Sunday, February 4, 2018

A Simple Cocking Aid for the Predom Lucznik Pistol

Several years ago, Nick made a cocking handle for his Predom air pistol.  I wanted to make something for mine, but other projects were taking precedence at the time and it was simply forgotten. Shooting my Predom a few nights ago brought the project back to memory and to the top of the project que.

Some inspection of the pistol revealed that the muzzle was deeply recessed--over two inches--and the barrel was counterbored to about 0.265" in diameter. 

I found a 1-3/8" diameter aluminum ball for a machine handle in the McMaster--Carr catalog.   























 The ball and a 2" long 5/16" shoulder bolt completed the parts list.




























The ball and bolt both have 1/4-20 threads. 





























Cut the head off the bolt...



























And turned down the 5/16" diameter to about 0.262" to fit into the end of the counterbore.

















































Did it in sections--keeping the overhand to a minimum--then polished it with a piece of maroon scotchbrite.





 

















Heat blued the shaft, then threaded it to the ball with some medium strength Loctite.


































Cheap, quick and no more hand pain.

More soon...

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3 comments:

  1. UnknownJanuary 20, 2020 at 5:09 PM

    Hi Derrick,
    I've just found this interesting and informative blog. Using a bolt inserting inside the barrel may affect the rifles (is it the wrod for grooves and ridges inside the barrel?) when cocking, i think. A considerable downward force will act on the lower side of the muzzle and a same amount force will act on the upper side of the barrel where the bolt end contacts the barrel. Why don't you use a kind of handle that grips outside the barrel?
    Regards,
    Tuan
    From Vietnam

    ReplyDelete
  2. derrick38January 21, 2020 at 1:45 PM

    Tuan, the rifling in the barrel does not go completely to the muzzle. The rifling ends approximately 60mm from the muzzle. The rod on the cocking aid is only 50mm long. The barrel was manufactured to accept a cocking aid similar to what I made.

    ReplyDelete
  3. UnknownJanuary 21, 2020 at 4:50 PM

    Thanks Derrick for your feedback. It's clear for me now. Your blog is extremely precious to me. With your detailed information and closeup photo, I've learned a lot about air rifle designs. I built for myself a .177 break barrel air rifle with max speed at muzzle of 470fps. I intend to build an underlever one with stronger spring hoping it can eliminate barrel droop that i face with the break barrel one.
    I do appreciate your works and your kind transfering such excellent information to the world.
    Regards,
    Tuan

    ReplyDelete