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baker72

Bayonet lug front sight location and Finish

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Hi all

Im having my barrel desporterized. my gun smith needs a reference point.

Im wondering if anyone could take and post a picture of their orignal barrel with a tape measure next to it, this way he can see how far the front sight and bayo lug sit apart.

Also what’s the correct finish park or blue.

thanks for any help 

cheers Will

 

 

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JSARs were thought to be Parkerized and that is the way they are usually refinished.  Actually, according to factory specifications, they were "blackened" by applying Du-Lite, a form of blueing on a sand or bead blasted surface.  Joseph Scott had an original tested by a metallurgist who confirmed that they were actually blued.  The bead blasted blue surface often takes on a greenish tinge (like Parkerizing) from the grease imbedded in and on the surface.  -Type 2 and 3 rear sights were often painted to cover brazing joints.

IMG_0671.JPG

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baker72: if you have an original "bayonet" that will help you with the spacing....as it will dictate where the front sight sits as well as the bayo lug...as both must be in right position for the bayonet to be attached

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Thanks guys all this info will help a lot I will post a pic of when she is done 

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Here are some diagrams which I've gathered from this forum at different times. The measurements are very close but as you'll see they differ from one diagram to another. Whether that's due to interpretation of 1.40 as 1&3/8ths inches.....I don't know. This first diagram was originally for a LMG or "Carbine" barrel, so overall length won't be correct for  rifle length barrel. The measurements from the breech end to the Barrel guide bushing, and from the muzzle back toward the bayonet lug should work. On the bayonet lug the cross pins will of course be on the bottom.

Carbine barrel tweaked for rifle.jpg

 

 

The next view is only of the front:

Front sight and bayonet lug.JPG

 

Yet another piece of info from Mr. Joe Scott:

 

Johnson barrel step cut info.eml

I've done several barrels myself and found that it's best to use a micrometer to check the I.D. of the bayonet lug, and the I.D. of the front sight which you are going to use, when determining the diameter of the barrel at each step. Some sights and bayonet lugs might differ and could cause a loose fit or too tight. Fit your particular bayonet lug and sight to your barrel.

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When measuring ID of lugs and sight, be sure there is no slight burr at entrances.  Use same tool such as dial caliper to measure barrel steps.  The lugs and sights are designed for a light press fit onto barrel, about .0005" to .001" tight.  I have been sent used parts that were loose or had been knocked off with a hammer.  If parts are loose on steps, you can prick punch all around steps to raise the effective diameter.  To align lug, sight along bottom guide lugs and align bottom of lug with them.  Use Loctite and let set 4-8 hours before reaming for taper pins (2/0 x 5/8 morse taper.)

To align sight, slip it on end onto first pricks and install barrel into receiver and sight down top of receiver to insure sights looks straight up.  Carefully remove barrel and put some Loctite on step and press to back of stop. Recheck alignment in receiver before Loctite sets.  Use 12" cresent wrench to tweek alignment

Let set,  and ream for taper pins.  If used parts, check carefully which side oridgnal taper entered from.  If you use the wrong side and ream again, pins will be loose.  Use Loctite on pins.  If everything is correct pins will protrude equal on both side.  If you have to buy longer pins, cut a little long with bolt cutter and grind end, then chuck in drill press and using file, round cut end.  Be sure pins are equal length.

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On 3/27/2018 at 6:50 PM, Joseph Scott said:

The front sight step is 1.375" from end.  The bayonet step is 2" back from the sight step or 3.375" from end.

I've been away from this site for a few years. You refinished a Johnson for me a while back, "converting" it from a Winfield, and put a new stock on it. Do you still re-finish them?

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A few years ago, I had a gunsmith in Texas refinish a M1 carbine for me. He did a phenomenal job!! His company is Warbird Custom Guns. He specializes in M1's, M1A's and M1 Carbines. I don't know if he would be willing to refinish your JSAR but it wouldn't hurt to ask. Good luck.

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