Measured the actual amount of choke in my SS

Machinist, I’m in agreement with Walter. 12 thou is a huge difference from groove to groove, you’d easily be able to see this kind of differential without the need for tools. Most rifling is only 4 to 6 thousands deep. Although I don’t see why a barrel would be inaccurate if one groove is deeper than another (the groove never touches the bullet, after all). It would increase blow by and make the barrel less efficient at driving a pellet and louder, probably; but this isn’t what affects accuracy.

I have some Starrett tools that I inherited from an old mechanic and they are wonderful and accurate tools, so I don’t doubt the accuracy of your measuring tools; but the methodology in obtaining your measurements might need to be looked at. I know I’ve hit myself on the head so many times with the palm of my hand that there’s a permanent indent on my forehead, everytime I figure out what I’ve been doing wrong, which is often. You know the old adage, measure twice, cut once? Well, in machining, it’s worse. I measure like 5 times and then sit down and think the process through 10 times in my head to make sure I’m doing it in the proper order. This is not hyperbole. This is my actual algorithym. Machining, especially lathing (due to the concentric rotation of the workpiece) will show differences in the finished product, sometimes dependent upon the ORDER in which cuts are made. So think it through, the entire project, before making the first cut. Don’t think about the finished product as an object you want. Think of anchoring points and rigidity in the machining and measuring process. Any way to reduce overreach?

Nice tools for sure!
They will not use those to measure bores of rifled barrels either.
They likely use a spot check of a batch using a modern version of a Sheffield Guage or modern electronic equivalent.
At the factory they likely know that the barrel will be a mirror image of teh button or mandrel and so would spend more inspection time on monitoring tool wear than the barrels.
Slug your barrel and see what the reslts are. Please?

Walter….

quote The Machinist:

This is what i’m using, a little older than the ones pictured but still very accurate..i’m not doubting the idea of pushing a slug through the barrel but I bet they dont do that at the factory..
[/img]

The way to measure a rifle bore is to slug it with a section of lead. Squash down a pellet until it is say 0.230″ and carefully push that into your bore. One in the breech and one in the muzzle.

Carefully push these out and measure under a magniying glass.

I highly doubt your barrel measures as you first posted.

Walter….

The best if you can get it is Cerrosafe where you take a cast impression of the bore.

How did you get these measurements? The method isn’t clear to me, did you use slugs? The variance seems really high.

Adam, most likely hammer forged over a mandrel.
soo there is no possible way for a barrel to measure out a groove that varies by ” 11 or 12 thou”

Someone must a been digging around in that barrel and messed it up.

That measurement I gave Jerry is from my HW barrel and all grooves are the same no variance discernible groove to groove.

Walter….

How are the LW barrels rifled? Is it done with a button?