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Posted: 9/16/2020 8:47:55 AM EDT
[#1]
Happens all the time.
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Posted: 9/16/2020 10:01:15 AM EDT
[#2]
Quote HistoryQuoted: Happens all the time. Not the best idea. At issue is that once the bullet exits the rifling, the propelling gases rush out at about twice the velocity of the bullet. In air or a suppressor entrance chamber), this is not an issue. However in the confines of a tube slightly over bore diameter (as would be the case in an adapter threading into the barrel), the escaping gases can start tumbling with poor accuracy or possible baffle strikes. If you have enough barrel thickness to do an internal threaded adapter, then you have enough thickness to choose an appropriate thread and do an external adapter, such as 7/16-28 in a 1/2" diameter barrel. In that way, the passage through the adapter can be significantly larger diameter with less upsetting of the bullet in flight. As they say, "been there, done that, got the T-shirt." |
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Posted: 9/16/2020 10:21:56 AM EDT
[#3]
It is for a Ciener 22 conversion in a 1911. An external adapter would require more lathe work than I am comfortable with. A normal barrel is in stock and 50 bucks, a threaded barrel is 223 bucks and out of stock. Counter boring is boring and threading once and making and appropriately sized adapter. External would be turning the barrel, turning the adapter to fit the barrel bushing making an adapter with internal and external threads.
Guess I need to set the lathe up soon. I hope I can find my 1/2x28 taps..... (single cut internal threads then clean up with tap) |
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Posted: 9/16/2020 10:47:23 AM EDT
[#4]
External or internal, it's pretty much the same work.
For external: Make the adapter, discounting final OD profile (to match barrel/bushing) Chuck barrel, turn and thread. Attach adapter (while still in lathe) and match OD's Quote HistoryQuoted:Not the best idea. The OP's Q was "Has anyone tried counter boring a barrel to insert a threaded adapter". He never asked whether or not it was a good idea.  |
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Posted: 9/16/2020 11:10:25 AM EDT
[#5]
I've recently see lever actions countered bored for a threaded adapter.
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Posted: 9/16/2020 11:10:54 AM EDT
[#6]
Quote HistoryQuoted: Not the best idea. At issue is that once the bullet exits the rifling, the propelling gases rush out at about twice the velocity of the bullet. In air or a suppressor entrance chamber), this is not an issue. However in the confines of a tube slightly over bore diameter (as would be the case in an adapter threading into the barrel), the escaping gases can start tumbling with poor accuracy or possible baffle strikes. I do it all the time, never observed or had reported a degradation of accuracy. The low clearance through an internal thread adapter is really no different than a lot of booster pistons or compensators. In some cases, there are good reasons for or distinct advantages to doing an internal thread on the barrels. Namely, it doesn't alter the profile or force cutting barrels back and/or relocating of sights, barrel bands, mag tube studs, etc.     
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Posted: 9/16/2020 11:25:42 AM EDT
[#7]
Quote HistoryQuoted: It is for a Ciener 22 conversion in a 1911. An external adapter would require more lathe work than I am comfortable with. A normal barrel is in stock and 50 bucks, a threaded barrel is 223 bucks and out of stock. Counter boring is boring and threading once and making and appropriately sized adapter. External would be turning the barrel, turning the adapter to fit the barrel bushing making an adapter with internal and external threads. Guess I need to set the lathe up soon. I hope I can find my 1/2x28 taps..... (single cut internal threads then clean up with tap) Don't kid yourself about the work involved. Doing internal barrel threading with adapters properly is no easier than external threading with adapters. When I do them, the barrels are carefully dialed in and counterbored on the lathe with proper attention to the new, recessed crown. They are threaded with rather expensive spiral flute bottoming taps, then a custom adapter is turned on another machine with a blank tenon on the front side. The adapter is installed in the barrel, the shoulder faced and the threads cut, all without ever removing the barrel from the chuck. Also, with very few exceptions, you don't want the adapter to bottom out in the counterbore. It should be very close, but the adapter should square on the muzzle. |
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Posted: 9/16/2020 2:09:28 PM EDT
[#8]
Quote HistoryQuoted: I do it all the time, never observed or had reported a degradation of accuracy. The low clearance through an internal thread adapter is really no different than a lot of booster pistons or compensators. In some cases, there are good reasons for or distinct advantages to doing an internal thread on the barrels. Namely, it doesn't alter the profile or force cutting barrels back and/or relocating of sights, barrel bands, mag tube studs, etc. https://i.imgur.com/mxSisLJ.jpg https://i.imgur.com/uqXKTKn.jpg https://i.imgur.com/vpRW1Lu.jpg https://i.imgur.com/ZYpxzXr.jpg https://i.imgur.com/2CkSeNz.jpg Where did you get those adapters and do they have a 1/2x28 one? Not that it matters that much, as long as I have a tap I could make whatever thread I wanted in the counter bore. |
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Posted: 9/16/2020 2:37:18 PM EDT
[#9]
Quoted: Where did you get those adapters and do they have a 1/2x28 one? Not that it matters that much, as long as I have a tap I could make whatever thread I wanted in the counter bore. He most likely makes them himself. |
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Posted: 9/16/2020 3:40:42 PM EDT
[#10]
Quote HistoryQuoted: He most likely makes them himself. They are very nice. Best I can do it ugly but functional. |
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Posted: 9/16/2020 3:56:01 PM EDT
[#11]
Quote HistoryQuoted: I do it all the time, never observed or had reported a degradation of accuracy. The low clearance through an internal thread adapter is really no different than a lot of booster pistons or compensators. In some cases, there are good reasons for or distinct advantages to doing an internal thread on the barrels. Namely, it doesn't alter the profile or force cutting barrels back and/or relocating of sights, barrel bands, mag tube studs, etc. https://i.imgur.com/mxSisLJ.jpg https://i.imgur.com/uqXKTKn.jpg https://i.imgur.com/vpRW1Lu.jpg https://i.imgur.com/ZYpxzXr.jpg https://i.imgur.com/2CkSeNz.jpg This forum really needs a "Like" button for posts like these, very cool stuff as usual. |
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Posted: 9/17/2020 10:09:07 AM EDT
[#12]
Quote HistoryQuoted: External or internal, it's pretty much the same work. ... The OP's Q was "Has anyone tried counter boring a barrel to insert a threaded adapter". He never asked whether or not it was a good idea. I have bored and internally threaded a barrel, and it is not a good idea. I am also an experienced machinist. |
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Posted: 9/20/2020 5:47:16 PM EDT
[#13]
@flowersforfoes
Nick at ECCO machine can probably help with your barrel needs |
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Posted: 9/20/2020 5:58:12 PM EDT
[#14]
Quote HistoryQuoted: @flowersforfoes Nick at ECCO machine can probably help with your barrel needs Nick at ECCO = sixtysixduece |
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Posted: 9/20/2020 6:03:32 PM EDT
[#15]
Quote HistoryQuoted: Nick at ECCO = sixtysixduece Doing the lords work he is  Thankyou ETA FWIW i was asking about the opposite of OP here. CZ/1911/glock type action Flush length, externally threaded end, (machined to barrel profile) thread protector/ extended adaptor to 1/2 x 28 or etc. |
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Posted: 9/20/2020 6:10:55 PM EDT
[#16]
Quote HistoryQuoted: Doing the lords work he is Thankyou Quote HistoryQuoted: Quoted: Nick at ECCO = sixtysixduece Doing the lords work he is Thankyou He’s doing a Beretta 81 for me |
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Posted: 9/21/2020 1:53:51 AM EDT
[#17]
Shieeit. I've got a post war 48 dated Mosin M44 that was counterbored by the Soviets as part of a refurbishment program. They did this to a lot of Nagants regardless if the crown needed it or not. Something about keeping workers employed for party quotas most likely. I doubt this post war rifle needed a counterbore as its one of the cleanest Nagants I ever have come across. This has me thinking if a threaded insert could make use of the already counterbored muzzle. It would be cool to keep the original outward aesthetic of the muzzle and retain the use of the side folding bayo but able to utilize a threaded insert to suppress it with one of my cans if I wanted. Maybe I'll have to see if Nick even thinks its feasible some day.
  That was a hard shot to get by the way. As you can see the counterbore was done pretty damn good. This carbines definitely a good shooter. |
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