Well if you can not get Goex or another black powder, there is nothing wrong with good old Pyrodex RS. Pyrodex, while dirty and such is still one of the most consistent powders shot for shot out there. That's why it lasted so many years and actually was recommended by many companies in their instruction manuals. It is also the most corrosive of all powders from tests I conducted.

Some of the other powders will shoot out of a Hawkins as well. APP (American Pioneer Powder) has good power, easy to clean up after, very little to no fowling, expensive, select stores carry it, 2f is a course powder, 3f much better grain size, and some rifles like it. Some rifles hate it. It also can be prone to absorbing water some claim, and hard to ignite in damp conditions. I personally have not experienced that.

Black Mag3 is a very powerful powder. Almost 15-20% stronger then Pyrodex RS. Cut your charges back, It too is clean burning, little fowling, excellent ignition, works good in most rifles, EXPENSIVE, and you almost have to order it from the factory. Also people report in the older batches, the powder was all clumped like a rock. I shot two pounds of it and never had any problems with clumping or anything else, other then cost.

Pinnacle is made by Goex/APP. It is a clean burning powerful powder. Easy to clean up. Lots of pop to it. Easy to ignite, hard to find, and expensive as well. Also another 2f big grains, 3f better. It is made by APP through a Goex patent. Many places do not carry it as well.

Triple Se7en 2f is a clean burning, easy to clean, powerful (10-15% stronger then Pyrodex) easy to find, cost effective powder. It can be hard to light sometimes in damp weather. It will also in many cases smoke your patch on the ball and so a wad must be placed between the powder and the patched ball. Triple Se7en can in some rifles (not all) produce a hard fowling which can fool people into thinking they have set the projectile when they are really just off the powder charge. Any time I shoot this powder I check a witness mark at each loading (as I do with any powder). I like this powder. It is more expensive then Pyrodex but cheaper then the other powders. Plus, many stores carry it.

If you like to shoot, and you can not get Goex, then for a traditional rifle I would stick with Pyrodex RS. It is a time and time again known powder that works. In damp weather hunting, just pull the nipple and put a few grains under the nipple and you will have a sure ignition.