IC, but I don't understand....

[blackscot]

All shot with #7.5 1-1/8 oz. field loads at 10 yards. Targets are poor-man IPSC style fabricated from leftover grocery bags.

Rem. 870 with 18-inch fixed cylinder choke barrel
http://i113.photobucket.com/albums/n232/blackscot/patterns/870-18C-75-10.jpg
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Rem. 870 with 20-inch fixed improved-cylinder choke barrel
http://i113.photobucket.com/albums/n232/blackscot/patterns/870-20IC-75-10.jpg
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Rem. 11-87 with 21-inch interchangable ("rem choke") improved-cylinder choke barrel
http://i113.photobucket.com/albums/n232/blackscot/patterns/1187-21IC-75-10.jpg
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Rem. 11-87 with 21-inch interchangable modified choke barrel
http://i113.photobucket.com/albums/n232/blackscot/patterns/1187-21M-75-10.jpg

There is hardly any difference in spread between the cylinder and improved-cylinder barrels on the 870, despite not only the different chokes but 2-inch length difference. I was expecting more.

There is a huge difference between the improved-cylinder on the 870 versus the 11-87, even though it's the same type choke and only a 1-inch length difference. I was expecting them to be the same.

There is hardly any difference between the improved-cylinder and the modified on the 11-87. I was expecting more.

Here are the caliper-measured choke diameters (I no longer possess the 870 cylinder barrel):

870 IC -- 0.724"
11-87 IC -- 0.720"
11-87 M -- 0.715"


:confused: :confused: :confused: :confused: :confused: :confused: :confused:
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[PALADIN-hgwt]

xxxxx

[blackscot]

Most users of #7.5 and #8 BIRDSHOT tend to use tighter chokes than your test barrels.......10 yards is pretty close to be checking the patterning ability of BIRDSHOT, unless you plan shooting them on the ground while feeding......

Thanks for the response.

Primary use is action-style 3-gun competition. Hence the tactical-ish targets.

The match stages actually feature steel targets within 20 yards for most shotgun engagements, which a tight enough spread is needed for adequate umph to knock down. My 870 had been just showering the plates, which would remain standing while laughing back in derision. Now I can see why. Am hoping that the tighter 11-87 will enable me to get even.


......For a longer discourse regarding Shotgun ammo I would suggest reading the info at the following link.......

What a great site! I'm going to spend some time around there.

[Robb Jensen]

Shotgun chokes is a weird science in itself.

That said I need some tighter extended Briley choke tubes for Joes matches ;) probably an Improved Modified along with some heavier loads my #8 Win SuperSport is a little too light, I think I'll go to #6s.