In my search to find a 45* chamfer cutting tool to time a gas cylinder lock. I found this. They're NOS 50+ years old, parkerized finish, and they must have cost a fortune when they were made. They look like an armorers tool. Anyway, cuts the chamfer beautifully. Times the lock in a minute. It's even center drilled top and bottom.
http://www.ebay.com/itm/45-Degree-Ch...item2ec114c61d
Here's a post on gas lock timing.
http://m14forum.com/gus-fisher/11791...-gas-lock.html
I dont see that they are for timing a gas lock,just deburring the holes. Even if you would ream the chamfer the locks would still hit and stop on the flats or am I missing something???
Damn Bill, I even posted the thread that you started on the subject! The gas lock has a 45* bevel on it as does the front of the gas pads. The two tapers mate under ideal conditions. Anyway, if you remove the gas cylinder and tighten the lock it should mate with the barrel at about 5:30. Cutting the countersink on the gas lock will allow you to achieve the perfect timing. Some gas locks will also need the rear face cut which I found was easy just by running the lock across the face of a sharp mill file.
Gus's answer.
Gus Fisher
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Sanding metal off the back of the Garand GC Lock is just about the last thing you want to do to fit a lock and I’m sure Hook would agree it is far better to have a lock that fits correctly.
The problem with sanding the rear of the lock is keeping it flat to the surface of the face of the GC AND you are cutting through the hardness at the back, if the lock is hardened.. It is actually better to file the back with a wide file that cuts the whole surface of the lock evenly, if you are going to do it.
Yeah, Hook can probably do it on a belt sander, BUT you have to remember when he was learning to do it, there were plenty of locks WHEN he screwed up some of the locks he used the belt sander on.
The OTHER way to do it is cut the chamfer in the lock a bit deeper with something like a 12 flute carbide crowning tool. Personally, I believe that is better because you don’t have to worry about messing up the fit of the back of the lock to the front of the GC. I did that on a very few Trophy Garands I went over and rebuilt before the FINE Folks at Crane sent us a whole batch of extra Garand GC Locks to swap as required.
Ahh, I understand, I wasnt thinking right.... Again
Is this tool the right size for a lock??
Thanks!!
The pilot is a little bit smaller than the hole in the gas lock, but it seems to cut straight held by hand. I suppose a piece of brass tube on the pilot will make this thing perfect.Quote:
Originally Posted by Orlando
Sold out.
Interesting that Ol'Ham jumped right in and was put in his place.
Oh well, snooze ya looze, looks like I missed out
Sold out because someone probably bought the lot to resell at $100 each!
If they were that smart, that's smart.Quote:
Originally Posted by Dave
I waited to long and missed out on getting one of these neat tools. The other day I received a package in the mail from Stu
http://i47.photobucket.com/albums/f1...Picture747.jpg
Just got done tring it out to see how well it works
Started with a lock that didnt time
http://i47.photobucket.com/albums/f1...Picture746.jpg
Added a few drops of oil to the cutter and twisted it a few times
http://i47.photobucket.com/albums/f1...Picture748.jpg
http://i47.photobucket.com/albums/f1...Picture750.jpg
Lock now times at 5:30
http://i47.photobucket.com/albums/f1...Picture749.jpg
Wasnt sure how well it would cut with a hardened gas lock but went through it like butter
Thanks Stu!!
That's what I'm here for Bro.
Thats cool. Now if we could find a way to "ADD" metal to the bevel and go one turn out instead of in, we could start changing the cycle timing and soften the recoil. I played with that awhile back, but then found the adjustable gas plugs do the same thing in the end. :) Stu- you going to be selling anymore of these?Quote:
Originally Posted by Orlando
I only bought 3, of which I kept 1, and Tim and Orlando got the other 2 but someone here got all the rest. Just don't know who.
OK, I'm confused. If the bevel inside the GCL stops against the bevel on the barrel, how does milling/filing the rear face of the GCL allow it to turn more? Once the two bevels meet you could mill the rear face of the GCL 'til the cows come home but it ain't gonna' turn any farther--Right or wrong?
Jon
Quote:
Originally Posted by musketjon
MJ, they aren't doing anything to the face of the GCL, they are cutting the bevel it self.
Jon, take a look at the 4th pic, you can see the shiney new bevel that I cut.
Jon, filing the rear face of the lock just trues it up. My Post-War high hump was visibly warped. A few careful passes on a flat file trued it right up. The depth of the chamfer determines where the lock stops as you said.
For those of us without one of these tools (or any 45 degree countersink) or drawer full of GCLs to try, how about high-temperature threadlock to secure the GCL against movement. Loctite has a high-temp blue threadlock (650F)
http://www.fastenal.com/web/products...ex?sku=0608687
Has anyone tried threadlock or other adhesive as a substitute for perfect mechanical chamfer fit? If not, can anyone think of any problems with this fix?
The gas screw pulls the cylinder up against the lock if it doesnt time right
Getting a lock that times perfectly is really splitting hairs and is a National Match mod. From what I have learned from a old time armorer having a lock that rests against the barrel shoulder keeps the shock from the recoil from wearing the barrel splines and barrel threads.
Picking out a lock that times was not done when Garands were originally assembled
After I posed the question about Loctite, I decided to play around a bit on the workroom with my drill press and an 82 degree countersink because I don't have a set of 90 degree ones. The barrel shoulder isn't a chamfer, so I think angle won't make any noticeable difference.
Long story short, using countersink with a light touch in the press allowed me to time the lock to exactly 5:30. The barrel is a Krieger in .308, so I'm not worried that much about WWII-era authenticity for this rifle. I just want it to shoot better than I can, and with the forward sight bouncing around with the gas cylinder, I needed to do something. Yes, I could have peened the splines, but I chose this route instead.
http://i369.photobucket.com/albums/o...medic/bar2.jpg
Shug, the GI spec calls for a 45* shoulder but as you pointed out standard countersinks are 82* and not 90*. I'm not sure about aftermarket barrels. Like Orlando said, this kind of fine tuning is reserved for match rifles. I just like having cool tools.
I would think the angle is important otherwise isnt it possible that the lock wont be against the barrel chamfer but just tigtened against the gas cylinder which would be defeating the purpose as all stress would be on the barrel threads
Orlando,
The gas cylinder doesn't have a hard stop from the splines before the gas lock reaches the chamfer, so I only have interference when the GCL is tightened against the actual shoulder on the barrel. Then the plug secures the GC to the GCL, which is solidly pressed against the barrel shoulder by the threads.
On the Krieger barrel, there is no chamfer on the barrel shoulder; it's flat so I'd have to counter-bore rather than countersink to have parallel mating surfaces. On my SA, there is a proper chamfered shoulder. But no matter what the angle of the GCL chamfer is, there will be interference when chamfer meets shoulder. If the chamfer angles match, both chamfers mate across their entire surfaces. If the angles differ, you'll have much less surface actually in contact. But with the relatively soft metal that the barrel and GCL are made of, there is some deformation and the metal creeps into a shape that somewhat matches the mating surface. End result is the shoulder still fixes the geometry of the GCL and GC.
I'll get a chance to get out to the range in the next week or so, and I'll report back on whether or not any play develops after cycling. Worrying any of this is probably overkill, but I enjoy experimenting even if it doesn't lead to anything useful. Plus I get to exchange ideas with others who forget more about Garands in a day than I'll ever know in my lifetime.
Allen