Off-set bore RF for a CF

[trotterlg]

I finally got going on the off-set bore 5mm Remington Mag RF Handi barrel.  First crack at ti I tried turning the barrel blank offset, this was a pain and the chamber wall ended up very thing on the turned down side, so scrap that idea.  I bored a 12 gauge stub to .810 through, counter bored both ends for an offset bushing and nut and then made up an offset bushing and a threaded offset nut.  I turned the barrel to .550 where it goes through the stub, and end up with the bore offset .125 inches which puts the fireing pin on the rim but not outside it.  This is important with the 5mm RF as it needs the entire rim supported due to it's high pressure.  Here is the progress so far, the front bushing is pressed in, you can see the offset threaded nut for the rear, I will position it and pin it to the stub so it won't turn, the screw in the barrel.  Larry

[stimpylu32]

Larry

Just wondering what you had to do to insure that both bushings were true to each other so the barrel did not run out at an angle ?

  

stimpy

[trotterlg]

That is a great question, first try I failed, it pointed off the right about a degree, I unscrewed the barrel and have rotated the rear nut, I am thiking of putting a couple of little pin holes in it so I can tighten the barrel down and then rotate the nut slightly to align it perfectly.  This is turning into another of those projects that starts out sounding like a good idea and then kind of goes down hill from there.  We will see how I do with it, I won't try another like it.  Larry

[trotterlg]

It's all chambered up and I have fired it a few times.  There are some interesting problems with doing RF barrels on a Handi.  Main thing is that the ejector has to support the case, there is not a thick web at the base of a RF cartridge so without support the case will just blow out at the ejector cutout.  I knew this going in on the project, I think when H&R does a RF barrel that they chamber it with the ejector installed so it is cut to support the cartridge.  Most likely this is the reason they will not sell a RF ejector direct to you, you must send the barrel in to be fitted.  I used a Hornet ejector, milled it a little narrower and then milled down the top until it just fit the chamber and supported the cartridge.  The 5mm Remington Mag RF is quite a lot higher pressure than any other RF cartridge so this is really critical.  Even with this tight fit you can see where the case is pushed out some at the ejector cutout, mine measures about .002 inches more where the ejector is.  I also machined off a little from the bottom of the ejector to allow it to drop down about .005 inches when the ejector is fully open to allow the ejector to work right, when I did not have this done the cartridge would hang up on the ejector after fireing.  I will post some more pictures when I get it finished up, it will be interesting how it shoots.  Larry

[PHATINJUN]

Larry what are you using for a bbl on this one? Kurt

[trotterlg]

It was one of the 20 cal barrel blanks for sale on AuctionArms.  Larry