Saw a polymer AK recoil buffer today. Are these actually useful, or just a waste?

Myself and others say they're a waste, other people say they're not. Go a Google search on them and read the myriad of pissing contests to your heart's content.

I was never for them but it might be some extra insurance with the cast rear trunnion US manufactures are using if it causes no issues. That's the only use I can see for them and not really sure about that.

Once again...did the good comrade general design it with one?  At any time?  NO.

If a particular AK needs a buffer...then the gun needs fixed...IO for example.

On some guns that is the fix. You could spend hundreds for a new receiver, & rebuilding your gun on that new receiver, or you could buy the buffer & the gun is fixed. Some Galil's came from the factory with a buffer. What's up with that?  GARY
http://24hourtactical.com/South-African-Recoil-Buffer-Galil-Golani-SA-R4R5R6-GALR4B.htm

Definitely strong opinions on both sides, before I was into the AK forums I added one to my WASR, didn't notice any difference but as I read more I decided that if your spring is strong enough you shouldn't be smacking the back of your receiver.  
I made a similar mistake back when I owned a Beretta 96 and was tying to tame some of the recoil, a popular fix was a silicone buffer that fit around the recoil spring that cushioned the recoiling slide from the frame. But it barely improved the felt recoil and jammed on the first range trip. Adding a Wolff xtra power spring eventually did what I wanted and was only a few dollars more than the buffer.

Save your money,thats all i have to say about them

Buffers seem to be a uniquely American invention to fix our 'Merican AKs. I use them in all of my still screw built AKs that are awaiting proper riveting. They do keep the trunions in place.

1. They were specifically designed with one incorporated as in the case with the R4.

2. They're milled receivers, so there's no chance of a rear trunnion being battered out the back of the receiver due to increased contact.

3. "Some" being the operative word. Obviously they weren't considered necessary on the majority of them, nor on the majority of AK's.

4. Saying that adding a buffer "fixes" the gun is along the same lines as using duct tape to fix a broken stock wrist. Sure, you can do that, but it's ghetto nonetheless.

ETA: For the sake of argument I will concede that there's nothing inherently wrong with using a buffer. As in if it doesn't cause malfunctions and gives you a warm and fuzzy feeling then go ahead and use it. But don't apply magical properties to them like they're going to significantly increase your gun's service life. Because as we've seen from Henderson's amazing thread, they do pretty damn well without them, as intended.

All AK's will exhibit trunnion strike to some degree or another, there I said it. For those that want to argue the point go watch some slo-mo videos of the AK cycling without the topcover...

Comm-bloc ammo is NOT loaded to Match ammo. specs so on occasion YOU WILL GET A ROUND WITH A BIT MORE PRESSURE. This along with the AK being what it is will allow the BCG to hit the rear trunnion leaving that telltale little mark. A weak recoil spring can contribute to this as well, However I've seen NIB PRE-BAN FACTORY MADE IN COUNTRY OF ORIGIN rifles do it right out of the box.

So either the factories that have built  them for decades in com-bloc countries have no fucking clue as to how to build an AK (not likely), or it's just one of those things peculiar to the AK design. You can put a more powerful recoil spring in it (which it wasn't designed for either), replace your existing spring with a factory new one, or add a buffer if it doesn't cause cycling issues. Your rifle, your call...

I've just chalked it up to an AK being an AK ...This was after trying out the remedies listed above. Some rifles had cycling issues with buffers, some I replaced the recoil spring with known factory new springs. After touch-up bluing the marks on the trunnions I noticed they would reappear at some point (??). So either new springs were junk (doubt it), or ammo varied a bit from lot-to-lot with a couple rounds being a little hotter causing the recoil impulse to be a bit stronger and therefore the BCG sometimes has enough momentum to hit the rear trunnion. Watched the slo-mo vids. a bunch and noticed that the carrier wasn't always consistent as to where it stopped during the recoil cycle and started forward again. Sometimes the carrier got closer to the rear trunnion, sometimes was nowhere near it (relatively speaking), other times it hit the trunnion.  

Thought about going extra power spring but since there is no free lunch...i.e. you increase spring rate making it harder to compress, it unloads harder as well, so now you have more force going into the front trunnion, so no free lunch and you haven't solved the supposed problem just switched ends where the force is being directed. Personally, I think I'll just leave it the way MTK intended, since probably he designed the rear trunnion to take the occasional hit, since he put those two LONG RIVETS thru there. Just my opinion based on personal research s take it for what it's worth, or don't. Like I said ...Your rifle, your call.

The habit of really shooting the hell out of guns, it not all that common.  Ammo is expensive or relatively scares in the rest of the world, so wearing out or breaking guns via shooting is rare outside of the first world.

You only really need it if your AK is out of spec and the bolt carrier is jumping off the rails. Another option is to use the Extra power recoil spring with a milled telescoping recoil rod.

Here's my take. One of my recent builds (AK74) has a Bulgarian Steyr barrel and it's slightly over gassed. You can here the carrier banging into the rear trunnion. I installed a buffer so I didn't have to hear the banging or clanging of the metal. Gun works great. Non of my other AKs have them. I think I paid $3 for it at the gun show,

The only real drawback to using a buffer is the chance of it disintegrating over time. It's possible a piece of it may jam the action. So if you like the way the rifle feels and you run a buffer, remember to check it for cracks and wear at every cleaning, and replace it went it looks like it's ready to die.

Maybe with the Black Jack buffer, but not the Buffer Tech. Much better made. 10 years & I haven't been able to kill mine.  GARY

Recoil buffer = your shoulder.

Safety = your finger.

Sight adjustment = aim different.

Straying too far from this philosophy results in increasing amounts of misery, anxiety, and useless cash outlays when it comes to AK's IMO.