Some guidance needed

[pashiner]

Hi folks! Long time reader, first time poster here. I've been playing with smooth bores and cheap foster slugs for a few years now, with the predictable results that can be expected, and have dabbled in bpcr reloading, but due to an unexpected Christmas gift (mossberg 535 with a rifled barrel) I thought I'd start reloading slugs. I'm liking the looks of the lyman 525 in a waa12 wad and AA hulls, with any of the recommended powders, but should I be concerned about blasting that slug out of a 2 3/4 shell in a 3 1/2" chamber? The gun is used, and came to me with a goodly amount of lead fouling in the chamber throat/forcing cone area, and I'd rather not look for trouble in a shotgun barrel. My guess is that somebody shot foster slugs in this thing, and leaded it up either through powder gas blow by, or through misalignment of the slug as it travels through the extra 3/4" of chamber space.
Is there a load recipe for the lyman 525 in 3 1/2" shells that would mitigate this problem? Or perhaps it's not an issue because of the shotcup/makeshift sabot? I've always been told that too much free bore is terrible for accuracy, but maybe it just won't matter in this case. I thank you all in advance for your opinions.

[Hogtamer]

Clean it good first if you expect any accuracy as with any rifled gun. You're probably right, somebody shot a bunch of the factory "rifled" slugswhich can't help but lead a rifled barrel. a 3" hull would probably help.

[pashiner]

I'm working through the long arduous process of lead removal this week, roughing up the lead with a stiff brass bore brush, and allowing it to oxidize for a day or so, then scrubbing out as much as i can with a "tornado" brush...repeat...repeat until hopefully my patches come out clean. I de-leaded a reproduction trapdoor carbine this way a few years back. Quite some work. I'm sure the 3" hulls will be an improvement over the 2 3/4" truball slugs i have for my smoothbore. At least there's available load data for 3" lymans.
I'd like to try to keep this shotshell reloading adventure at least fairly economical, and with the availability of cheap roll crimpers, that seems like the way to go, at least at first. I know the plastic Lee shotshell loader is reasonably priced, but I won't be using the shot dispensing or powder dispensing functions, because i weigh all my charges. Am i asking for trouble by priming/depriming with hand punches, and seating wads with the same drill press (turned off of course) i would chuck the roll crimper in? Once I get a load the gun likes, I'll invest in a mold, and maybe a MEC 600 slugger or something, but I'd sure hate to buy stuff that I'll end up selling at a loss.

[elvas]

Didn't have any accuracy issues when loading the Lyman sabot slug or any other slug in 2-3/4" hulls and using it in a Benell Nova with 3.5" chamber and smoothbore barrel.