choke question

[stevehaun]

I know this is probably covered in Brister's book but I loaned my copy to a friend...
If one has the same gun, same barrel length, same choke but different gauge, will the pattern be of a similar diameter at 20 yards?
Example:
remington 870, 28 in barrel, improved cylinder choke - 12 gauge versus 20 gauge - both fired at the patterning board from 20 yards. Will the patterns be of a similar diameter?

My first stab at this would be that this is totally unpredictable.

 

[RNB65]

Theoretically, yes. The pattern with a smaller bore gun will be less dense since it throws less shot, but the effective pattern size should be the same. In reality, there are so many variables involved the only way to know for sure is to set up a pattern board and analyze/compare patterns. I'm guessing you'll find that the gun with the smaller bore will probably have a few more holes in the pattern than the larger bore, particularly around the perimeter. That's the reason I don't ever bother trying to shoot sporting clays with a 20ga. I need as much shot density around the extreme perimeter of the pattern as I can get.

 

[evbutler462]

Tell your friend to get his own copy of Brister's book. It is $5.50 online ay alibris.com.