swo1.completely different in every single way possible.before i go any further thank you for appreciating my firearms.not many do. Only if you where a military man or up on history or rare firearms.most have never heard of half my guns,so thank you.i hate cleaning ar15`s.the bolt with it cotter pin,cam,firing pin,the gas tube always fouls up at the worst times.i carry a dozen pipe cleaners with me so i can gt the darn thing to eject,finicky with ammo.everyone knocks ak47`s.look at what ar15 companies are doing,either a retrofit spring and piston system exactly like the ak47 or now straight up making them piston driven like the ak47.people say ak47`s are garbage as far as accuracy.i own twenty five ak47`s and can tell you.if you use good brass.shoot three shots at a time,no rambo 30 shots in 20 seconds.at 100 yards you can easily do a four inch grouping with open sites.it is an internediate cartridge,like a 30/30 give or take.good to about 150 yards tops with practice.but it is a large arching bullet,so the moa is crap.but again it is no sniper gun.it is what it is.in the early 60`s a spanish designer came up with a design unlike the gun world has ever seen.it is a huge two piece bolt that runs on tracks with rollers and the firing pin slides in the middle with a stop.the rollers are actually the headspacing,so if your spent casing start coming out screwed up or it won`t feed likely you go up a size in rollers and it has a huge buffered spring in the back that pushes it forward.like two feet long and has a huge buffering system so the gun has zero kick even if you dump twenty rounds of 7.62nato.the muzzle brake and buffer keep the gun on target and it does not climb like you think it would.the simplest design in the world.the stock is held in by two pins.you push the pins out and there are two holes in the stock to put the pins so you do not lose them.pretty ingenious.the stock comes off with the buffer spring.you turn the gun down and the whole bolt carrier rolls out of the gun.inside there are tracks for the rollers,very cool.you take a small screwdriver and put it between the two part bolt assembly which is humongous and turn and the extractor and firing pin and rollers drop free.spray them down with brake clean.spray them with a good gun oil.as the two parts to the bolt carrier are apart you push the firing pin in the back,the extractor sits on the right side,huge ejector.as your ready to push the two pieces together,you roll the rollers into place on the carrier and push them together locking the rollers and extractor in place you shove the whole carrier back in.push the pins out the stock.pop the stock back on.push the pins in and your done.the bolt carrier is about six inches long and two inches wide and is made out of rhynemetal.a metal so strong they use it in super high rounds per minute machine guns.with three parts in it and the rollers that slide in the guides.the gun barely gets dirty.you could not lose a part if you tried.i spray out the whole inside cavity with brake kleen and spray a good gun oil inside,do the same with the bolt and carrier and pop the stock back on and your done.i do not heat the barrels of my guns up.but once in a while i will blow through the 20 round clip just to make sure it is feeding properly and as fast as i can pull the trigger on a target i can hold a pie plate group.you use a car feeler gauge to make sure you have the right roller size and head spacing.the only gun easier to clean is an ak47 and even the ak47 the top cover is a pita sometimes.the gun is a big long heavy durable and accurate firearm.the bolt carrier design was used in the cetme.the g3,h&k91 and any other h&k design and the germans make some of the finest weapons out there.but they bought the delayed roller blowback design from the spanish.if you googled it.the whole gun and carrier show up and you will not believe how simple and huge these parts are.i have never had any hiccups out of any of my guns,never changed rollers and head check with a feeler gauge now and then.there are tons of factory parts cheap.i could give you a million different places to get parts.it is even simpler to take apart than a fal and the parts from a fal basically fall out and go back together in one unit.you will be impressed if you ever shot one or dissasembled one.like i said as fast as you can dump 20 rounds of 308 the gun stays on target and zero kickback.you could shoot the gun all day.they even make five round mags and i shot hogs with it and coyotes.accurate gun for what it was built for.thanks for asking and appreciating my collection.as i said not many people know what kind of guns they are.a ppsh43 that shoots 7.62x25.who would even know what that is if they where not a history buff or like and appreciate miliary rifles...i will keep posting em..i hope you got some info you can use.ptr91 makes a beautiful one. Not german of course but for a very reasonable price for about 1k or so.the guns are indestructable.truly a fine design..