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Miroku 92 needs a lighter hammer spring for heavy trigger pull?

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8.5K views 17 replies 4 participants last post by  cvarcher  
#1 ·
I have a beautiful Win/Miroku 1892 rifle which I sent to Turnbull for a conversion to half cock safety. They removed the tang and welded and reblued the action. It works feeding and cycling the rounds but the trigger pull is off the scale past 6lbs. I had given them a wolf Ruger Blackhawk lighter coil spring to put in to supposedly lighten the trigger pull. It breaks clean enough but the pull is god awful hard. I'm also wondering why they didn't choose to go with the original flat spring since its now a half cock older design. I tried emailing them but I get no response. Has anyone else solved this problem with the Miroku 92 trigger pull? I need good advice here as I already spent way too much . Should and how would I convert it to a flat spring if that's whats needed as I don't really know. Or what hammer spring should I use to lighten up on the trigger pull? Or does the sear and hammer just need some stoning action?
 
#2 ·
IF by half-cock conversion you mean the hammer was replaced, it just means it needs fitting just as any hammer/sear interface does.
The reason for coil springs is because they're MUCH cheaper and easier to duplicate to very tight tolerances.
 
#3 ·
I dont think it was replaced but more recut to add the notch.

But if they did that you would think they would mate the trigger sear and hammer surface nice and smooth-right? Coil springs are more durable than flat springs . But flat spring may make a lighter smoother pulling hammer. Either way though shouldnt the spring be lightened up more or replaced. With all the Japanese reproduction 92s out there I would think there must be someone who successfully lightened the trigger pull somehow. Mine does not have that rebounding hammer system anymore either.
 
#4 ·
"Trigger pull" on a rotating hammer depends on the friction between parts and the strength of the hammer spring, but that strength is determined by how far from the pivot point the spring applies pressure to the hammer. It's all in the geometry, friction and spring forces. Leaf springs are much more proportional than coil springs and give a better (or at least different) 'feel' in cocking.
I don't know what Turnbull's trigger pull tolerances are but 4 to 6# on a lever action is 'normal'.
Jim Brockman has a great reputation for trigger work on all levers. I'm sure there are others.
 
#7 · (Edited)
Oh Ive shot more than 100 rounds thru it already. My 45 lc loads are stout but very accurate . I think I could shoot it even better though if the pull wasn't so hard. Thankyou for the info link to Mr. Brockman.By the way, I have a Marlin 1894 and 336 and 39A and changing out the hammer springs plus a little polishing of the surface and lubed my pull weights are 2.5 to 3.5lbs. Id like them to be a touch lighter but these are adequate .I recently bought a Win 52B 22 bolt action rifle and that micro motion trigger is set to 24ounce.Oh man has that spoiled me. Different animal though.
 
#9 ·
Yes, I do realize that but the balance needs to pivot more in the lighter trigger region. Unless there some geometry contortion going on that Turnbull left in the conversion. Thats why I think I need a good gunsmith to take a look at whats going on . It certainly must go bang when the trigger is pressed too.
 
#10 ·
I reduced the trigger pull in my Marlin 1895 from a creepy 5 lbs. to a clean 2 lbs. (with no flop) with a Bullseye trigger kit. No change in hammer spring.

My Chiappa 1892 clone has a very good 4 lb. pull, but it has the original style spring, not coil. Even so, I agree with JBelk that your heavy pull is friction caused. Reducing spring tension is likely to just result in light hammer strikes, without changing the pull quality much.
 
#11 ·
just mailed off the 1892 Miroku to Mr J Brockman

Sure hope he does good on this. The trigger pull weight is at 6lbs which is just too heavy for me. Also the lifter or carrier that raises the bullet when it comes out of the mag tube sometimes gets stuck and doesn't lift the cartridge. You have to close and open the lever a few times and then it snaps upward. I think its dragging along the right side of the wall inside the breech.Maybe just needs some polishing up .
 
#12 ·
Mr. J Belk--thankyou for sggesting Jim Brockman

I just got my Miroku 1892 rifle back from Mr. Brockman (gunsmith out of Idaho). This was the rifle Turnbull converted to half cock safety but left the trigger pull horrible. They never even acknowleged my emails. The pull weight was off the scale past 6lbs and now its a sweet 3 1/4 lb pull breaking clean with no creep or overtravel. Cant wait to test it out at the range with my heavy loads.


Thanks --Corrado Vasquez
 
#13 ·
I just got my Miroku 1892 rifle back from Mr. Brockman (gunsmith out of Idaho). This was the rifle Turnbull converted to half cock safety but left the trigger pull horrible. They never even acknowleged my emails. The pull weight was off the scale past 6lbs and now its a sweet 3 1/4 lb pull breaking clean with no creep or overtravel. Cant wait to test it out at the range with my heavy loads.


Thanks --Corrado Vasquez
Sweet! What happened with the lifter?
 
#14 ·
lifter, well I dont know what was wrong

but it seems to be freed up working ok now. Every now and then if you moved the lever thru the cycle very slowly it would stick or stay down not lifting the cartridge. So I mentioned that to Mr. Brockman. Maybe he needed to polish or smooth it. I don't know. When we get it to the range I will better test it all out an post my findings.
 
#17 ·
It's not a matter of 'smoothing' but of cutting the surface to the correct dimensions first. Marlin, Winchester and the Mirokus operate with almost identical mechanics. The lever has a lug that engages on the lifter/carrier that pivots the carrier and cams the new cartridge into position. That lifter 'dog' is a spring loaded ratchet so it only operates in one direction..]just as the bolt starts going forward. Where the dog contacts the lifter/carrier is a critical junction that used to be hand fitted before heat treat. (You'll see file marks there on pre-64 Model 94s and most Marlins.) Most guns are now assembled as machined or cast with non attempt to make it really right. If it works, it passes. It's called "Timing the carrier" and Brockman certainly knows how to do it!
 
#18 ·
WOW, that was a very informed explaination indeed. NExt time I do a cleaning inside I should take note on all these movements and timing. And I'm glad you directed me to Mr. Brockman. --CV
I reload and I'm using 300gr Hornady XTP slugs over Lil Gun .Its an accurate stout load of about 1640fps.