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Cas City Forum Hall & CAS-L  |  Special Interests - Groups & Societies  |  1860 Henry (Moderators: Flint, Major 2)  |  Topic: I should read old posts here more... 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: I should read old posts here more...  (Read 612 times)
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« on: December 11, 2017, 02:19:02 am »

I really didn't like the funky safety-equipped firing pin extension on my Win/Miroku '73, so I quickly replaced it with one of the replacements by Pioneer Gun Works, and the stock firing pin extension went into my parts box.  I recently acquired a Win/Miroku '66, and it broke the bank.  And it being so close to Christmas, I won't have any discretionary funds any time soon.  So while slicking up this rifle, I began to pay closer attention to exactly how this safety actually works (I'd let it remain a mystery before).  All it consists of is a stud that is raised on the top of the extention, and that stud passes through a short channel in the receiver until it abuts against the end of that channel, physically preventing the F.P.E. from moving forward enough to hit the firing pin.  A spring-loaded plunger sticking out of the back of the F.P.E. communicates with that stud, and if the plunger gets depressed--like when the hammer hits it---, it cams the stud down into the body of the F.P.E. allowing the F.P.E. to travel forward unimpeded, smacking the spring-loaded inertial firing pin, which sets off the primer. 

I don't know why I let that remain a mystery for so long.  A simple Google search tonight yielded a post here from Pettifogger explaining that very thing.  Lots of valuable information on this board.

Anyway, I've a question to go with this post.  When tuning these toggle links, I've found that hammer spring resistance is the biggest contributor to stiff levering.  And on Uberti rifles, I've typically ground down (or more accurately "filed") the mainspring to reduce that resistance.  I have to find a balance between an effortless levering and reliably setting off a primer, and this has always presented me with the possibility of having to order a new mainspring if I take it too far (fortunately, I've yet to ruin a Uberti mainspring).  So I was pleased to find that the Miroku rifles have a strain screw that allows one to adjust the mainspring tension.  My question is, is Miroku's F.P.E. safety a drop safety, or a slamfire safety? 

That plunger spring in the safety, along with the friction of the moving safety parts requires a stronger hammer blow than is ideal if one is working towards a light action.  On my '73, I just replaced the F.P.E. with one from Pioneer Gun Works and didn't give it a second thought.  But this time around, with money being tighter, I've considered just removing the safety parts from the stock F.P.E.  This won't remove much weight from the F.P.E., and it will almost certainly remain heavier than those hollow replacements from Pioneer Gun Works and therefore have more inertia.  Is this going to make the rifle more prone to slam fires, or was this just intended as a drop safety in case the rifle lands on its Muzzle?
American Plainsmen Society
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« Reply #1 on: December 11, 2017, 05:55:26 pm »

I think the article you are referring to just removes the parts from the firing pin extension. I never ground any of the springs on my Winchester. Just put thin spacers under the lever and lifter springs and back out the mainspring screw a turn or two. Total cost less than a quarter and can be returned to stock in a matter of minutes if you desire.

WARTHOG, Dirty Rat #600, BOLD #1056, CGCS,GCSAA, NMLRA, NRA, AF&AM, CBBRC.  If all that cowboy has ever seen is a stockdam, he ain't gonna believe ya when ya tell him about whales.
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« Reply #2 on: December 12, 2017, 12:43:10 pm »

First things first.  First a CAVEAT:  I'm on Safari about a bazillion miles from my shop and can't just trip down the stairs for reverence material.  First another CAVEAT;  I no longer have the parts to look at anyway.  Belonged to someone else.  SO:

Toggle Link Rifle 101:  The specific resistance felt in the lever - 25% is from the combined resistance of the Lever Side Springs.  Stock, they are too heavy (Uberti).  65% is the Main Spring (OEM is too heavy).  20% is parasitic drag from the action parts (Bolt dragging, Links dragging, Carrier Block dragging, Hammer Dragging.  Stage six and the shooter is tired.

First step is to reduce or replace the Lever Side Springs.  I like SlixSprings.  If not included in the Carrier Block Lever, ADD Positive Slam Down.  Then reduce or replace the Main Spring.  I find it interesting the Miroku 66 has a Main Spring Strain Screw.  I add that to Uberti 66s.  Then polish all the areas that interact with other areas (very time consuming).  Now reduce or replace the Rising Pin Return Spring.  Stock is too heavy.  On a Miroku, gut the Extension Rod.  All those little safety parts are redundant.

With Positive Slam Down, the lever powers the carrier block, not the side spring.  Done correctly, all the side spring does is hold the carrier block UP while the bolt strips a round.

In actual answer to your question OD, I have no clue.  Never even thought about it.  The Extension Rod Safety parts are superfluous.  A reduced weight Extension Rod is unnecessary.  Polish the OEM rod.  An aftermarket Carrier Block will not work in a Miroku.  Polish the OEM part. 

Have FUN with it.  I'm jealous.  I actually want one of those Miroku 66s.  Just cause  Cool
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Cas City Forum Hall & CAS-L  |  Special Interests - Groups & Societies  |  1860 Henry (Moderators: Flint, Major 2)  |  Topic: I should read old posts here more... « previous next »
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