The Hunter's Life

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Brithunter 10-30-2010 09:02 AM

the .280 AI project
Ok so here is the barrel set up in the Colchester lathe:-
I clocked up the chamber using a DTI (Dial test indicator "Clock") then trued up the tenon and turned the shoulder back by 0.050"
The counter bore for the bolt head had to be deepened to 0.274" to match that of the Monarch's take off barrel. I also skimmed off the face to true it up. The barrel wae turned around and the lands clocked up then a spigot turned and threaded 1/2"UNF:-
To accept either a Sound Mod or Muzzle brake should I wish to use one then the barrel was polished to remove a lot of the finish profile turning marks but it still requires finish polishing:-
As you can see more polishing is required or those lines will show up in the blacking :Banghead:

The stock off the recently acquired Majestic is being used as the barrel channel had been butchered and this CF2 barrel is of slightly heavier profile. The chamber area is much heavier than the Monarch barrel was. I had to do quite a bit of inletting to get the action to sit down in the stock and the barrel channel at the action end needed quite a bit of wood removal. I have to do a bit more yet and make sure the action is sitting level in the stock:-
As it appears to be correct this side but:-
Slightly high this side and not quite down in the channel as yet:-

Oh yes I have roughly polished off the old blacking from the action as we might as well do the whole thing if the barrel is to be blacked it would probably show up the old blackign on the action. We now await the arrival of the expensive .280 AI reamer and head space gauges

Alboy 10-30-2010 12:07 PM

Re: the .280 AI project
You make sound so simple.

Brithunter 10-30-2010 01:56 PM

Re: the .280 AI project

Originally Posted by Alboy (Post 108731)
You make sound so simple.

Alboy apart form the lathes it's all done with hand tools. I really do need to get some stock inletting chisels. I only have three bevel edge straight wood chisels and I have to carefully use them with the stock on my lap hence the barrel channel is rather rough. Gives a good key for the glass filler though. I shall be using glass reinforced body filler to bed this rifle. Not the norm I'll grant you but as the stock is so thin the glass fibre strands should help stiffen and support it.

The machining is actually quite straight forwards.... remember I have been a machinst for quite afew years. :p. Precision rifle smiths would probably cringe at the way I have done it. I cannot get to the muzzle end with the barrel in the 4-jaw as the headstock of the Colchester is too long to do so. My aim precision wise when the rifle is finished is for it to group in under MOA or close to MOA which I feel should not be unreasonable given it's a normal production barrel and action. no blueprinting has been done to it.

I have made enquiries about a new BSA replacement stock should this proove not to be viable due tot eh sanding done by some previous owner and a brand new BSA stock from John Knibbs is 117.50 with tax. I have asked if he can pull a few out so i can go and select the one I like the best.

Hopefully the reamer and gauges will arrive about the same time as the shop get teh .280 Rem ammo in for me. In 25 years they ahve never been asked for any .280 Rem ammo :eek:. it's not what one could call a common cartridge here :p.

22hornet 10-30-2010 10:26 PM

Re: the .280 AI project
Looking good BH. Keep us posted as the work continues.

gitano 10-31-2010 07:20 PM

Re: the .280 AI project
Thanks for the pictures, BH! Good job! Looks great!.

Maybe you can show me how to make reamers. :stars:


branxhunter 11-01-2010 04:41 PM

Re: the .280 AI project
It is always rewarding to watch someone who is:
  • good at what they do, and
  • passionate about their work
even if by photos posted on-line. Great photos they are too. Watching with interest and admiration,


Brithunter 11-01-2010 07:22 PM

Re: the .280 AI project
Hmmm I will see if I can find the place as there was a site I visited which someone had done a presentation on how he made a chamber reamer out of drill rod for a specific project.

The hardening is the trickiest bit as I see it. Milling the flutes is pretty straight forwards BUT ................................ you would need a dividing head or indexable horizontal chuck to get the flutes correctly spaced although it can be done using a pointer type rest or by clocking the flats of the drive square level.

I suppose having worked on commercial places so long I tend to think of using the "right stuff" for the jobs rather than how it can be done. We have a dividing head and the tail stock centre to support such jobs plus I picked up a T-bo indexing head and PCD drilling fixture from one place I worked. It can be set to do up to 32 divisions and is what I woudl use for milling octogon barrels :kiss:.

The next biggest problem with making a chamber reamer is getting the sizes and tapers correct and with something liek an optical comparitor it's difficult to check them. The one I used to sue magnified the part 50X and had a graticle on the screen so you could take measurements plus it had to DTI's for measuring the X & Y axis.

As these are old hat now and lots of firms no longer use them I was hoping to pick one up but nothing has happened on that score due me not goign lookign for one :o. Right now we have nowhere to set one up as do take a bit of room like the big ole Colour CRT TV's.

gitano 11-01-2010 07:33 PM

Re: the .280 AI project
I have a dividing head but I haven't settled on a tailstock for my mill.

I have a programmable oven that goes up to 2200 degrees F. It's pretty skookum, but its kinda small. A Mauser action is the max I can put in it. Of course that's plenty room for a reamer.

I made a simple reamer in an attempt to cut a bullet-forming die. I doubt that thing would cut hot butter. But... it was made fro 12L15, and I am told you can't make that sharp. I have some 4140 rod. It's about 1.25" in diameter, so it'll have to be turned down quite a bit for a reamer.


I suppose having worked on commercial places so long I tend to think of using the "right stuff" for the jobs rather than how it can be done.


The next biggest problem with making a chamber reamer is getting the sizes and tapers correct
Bingo again!

I also don't have a grinder to sharpen the flutes (not that kind of grinder anyway).

Looking forward to seeing more on this project.


Brithunter 11-02-2010 03:12 AM

Re: the .280 AI project

Just had a thought on reamer steel. Can you get "Silversteel"? it comesin short lengths of 12-18" normally and soemwhere we have a piece of 1/2" diameter it's a type of toolstell and so hardens well but would need a little bit of tempering or it would be brittle. Stubbs is one manufacturer and the one I am familar with:-

Just found this supplier:-

A 13" length of 9/16" is 7.18 + VAT. Methinks I'll order a couple of rods.

To turn the taper you would have to set the tail stock over or use the compound slide. Moving the tail stock is the correct way but then of course you have to clock it back true which can be a right PITA so for the length if you don't mind feeding by hand the compound slide method will work with care. You will have to leave it at least 0.010" plus for grinding and stoning. The reamer will require a small undercut at the junctions of angles to get the sharp profile in the chamber. The junction of shoulder and neck will usually have a small radius. chamber prints will show this.

sakorick 11-03-2010 03:16 PM

Re: the .280 AI project
It's a wonderful project and a wonderful caliber. I'm interested in what method of blueing you will use and why the break? The 280AI has long been on my to do list as it's a near ballistic twin to the 7MM Rem Magnum. Please keep posting the pictures as the story unfolds. Regards, Rick.

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