What’s with this rifling?

[ammolab]

Originally Posted by ABN_CBT_ENGR
I blew your pic up to the point of pixilation so are you referring to those "striations" going lengthwise along the bottom of the grooves in every rifling?

If so, and its a "modern" manufacture (say less than 10 years old) then more likely than not it is a micro grooved cut to create a class characteristic for a particular model of firearm and as its shot it will develop into an individual one as well.

This information is sent to the ATF and FBI and loaded into databases for firearms ID.

I found out a lot of requirements when I started the process of upgrading my old FFL to Type 10 title 2 SOT 3 as a manufacturer.

I base that on the picture and the overall uniformness and fact its the same in all of them ( at least from what I can see until it gets blurry)

If that not it then it looks like a very worn button chattering- that would be possible because most of those small barrels are made in a long stock and rifled ( easier to load and work in the CNC) then cut/chambered to various lengths as needed.

I cant see a mandrel making those marks and if it was a broach then the operator must have been asleep.

I would guess its a deliberate class characteristic added to make the ATFE happy- many manufacturers are doing that and keeping it on the down low these days.


It might be leading, but it for sure is NOT a new type of ATF required "micro grove" rifling for identification. I have looked down hundreds, maybe thousands of S&W barrels,both new and old, and this one is unique. "Chatter" would not be longitudinal from a button but across the groove...a button would have to have a sharks tooth patterned wear to make that surface. Not too likely.

Scrub on it and see if pukes lead.

 

[ABN_CBT_ENGR]

Originally Posted by ammolab


It might be leading, but it for sure is NOT a new type of ATF required "micro grove" rifling for identification. I have looked down hundreds, maybe thousands of S&W barrels,both new and old, and this one is unique. "Chatter" would not be longitudinal from a button but across the groove...a button would have to have a sharks tooth patterned wear to make that surface. Not too likely.

Scrub on it and see if pukes lead.


Dude, so have I ( and thousands of other parts of all flavors in terms of machining inspections) and theres not much to be gleaned from a grainy 2D picture on a board.

I grant you its different- unique is a different thing because I don't do many revolvers. It might be.

Sharks tooth would be if its made for purpose but its very "uniform" to be random.

As far as ID characteristics, theres more there than most people think. I did 2 just in the past 4 years for a manufacturer in south Ga. and another near Myrtle Beach in SC. ( not counting things for me). I'm not talking about firing pin stuff (that doesn't work very well or long).

That's high level IP and trade stuff they don't like to talk about. I don't mean stuff from Brownells, Pacific Gauge or made a Webb barrel making video either.

But anyway, just an opinion based on an observation from a picture- nothing more.