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Thread: Question regarding machining of an Air Pistol Barrel

  1. #1
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    Question regarding machining of an Air Pistol Barrel

    Maybe not in the right section, but I'll carry on anyway. I fancied converting my Feinwerkbau P44 to full length with Carbine Cylinder but couldn't source a second hand barrel and a new one was £234 (which made the conversion non viable). How easy is it to machine ports into a Barrel (at the Breech end for air inlet and along the Barrel length for "braking Muzzle Flip") ? I've got a Milling Machine and Lathe and various tooling for both, but am wary of leaving Burrs inside the Bore and seek advice as to "drilling" a hole with a perfect "break through" to the bore. I've thought about tight fitting Brass or Lead Slugs, but is there any other way to do it that I should consider.

    Thanks in advance for all helpful suggestions.

    Vic Thompson.

  2. #2
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    Mar 2004
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    Hi Vic

    When I drill a transfer port hole, I always use a new quality HSS drill bit and run it at high speed.

    HTH

    Atb

    Ben

    PS Do you still have a VX111 silver Leupold you would like to sell to me, a long shot, but if you don't ask.
    Last edited by master_shriller; 18-06-2018 at 11:36 AM.
    master(dot)shriller(at)gmail.com

  3. #3
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    For precise perfect holes I use a smaller drill bit then go through with a reamer of the exact size needed.
    Remember, it is the strongest character that God gives the most challenges.

  4. #4
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    You canít avoid burrs in the bore.

    Look at getting it spark eroded.
    A man can always use more alcohol, tobacco and firearms.

  5. #5
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    What I do to get a clean hole in tube is to drill a millimetre under size and open the hole with a slot mill, you need a milling machine for this. This will still leave a burr but very small. Also try pushing a tight fitting piece of dowel down the barrel to the point where the hole will be, that way the edge of the hole will be better supported so resisting the cutting forces.

  6. #6
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    There are very few things I won't do myself on a lathe or mill but porting a barrel, especially as precision as a match target pistol is one of em,

    Any machining method is likely to leave a burr that will effect pellet stability, also you need to ensure the holes are in the rifle grooves and not the lands, This would taken some very careful maths (something i'm sure your capable of) and also some VERY precise machining, the space in the grooves is very tight to the size of holes needed to make the porting effective, EDM would I think be the best method if you were to go ahead.

    Machining an alternative and already ported barrel from another supplier to fit would be an easier option. (lp10, lp50 etc)
    Morini 162ei, Steyr LP5,
    Vintage Collection - Walther LP53, Original Model 5, Haenel Mod28, HW77, BSA Club Standard, BSF S20 Match, plus lots more

  7. #7
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    thanks for he replies to date everyone. Looks like a new Barrel could be on the cards. A machined up LP10 Barrel would do the job (maybe) as it's ported for the gas transfer, but buying one of those wouldn't be cheap anyway. I've got an LP2 Barrel that I could use for starters but it's too short and whilst I could machine a sleeve for the end, I really want rifled barrel all of the way so that I can maintain the MV otherwise velocity or shot count would be compromised. Regarding the Transfer Port burrs caused by Machining through the Transfer port could possibly be eliminated by a Bore Skim as the first part of the P44 Barrel appears to be smooth and above nominal calibre size.

    Vic Thompson.

  8. #8
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    Quote Originally Posted by Vic Thompson View Post
    thanks for he replies to date everyone. Looks like a new Barrel could be on the cards. A machined up LP10 Barrel would do the job (maybe) as it's ported for the gas transfer, but buying one of those wouldn't be cheap anyway. I've got an LP2 Barrel that I could use for starters but it's too short and whilst I could machine a sleeve for the end, I really want rifled barrel all of the way so that I can maintain the MV otherwise velocity or shot count would be compromised. Regarding the Transfer Port burrs caused by Machining through the Transfer port could possibly be eliminated by a Bore Skim as the first part of the P44 Barrel appears to be smooth and above nominal calibre size.

    Vic Thompson.
    I know of a ported LP50 full length barrel, It was offered to me for my LP5 but I prefered the original LP5 barrel, It's mint having only been fitted for a short while before being swapped for a compact barrel and shroud, Can find out a price Thursday for you Vic, It's definately still available as is still in my Gun cabinet although it won't be me selling it. You'd be more than welcome to collect or can meet at Kempton,
    Morini 162ei, Steyr LP5,
    Vintage Collection - Walther LP53, Original Model 5, Haenel Mod28, HW77, BSA Club Standard, BSF S20 Match, plus lots more

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