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Thread: Rimfire Rolling Block conversion

  1. #1
    Boolit Man
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    Rimfire Rolling Block conversion

    I am contemplating a project and wonder how difficult it would be to convert a rimfire rolling block to centerfire. My new lathe should be delivered soon and I've cleaned and adjusted my mill. I'm just looking for a simple project and may have located a rimfire in poor condition cheap. May plans are to chamber and barrel in 25-20 or a 32. It will be used with low pressure boolits.
    Advice and ideas are much appreciated.

    Shelly
    “You only make one mistake in this business – you’re either an expert or you’re dead.”
    Col. Thomas J. Kane

    "EXPERT= Ex is a has been, spurt is a drip under pressure" Unknown

  2. #2
    Boolit Master Jedman's Avatar
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    There's not many rimfire rolling block rifles that are strong enough to be converted to CF.
    You would need to mention what rifle you are working with, A Remington no. 4 or no. 6 or any of the Stevens or other brands that were made for 22 rf are to weak.
    Remington did chamber there no. 1, 1 1/2, & 2 rifles in all sorts of rimfire calibers and they all would work but the conversion can be done by several ways.
    If your going to convert the breech block you would first have to determine the spot the hammer strikes the firing pin and plan from there. You might be able to increase the diameter of the pin and turn the striker point offset facing upwards to work with a cartridge that is not much larger in diameter than what the rifle has now.
    If you have to make a much larger pin you will have trouble with the increased mass weight and the hammer might not have enough power to fire a CF primer.
    Another option that depends on how large your barrel shank diameter is would be to turn the shank eccentric and index the chamber where you get the pin centered with the primer and the bore running "uphill", I have a rifle barreled like that and it can work.

    If you do try to use a 25-20 or any other bottle necked cartridge I would "shorten " the cartridge and the chamber by .030 just so factory cartridges could not be chambered and shot in your rifle.
    To do that you need to remove that .030 off the bottom of your full length sizing die and after sizing your brass trim what's needed off the neck there is enough taper built in to all bottle necked cartridges so that to remove .030 wount hurt anything.
    If your working with a pre chambered barrel you can remove what's needed from the breech end and recut the rim cut on your lathe or if using a chamber reamer first make up some dummie cartridges with your shortened die and use them as your gauge.
    You can look on YouTube to see if there is any videos of a similar conversion and maybe you will pick up a workable idea but if you are starting with a light built rimfire rifle I would advise
    Don't Do It ! the steel used on early rifles was soft and with the increase in breech thrust your gun will shoot loose quickly as many couldn't handle the increased thrust of hi speed 22 rf shells.
    If you think you have a suitable rifle to start with post what your using and people will help but I think you wount get many to stick there neck out on your question without knowing more.

    Jedman
    Last edited by Jedman; 03-10-2018 at 10:37 AM.

  3. #3
    Boolit Master

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    Use only an action strong enough for a full load or you will be creating a danger for someone down the road. There is no great trick to the conversion we weld up the block and using the mill cut the new firing pin channel.

  4. #4
    Boolit Master pietro's Avatar
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    .

    FWIW

    I converted a petite solid-frame .32RF Remington #4 RB to CF one evening, which enabled me to shoot it with readily available .32 Short Colt ammo (Winchester makes a couple of runs each year).

    I did it via first dropping a Sharpie downbore against the face of the closed breechblock to mark the center.

    I removed the firing pin & ground it's forward face flat, then re-installed it in the breechblock so I could drill the new 1/16" FP hole through the breech face, dimpling the flat face of the FP in the process.

    I removed the FP again, and drilled the dimple about 1/4" deep for the new CF firing pin, made from the shank of the (sacrificial) 1/16" drillbit (cost me $3, new @ Sears) used for the FP hole in the breechblock.

    I soldered the drillbit shank into the FP face (epoxy will also work), installed the FP into the breechblock again to mark it for length/protrusion, ground it to length & rounded/polished the new FP tip.

    Done.

    The bore still looked like a sewerpipe, from shooting corrosive ammo when it was young (1902-ish) - but it shot the commercial .32 Short Colt ammo accurately enough to bag squirrels when I took it dancing.

    .
    Last edited by pietro; 03-11-2018 at 10:12 PM.
    Experience is a wonderful thing - It lets you recognize a mistake, when you make it again.

  5. #5
    Boolit Man
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    I was looking for a CF Rem RB but found a 32 RF. I just found Simpsons web site and will try to snag a centerfire there and pass on the RF. I was looking for a simple project to play with. Thanks for the input. I think I need to do more planning before jumping into it.

    Shelly
    “You only make one mistake in this business – you’re either an expert or you’re dead.”
    Col. Thomas J. Kane

    "EXPERT= Ex is a has been, spurt is a drip under pressure" Unknown

  6. #6
    Boolit Master


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    Tell me about Simpson’s web site?

  7. #7
    Boolit Man
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    https://www.simpsonltd.com/ I called and the nice lady said they post guns everyday and I have to be quick if I find one I want. They only take phone orders. There's some interesting stuff on there.

    Shelly
    “You only make one mistake in this business – you’re either an expert or you’re dead.”
    Col. Thomas J. Kane

    "EXPERT= Ex is a has been, spurt is a drip under pressure" Unknown

  8. #8
    Boolit Master Cheshire Dave's Avatar
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    WARNING do not go on Simpson's website. Addictive and dangerous to your bank account. Found a neat CZ combo and had to have it. Now I keep looking for other cool stuff. They have a bunch of 9.3x57's .

  9. #9
    Boolit Master waarp8nt's Avatar
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    Quote Originally Posted by Cheshire Dave View Post
    WARNING do not go on Simpson's website. Addictive and dangerous to your bank account.
    If you think the website is bad, try going to their store without your wife. Its like leaving your V10 truck running while putting gas in at the gas station.
    Boolits Feedback <> Gunbroker Feedback

    Just remember son, many times free advise is worth what you pay for it. ~ My Dad

    Bluegrass...the speed metal of country music!

  10. #10
    Boolit Master
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    Re: V10 Idling while Pumping in gas.
    Laughing, I remember Some Post WW2 hot rods built around Allison V12 !710 cu. in. Super charged Engines and the occasional Rolls Royce Merlin or Packard Merlin copy powered ones also. Super charged V12s of around 900 hp unsupercharged and 1800 hp supercharged.

    Chev. William

  11. #11
    Boolit Bub
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    Quote Originally Posted by Cheshire Dave View Post
    WARNING do not go on Simpson's website. Addictive and dangerous to your bank account. Found a neat CZ combo and had to have it. Now I keep looking for other cool stuff. They have a bunch of 9.3x57's .
    They do have a lot of neat stuff. Ive got a couple of rifles from them.

  12. #12
    Boolit Master
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    Simpson's is cool and every time I've dealt with them has been a pleasure. You do have to be quick. I am convinced there is someone sitting on their doorstep as they unload the truck. That or half the old/European gun cranks in the US are watching their site by the minute. We're about 4 hours from them and friends of mine who have been there have been impressed. I've either been smart enough or unfortunate enough to not have made the trip....
    "In general, the art of government is to take as much money as possible from one class of citizens and give it to another class of citizens" Voltaire'

    The common virtue of capitalism is the sharing of equal opportunity. The common vice of socialism is the equal sharing of misery

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BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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