What are barrel and barrel nut thread sizes ?

Information on Malfunctions and Care of your Model 8 & 81
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cantgrowup
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Joined: Tue Apr 23, 2019 9:27 am

What are barrel and barrel nut thread sizes ?

Post by cantgrowup »

Well, I just had to buy another Model 8 in .30 Rem (1927) and having issues with getting the barrel nut back on the barrel threads all the way. I had taken the rifle completely apart and the barrel nut came off easily. However, when trying to reassemble the barrel assembly, the barrel nut started having resistance with the final 1/4" or so. The threads started to bind. Like a fool, I figured more force was required and even with oil, almost bonded the two items together. I got the barrel nut back off again using minimal heating. I had done nothing to the threads on the barrel or nut other than clean with a brass brush. So before I try assembly again.... I would like to determine what size tap and die to buy to chase the threads.

The barrel thread OD appears to be 0.538" and the thread count is 24 tpi. The closest to that would be an SAE 1/2"-24 tpi. I know that "rifleman" had at one time seen the thread sizes used on 8/81, but he couldn't find the info again. I don't own those size tools, and before I buy them was wondering has anyone out there used 1/2"-24 tpi tap and die to chase the threads on their Model 8/81 barrel/barrel nut?

Note: I had originally measured incorrectly and thought it was a 9/16"-24 die that was needed. I measured the OD of the barrel threads instead of the barrel nut ID... silly me :? . The barrel nut ID is 0.499", hence the 1/2"-24. But no one has responded to my original post, so I've now ordered a 1/2"-24 tap and die to see if they will work.
Last edited by cantgrowup on Wed Sep 09, 2020 4:58 pm, edited 2 times in total.

cantgrowup
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Joined: Tue Apr 23, 2019 9:27 am

Re: What are barrel and barrel nut thread sizes (1/2"-24?)

Post by cantgrowup »

Okay... I give up. The 1/2"-24 tap and die came in and they don't fit either. Too small, and the 9/16"-24 tools were too large. So... I brought the barrel and barrel nut to a competent gunsmith that builds rifles and he is going to mount the barrel in his lathe and chase the threads. I'll let you know how it turns out.

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Phyrbird
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Re: What are barrel and barrel nut thread sizes (1/2"-24?)

Post by Phyrbird »

Been there, done this. 4hours with a triangular needle file. :? File a little, test fit a little, more file, get it close then tap with a soft face hammer to swage the threads for fit. :twisted: :twisted: More file a little, repeat. Work your way down the threads one at a time till minor tite. ;)
The biggest cause of damage is getting the nub on the barrel washer not in the groove in the threads. Watch this carefully, they WILL go together wrong if you try hard enough. I've had 3 that Goobersmith :twisted: :twisted: had fouled up. :!: :!:
Phyrbird
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cantgrowup
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Joined: Tue Apr 23, 2019 9:27 am

Re: What are barrel and barrel nut thread sizes (1/2"-24?)

Post by cantgrowup »

Yes... reinstalling the barrel in the shroud assembly and getting the little washer nub to line up with the groove in the barrel thread used to give me fits. Then I started marking the end of the muzzle with a black Sharpie indicating where the groove is and then I can easily rotate the barrel to line up the groove/marking with the washer nub before pushing the barrel through the washer.

Rifleman
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Joined: Wed Feb 28, 2018 4:07 pm

Re: What are barrel and barrel nut thread sizes (1/2"-24?)

Post by Rifleman »

cantgrowup wrote:
Mon Sep 07, 2020 10:10 am
Yes... reinstalling the barrel in the shroud assembly and getting the little washer nub to line up with the groove in the barrel thread used to give me fits. Then I started marking the end of the muzzle with a black Sharpie indicating where the groove is and then I can easily rotate the barrel to line up the groove/marking with the washer nub before pushing the barrel through the washer.
Good idea! I'll have to do that the next time I disassemble either of my 81's. The several times I have had the barrel/shroud disassembled on them I didn't have any problem getting things lined up and properly threaded, but there is a first time. I took it slow and easy, not being in any hurry. I marked each surface with a 'mark on anything pencil' how they came off of the rifle and how they mated so as to get them properly assembled.

cantgrowup
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Re: What are barrel and barrel nut thread sizes (1/2"-24?)

Post by cantgrowup »

Well.... my gunsmith was able to mount the barrel in his lathe, centered it up on the bore axis and re-turned the barrel threads. He said the setting that he had to use to chase the threads was 17/32" - 24 tpi. Now the barrel nut threads back onto the barrel easily... and I've now reassembled the barrel assembly and installed it on the receiver. This work costs $75, but well worth it since I did not have to try and redress the threads myself with a thread-file. I will let you know how it shoots at a later date.

Rifleman
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Re: What are barrel and barrel nut thread sizes ?

Post by Rifleman »

cantgrowup wrote:
Wed Sep 09, 2020 4:14 pm
Well.... my gunsmith was able to mount the barrel in his lathe, centered it up on the bore axis and re-turned the barrel threads. He said the setting that he had to use to chase the threads was 17/32" - 24 tpi. Now the barrel nut threads back onto the barrel easily... and I've now reassembled the barrel assembly and installed it on the receiver. This work costs $75, but well worth it since I did not have to try and redress the threads myself with a thread-file. I will let you know how it shoots at a later date.
WOW!!! The 17/32"-24 tpi needed is really cutting the pie pretty precise......halfway in-between 16/32 (1/2)" and 18/32 (9/16)". Don't know if I've ever seen or heard of anything threaded for 17/32". Glad it worked out for ya!!!!

cantgrowup
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Re: What are barrel and barrel nut thread sizes ?

Post by cantgrowup »

Well.... he said that he did not cut the threads again, but merely chased it using that setting. So, the original factory thread dimensions would have been different. I'm not doing the math because that sounds an awful lot like 16/32" or 1/2" which is what I had a die for and it wouldn't fit over the barrel muzzle. :x So maybe his measurement was slightly off, but he redressed the threads and now the rifle is back together. :D I still wish I knew I knew how I buggered up the threads to begin with, because the barrel nut came off easily the first time. I can't see how it happened, but it did. :? No wonder these rifles became obsolete! Too complicated!

I just thought I'd let the forum know of my travails in case it could help them.

cantgrowup
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Re: What are barrel and barrel nut thread sizes ?

Post by cantgrowup »

Shot my new "troublesome" .30 Rem for first time. Twenty rounds. Functioned okay... had one failure to extract, but empty case wasn't stuck (I guess the extractor just didn't get a good grip). Fired two and three rounds okay from magazine. Two times, the bolt didn't fully go into battery and I had to push forward on bolt handle. I loaded up the magazine one time with five rounds and the third didn't feed correctly, but those were the only problems (4/20 = 20% unreliable?). Since I replaced the entire bolt carrier and bolt, maybe it just needs breaking in. Maybe it needs a stiffer recoil spring. But when it did shoot, it shot well. Here are the last five rounds at 50 yards.

Image

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Bandersnatch
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Location: Lower Alabama

Re: What are barrel and barrel nut thread sizes ?

Post by Bandersnatch »

Ooh, a nice little group in the center. Seems to shoot well.

Perhaps a touch more lube and some more shooting to break it in?
I am the cat who walks by himself. And all places are alike to me.

chas1949
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Joined: Wed Oct 02, 2013 12:40 pm

Re: What are barrel and barrel nut thread sizes ?

Post by chas1949 »

Just because in case no one mentioned it, another member here is making new barrel nuts and washers. He must have thread size info you need.

cantgrowup
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Joined: Tue Apr 23, 2019 9:27 am

Re: What are barrel and barrel nut thread sizes ?

Post by cantgrowup »

You know... I didn't even think of that. I'd told him that I'd order one or two of the barrel nut/washer sets but did not even think to think that he might have the actual sizes. I'll ask him. Thanks!

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