Saturday, April 7, 2012

Hi Point drum conversion work.

I don't have any pictures for this post, but I hope to have some up soon.

I have been working on a couple other projects over the last couple weeks in an attempt to get my mind off the Hi Point drum conversion and avoid burnout.
I'm glad I did. I had a new idea on how to get the drum conversion not only working, but make it even better than before.

My original work on this project included modifying a factory mag and welding it on top of a Suomi drum. My results weren't bad, but they weren't 100%, either. I had some jams and some simple issues. Shortly thereafter, I had some personal issues enter the picture that kept me from getting much further on it. I picked up where I left off after a few months, and have tried making new mags to weld on top of the drum, I've smoothed out the inside of the drum to reduce friction, and generally just tried a number of things to get it to work. In my last installment, I had smooth feeding from the drum, but couldn't get the rounds to point up enough to get them to enter the chamber efficiently. I did some work in my CAD program that showed me the problems I was facing. This is a simple fix, but I was still pretty tired of messing with it, especially with all the other projects sitting here.

Anyway, I thought about the whole project, and decided that one of the things I didn't like was how the end product would be just one drum, and it would be prohibitively expensive for anyone to have more than one functional drum assembly. What if I could design a system that allowed me to swap out drums? IF this was possible, it would mean that I wouldn't have to modify the drums. It would require one simple modification that could be done by the owner of the drums. It would cut the overall cost by at least 25%. It would mean that the owner could have as many drums as they wanted, and they wouldn't have to ship them to me for heavy modification.
The more I thought about it, the more I decided that simply welding a mag tower to a drum was just not good enough. I sat down and got back in the CAD program and came up with a steel base that the drum would attach to, similar to a Suomi magazine well, but has a sheetmetal mag tower. There are other drums on the market that have detachable mag towers, so this shouldn't be impossible. Since there won't be as much welding, this should prevent metal shrinkage and burn-through.
The best part? It's cheaper in the long run. Even if the mag tower costs close to the same as the original projected modified drum assembly, it allows the end user to swap out $30 dollar drums as they see fit.

I have some metal pieces cut out and ready to finish machine for the project. The overall design is nothing special, the only specialty part is a sliding cover that fits inside the drum attachment point and keeps rounds inside the magazine from sliding out when the drum is removed. The mag well will look just like it would have on the previous design, but will have a drum mount welded or bolted on.
I am also looking in to the possibility of machining the assembly out of aluminum to save weight, but this remains to be seen.
I will be updating on this idea soon, it should prove to be interesting as to the results. Of course, for anyone following along, final part dimensions will be available to those who desire to build their own and save a buck. If I can make this work, I would of course like to make money off of it; I AM an unabashed capitalist. =)
However, I am also not against helping fellow gunnys out as much as I can. It's not like any of my ideas are THAT original.


  1. This is exciting news -- ingenious!


  2. Oh, but I should have mentioned: I'm no engineer, but I'd worry about the long-term wear of steel on aluminum, though those more knowledgeable may know better. But this new direction sounds awesome.


    1. I would consider the use of a steel bolt carrier in an AR15 upper receiver. There is little appreciable wear on the 7075 aluminum receiver in part because of the anodizing on the receiver.
      Should I machine the drum attachment point out of aluminum, it will be 7075 aluminum and be anodized. The mag would be made of stainless to prevent galvanic corrosion and would be attached by clamp and setscrews.
      I'm betting I will stick with steel, at least for now.

      Thanks for your input, though, as I'm sure plenty of others are thinking something similar.

  3. Did you ever finish the Hi-Point mag conversion yu were doing? If so what is the link to that, id love to read more....

    1. I'm still plugging along on it, been too busy with life lately to do anything else.

  4. I would like one of these. I liek the idea of placing a permanent peice inside the gun the being able to swap multiple drums. What are you looking at final cost to the buyer of one of your amazing inventions? I have the Hi-point 995ts. Oh and what fun it would be to put a drum on my Hi-Point .40S&W!