Does firing slugs affect shot pattern much?

[Wild Gene]

I was out with my shotgun to double check my 50 yard zero with slugs. After I did a wipe down of my shotgun, I noticed a lot of lead built up in the choke tube. It is an IC tube. I was curious if anyone has ever patterned their shotgun with birdshot, then fired a bunch of slugs, then patterned with birdshot again to see if it shrank the pattern much?

wg

[BiggenF15]

I'm a skeet shooter by trade and used to be very diligent not to allow too much lead or plastic wad residue to get built up on my chokes. I was talking to a guy who rarely (if ever) cleaned his gun and I told him he had to be tightening up his pattern by allowing all of that junk to build up in the chokes. He disagreed so we tested the patterns.

We patterned his gun dirty, then cleaned the chokes thoroughly (needed an electric drill with a bronze brush) and patterned it again. The pattern from the dirty choke was almost imperceptibly smaller - certainly not smaller enough to worry about. I was surprised, but he was right.

I don't know if this experience directly addresses your question about shooting slugs because we didn't shoot any. However, lead or plastic built up in the choke is what's going to cause a difference in the pattern, I don't think it really matters whether it was deposited by a slug or regular bird shot. Also, we conducted the test with skeet chokes - I'm not sure if the results would change with tighter chokes but I doubt it.

If you test your shotgun the way you described in your post, I doubt you'd see a difference but I'd be interested in the results.

[Wild Gene]

That is exactly what I was asking. I was playing with a new shotgun. I patterned it with birdshot. After that, I went and checked the zero with slugs and an IC choke tube. When I was finished and back in the shop doing a take down and clean/re-lube I was horrified at how much lead was in the choke tube.

I peeled out what looked like an un even layer of aluminum foil. I never even thought to check the pattern again, but did try to mic it and there was a layer that was almost around a couple thousandths thick. I did not have the correct tool to accurately measure the internal dimension, but if an IC is .720 and a Mod is .710, then I effectively had a different choke tube in my gun. In a mixed stage, there is not too much you can do about it, but in a slug only stage, I'm thinking it would actually be worth it to have a dedicated tube for slugs.

I'm going to actually check this next time I run a lot of slugs through my barrel.

wg