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Installing a Rimfire barrel on my MK3

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D

DBlue

Member
Dec 14, 2022
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USA
When I was building rimfire benchrest rifles I had this killer shooting Benchmark barrel on an action of mine, I saved it in case I ever wanted to build myself another rifle. I thought of a way that I could turn it down without hurting the internal bore and I'm going to fit it on my MK3. I test fitted it today and it fits perfect, I just need to fit a .22 cal. transfer port and get a .22 cal. probe as my rifle is .25 cal. right now. With the reduction in weight from turning it down and getting it locked into the power block and the tensioner clamp, I think it should work very well......I will find out very soon......:)

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Exodus said:
Are you planning to thread the breech to accept the barrel inlet and transfer port? Or going machine a transfer port, o ring and lead into that barrel. The previous is considerably easier I would think. Keep us up to date. I’m very curious how well this works. I’ve got a Beyer barrel I’m thinking about doing this with.
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I've got both the transfer port and the other stainless barrel housing piece ordered, after I get them and measure the dimensions of them I can better determine the best way to do it...Looking at the one on this .25 cal. barrel I'm thinking I can just machine the end of the barrel down more and thread the outside of the barrel to fit the brass transfer port and machine the rest of the length that fits in the power block to the same dimensions as the factory stainless housing insert....I really need to get the parts first to see what I have to do. I have thought about just like you said to, just machine the end of the barrel and mill in the transfer port and machine for the o-rings directly on the barrel....I can do it, but I'm thinking I would rather have the brass transfer port on the end of the barrel.....???
 
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One things for certain, your gun isn’t going to move when you squeeze the trigger with that hunk of metal on it. I built a 605mm TJ for one of my Impacts and that gun now weighs a ton. And it’s just a standard profile barrel. I just machine my barrels to accept a brass TP. But I leave a little extra near the bore on the machined area before the M12x1 threads. That way I have material to play with as I mess with my seating depth for different slugs.
 
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DBlue said:
I've got both the transfer port and the other stainless barrel housing piece ordered, after I get them and measure the dimensions of them I can better determine the best way to do it...Looking at the one on this .25 cal. barrel I'm thinking I can just machine the end of the barrel down more and thread the outside of the barrel to fit the brass transfer port and machine the rest of the length that fits in the power block to the same dimensions as the factory stainless housing insert....I really need to get the parts first to see what I have to do. I have thought about just like you said to, just machine the end of the barrel and mill in the transfer port and machine for the o-rings directly on the barrel....I can do it, but I'm thinking I would rather have the brass transfer port on the end of the barrel.....???
Click to expand...
I’m planning to machine for threads and using a brass transfer port. I can easily change transfer port profiles that way.

Vetmx said:
One things for certain, your gun isn’t going to move when you squeeze the trigger with that hunk of metal on it. I built a 605mm TJ for one of my Impacts and that gun now weighs a ton. And it’s just a standard profile barrel. I just machine my barrels to accept a brass TP. But I leave a little extra near the bore on the machined area before the M12x1 threads. That way I have material to play with as I mess with my seating depth for different slugs.
Click to expand...

The beauty of a Beyer barrel is its weight. It’s almost as light as the FX barrel system. But could see what you mean using SS. Need a dolly to move it around haha.
 
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Lewis said:
Watching with interest.
I love this idea and hope it works out well.
Have you thought about what projectiles you would use? Assuming it was intended for rimfire .22 at 1000 fps +/- may be near the limits of the M3.
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This barrel would be used for slugs only....I don't think I will have any problems getting them fast enough, I've shot some .25 cal. 41 grn slugs well over 1000 fps. with it. Most match grade .22 rimfire ammo is around 1040 - 1070.
 
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Roachcreek said:
That is a stellar project.

I would think you will get Eley 22 or match performance. I am doing the same power level, 105 FPE, with my Kral Bighorn with a 28 inch TJ 1-14 twist, however it is a .250 bore so my bc is slightly lower.

Good luck,

Roachcreek
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Thanks.......this is a 5 groove barrel with a 1-16 twist....It was a killer shooting barrel with the right lot# of Eley ammo...I had it on a Stiller 2500X action and it would shoot 250's with high X counts all day long shooting IR 50/50 matches. I know shooting it on an air rifle is no guarantee that it's going to do well but it's a good start anyway...lol
 
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DBlue said:
When I was building rimfire benchrest rifles I had this killer shooting Benchmark barrel on an action of mine, I saved it in case I ever wanted to build myself another rifle. I thought of a way that I could turn it down without hurting the internal bore and I'm going to fit it on my MK3. I test fitted it today and it fits perfect, I just need to fit a .22 cal. transfer port and get a .22 cal. probe as my rifle is .25 cal. right now. With the reduction in weight from turning it down and getting it locked into the power block and the tensioner clamp, I think it should work very well......I will find out very soon......:)

View attachment 358338
Click to expand...
What is the length of the portion that you turned to fit the receiver? I've been making barrels for these for a while now and havent had to reduce the diameter to fit the receiver up to this point.
 
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Benchmark barrels are one of the very best barrels made period!!!!! There is no competition this is a far superior barrel to any FX or TJ barrel no offense.... Benchmark barrels has many world records with there 22 or barrels.... In the past for powder burners I probably bought 10 Benchmark barrels.... All shot great cleaned up perfectly.... Interior finishes smooth shiny beautiful machining Marvel.. Best of idea for a more accurate FX!!!!!!!😀😃
 
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