One for the Rifle Builders

[1967spud]

Whats the defonition of a short chambered barrel as in this Vid Clip?

 

[Gunsgobang88]

Hi Spud,

 

It appears that the chamber is not cut to full length, after the barrel is fitted to the receiver the chamber is cut to full depth by hand using an extension through the receiver,

 

Alan

[baldie]

Thats the beauty of youtube...it shows people like this up for the absolute zero knowledge of what they are doing.

You cannot chamber a barrel in a 3 jaw chuck. I,ve never yet seen one that ran perfectly true with a ground bar in its jaws, never mind a barrel.

I,ve also never yet, in fitting hundreds of barrels, found one where its bore run perfectly true to its ouside diameter, so you cannot work from the bore in a chuck that has no capability of being adjusted.

There are 3 and 6 jaw self centreing chucks available with a backplate that contains 4 adjusters, enabling the chuck body to be adjusted like a 4 jaw.....but this isn,t one of them.

Notice the shots of the dial guage dont actually show it touching the barrel whilst its being spun ?

Bartliens used to be one of the best barrels going for bore/outside diameter tolerances to match each other....typically 0.002" to 0.003" , but of late these tolerances have risen quite a bit....they are simply too busy, and i think personally that quality is suffering. I,ve had a few lately where the steel has had hard and soft spots in it.

 

You then have a shot of a bolt nose counterbore being used....again the sign of a rank amateur. These are used only for mass production, which admittedly is probarbly what this guy is doing.

They cut a bolt nose recess at .705" , which can be 0.015" over the bolt nose diameter.....and thats too much.

No evidence of ANY lubricant on the reamer, either muzzle fed or sloshed on the reamer.....imagine what that chamber looks like....and also how shagged the reamer will be. The reamer holder is shaking like a shiting dog.

 

Buying this barrel and then risking putting a new chamber reamer into it would be akin to sticking your pecker in a pit bulls mouth.

 

How the hell do people like this get on in business ?

[Ronin]

Nice Southbend though.....

 

Agree with Daves comments - the indicator tip prbablt wasn't touching the OD and that isnt the way to dial a barrel - the bore is what counts - at BOTH ends.

 

 

Not the way I do it,,and never will be.

[bradders]

What you have there, although you've probably never seen one, is an independent 3 jaw chuck.

Very common in America and very easy to use.

 

For reasons unbeknown to me, they were never very popular over here.

I did see the dial gauge move though....even with my bad eyes.

 

The reamer by the way is a 4 flute rougher

[Ronin]

Bradders, your right, the dial guage did move a flicker, I stand corrected, however theres no way that the bore diameter was dialled in, you can see how much out the chamber is on the movement from the way the Bald Eagle reamer holder moved laterally.

[bradders]

Bradders, your right, the dial guage did move a flicker, I stand corrected, however theres no way that the bore diameter was dialled in, you can see how much out the chamber is on the movement from the way the Bald Eagle reamer holder moved laterally.

Yes I agree, it's a bit exaggerated I think because I have a feeling the vid's speeded up a bit.

But, if the barrel had been countersunk at both ends to run true on a centre (as some mfr's do) then we aren't to know that the OD isn't concentric to the bore.

 

I think this is the case here.

 

Ask 20 gunplumbers how they turn and chamber a barrel and you'll get 20 different answers.

There's also the old adage of 'how much really matters' and in many cases it doesn't.

 

Dave, you said I,ve had a few lately where the steel has had hard and soft spots in it.

 

Barrel mfr's don't make the steel, that's done at the crucible so they have no control over it.

 

I saw a barrel recently with a pocket in the chamber. Couldn't explain it, looked like the steel had a pore in it that just so happened to show up with the reamer.

[baldie]

It may be an independant chuck, or it may not Mark. On the video, you cant see the holes for the chuck key. If its an independant, they would be over the jaws , not inbetween like on a scroll 3 jaw.

Setting up in an independant 3 jaw must take forever ? By moving one jaw, you would be working against the other two, rather than just one [ the opposite jaw ] on a 4 jaw.

 

As you say, thats probarbly a roughing reamer too.

 

The correct use of a roughing reamer is never to wind it in so far that the finish reamers pilot cannot enter the bore before it starts cutting on the finish reamer shoulder.

 

This guy is now relying on his finish reamer following the chamber exactly, until the finish reamer pilot "finds " the bore again.

The chances of that happening , using a floating reamer holder such as the one he is using....are virtually nil. In fact, he will be lucky if he doesn,t snap the neck off the finish reamer.

 

As you say, 20 different people will have 20 different methods , and a lot of it doesn,t make any difference whatsoever , but i,ve always been of the opinion, that if a jobs worth doing, its worth doing well/correctly and vid,s like this just make me shudder personally.

 

I take your point about steel....i spent 8 years making it , marine grade stainless in both AOD and VOD vessels , plus pouring it in any amounts from 500cwt valves to 60 ton castings.

Steel is made to a recipie like a cake. Its samples at several stages in the furnace and alloys added etc, plus a final ladle sample "at the death" and a poured finish sample to match the casting. Fascinating subject.

Impurities or concentrations of elements such as chromium or nickel could explain hard/soft spots in a barrel, but i would have thought these would have been evident in the button or cut rifleing process, because they show up easily on a hand held reamer.

Thats a quality control issue for me.

Luckily it never affects how a barrel shoots.