Have you field stripped it, cleaned and oiled it thoroughly. I only have one m-44 and haven't had problems yet, I always clean and oil it after shooting. But who knows maybe I will run into the same problem soon and be asking the same question.
What you have is the cartridge case binding in the chamber not allowing the bolt to open. It's not at all uncommon. Follow these instructions courtesy of NotPC and it should fix it:
As some rifles can use coated cartridges without problems, the trouble is not universal.
1) Make sure that your chamber is absolutely clean and free of any residue. It may have to be thoroughly scrubbed by using lacquer thinner and a 20 gauge shotgun brush driven by an electric drill. I recommend stopping at 30 second intervals and cleaning out the trash. One or two minutes time should do the job. Microscopic residue may have been compacted into the grain of the steel over a 60 year period by thousands of "50K p.s.i. poundings". Compacted residue may appear smooth and reflect light, giving the false impression that a chamber is clean. Not necessarily so. In addition, the use of "de-leading wool" wrapped around the brush is an excellent method to hasten the process. Rust removal will require a little more effort.
2) If this does not solve the problem, one may have to use copper-washed steel-cased or brass-cased milsurp ammo. Some folks use commercially available brass cases and manufacture their own ammunition. Also, some commercially-loaded ammunition is brass-cased.
Yes, a good cleaning in the breach. A lot of surplus ammo is laquer coated. (I guess that's what you are useing) It's a bit of a pain. Dcomf gave good advise. I have 5 of em,all diff. but still ran into the same problem.
The Mosin Nagants all had this problem,in the 2nd world war as well,both the long rifles and the carbines...when the Soviets introduced the Mosin Nagant,they were looking mainly for a cost-effective,simple to clean and maintain,while providing their infantry with a weapon to combat the Winchester repeaters that the Turks were using at the time (I think it's the Turks,don't quote me on it)
The problem with using a cost effective design is,yes,you'lle run into stupid little problems like that,the way I've combatted this,is closed the bolt until I felt it stick...then oiled and scrubbed the area ,and worked it...it still sticks,but not as badly. The Russians,to counter the sticking gave the bolt a rough slap to knock it free,I wouldan't recommend that as you may damage the bolt and/or the reciever. This is assuming that,you are talking about after you fire,when you wish to eject the spent casing...if it's "Jamming" when you are going to re-cock it...again,alot of Mosins have that problem,but as stated by another member above,I think that a good cleaning,and decent ammo would help,not fix,but help the problem...But from my experience with the Mosins,this is a common occurence and theres really not much,aside from oiling it to death,you can do about it.
Also,the condition of the bolt/breach itself could be the problem,is it pitted? scratched?..are all of the surfaces that the bolt comes in contact with damaged? all those things would be a factor as well..
Check all above information as it is all pretty much on the money, another possibility is the ammo you are useing is to hot and heavy, the M44 was designed to shoot 147 grain ammo, I know there are heavyer bullets available but they were origenally designed for the russian machine gun, I have shot some myself with out any problems but I would keep an eye on pressures, as these rounds will expand in your receiver and cause you to have to beat them out with a hammer and dolle rod, I recently got a whole case of this junk, and as you know or will find out there are no returnes on ammo, so try to test drive any you can before you buy in volume, Lacquer is usually the culpret with the sticking action, but just thought I would through that out there for you to think about. Hope it helps.