I have been building muzzleloaders for almost 40 years now. No one builds a kit like this expecting to save money and get an authentic product.
These kits are a great starting place for someone who doesn't have the skill or time to carve a stock. There is enough wood in these stocks that, after some research and patience, you can finish a really nice looking rifle.
The value of a kit like this is that you can make a really nice looking gun and put your own sweat into it and wind up with something that looks ten times better than the factory made one.
Dispense with practicality and logic. No one who shoots black powder does so out of sound logic and practicality. With research and a bit of time, a kit like this can look like a million bucks.
My first muzzle loading gun was a Safari Arms Investarms Hawken kit.

Definitely enough wood to get creative. This is the 2nd kit Ive built. The 1st one as an adult with proper tools, and more patience. Haha. Im very pleased with how it turned out. Can't wait to develop loads and get a deer with it!

I've assembled lots of these kind of offshore "screwdriver" trad muzzleloader kits, the last 2 were Lyman (Investarms) GPRs. In comparison, the Gemmer kit is essentially a GPR kit. Without doing any stock woodwork/finishing, once these kit guns are literally screwed together they can be loaded/shot. However, there's always a bit of fitting of some parts to the stock, particularly the lock to its stock mortise.

For this kit, I had to relieve some wood in the stock's bbl channel to allow the bbl to fit. The coil spring flint lock that comes with the kit is decent and will work well enough, but I prefer the better L&R RPL05 lock and that's what I installed - this lock requires a Lot of lock mortise work and is probably not for a newbie to gunsmith work.

It takes rasps, files, scrapers, and sandpaper to take the proud stock wood down to the metal furniture. This can take some time in order to make it both fit and look good = lots of elbow grease. The wood sealing and finish can be any clear coat and staining is optional. Browning the bbl is optional, I prefer to leave them in-the-white to patina on their own as was sometimes done back in that era.

In essence, you don't need to be a gunsmith to build these kits, but you do need to have some hand tool skills along with some time and patience.

For saving $100-$150 by building the kit, you need to weigh the cost versus the work efforts.

If I were to do this again which I wouldn't, I would buy the caplock kit rather than the flint lock. The Gemmer Hawken kit is said to be a copy of the Lyman Great Plains Rifle, but having assembled many of the Lyman Rifle kits in past years, the Gemmer Hawken kit is inferior in quality by quite a bit. This kit is quite over priced for the quality you get with it. I have to admit that I have no one to blame but myself for being drawn in to this purchase but being a custom rifle builder I was very disappointed for several reasons. why did I buy a kit gun then? I have a reason but wont get into that. Will the gun function with the current state of quality? Yes. Will it be reliable? Probably, but with a lot of thoughtful work. What are the issues it has?
1. the inletting of most of the parts have pretty big gaps
2. the quality of the double set triggers is substandard. biggest issue is that they cannot be adjusted properly as they are. the double set sear engagement screw is too short. the trigger sear bar engagement with the lock sear is not correct. Can these be corrected? yes if you know how.
3. The flint lock hammer is not the same scale as the architecture of the rifle profile and looks too small. The size is more for a pistol not a rifle. There are a lot of other issues with the lock as well. the general design of it is mediocre, maybe a little less. I should have known better. Simply, stay away from the flint lock, unless you understand lock geometry and flint lock fitting at installation. Will it work? yes, generally. I believe the cap lock would be much better for most people regarding assembly, adjustment and reliability.
4. the assembly hardware is not that great. all of the machine screws for the lock and tang are undersize. will they work? yes. but I will be machining better ones for this rifle.
5. The breech and tang mortice in the stock has way too much wood removed. I would highly suggest that the builder epoxy glass bed the breech components in the stock to prevent cracking. Gray Marine Tex is perfect for that.

These are the biggest issues with the kit. there are others but stating them would be too picky and are mostly personal preference issues.

What are the positives? The flint lock kit will generally make a functional muzzleloader, but you must be very careful with the lock installation and be sure to eliminate the big gap between the lock and the barrel so you don't blow the lock off of the gun with priming powder entering the lock mortice. It will make a nice gun if you have pretty good knowledge of what you are doing. I like the fact that they leave a good amount of wood in the stock to shape it properly. The barrel fits tightly in the barrel channel, I wish they had paid more attention to the other component inletting. The furniture is not bad and will produce a nice looking rifle, with the proper amount of work. no issues there for the most part. The length of pull will work for most people.

The kit provides all of the parts to assemble a functional rifle. But it is not one of the higher quality kits I've assembled.
I did do a parts price comparison after receiving the kit to what it would have cost to build a high quality custom cap lock J.S. Hawken Muzzleloader without labor cost. The difference was 78.00$ more for custom rifle parts. So consider that.
Final comments: This would be an Ok kit at half the price. It is a Hawken in name only if that matters to you. Had I been able to look at the kit before buying it, I wouldn't have, but It'll be a nice gun when I'm done with it. hope this helps.........

Bought this flintlock kit to have something to do over the winter here in Pennsylvania. and my first impression was that this was going to need some elbow grease a lot of extra wood (I don't mind because I would rather have enough than not enough) but the metal cast parts required a lot of filing and fitting. Little bummed out that the trigger guard wasn't centered correctly with the trigger assembly. It sits off to the side about 1/8 of a inch. Then the trigger assembly I got with the kit had a big crack going all the way around the trigger housing ( they sent me a new one.no charge on my part) then after all stained and blued i noticed when I would run a cleaning patch down to bore the patch would come out torn In two places. And the same after shooting PRB my patches were torn in the same spots. But didn't effect accuracy. Would I recommend it to a friend. Probably if the price was a hundred dollars cheaper. But not for what the price they are going for.