How many out there shoot the old "Goose Gun" and reload for it?
Just trying to come up with some good safe loads in this gun for varmints ( coyotes, coydogs, bobcats,etc. ).
At present I am shooting Remington 3.5" BB`s! Also having barrel shortened back to 26" and threaded for chokes.
I remember those old loooong-Tom bolt-shotguns! From Marlin.
Never shot one altho I think back in high skrewl days (30+ years ago!) considered getting one.
Recently (two days ago?) saw a 'Goose gun magazene' for sale on eBay! Was less than $30. I agree with Bigeasy; stay withinn recommended load recipe and you should be fine.
Also I think you're smart for modifying the barrel length and chokes
(provided they're done right; proper metal amount removed inside before its threaded to maintain correct bore diameter to muzzle).
In addition,
if I was a 10 gauge shooter, would bust my azz to learn to reload 2-3/4", 2-7/8", and 3" shells as well as the 3-1/2inchers! Would give you much more versatility for use on more than just geese or coyotes. (just a suggestion)
Ballistic Products.com sells a lot of components for the 10 ga, and loves that gauge.
Check out fleabay maybe for a "cheap" replacement magazine?