Screw cutting a rimfire barrel

[old man]

On 15/01/2019 at 08:20, Jimiles said:

I am going to take my Remington 597 to a local machine shop and ask them to shorten the barrel to about 14"and then re-cut the thread. They've not done this before but they're quite happy to simply replicate the original pattern. Before they do this can anybody explain why there is such a wide & deep groove as arrowed between the thread and the machined face? Why can't the thread simply continue up to the face?  I am concerned that this groove looks to be quite deep but surely removing so much metal here is creating an unnecessarily weak point in the barrel. 

My other concern is the crown of which I've got no understanding at all. Looking at my rifle it appears to be a simple rounding of the muzzle area with a slight chamfer cut inside the bore. Is that all that is required or should I use this opportunity to get a more elaborate crown machined?

 

It's simply there to allow the threading tool to be stopped before it hits the face of the barrel. 

[Big Mat]

3 hours ago, old man said:

It's simply there to allow the threading tool to be stopped before it hits the face of the barrel. 

 

And to allowed whatever to screw up to the shoulder. You can stop the threader before it hits the barrel whether you put an undercut in or not

[wildrover77]

Gunsmith are not wizards with special powers.

Any good machinist can do the job.

 

[Bazooka Joe]

4 minutes ago, wildrover77 said:

Gunsmith are not wizards with special powers.

Any good machinist can do the job.

 

Have to agree.....

[Old farrier]

However you should be careful as you’re machinists may not have a fac or a license to work on them 

personaly think it’s a can of worms you could be opening 

[mick miller]

This guy did two of mine https://bartongunworks.com/#gunsmithing

£65. Anymore is too much and there is no need to proof afterward.

[old man]

11 hours ago, Big Mat said:

 

And to allowed whatever to screw up to the shoulder. You can stop the threader before it hits the barrel whether you put an undercut in or not

Yep but you need an undercut to stop a threading tool in if not using a die, I was thinking of much larger diameters cut on a lathe in a previous life.

[Big Mat]

2 hours ago, old man said:

Yep but you need an undercut to stop a threading tool in if not using a die, I was thinking of much larger diameters cut on a lathe in a previous life.

You don't need an undercut to stop a tool, that's the human operating the lathe that does that! 

[bruno22rf]

Bread and Butter work with a CNC Lathe.

[Vince Green]

On ‎15‎/‎01‎/‎2019 at 11:32, Flyboy1950 said:

Quite right you don`t need it reproofing as you are the owner. When you come to sell it however, you will have to have it reproofed.

FB

Nobody ever asks in my experience

[Salopian]

I highly recommend Mike Norris Unit G2  Sandford Industrial Park , Whitchurch SY13 2AN          0845 5212995

[Jimiles]

3 hours ago, Salopian said:

I highly recommend Mike Norris Unit G2  Sandford Industrial Park , Whitchurch SY13 2AN 

Thanks Salopian, Brock & Norris were actually the first recommendation given to me...and I may still end up going there. It is their price that made me think twice, Brock & Norris charge £125 plus VAT to do this work. When I factored in the fuel costs to take the rifle up to Whitchurch and then go back and collect it on completion its going to total up to about £140. It was at that point I thought I'd try a machine shop!

[Touchstone]

1 hour ago, Jimiles said:

Thanks Salopian, Brock & Norris were actually the first recommendation given to me...and I may still end up going there. It is their price that made me think twice, Brock & Norris charge £125 plus VAT to do this work. When I factored in the fuel costs to take the rifle up to Whitchurch and then go back and collect it on completion its going to total up to about £140. It was at that point I thought I'd try a machine shop!

If you ask, there’s a decent chance he’ll do it while you wait by arrangement.

T

[old man]

8 hours ago, Big Mat said:

You don't need an undercut to stop a tool, that's the human operating the lathe that does that! 

You need an undercut to give the operator a linear distance to stop the tool in.

[Big Mat]

42 minutes ago, old man said:

You need an undercut to give the operator a linear distance to stop the tool in.

You should have said that in the first place 

[welshwarrior]

23 hours ago, wildrover77 said:

Gunsmith are not wizards with special powers.

Any good machinist can do the job.

 

Yes and when you need you rifle rebarreling or bedding or trigger tuned or stock chequered the machinist won’t help as he doesn’t have the experience or tools but the gunsmith will be shut as he went out of business.  Don’t be afraid to support your local trades men of any type.  

[PPP]

Agree with Welshie BUT shape gun smiths will sub this out to machinists anyway and pocket the 100 quid, sometimes don’t help themselves

[activeviii]

make sure the machine shot do not hammer a mandrel into the bore to use for centring. seen it done, had to recut.

the one reason to put a relief or back cut in is to the mod shoulder has good meat to butt up to and square up. a good screw cut, dont to your mod and a good shoulder is paramount.

you can cut the thread the other way, basically spin it all the other way, still cutting the thread right handed but having the cutter start as the shoulder end. then you can run the lathe faster and not worry about cutter crash. you only need enough relief cut to start the cut, cutter dependent. if its cnc then no need to worry, they can rattle it out, longest part is setting up.

20 minute job, just remember to clean the bore after. and make sure they crown it properly so no burr in the bore. 

all ready said, none pressure part. no need for proofing. 

[Dibble]

4 minutes ago, activeviii said:

you can cut the thread the other way, basically spin it all the other way, still cutting the thread right handed but having the cutter start as the shoulder end. then you can run the lathe faster and not worry about cutter crash. you only need enough relief cut to start the cut, cutter dependent. if its cnc then no need to worry, they can rattle it out, longest part is setting up.

but would you have to cut with the bottom of your threading tool? I don't think you could get it high enough to center on mine (Colchester Bantam).

[activeviii]

7 minutes ago, Dibble said:

but would you have to cut with the bottom of your threading tool? I don't think you could get it high enough to center on mine (Colchester Bantam).

 

 

lift off the tool post and put two cutters on the slide and then the post on top and bolt down. cutters just shim it up. use slips if you have them

Edited January 17, 2019 by activeviii

[welshwarrior]

36 minutes ago, PPP said:

Agree with Welshie BUT shape gun smiths will sub this out to machinists anyway and pocket the 100 quid, sometimes don’t help themselves

You’d have to add them to the RFD insure them and then transport to and fro doubt it get sub out often, he’ll have a lathe for numerous other jobs so it’s just time and consumables  

[Foolofatook]

Best man at this can be found at Turnright Galloway. Check on Google and no it doesn't require reproof.😉