Chamber Finishing

[Toolbreaker]

https://cogsdill.com/products/burnishing-tools/gun-chamber-burnishing-tools/

Interesting find. I was under the impression that a little "tooth" in a chamber is a good thing to reduce bolt thrust. I wouldn't think that Cogsdill would sell snake oil. Thoughts?

 

[Kevin Taylor]

I would take the first cartridge fired and put it on a mandrel. A little 600 grit, and spun it by hand in the chamber. Found it did not do much, so quit doing it.

With the exception of a 22-250 that went to Kansas, my rifles shot well.

 

[DaveTooley]

Consider the tooling we use to that used by manufactures. Ours slices and theirs plows. Large high HP machines that muscle out material. Each leaves a different finish. Also many barrels/chambers are plated internally. That requires a good finish.
I polish with 240 for uniformity in the finish.

 

[Toolbreaker]

I was thinking that a low RA finish might be a spec on some military chambers, but I really wasn't sure. I believe you're correct with the commercial application, though. A burnishing tool may very well extend the run between changing reamers on a production basis, at least in regards to chamber finish.

 

[Stan Taylor]

Here is a gammit of my high dollar burnishing tools.

 

[DaveTooley]

Damn Stan I feel unworthy after seeing your high dollar assortment.

 

[hpshooter]

"Here is a gammit of my high dollar burnishing tools."

The construction and wear on the handles of those tools tell me they have been around Douglas for a long time. Amazing, no batteries and no digital read outs and still working!

I missed seeing those when I visited you a couple months ago! Did you find a scope mount to your liking for your M1-A?

 

[shortgrass]

My tools work just like Stans'. I never go finer then 320g.

 

[Will Henry]

I polish with Scotch Brite. I have tried a ball hone for remedial work on a rough chamber and it worked surprisingly well but a chamber shouldn't need that much. WH

 

[STS]

Here is a gammit of my high dollar burnishing tools.

Stan, you need to spend a little time polishing out the top of that table.

 

[Stan Taylor]

Stan, you need to spend a little time polishing out the top of that table.

We do clean it off every Friday at clean up time that ole benchtop has probably had at least 140,000 barrel chamber's polished there, so actually I think it's pretty darn clean LOL

 

[shortgrass]

I polish with Scotch Brite. I have tried a ball hone for remedial work on a rough chamber and it worked surprisingly well but a chamber shouldn't need that much. WH

A good chamber cut with a sharp reamer doesn't need much polishing. Just a bit sometimes to give the brass some 'tooth' to bite into when it expands from firing.

 

[tobnpr]

Must be above my pay grade...
Purports to "slick-out" a reamer's surface finish, to 15 micro-inches which according to the chart I checked, is the equivalent of 240 grit.

https://www.ljstar.com/resources/surface-finish-charts/

WTF? We use 240 grit paper to roughen the chamber walls, not slick 'em out!

What kind of reamer leaves a surface finish that 240 grit will result in a smoother finish?

It's been a long day, but this ain't making any sense to me

 

[Dusty Stevens]

Must be above my pay grade...
Purports to "slick-out" a reamer's surface finish, to 15 micro-inches which according to the chart I checked, is the equivalent of 240 grit.

https://www.ljstar.com/resources/surface-finish-charts/

WTF? We use 240 grit paper to roughen the chamber walls, not slick 'em out!

What kind of reamer leaves a surface finish that 240 grit will result in a smoother finish?

It's been a long day, but this ain't making any sense to me

Looks like a mass produced hammer forged type setup where they run a few hundred more chambers than they should on a reamer. May also be prepping it for chroming

 

[Danny1788]

I use a super high dollar Bic pen body slit and wrapped with 320grit Emory clothe around it. Swipe it in the chamber back and forth a few passes.

 

[Stan Taylor]

I use a super high dollar Bic pen body slit and wrapped with 320grit Emory clothe around it. Swipe it in the chamber back and forth a few passes.

You would have made a damn good marine improvise overcome an adapt.

 

[hpshooter]

"I use a super high dollar Bic pen body slit and wrapped with 320grit Emory clothe around it. Swipe it in the chamber back and forth a few passes."

Split dowel rod works pretty good.

 

[HillbillyLongRifle]

I just use a wooden dowel with a piece of 320 on it for some. Others i dont even bother to polish from the reamer finish.

 

[Stan Taylor]

Here is a pic of our polishing set up,
the collars on the left are for muzzle end support.

 

[INTJ]

Maybe I am doing it wrong? I use a dowel with 400 grit duct taped to it, and when I am finished chambering make a few passes while the barrel is still in the lathe.

Should I use a rougher grit?