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Barrel Removal


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#21 Bob

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Posted 01 October 2003 - 04:27 PM

You guys are getting me excited!!! Go read the patriot act and other such .GOV stuff. If you don't play the game by the rules they will shut off NICS (controlling you're access to weapons?)



Es ist gut für's Vaterland!


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#22 Grey Crow

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Posted 01 October 2003 - 06:01 PM

Being in animal control with a fair amount of rural area I had directions that really take the cake..

The guy said turn left 3 miles before the old landmark. Umm, OK!!

Gun Loss Scenario:
Funny thing happened to me when I was squirrel hunting. I was running through the woods after one of the lil critters, I had all of my guns, as I ran one by one they fell off and I lost them all. We hunted for them for hours even tried metal detectors, and to this day we still haven't recovered one piece. It's a crying shame Mr. Gov. Man. Loosing such a great collection in one afternoon. unsure.gif

Somewhere along the conversatiuon I think we took a wrong turn WAY off Topic!!
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#23 LIONHART

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Posted 01 October 2003 - 06:43 PM

Guns? What Guns? I sold all of mine at a Gun Show some years back, when Gun Shows were legal! Please don't tell the Gestapo!(Oh Sir, that AA Gun that I have set up in the back yard is just for looks!)
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#24 bigred

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Posted 03 October 2003 - 05:09 PM

I hope that we are able to turn the tide and fight these unconstitutional laws. The NRA and many other organizations have been making some good gains in the war, but it will be a long struggle. We must be more active than our enemy.

If that terrible day did come, I would not flee the country. Like the President (Heston), they'll take it out of my cold, dead hands. My favorite t-shirt says, "If the government comes to take your guns away.... give them the ammo first!"

I agree. Second Amendment all the way baby!
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#25 Zamm

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Posted 03 October 2003 - 09:26 PM

Hmmmmmmm, perhaps a little story,

Back in 1977, I was at the range with my Westy 27A1 semi, drum and all, chopping away at a silohette
target from the hip. Make a long story short, another guy at the range see's me with my semi Thompson, takes down my license plate number on my Jeep and calls the local police. They tell him to cal the BATF field office. He does, and the screw starts to turn.
All of a sudden I have a guy call me out of the blue and tell me someone told him I knew something about WWII guns and could he come over and show me some and see what they were worth.
Now I'm young, early 20's so I don't think about this too much and invite the guy over for dinner. Nice young guy about my age, comes over with a Luger and a 1911 .45... Asks me if I have any guns, I say sure and show him some of my rifles (enfield, mausers, etc.. run of the mill stuff).
He asks if I have anything rally speacial, I say well, theres my Thompson. I show it to him, he picks it up and looks at it and says "wow, can I take it outside?" I say why while he's walking to the front door and opening it.
Then all hell broke lose just like a movie! In they came about 15 ATF agents with there guns out. Man it was me, my wife and two other friends, hands up the whole bit!
I was slammed against the wall with a Colt .357 python under my ear (it was january and I'll allways remeber how cold that fricken barrel was, and the sight of the hollow points in the cylinder!).
Well, after a few minutes of looking at the gun, they decided it was a semi ( I guess the stamping on the side helped out in that area!!).
They apologized for any incovience and made me sign a statement that I invited them in! They also gave me the search warrent ( which I still have, a nice memento of my goverment protecting me).
Moral of the story: At least no one got hurt, which could have happened by any accident. I wound up getting rid of all my firearms except the Thompson. I decided that I was going to keep that forever! I think you guys get what I mean....

Epilogue: They turned out to be pretty nice guys, my wife made them coffe and we sat around for a half hour or so, them telling us about the raid on the Hell's Angels the night before in the city. I asked how did this start, and they told me about the "upstanding" citizen and his phone calls. They also said that the guy who called the raid after holding the Semi would be sweeping the office for a while.
Total cost for this investigation ( My phone was tapped and they had servailence on me for a week and a half) was over $15,000. 1977 dollars!!!

Man, I'm getting tired of defending my Thompson!
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#26 giantpanda4

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Posted 03 October 2003 - 09:55 PM

Back on the title subject.... (sorry, I am an engineer!)

What is the torque spec for thightening a barrel to the reciever?

When a barrel is marked for reassembly - I know it has to line up for the front sight - what kind of torques are you reading when you achieve your mark?

And - has anyone actually measured the RELEASE torque of a well shot assembly? I have read here that it tightens with shooting... someone mentioned what translated (if I remember right) to about 5 degrees of rotation.

Thanks for the above photos! Pictures definitely do speak a lot of words!


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#27 Zamm

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Posted 04 October 2003 - 07:28 AM

Phil, yeah, I was scarred sh*tless, big authority figures and all...
But man, even when I was against the wall, I could not for the life of me figure out what I had done wrong.
When I asked one of the agents replied " Illegal ownership of a full automatic Thompson submachinegun"
That's when I kind of felt relieved and said " boy you guys are going to be really embarred"
Well the first expert who took the firearm from the point agent said "christ!" or something like that... and it was all over. We were told to put our hands down ( funny, I kept putting mine back up when ever they asked a question!)
Yeah, if I was a little older and seasoned things would have been quite different, no kidding! I would have a little bit of a suit going... But a friend at the time was a local police officer, and his suggestion was to let it be, as long as no one was hurt, it would not be worth the trouble going up against these guys... ( he even alluded to them pulling me over in my car one day just to find a sawed off shotgun in the trucnk or something like that!)
Well, it's just become one of those storys you tell people.
But no one is getting my semi-westy! No sir!
Cheerio, C
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#28 PK.

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Posted 04 October 2003 - 09:34 AM


The alignment thing is very interesting as the evidence seems to indicate that both marked and unmarked parts exist and the GI receiver drawings nor the original A/O barrel drawings show any requirement for barrel thread or other thread timing. As far as I have been able to determine, new barrels did not have grooves for the front sight pins as the sights were installed after the barrels were installed. Otherwise, not only would the barrel threads at the receiver have to be timed but also the threads at the muzzle and in the Cutts. Also, NOS sights are not drilled for the pin.

Concerning barrels with the witness mark being installed, I have seen guns with such (replacement) barrels installed and the witness mark wasn’t even close to being where it was “supposed” to be. In a practical sense it doesn’t matter; if the chamber and receiver are cut properly the headspace will be fine. The sight being installed after the barrel, the notch resulting from drilling the pin will be on top. Any turning operation to bring the mark inline would require subsequent re-chambering to establish proper headspace. I can’t see any military command going to all that extra work when it isn’t necessary.

Years of experience did not allow me to accept the “self tightening” barrel theory. I decided to put the question to a friend who is mostly retired from a long carrier as an engineer with Winchester, Marlin and his own firm consulting to all the majors in New England. He chuckled and ran the numbers and concluded that a 45 caliber 230 gr FMJ bullet at normal velocities will apply .428 ft/lb. of torque to a 16” twist barrel. Less than a half a pound. If you think about the barrel in a 1911 pistol and how it works, a torque powerful enough to tighten a barrel in a TSMG receiver would ruin the gun is short order and preclude its function by impeding the slide and barrel movement. This simply does not occur.

How much torque is right for a barrel installation? I know of no values being published. TM9-1215 says to remove and install barrels with a strap wrench. Well, I haven’t found one yet where a strap wrench was an adequate tool for the job. I freely admit barrels are installed by feel that has been developed over years of experience. If all the interfaces are correct, I will hazard a guess that 40-50 ft/lbs. might be a reasonable number based on putting my torque wrench (yes, I have some automotive tools) into my vise, “feeling” it and trying to relate it to the tools used in barrel installation. As you pointed out, there are many factors in the interface that must be considered as well.

Removal torque is another matter of course and is affected much more by corrosion, dried, hardened oils and other gunk that may have seeped into the interface over the years (and been baked or boiled or broiled or frozen in place) than by the installation torque.

This is an intriguing topic and I will be interested to receive a copy of Doug’s GI barrel drawing when it becomes available. I hope a comparison to the original A/O drawing will shed additional light on the subject

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#29 Zamm

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Posted 04 October 2003 - 09:42 AM

PK,
I forgot what this thread was about!
Thanks for taking the mystery out of that particular operation.
When people say to let an experienced 'smith change the barrel, now I know why...
Interesting how little force is transferred by a bullet passing through the rifling in the barrel also.
Thanks!,
Zamm
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#30 SecondAmend

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Posted 04 October 2003 - 04:06 PM

IMHO any TSMG barrel tightening effect is likely more complex than the simple calculated 0.428 ft-lb of torque. The TSMG barrel is subject to approximately 10 of such torque incidents per second in, in many cases, two, three, five, and 8-10 second bursts (corresponding to XX, XXX, L and C type magazine dumps, respectively). IMHO the repeated incidents are not unlike an impact wrench effect. A lot of small hits in a very brief time.
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#31 PK.

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Posted 04 October 2003 - 09:29 PM

If a barrel is properly installed with, say, 40 ft/lbs. torque I don’t care how many times you hit it with ½ ft/lbs. force, you will not move it. You would have to overcome the yield strength of the metal to do so and it ain’t gonna happen. If so, you would straighten out the rifleing first.

If the barrel is not properly installed and is only bearing on some small area it may be possible, but I believe it unlikely. I don’t doubt what Phil is saying; he is neither fool nor liar, but we don’t really know what the gunsmith did.

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