forcing cone??

[keith44]

Some time back (earlier this year) I bought two 20 ga Pardner barrels (different lengths), with the intention of fitting both to rifle frames (SB2) to make combo guns, or possibly turning them into "Paradox" barrels.  While I have yet to measure the bores, something about these feels weird.  Do these barrels have a forcing cone?  I cannot detect one with a tight fitting mop, like I can feel on my 870 barrels.  I am thinking of running a forcing cone lengthening reamer into one, and maybe porting it as well, after I get them fitted.


Anyway, does anyone have any clue about the forcing cone of a 20 ga Mod choked Pardner barrel??

[Airsporter]

I'm thinking all shotgun barrels have a forcing cone, except muzzleloaders.

[keith44]

all breech loading shotgun barrels should, some are really short with abrupt angles, the better ones are long with a good taper to the bore diameter.  As inexpensive (note: I am not calling these guns cheap  ) as these guns are I'm betting the cone is little more than a radius at the end of the chamber.

[Sprint]

The industry standard (SAAMI) angle for shotgun chamber forcing cones is 5 degrees. IIRC, all shotgun barrels manufactured by H&R/NEF had the forcing cones changed from 5 to 15 degrees sometime in the 1990's.
 
Sprint
 

[jpshaw]

I don't know from what angle the forcing cone is measured from.  I guess I'm asking is 15 degrees a LONGER cone then 5?  In rifle shoulder angles the greater the angle the more radical the reduction angle (shorter distance).  The gentle angle of a .30-30 is 15 degrees while the shorter reduction of 30 degrees in a 300 Savage is much more pronounced. 

[keith44]

The industry standard (SAAMI) angle for shotgun chamber forcing cones is 5 degrees. IIRC, all shotgun barrels manufactured by H&R/NEF had the forcing cones changed from 5 to 15 degrees sometime in the 1990's.
 
Sprint

So I could have a 5 degree forcing cone barrel here...hmm
time to break out the id calipers

[Ranger99]

if you don't, it's easily remedied.
l.f.c. reamer, then polish chamber,
and i always follow with barrel polish.

[Sprint]

I don't know from what angle the forcing cone is measured from.  I guess I'm asking is 15 degrees a LONGER cone then 5?  In rifle shoulder angles the greater the angle the more radical the reduction angle (shorter distance).  The gentle angle of a .30-30 is 15 degrees while the shorter reduction of 30 degrees in a 300 Savage is much more pronounced. 

Your assessment is 100% spot on!  When I posted, I must have been thinking one thing and wrote another. Sorry for the confusion.
 
Sprint
 

[jpshaw]

So I assume they changed the cone from 15 degrees to 5 sometime in the 1990's?  Would like to know what date that was since I do have a 1999 20 gauge barrel.