|
|
|
S |
M |
T |
W |
T |
F |
S |
|
|
|
|
|
|
|
1
|
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
|
9
|
10
|
11
|
12
|
13
|
14
|
15
|
|
16
|
17
|
18
|
19
|
20
|
21
|
22
|
|
23
|
24
|
25
|
26
|
27
|
28
|
29
|
|
30
|
|
|
|
|
|
|
|
|
1 members (SKB),
294
guests, and
5
robots. |
|
Key:
Admin,
Global Mod,
Mod
|
|
|
Forums10
Topics38,579
Posts546,636
Members14,425
| |
Most Online1,344
Apr 29th, 2024
|
|
|
|
Joined: Jul 2003
Posts: 230
Sidelock
|
OP
Sidelock
Joined: Jul 2003
Posts: 230 |
I was fooling around at the bench the other day and decided to try measuring the choke on some shotguns to compare with what they were marked. Most came out pretty close to what they were stamped, but a 12 ga. 870 marked full measured .709 (modified).
To measure, I was using the micrometer I use in reloading rifle rounds which has a 0.6 inch reach for the inside diameter measuring function. Is this enough reach to catch the choke? Or, could the choke be further back in the bore than I can reach with this micrometer?
|
|
|
|
|
Joined: Jan 2002
Posts: 468
Member
|
|
Member
Joined: Jan 2002
Posts: 468 |
You are "catching" the choke, but all you have is the exit diameter......without knowing the bore diameter, you will have no way of knowing what the choke constriction is.....fixed choked Remington barrels have been known to have bores from .722" to .745".....
|
|
|
|
|
Joined: Jan 2002
Posts: 2,307
Sidelock
|
|
Sidelock
Joined: Jan 2002
Posts: 2,307 |
To expand, choke is expressed as the difference between actual bore diameter and actual muzzle diameter, measured to .001. You have only half the equation so far.
|
|
|
|
|
Joined: Jan 2002
Posts: 5,954 Likes: 12
Sidelock
|
|
Sidelock
Joined: Jan 2002
Posts: 5,954 Likes: 12 |
To add a couple of more tidbits - I have measured full chokes within a cone length range of seven inches long to one inch long. Further, some chokes have a parallel exit section that is over an inch. You need a fairly long reach mike to really measure choke profile.
|
|
|
|
|
Joined: Feb 2006
Posts: 3,738 Likes: 56
Sidelock
|
|
Sidelock
Joined: Feb 2006
Posts: 3,738 Likes: 56 |
I would say you would have to get back into the muzzzle at least 3" to get past the choke. The trouble is you can't use a telescoping gage because you will be compress the gage by the time it reaches the choke. You really need a bore gage, one that has a dial indicator that you push into the muzzle set to a size and then zero then read how many thousands negative it reads. Bore size 12 ga.,.729 (typ), choke .709= modified.
Some have a reading depth of 14-16 inches, good for measuring both ends.
David
|
|
|
|
|
|
|
