Mono Blocks

[Jetwrench]

Hi guys, I have a question for you. I want to take a Handi Rifle and make a different caliber by using a 12 Ga bbl and use it as a mono block. The reason for that is ( I hope ) to have more than one barrell fit the mono block, and in that way have a larger range of cartridges to work with. I am not going for large cartridges here, things more like 300 whisper, 256 Win Mag. Thing is I know nothing about the conversion or if it is possible to do what I would like to do. So please feel free to give any advice. Just remeber I need the basics on this, as well as the bigger picture. Thanks for any help. Jetwrench

[pietro]

[The reason for that is ( I hope ) to have more than one barrell fit the mono block, and in that way have a larger range of cartridges to work with.]

I'm a little unsure of your intent, since that statement is at odds with monoblock construction.

Your statement seems to say that you would like to switch barrels in/out of a given monoblock - but barrels are generally "sweat soldered" (soft or silver soldered) semi-permanently into it's own individual monoblock.

That means you would need to build a separate monoblock for every barrel, and fit it to the receiver - after the barrel was fitted to the block, complete with extractor mechanism/machining, etc.

BTW - I know you posted "Handi Rifle", but be sure centerfire rifle barrels are never used on a cast shotgun (SB-1) frame.

.

[Cap'n Morgan]

It is possible alright, as long as you stick to the "weaker" calibers, and you know how to use a lathe. If you use a 12 gauge barrel you should chop it off just in front of the hinge. Use a lathe to bore the chamber straight (a shotshell chamber is slightly tapered) and cut internal threads in the front. I would go with 16 TPI over at least half an inch. The barrels should be turned wit as close a fit as possible, and with a shoulder to tighten against the base barrel. I guess you could make the barrels as drop-ins using a rim to keep them in place, but i wouldn't recommend it.


Each barrel must be fit individually to ensure the extractor aligns with the slot in the base barrel. Depending on the case, different calibers will need individual extractors (you can probably buy spare ones, and modify them) With a little ingenuity you can mount the barrels in the tool post, and cut the extractor groove with a 1/4" end mill clamped in the chuck.

The system should work okay with open sights or a scout type scope. A scope mounted on the original base barrel is a bit more iffy, unless you tighten the barrels real good.

[Jetwrench]

Peitro, the reciver is an SB2 with a 270 barrel so no worries there. Yes I would like to swap the barrels but did not know they were soildered in.

Cap'n Morgan, I had thought to use the 12ga rim and a barrel nut to secure the barrel to the block. but that will require a dismount of the sights with a barrel change.

I am learning guys, keep it coming,and thanks. Jetwrench

[SwedeNelson]

jetwrench

Send your reciver (SB2) in and have what
ever barrel you want fit to it.
http://www.hr1871.com/Support/accessoryProgram.asp

Its not a bad price and it gives you
what ever you want.

Have a rimfire reciver going in to get
one of every rimfire they offer.

Swede Nelson

[Jetwrench]

SwedeNelson,
That is the plan for 3 of their offerings. But they offer no 221 Fireball barrel, no 300 whisper, no 256 win mag and no barrel in 6.5mm at all. And to top it off they wont sell unchambered barrels, so I will have to get creative, make some chamber inserts (dont like inserts) or get some more barrels for my TC Contender. Jetwrench

[Bret4207]

Peitro, the reciver is an SB2 with a 270 barrel so no worries there. Yes I would like to swap the barrels but did not know they were soildered in.

Cap'n Morgan, I had thought to use the 12ga rim and a barrel nut to secure the barrel to the block. but that will require a dismount of the sights with a barrel change.

I am learning guys, keep it coming,and thanks. Jetwrench

I was going to suggest a nut, ala Savage, but you beat me to it. Should work, maybe not so pretty, but heck, it's a Handi rifle to start with.

[John Taylor]

If you have a mill you can make new barrel lugs and silver solder them on. Have done this before and it works great. May not work on high pressure rounds but the original 12 gauges were silver soldered before they started welding them. I put a 38-55 on a T/C the same way but left a ring on the barrel to match a groove on the block for extra strength. The barrel and block on an H&R are not mono blocks, they are 2 pieces soldered or welded together. A true mono block could be machined to fit, might be a little fun doing the extractor.

[Jetwrench]

Bret4207, Yea that handy has never been accused of being a work of art.

John Taylor, I dont have a mill. But, what you have posted makes me think. I could have a barrel lug made. turn a "barrel" stub with a robust "rim" grove in it for the barrel to seat on. Then go to a barrel nut, sweat on or what ever. I would want to weld the lug on the new stub for more strength, (would not weld on the barrel) I read in another post that a fellow bought an extractor from Brownells I think. Also thanks for getting me straight on the Mono Block name, that makes sense. Is there a name for the 2 peice lug-barrel part? Thanks again guys, and let me know what you think.Jetwrench