Dirty Choke = Tighter Pattern?

Dear Technoid:

Have you done any patterning to determine the effect on pattern from the plastic and carbon residue buildup in chokes? I haven’t, but it seems to me that, since a few thousandths of an inch makes the difference between a skeet and an IC, the residue must have the effect of increasing constriction with consequential tighter pattern. What do you think?



Dear Tom,

I think that you and are I thinking too much about this stuff.

To ‘fess up, I have never done dirty choke/ clean choke comparisons. That doesn’t mean that I have never shot with dirty chokes. I sure have. Sloth may be one of the Seven Deadly sins to you, but it’s mother’s milk to me. Less than perfectly cleaned guns are the way I live my life.

So let’s look at the theory of the thing. I’ve allotted half a cup of coffee to this question.

1) Some choke borers (Lujitc, for example) feel that rough chokes delay the wad and help it separate from the shot column. They feel that this keeps the wad from pushing into the shot column and results in a better pattern. Lujtic often scribes a circumferential groove in his chokes just to strip the wad. Other choke makers use certain types of porting in hopes of doing the same thing. PatternMaster chokes used pronounced nubs inside the choke to strip the wad (and strip it it certainly does- the wad comes out looking wrecked).

So, if a dirty choke “roughens” up the bore, in theory is should “improve” the pattern by delaying the wad and keeping it from blowing into the shot column. I’ve never quite been able to figure out if the claimed “improvement” is a tighter pattern or a more consistent one. My guess is the latter.

2) A dirty choke, in theory, should become a tighter choke by the amount of carbon, plastic and lead deposited. That should make the choke shoot tighter, in theory, as you suggest. But in my experience, the choke part of the barrel often doesn’t garbage up as much as the area just past the forcing cone in front of the chamber. That’s the area that really dirties up in my guns. If that’s the case, in theory, the bore could get more buildup than the choke, so a really dirty barrel would, in theory, lose choke as the barrel ID tightens up quicker than the choke!

There. And that’s just how many angels can dance on the head of that pin. Coffee’s gone. So am I.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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