Camp Cook:
Found the manual! It has instructions for the Models 87, 93 and 90. Sorry, thought I might have an extra copy of the book, but found only one. If you'd like copies of the material, pls pm me your mailing address and I will scan and copy the pages and send them to you.
No, you do not have to clean the breech plug after every shot. After each session, as CreamySmooth suggested. Any good commercial anti-seize grease designed for muzzleloaders will work fine with your GA-90. A cheaper alternative is ordinary white lithium grease. A trick I use all the time, is to wrap the threads with teflon plumbers' tape. Works equally well with breech plugs, as it does with percussion cap nipples and flintlock vent hole liners. For added ease of removal, simply smear a dab of grease on the plug before installing it.
I see you plan on using 270 grain Speer bullets for hunting. I would start at 100 grains and work up to the optimum load. No need to go beyond 120-130 grains, as the law of diminishing returns kicks in and you will get more blast and recoil for little real gain. Plus, you will need to be mindful of velocity, as these bullets are often used in law enforcement, so are designed for rapid expansion, rather than deep penetration. Personally, I would not choose these as a hunting bullet, primarily for that reason.
My experience has been that most muzzleloaders....the Gonic being no different, offer best performance with saboted bullets, with medium/heavy powder charges. More doesn't always mean better.
I have always preferred Pyrodex RS in mine. Also Goex Ffg, for light varmint loads. Triple Seven works fine, too. I haven't tried Blackhorn either, but it should work well, too.
Another bullet you can try....one of my favourites, is the 44/265 grain Hornady jacketed flatnosed bullet. This bullet, factory loaded in the 444 Marlin is a good performer on medium-sized game, like deer, bear, etc. It is also my personal choice for bear.
Again, start at 100 grains and work up to the optimum load for your rifle. Though I found 120 grain charges of RS performed very well with this particular bullet at average hunting distances...100-200 yards...100 grain charges performed equally well, with less recoil. If you shoot a lot beyond 200 yards or more, go with the heavier charge.
The last few years, my go-to bullet is a 44/310 grain cast lead, gas check bullet thrown from a Lee mould. Very hard hitting. In my GA-93, this flatnosed, Keith style bullet prints one hole right on top of the other at 100 yards, using 120 grains of RS. Worth a try. By the way, I've used this bullet with and without the gas check and found no appreciable performance difference between the two.
Hornady XTP bullets are kinda the "belly button" bullet that disappear off the shelves every hunting season. Great bullet for deer. I usually don't see a reason to load hotter than around 90-100 grains with these.
I see you managed to scrounge up some 430 grain, 50 caliber bullets. An excellent choice for all around heavy game shooting. This bullet likes 120-130 grain powder charges.
Hope some of this is useful.
Regards: Alex
