Need a barrel OD ground

[dgeesaman]

I have a barrel of particular interest that was machined for a clamp-style receiver at 16mm. It was not machined well and this surface is wavy and inconsistent by a couple thou.

I’d like to put this barrel in my RAW which needs to be .625 (+0/-.0005) diameter. So I assume the only good solution that keeps the length is to OD grind down to .625 and hope for 90-95% cleanup. (To be clear I only want the receiver end ground - not the whole length)

Suggestions who can do this? The local machine shops might but they aren’t barrel people. Bonus if they can machine the port and chamber too.

 

[6gun]

I have a barrel of particular interest that was machined for a clamp-style receiver at 16mm. It was not machined well and this surface is wavy and inconsistent by a couple thou.

I’d like to put this barrel in my RAW which needs to be .625 (+0/-.0005) diameter. So I assume the only good solution that keeps the length is to OD grind down to .625 and hope for 90-95% cleanup. (To be clear I only want the receiver end ground - not the whole length)

Suggestions who can do this? The local machine shops might but they aren’t barrel people. Bonus if they can machine the port and chamber too.

A manual machine job shop can easily do this. You have all the right call outs with dim and tolerance.

 

[Motorhead]

Grinding requires doing so on a Live and dead center spinning blank via bore. If bore hole is not exactly center of blank you may have an issue.
Most grinding fixtures I've ever seen dont have a 4 jaw chuck that would allow O.D. run out to be adjusted, tho such chucks and adjustable run-out type fixtures do exist for Lathes.

Being so close to spec size wanted already is going to be tough .... Wish you the best in getting someone to take this on

 

[dgeesaman]

Grinding requires doing so on a Live and dead center spinning blank via bore. If bore hole is not exactly center of blank you may have an issue.
Most grinding fixtures I've ever seen dont have a 4 jaw chuck that would allow O.D. run out to be adjusted, tho such chucks and adjustable run-out type fixtures do exist for Lathes.

Being so close to spec size wanted already is going to be tough .... Wish you the best in getting someone to take this on

I forgot to mention that using tubing mics I did confirm the ‘wall’ thickness to be uniform within a few tenths, which is to say it’s well centered at the very breech end.

Also I don’t mind losing a bit of the end. If they want to overbore, machine center, or turn down 1/2” for grinding, that’s a lot better than losing 4-5” of length.

I do wonder if a lathe with grinding attachment will work. I hear they’re a mess to use but for doing barely more than a spark-off it might be ideal.

 

[Airgun-Revisions]

I forgot to mention that using tubing mics I did confirm the ‘wall’ thickness to be uniform within a few tenths, which is to say it’s well centered at the very breech end.

Also I don’t mind losing a bit of the end. If they want to overbore, machine center, or turn down 1/2” for grinding, that’s a lot better than losing 4-5” of length.

I do wonder if a lathe with grinding attachment will work. I hear they’re a mess to use but for doing barely more than a spark-off it might be ideal.

It’s going to be tough to find a shop to grind it properly and or not mess it up. Properly meaning the right machine to do the job. Crosman, Daystate ect do have custom center less grinders for this. A lathe grinding attachment can do it but would definitely still need a good follower on the opposing side of the wheel.

 

[6gun]

It’s going to be tough to find a shop to grind it properly and or not mess it up. Properly meaning the right machine to do the job. Crosman, Daystate ect do have custom center less grinders for this. A lathe grinding attachment can do it but would definitely still need a good follower on the opposing side of the wheel.

My mind goes to an engine rebuilding machine shop that can grind cranks and cams.

 

[Airgun-Revisions]

My mind goes to an engine rebuilding machine shop that can grind cranks and cams.

lol. From age 16 to 29 that’s what I was doing. Complete machining and rebuilding any and all internal combustion.

 

[Motorhead]

lol. From age 16 to 29 that’s what I was doing. Complete machining and rebuilding any and all internal combustion.

As with nearly all one off machining jobs your paying for mostly SET-UP time, as the actual doing happens very quickly.

 

[Rolland]

I have a barrel of particular interest that was machined for a clamp-style receiver at 16mm. It was not machined well and this surface is wavy and inconsistent by a couple thou.

I’d like to put this barrel in my RAW which needs to be .625 (+0/-.0005) diameter. So I assume the only good solution that keeps the length is to OD grind down to .625 and hope for 90-95% cleanup. (To be clear I only want the receiver end ground - not the whole length)

Suggestions who can do this? The local machine shops might but they aren’t barrel people. Bonus if they can machine the port and chamber too.

That is normally a straight forward job for a machine shop, find a gunsmith shop. Most shops are set up to thread barrels either chamber end or muzzle. We do that all the time here altho it makes it easier if the barrel can be removed from the action. Set in a four jaw chuck and centered. Much the same as treading the muzzle for a brake or silencer.
Good luck on the project

 

[Airgun-Revisions]

As with nearly all one off machining jobs your paying for mostly SET-UP time, as the actual doing happens very quickly.

Customers need to understand that. Production and single jobs are two different bears. What also adds to the time is the experience to not mess the part up. We only have one shot so it needs to count.

 

[markhooper]

what do you need ground on the barrel.. muzzle or breach? I likely can do it in my lathe with a live center.. PM me if you want to.
Mark

 

[markhooper]

what do you need ground on the barrel.. muzzle or breach? I likely can do it in my lathe with a live center.. PM me if you want to.
Mark

or are you wanting the entire length machined?
Mark

 

[Ca_Varminter]

I don't know what is goals is ... going with a Ground barrel end to fit your receiver.
On my custom Titanium Rapid.....
I turned down the end of my LW Poly barrel on my lathe to achieve a Solid fit!!

 

[dgeesaman]

what do you need ground on the barrel.. muzzle or breach? I likely can do it in my lathe with a live center.. PM me if you want to.
Mark

Just the breech end.

If your lathe can skim .000-.002 per side without chattering or making it worse, it could work. I assumed only grinding would work here because of the varied and minimal stock allowance.

 

[markhooper]

Just the breech end.

If your lathe can skim .000-.002 per side without chattering or making it worse, it could work. I assumed only grinding would work here because of the varied and minimal stock allowance.

well if it is pretty round and straight could just spin at high speed with emery cloth,you'd get a good finish but it will take off any current finish..
you didn't mention if it was just the breach or full length..
generally lathe tooling will leave very tiny, like threading marks, so I pretty much always finish up with emery cloth.. depends on how much needs off but I have 3 different grits and the fine makes a mirror polish
Mark

 

[dgeesaman]

I don't know what is goals is ... going with a Ground barrel end to fit your receiver.

The goal is to rescue a barrel with a breech end that is poorly machined at ~.629 diameter to a good 0.625 diameter.

Obviously a turned finish is perfectly acceptable if you have enough stock allowance for a clean cut. With this being uneven and barely larger than finish size, I assume turning is risky.

 

[Ca_Varminter]

Well if you can't find someone with OD grinder....
You still can turn down your barrel...
Use Sharp HS steel cutters..
If it doesn't clean up @.625".. Turn it down more and Sleeve it.....

 

[Motorhead]

Just the breech end.

If your lathe can skim .000-.002 per side without chattering or making it worse, it could work. I assumed only grinding would work here because of the varied and minimal stock allowance.

Have yet to get a uniform cut w/o striations on a standard steel LW barrel on a lathe. Stainless LW's machine wonderfully !!
If @ .002" removed is all you need, I would be incline to lathe spin it and strap sand it to spec measuring as you go.
This technique I commonly use to remove machining striation marks when stopping a tad larger than required O.D specs. Works great !!!

 

[dgeesaman]

Have yet to get a uniform cut w/o striations on a standard steel LW barrel on a lathe. Stainless LW's machine wonderfully !!
If @ .002" removed is all you need, I would be incline to latch spin it and strap sand it to spec measuring as you go.
This technique I commonly use to remove machining striation marks when stopping a tad larger than required O.D specs. Works great !!!

But will it remove the egginess I've measured?

David

 

[Motorhead]

But will it remove the egginess I've measured?

David

out of round ... no
but the amount of out of round pending how much may not really matter if you can achieve a nice AKA: sizzle fit between barrel & receiver. Once snugged down with retention screws your really quite solid.