Issue with Miroku Bess

[Sylvanrush]

Hello,

I have a Miroku Bess with a strange issue - the hammer won’t go to full-cock when the lock is installed into the stock; however, if I remove the lock, it works fine - the sear clicks nicely into the tumbler teeth and engages half-cock and full-cock. The teeth on the tumbler aren’t worn down, it seems like something about how the lock fits into mortised cavity that’s impeding the sear from cleanly engaging the full-cock notch on the tumbler. Has anyone else run into this issue? The stock appears to be Miroku - the lock is definitely Miroku.

thanks!

-Drew

 

[necchi]

The symptoms you describe are typical of the trigger set too high in it's mortise. The trigger bar is riding against the sear arm.
It's common with older guns that may have compressed wood from over tightening screws.
There's a few ways to repair, spacers or rebedding the trigger, or removing some of the top of the trigger bar,,
Just throwing out ideas,, others will share also

 

[Phil Coffins]

Either the trigger bar or the wood is the issue.

 

[SDSmlf]

95% chance the answer is in the two previous posts. You just have to figure it out. Can you feel the sear bar making contact with trigger as you come to full cock?

 

[EC121]

Hold the sear bar in a candle flame to black it. Then install it and work it a few times. Chisel away the black in the inlet. The bar is either hitting the bottom of the hole or dragging in the hole.

 

[dave_person]

Hi Drew,
This should be easy to figure out. When the lock is at rest, half cock, or full cock, does the trigger rattle against the sear or is it under pressure from the sear bar. If it rattles it is not the trigger bar that is the problem. Then, you need to see if there is wood within the lock mortise that is preventing the sear from fully engaging the tumbler notches. It could either be wood on the bottom of the big hole for the sear bar, wood underneath the forward toe or tooth of the sear, or possibly the bottom of the sear hole is too shallow and end of the sear bar rubs against the bottom of the hole. Also check to make sure the bar of the sear does not drop below the bottom edge of the lock plate at half or full cock. If it does, you have a real problem.

dave

 

[Sylvanrush]

Thank you everyone for your thoughts - one thing I neglected to mention was when I drop the lock into the mortise, I left the trigger out - so it's not in the equation (not yet anyway! - I pull the hammer back into half-cock and it clicks in nicely, when I go to pull it into full-cock (again, no trigger in place) the sear seems to get hung up on something preventing it from clicking into the full-cock notch on the tumbler. I will try the candle blackening trick to see where the sear might be making contact inside the mortise

Dave, the sear bar does dip slightly below the bottom edge of the lock plate - here's a quick video:

 

[SDSmlf]

You should be able to see a mark or slight indentation inside mortise where that sear bar is contacting. If not and the candle black doesn’t help (the wood may be dark already), lipstick or even chalk on the bar will reveal where it is hitting the stock.

 

[Artificer]

Hello,

I have a Miroku Bess with a strange issue - the hammer won’t go to full-cock when the lock is installed into the stock; however, if I remove the lock, it works fine - the sear clicks nicely into the tumbler teeth and engages half-cock and full-cock. The teeth on the tumbler aren’t worn down, it seems like something about how the lock fits into mortised cavity that’s impeding the sear from cleanly engaging the full-cock notch on the tumbler. Has anyone else run into this issue? The stock appears to be Miroku - the lock is definitely Miroku.

thanks!

-Drew

Besides the Tail of the Sear hitting the wood inside the lock mortise, there is another thing UNIQUE to a Miroku Bess that can be causing part of your problem.

Look at the inside of the trigger bow of the trigger guard under the trigger and slightly back from there. If you have a ding or even a TINY shiny spot there on the inside of the trigger bow, you have to shorten the bottom of the trigger so it no longer hits the trigger bow.

The only reason I know to look for this is one of the other members of my old re-enacting unit, the Major's Coy, 42nd RHR, had this problem for some time with his Miroku Bess. A couple gunsmiths had looked at it and found nothing, so he had completely disassembled it, found nothing he could see wrong, and left it in pieces for a number of years because he couldn't fix it. After I joined, he said he would donate it as a loner piece to the Coy, if I could get it to work correctly as he had since purchased another Bess.

I had to supply a couple parts he had lost while it was in pieces and fixed the sear tail hitting the wood, but it did not completely stop the problem. Have to admit it drove me nuts for almost two hours before I found the very tiny shiny spot on the trigger bow. After shortening the bottom of the trigger, everything worked perfectly.

Gus

 

[dave_person]

Hi,
The sear likely is hitting the mortise at the lower margin of the deep hole for the sear bar. Just make sure the hole is also deep enough so the end of the sear bar is not rubbing on the bottom of the hole. I am very familiar with Miroku locks and have worked over several. Do you have a grinder or Dremel tool with grinding stones? If you do, after determining where the sear is catching on the mortise and clearing away that wood, I recommend that you grind a little off the lower back edge of the sear bar so it does not drop below the edge of the lock plate at full cock. That lock has design issues but if you clear the lock mortise where the sear touches it and grind a little off the sear bar as I mentioned, I think it should be fine. Let me give you a little tutorial on these locks. A Miroku Bess lock should always be treated as if it was a 3/4 finished kit. The components are of very high quality steel and the castings are superb. The fitting and finish sucks. Ideally on any lock, the sear bar remains in the same position relative to the edge of the lock plate when at rest, half cock, and full cock. That allows the simple trigger to be installed so it snugs up against the sear and remains under pressure from the sear in all cock positions, hence, no trigger rattle. In your case, the lock geometry is such that the sear bar drops lower each step from rest, half cock, and full cock, so it is lowest at full cock. That is poor geometry. Assuming your trigger rattles on the sear at all lock positions, in my shop, I would weld steel on top of the trigger bar. Then, I would clean up the offending wood in the mortise and grind off the back edge of the sear bar so it does not drop below the lock plate at full cock. I would grind enough off such that humidity swelling the mortise would not have any effect. Then I would fit the trigger with extra steel welded on top of the sear bar so it is snug to the sear bar at full cock and there is no rattle. Because your sear changes position at each lock step, the trigger will rattle at rest and half cock but not full. In your case, I think you can resolve the half and full cock problem doing what I suggested but you may still have trigger rattle at all lock steps and that is OK. Besses were not meant to be fine target shooting guns.

dave