could be had with the 22TCM in an AR with a 16" barrel could be in the 3000fps range easy. This is just something I wondered about since the formed brass is easy to get -- it's the rest of the parts that make it a problem. Not sure you can post a price for your magwell adapter here but if you could IM me the price I would appreciate it.
Charlie
edit to add: I wanted the price on the M1 Carbine magwell adapter.
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Post by HMC710 on Feb 13, 2015 12:36:27 GMT -5
Hey Charlie, I have not had luck with the 22RE or TCM working in stock M1 mags. The body is too short for the follower to work well. We might be able to make a different follower and see if that works, one of those spare time projects. Both the RE and TCM are in need of a longer mag for the longer bullets....
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Post by 22boomer on Feb 14, 2015 11:52:01 GMT -5
Hey Charlie, I have not had luck with the 22RE or TCM working in stock M1 mags. The body is too short for the follower to work well. We might be able to make a different follower and see if that works, one of those spare time projects. Both the RE and TCM are in need of a longer mag for the longer bullets.... I know what you mean now about the M1 mag and the 22TCM. I tried more tests with some of my favorite 22 bullets and it was a no-go 50% of the time. There is another fellow that is using regular GI mags or maybe Magpul mags for the 22 TCM but he is using really heavy bullets for subsonic work. If there was a way to make a spacer for the front of the Magpul or GI mag that also acted as a feed ramp maybe that would work with the 22TCM. I'd have to see what could be done with the mag follower. I've tried the 22TCM in the PPS-43 mags but, due to the length of the cartridge case, you can't use really good 22 caliber bullets because of the overall length becomes too much for the PPS mag. I love the 22 Reed express but I had to go to CZ-24 subgun mags to get them to work in the AR reliably. I could not seem to get the 22RE to work well at all in the PPS-43 mags but then I don't have any machining equipment to make stuff -- have to do everything by hand. Your idea of a different M1 carbine magazine follower might work out really good. I did notice another problem with the M1 mag and that is the front edge is low and could allow the second 22TCM cartridge to move too far forward and screw things up when the top round is being loaded. I sure would like to find an easy way to use the 22TCM in an AR since the formed brass is so easy to get.
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Post by HMC710 on Feb 15, 2015 10:33:47 GMT -5
As fate would have it, rumor is we are doing a TCM so we'll see how it goes. I agree 100% both 22's are great rounds if you can put some good bullets in them. Hopefully I can start getting back on track.... Woo Hoo, up to -6 degrees in the great white north!
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Post by 22boomer on Feb 15, 2015 15:07:47 GMT -5
As fate would have it, rumor is we are doing a TCM so we'll see how it goes. I agree 100% both 22's are great rounds if you can put some good bullets in them. Hopefully I can start getting back on track.... Woo Hoo, up to -6 degrees in the great white north! Are you doing this TCM project under a contract or did you decide to go at it yourself? I'm still going to try to figure the mags out unless you have a sheet metal department that might be able to make some.
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Post by HMC710 on Feb 15, 2015 17:45:24 GMT -5
" make some..." I'm still trying to get some 10 rounds M57's done......
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