What kind of bore reduction in barrel? How to measure it?

[Naphtali]

I have a barrel blank that I think has either choke or taper bore. Bore diameter of muzzle is several thousandths smaller than breech.
1. I want to determine which type of reducing bore I have.

2. I also want to identify if taper bore, at least in several steps - say, every couple of inches? - what is the bore diameter change, or if choke bore, where choke begins.
***
How do I do this without owning tools, such as bore scopes and air gauges?

[Lucky R A]

 I suppose since you obviously have a micrometer, you could slug the bore starting from the breech end.  Use a stout wooden ramrod blank to drive a oversize lead slug down the bore stopping at specific locations and then drive it back out from the muzzle and mike the slug.  Continue on throughout the bore to within an inch or so of the muzzle.  The resultant micrometer readings of the slug(s) should give you a map of the interior of your barrel.
Ron

[Dphariss]

I have a barrel blank that I think has either choke or taper bore. Bore diameter of muzzle is several thousandths smaller than breech.
1. I want to determine which type of reducing bore I have.

2. I also want to identify if taper bore, at least in several steps - say, every couple of inches? - what is the bore diameter change, or if choke bore, where choke begins.
***
How do I do this without owning tools, such as bore scopes and air gauges?

Bump up a lead slug at the breech and push it out the muzzle. Run a lightly oil patch though the bore first. This will find the first tight spot up from the breech and subsequent ones if they are tighter than the first one.

Dan

[Naphtali]

Me and mic, a cylinder of lead and a rod. Push a little; check a little. Push a little; . . . I can do this. Thanks guys.

[aflo]

I can understand the idea of a bore reduction for a shotgun. What is the logic for a rifle?

[okieboy]

 Many very accurate barrels have been choke bored, Walter Cline wrote about this. The choke is usually from .001-.002" and goes from the breech to within about 6" of the muzzle. The basic idea is that the last 6" provides the tight loading that produces accuracy, and the larger bore makes loading easier, which means less bullet deformation. I believe that at one time Bill Large would include in his adds, "Don't cut the last 6" of the muzzle, that's where the secret is at."

[JDK]

I don't see where Naphtali said the bore was rifled or not.  Could be, he didn't indicate in his post.  J.D.

[Bob Roller]

I owned a fine Whitworth semi military match rifle in caliber .451 with an Alex Henry barrel and from the muzzle to the top barrel band was about 8" and it had a very noticeable choke and when it fired,it has a keen "crack" much like a smokeless powder rifle. Accuracy was superb.

Bob Roller

[Dphariss]

I can understand the idea of a bore reduction for a shotgun. What is the logic for a rifle?

Done right they are very accurate and load easy.
Read the Chapter on the Hoffman and Campbell rifle in John Baird's "Hawken Rifles"
TK Dawson details the choke and the "freed" muzzle.
A great many original rifles were choked.

Dan

[Pete G.]

The Enfield rifled muskets had a straight bore with tapered grooves. I have an Armi Sport replica cut the same way. Grooves are almost not visible at the muzzle. How this is accomplished escapes me, but it is a very accurate rifle.

[dannybb55]

It seems that this trick was used for ant-tank rifles in the 30s and 40s. Sometimes a tungsten core was included in the projectile for extra punch. Nothing is really that new eh?