Gunsmithing question

[Dagalee]

It's been said that 7.62x39 Handi FTF was from mil-sup ammo with harder primers and some primers were slightly seated deeper.
I've seen mentioned where some people have made longer firing pins.
How much longer ? .005 , .010 , .020 ?
Would this cause problems with reloads ?
Thanks

[geezer56]

I have seen this tried.  Too far can cause pierced primers on reloads.  The best method is just to start out with decent handloads and by pass the mil spec primers all  together.  Most folks just remove material fron the transfer bar where it contacts the frame, letting the firing pin protrude as far as physically possible.  Sometimes this helps.  I have a 7.62X39, it is easily the most accurate handi that I have ever had.  I had the barrel on 2 different frames, one was FTF on mil surp ammo, the other one shoots anything, both frames are totally stock.  Easiest thing is to just by pass the mil spec ammo, if it shoots acceptably, you are done.

[trotterlg]

Not a gunsmith but most military rifles have a lot more fireing pin protrusion, like .030 more.  They also directly connect the fireing pin to the hammer while the H&R has a hammer, transfer bar and seperate fireing pin.  The H&R somewhat relies on the inertia of the pin to set off the primer, the hammer has a stop built in so that it does not push the pin to it's limit in the action.  Put shims between the hammer and transfer bar to see how much more travel the pin can have, my guess is you will see quit a bit more.  Some people grind a little off the hammer stop which lets the hammer drive the pin a little further into the primer.  I would sit down and look at the physics of the handi action and figure out how the get a little more energy into the pin.  Larry

[quickdtoo]

I've gone to .063" on large rifle primers with no problems, as Larry said, removing material from the tip of the hammer will increase pin travel, but be careful that it doesn't allow the hammer to contact the firing pin directly without the trigger pulled, some hammers aren't relieved as much as others in the transfer bar contact area. 

Tim

[Dagalee]

Thanks everybody
Ill be careful with the files and stones

Dagalee

[nanuk-O-dah-Nort]

I've noticed on most of mine, when the Bar is pushed flat against the receiver, the pin comes out 0.060 or so amount, but if I use a plastic rod, and force it from the back, it can come out even more....

I'm really not seeing the advantage of relieving the hammer, save for a bit more OOMPH..  but how much??

[Spanky]

Go with a 30-30 barrel instead... that'll solve any ftf issues.
 
 
 
Spanky

[gcrank1]

Old rule:
Do not remove any metal unless you absolutely KNOW and UNDERSTAND what the problem is.

[nanuk-O-dah-Nort]

I've got a couple gunsmithing books that discuss the FP issues, regarding bushing to smaller diameter, and make a rebounding one without the transfer bar.

there was good discussion on what makes a good strike.

I'll have to dig those out, and go through them again.  I think the H&R would convert rather easily, and bushing to smaller diameter should be pretty straight forward as well.

[gcrank1]

The standing breech is really pretty thin there.

[quickdtoo]

The firing pin isn't parallel to the bore either, it's at an angle which further complicates bushing, Fred has good info on firing pin improvements on his website, link is in the FAQs.

Tim

[nanuk-O-dah-Nort]

most of the bushed pins in the one book were also on an angle....

the secret was to leave extra at the breech, and file it flat to the face...