There was some discussion of this here or in the lever-action forum a while back but I can't find it now.

Anyway, I don't think this possibility was discussed there:

Is there any possibility the Miroku hammer (cut away for the lawyer's safety) could be replaced with a hammer made for an old Winchester '86?

I'm wondering if the lighter, rebounding Miroku hammer may be responsible for the misfires, which are apparently not uncommon with the Japanese rifles.

Thanks in anticipation.

No; the new one uses a coil mainspring; originals use a flat one.
Try a stronger coil spring. Wolff probably/might make one that would fit.

Thanks dpcd, since there is space on the coil-spring 'spindle', do you think a washer that tightened it up might help?

Yes as long as the spring doesn't compress and stop the hammer from fully retracting and cocking. Won't hurt to try it.

Thanks, dpcd, that extra space needed to engage the sear, might just be the rub.

It may be few days before I try it.

Send it to me and I will fix it.
I know......

Thanks but yeah, sending it could be one thing, getting it back quite another.

One of our members PM'd me suggesting the answer might be to polish some part of the hammer-rebound spring. He said the Cast-bullet forum had stuff about the matter but I can't find the thread.

Has anyone here heard of this method?

Here is what I would do if my 86 misfired; deactivate the hammer rebound feature by cutting off the lower leg of the hammer strut. It looks like a snake tongue.
Then all the mainspring force will go forward and none backward.
There is no trigger rebound spring; just the main spring, and polishing that won't help.
The rebounding hammer design is from a lawyer; not an engineer. Since the firing pin is inertia activated anyway and no direct hammer to primer contact, the rebound is just for looks.
COA 2: lathe turn a longer firing pin.

Thanks for those ideas, dpcd. I take it that the bit pointed to by the 33 is the 'snake's tongue' to cut off.

Since you think it can be completely eliminated, I might start by polishing or shortening that bit and see what happens, and cut it off if needed.

I'll ask if my buddy the retired fitter/turner would consider making me a longer firing pin.

Those measures plus a possible washer behind the mainspring ought to get us somewhere.

quote:

Originally posted by sambarman338:
Thanks for those ideas, dpcd. I take it that the bit pointed to by the 33 is the 'snake's tongue' to cut off.

Since you think it can be completely eliminated, I might start by polishing or shortening that bit and see what happens, and cut it off if needed.

I'll ask if my buddy the retired fitter/turner would consider making me a longer firing pin.

Don't do both these mods. One or the other. If you do both, never carry it with a round in the chamber, and never sell it.
I would start with DPCD's suggestion.

Thanks Peter, I might start with the modifying the snake's tongue and a washer as they are probably easier to get than the firing pin and don't require the lathe favor.

I've managed to add about 2mm of washers in front of the mainspring and polished the tip of the 'snake's tongue'. It does seem to fire the deeply primed cases I had on hand but the imprints still look minimal. (There is now a little slop at the end of the rebound, so I pull it back into the locked position if it doesn't happen automatically.)

Watching the disassembly YouTubes I see that the firing pin is tethered by a pin linking the breech block with the finger lever, though the video did not show the firing pin removed.

Is it possible the firing pin's travel is limited by a shoulder at the rear of the lever pin and that removal of metal there might allow it to penetrate farther?

quote:

Is it possible the firing pin's travel is limited by a shoulder at the rear of the lever pin and that removal of metal there might allow it to penetrate farther?

I guess anything's possible but it's easy to check.
Dismantle the rifle, then re-assemble everything that attaches to the bolt outside the receiver, and with the lever in the closed position, push the firing pin forward and check pin protrusion. It needs to be at least 1.5mm.

Be careful to get the lever in the closed position as that probably has a cam surface to pull the firing pin back when the action is opened.

If you don't have enough protrusion, start removing parts one at a time, re-checking protrusion each time until you find what affects it.

One more thought: contrary to currently-popular belief, you don't have to smash a primer to smithereens.
I have some rifles with relatively light primer strikes (one is light enough that some brands don't fire reliably), but the velocity spreads and deviations on carefully-loaded ammo are as good as on any other rifles I load for and pretty much as good as the people I trust are bragging about.

Thanks again, Peter.
Pushing the two-element firing bin forward when the action is open shows at least 1.5mm, possibly 2mm of protrusion. There might be more but it is surprisingly hard to do, holding the lever open etc. However, you have brought up a good point - that when the action is closed the cross pin may inhibit the travel somehow not seen when the action is open.

I might wait a bit for other responses because actually removing the firing pin was not covered in the YouTube video I watched, and I'd rather not do it if someone knows it's a waste of effort.

Correction. I said there was now a little slop in the hammer when uncocked and that I pulled it back to the locking notch. In fact the slop is behind the notch and it locks every time, as it should.

I think I might load up some new ammo and make sure the primer is just flush with the back of the case, rather than below it as I usually do.

To check actual firing pin indentation on a primer just use primed empty cases which can be fired inside a shed or garage with an old towel wrapped around the muzzle to cut out most noise if in a residential area.
Light strike can be indicated in a live round fired due to headspace allowing the primer to back out on firing then pressure forcing the case head back against the bolt face and reseating the primer.

Taking pressure out of the equation allows true indentation to be observed.

Seating primers flush will not usually help with ignition as the primer is driven forward in the pocket by the pin strike absorbing some of the pin energy.
You can see the two or three anvil legs protruding slightly below the primer cup and these legs need to be seated hard onto the floor of the pocket which helps sensitize the primers.

Thanks Eagle, I've done the live-primer/empty-case exercise and though they went off, the indent was tiny.

As I've said before, I'm tempted to leave some of the crap in the bottom of the primer pocket to stop the primer being driven forward. Maybe I'll make two batches (cleaned and not-so-much) and see what happens.

If these rifles were cars, someone would have shamed Winchester into doing a recall by now. Maybe if the odd bear hunter came to grief because of rifle malfunctioning, someone would listen.

Maybe, but my Win/Miroku works fine. If I had your rifle, I could make it work.

I'm sure you could, Tom, and with luck so will I.

It is not all that bad but if I'm to take it hunting I'd like to trust it as much as I have my Sako and Mauser rifles.

My mentioning a recall is in reference to the commonality of complaints about these rifles found in googling the subject.