Sighting Troubles

[palheid 0]

First time posting here, so here it goes.

Have a B-prefix model Johnson for sometime and never really shot it for a time. The original rear sight peep had been v-notched and the first time I did shoot it the gun wasn't cycling correctly (not picking up a round from the mag). Took it home and gave it a through cleaning, bolt and such was gummed up with old oils, etc. Put it up for couple of years then purchased a M2 rear sight with the peep hole intact and put it on the gun, no problem.

Second time out with it this past week and firing some Greek ammo from the CMP @ 100 yards. Was using a SR-C target (Repair center for the SR 200 yard matches, measures 24" x 24" with 13" black) . Shots were hitting the right edge of the paper at 4-5 o'clock. Adjusted the front post sight picture a bit differently and moved the rear to the left a few clicks and the following shots were still to the right but at three o'clock. To make a short story shorter I moved the rear all the way left and by aiming to the left nine o'clock position right on the edge of the black was able to put 4 shots (talking bench resting here) scoring in the X! Three inside and one touching the ring at nine.

Sure damn happy about the accuracy! Gun cycled great, ejected and picked another round without a hitch. So I'm happy on two out of three counts, but what am I missing about setting up the sights? Kind of reminds me about shooting the CMP M1 Carbines, seems like everyone has the rear almost crank to the left. Most people at the Perry matches say "That's the way they are". This though is another matter, any thoughts or remedies come to mind?

Thank-you,

Pete

[emmagee1917 0]

That's off quite a ways. Four things come to mind. One - is the rear sight assmly itself centered on the reciever ? Could the whole assmly be tapped over to center the block? Two - Is the front sight blade centered in the front sight block ? Is the front sight block itself top-dead-center in relation to the rifle or does it have a cant ? If canted , it would have to be removed , the bbl pin grooves welded up on the low side , the sight reinstalled straight , and the pin holes punched out again. Three - Is the bbl itself straight , or can you detect a bend to the right ? Fourth - check your crown for a burr or nick which could be throwing your bullets off as they leave the bbl.

Others may have other ideas. You might consider sending it to Mr. Scott.

Chris

[palheid 0]

Thanks Chris.... you bring up a couple of points that'll I'll check on this next week. We'll post the results.

Pete

[Gman 0]

Hi Pete,

I've also got a B prefix model and after re-centering the whole rear sight assembly my peep is still half way to the edge. Saw a video of a guy shooting his Johnson on YouTube and when he put his rifle down his sight was most of the way to the left. Maybe they all do it.

Regards,

Gary

[Barry in IN 0]

Mine is most of the way to the left too. I doubt the windage knob would go two or three full turns more left.

[Joseph Scott 0]

Left offset sight is not a normal condition. If the front sight looks absolutely straight up, then I would suspect a warped barrel.

[palheid 0]

Mr. Scott,

Is there a way to check for a warped barrel that a non-gunsmith type could do?

Thanks!

Pete

[Joseph Scott 0]

To check for a warped barrel, the best way is to use two v-blocks and a dial indicator. Almost all machinists will have them. Set the barrel in the v-blocks, one at each end, put the dial indicator so that it reads on the top of the barrel and slowly rotate it. Try several locations. Any variation more than .010" is not good. You can also make vee notches in 2"x4"'s to set barrel in. Get an adjustable pointer and set it on top about in middle between lug and collar. Rotate barrel and eyeball changes. If it is obvious this way, find a machinist to do detail check. I had one that had been leaning in a corner and got hot enough to warp 1/16". Harbor Freight sells an indicator and base cheap if you need one.