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Discussion Starter #1

I'm wondering if anything like the Blitzkrieg Hydraulic Buffer could be designed for the Sub2000?

Felt recoil is probably the biggest drawback to direct-blowback designs. With the surge in popularity of 9mm in the AR world, Blitzkrieg has made a hydraulic buffer for 9mm ARs which dramatically reduces felt recoil by acting as a mini-pneumatic shock-absorber piston in the buffer tube. https://www.blitzkriegcomponents.com/ProductDetails.asp?ProductCode=AR15-KYNJP-9C




 

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Maybe one could be made for the sub2k, but it would need to be pretty small. I also think it would be a part in search of a problem. I'll explain.

There are polymer buffers already and they don't allow the bolt hold open notch to do it's job, and they are maybe an inch long if memory serves. So IMO a lot is given up to get the minimal effect that it would provide. More on that in a bit. But back to your question, I don't think one could be made small enough.

I've read of folks expressing a desire for recoil reduction on this forum but it's only a 9mm with 9mm recoil. Assuming it halves the recoil (it won't), half of nothing is still nothing. It's not like it actually has significant recoil to begin with. Personally I don't see the need. Having written that I did try one of the polymer offerings because I shoot competition and if it gives even a few more points it's worth having. But I thought the negative of losing the hold open notch far outweighed any recoil mitigation it provided.

Too, the long bolt travel on the Sub2k means that it doesn't butt up against anything at the farthest rearward travel of the bolt. I think if anything helps, adding the heavy bolt weight will take care of it. They were designed for the .40 (I think) but they work fine for 9mm, even the butterfly fart loads I shoot in competition. The buffer I had in mine? I doubt the bolt ever touched it. It prevented use of the bolt hold open notch so it didn't last long installed in mine. I think a hydraulic offering would be lots more expensive with the same negative, and do almost nothing unless it was really long and even more obnoxious than the polymer ones.
 

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Discussion Starter #3 (Edited)
Maybe one could be made for the sub2k, but it would need to be pretty small. ...
No, not like the bolt-buffer disks by MCarbo and Tacticool as you mentioned. But something to replace the bolt/carrier on the Sub2000. If the back half of the bolt as cut down and replaced with a pneumatic buffer or the whole thing was designed to replace the bolt, locking into the bolt head, wouldn't that be possible? Though, the mass would need to be replaced with something equally as dense to slow the bolt. I'm not just spit-balling here.

 

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That's exactly what it is, dead mass. It's a blow back gun. That's how it works. It doesn't get simpler than that.

But going off of your illustration, the bolt group doesn't hit anything now, one can't get a more gentle operation than something coming back against a spring, hitting nothing and being pushed back forward. So why would you want to spend big bucks to get it to hit something that it doesn't need to in it's travel? It would create problems that would then require something expensive to fix it, like a hydraulic buffer and eventual parts replacement. The problem doesn't exist now so why make parts that would create it?

If it hit something at this time in order to come to a stop, the hydraulic buffer might make sense as placed where you have it, but it doesn't hit anything to stop that I ever saw evidence of. Maybe if one used +p+ ammo it might make sense, but that's off limits for the rifle. +P can be used but only on a very limited basis and never is best. If you want a rifle that uses a hydraulic buffer, rather than trying to redesign the sub2k into something it was never intended to be why not get an AR type and get the hyd' buffer put in it where it's designed to work?

You'll find that hyd' buffers aren't there to cushion something stopping but to cushion and smooth out the recoil impulse as the BCG starts to move to the rear. Do a 'net search for Enidine Hyd' buffer for more information. I have one, they work, but they can't be purchased today. Others are available though today and the hyd' portion is always used to the front and never pointing back. That's in ARs.

There are guns that use hyd' buffers against the bolt to cushion it (Swiss made B&T) and they work exactly the way you suggest, but that isn't the Sub2k or the AR family. Look at the way B&T guns work and you'll see your suggested design, sort of. I think B&T has manuals posted for downloads, with exploded views. But they are designed with hyd' buffers in mind. I don't even know if the buffer in my GHM9 has ever been used. I think it's there mostly for NATO sub gun ammo and +p and +p+ ammo. It has a heavy bolt and a heavy spring rate, more so than the sub2k.
 

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I can imagine a hydraulic bolt weight. This photo shows the hydraulic buffer right next to the bolt weight it would replace. Flip the buffer 180 deg and fashion a hook to attach it to the bolt.

But I have no idea how to predict the effect replacing mass with hydraulic resistance will have on a blowback ignition sequence.
 

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Discussion Starter #6
Flipped image in the earlier post. As both you and BJK mentioned, the reduction in mass would have to made up with a weighted piston probably. I'm not a firearms designer so this is just daydreaming but I thought I'd share.
 

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I too, am not a firearms designer. I believe the Bolt mass weight is designed to allow the bullet to completely leave the barrel length. Pistols use the weight of the slide, AR's allow exploded gases to add opposing pressure. Different spring rates help, but even then it usually is a small change in the portion of the designed rate. I would like to think a Progressive Spring style would be the best. Or, a mechanical screw type to adjust the pre-load/unload pressure to the spring. If I had lots of time, friction rated O-Rings around the bolt weight, or a tapered / funneled style of weight inside the stock tube. Always, the variable is the bullet weight, and gun powder energy. And, you should consider the environment, ( Hot / Cold ) to change the equation as well. Oh, to much thinking, I must rest at a Holliday Inn Express!!
 

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Maybe one could be made for the sub2k, but it would need to be pretty small. I also think it would be a part in search of a problem. I'll explain.

There are polymer buffers already and they don't allow the bolt hold open notch to do it's job, and they are maybe an inch long if memory serves. So IMO a lot is given up to get the minimal effect that it would provide. More on that in a bit. But back to your question, I don't think one could be made small enough.

I've read of folks expressing a desire for recoil reduction on this forum but it's only a 9mm with 9mm recoil. Assuming it halves the recoil (it won't), half of nothing is still nothing. It's not like it actually has significant recoil to begin with. Personally I don't see the need. Having written that I did try one of the polymer offerings because I shoot competition and if it gives even a few more points it's worth having. But I thought the negative of losing the hold open notch far outweighed any recoil mitigation it provided.

Too, the long bolt travel on the Sub2k means that it doesn't butt up against anything at the farthest rearward travel of the bolt. I think if anything helps, adding the heavy bolt weight will take care of it. They were designed for the .40 (I think) but they work fine for 9mm, even the butterfly fart loads I shoot in competition. The buffer I had in mine? I doubt the bolt ever touched it. It prevented use of the bolt hold open notch so it didn't last long installed in mine. I think a hydraulic offering would be lots more expensive with the same negative, and do almost nothing unless it was really long and even more obnoxious than the polymer ones.
I am a newbie to the Sub 2000. Having said that I noticed you saying that the bolt never hits anything in recoiling. However when I read the adds for recoil reducers the small washers are supposed to cushion the bolt from striking that bit of hard plastic...Is that correct or am I reading it wrong? Also if what you say is true, and I believe you as I got some good info from you with the use of those models to help unfold my Sub 2000 in an earlier post. It seems someone is sort of fibbing as to what those washers accomplish.

So to make a long question short. Does the little washer actually prevent the recoiling bolt from hitting the plastic thus reducing felt recoil?
 

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Maybe with ammo that one isn't supposed to use in the S2k they'll work. Maybe. If it made a habit of hitting the piece at the end, it's made of plastic and it wouldn't last very long. But that's my opinion. What isn't my opinion, is that plastic can't take being smashed against to any degree. There's never been one made that can stand up to that in the long term.

Understand that people are out to make a buck. It's like firearms lube. Each one is the best that ever was. Just ask the folks selling them.

In some firearms a hydraulic buffer is designed to be part of the action and to do exactly that, but the part is designed in. The foam ones are only a few bucks and I think most folks just shrug and buy one. I also think that's what the makers of them hope for. It's more or less free money (It's only foam!). But I've also been a curmudgeon for years now. I've also seen lots of snake oil being sold.
 

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Maybe with ammo that one isn't supposed to use in the S2k they'll work. Maybe. If it made a habit of hitting the piece at the end, it's made of plastic and it wouldn't last very long. But that's my opinion. What isn't my opinion, is that plastic can't take being smashed against to any degree. There's never been one made that can stand up to that in the long term.

Understand that people are out to make a buck. It's like firearms lube. Each one is the best that ever was. Just ask the folks selling them.

In some firearms a hydraulic buffer is designed to be part of the action and to do exactly that, but the part is designed in. The foam ones are only a few bucks and I think most folks just shrug and buy one. I also think that's what the makers of them hope for. It's more or less free money (It's only foam!). But I've also been a curmudgeon for years now. I've also seen lots of snake oil being sold.
Thanks for your opinion. I also cannot imagine the plastic taking a beating like that for any length of time.
 

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Maybe one could be made for the sub2k, but it would need to be pretty small. I also think it would be a part in search of a problem. I'll explain.

There are polymer buffers already and they don't allow the bolt hold open notch to do it's job, and they are maybe an inch long if memory serves. So IMO a lot is given up to get the minimal effect that it would provide. More on that in a bit. But back to your question, I don't think one could be made small enough.

I've read of folks expressing a desire for recoil reduction on this forum but it's only a 9mm with 9mm recoil. Assuming it halves the recoil (it won't), half of nothing is still nothing. It's not like it actually has significant recoil to begin with. Personally I don't see the need. Having written that I did try one of the polymer offerings because I shoot competition and if it gives even a few more points it's worth having. But I thought the negative of losing the hold open notch far outweighed any recoil mitigation it provided.

Too, the long bolt travel on the Sub2k means that it doesn't butt up against anything at the farthest rearward travel of the bolt. I think if anything helps, adding the heavy bolt weight will take care of it. They were designed for the .40 (I think) but they work fine for 9mm, even the butterfly fart loads I shoot in competition. The buffer I had in mine? I doubt the bolt ever touched it. It prevented use of the bolt hold open notch so it didn't last long installed in mine. I think a hydraulic offering would be lots more expensive with the same negative, and do almost nothing unless it was really long and even more obnoxious than the polymer ones.
did you use the Tacticool buffer?? the M*CARBO recoil buffer (when installed) allows the locking of the bolt..
 

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I don't remember whose I bought. But my bolt wouldn't lock open so it must be the Tacticool version.
 

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Discussion Starter #13
I believe the buffer does make contact with the buffer, albeit slowed down enough by the recoil spring not to damage it over time. Funny, but of the plethora of threads discussing plastic Sub2K plastic parts that have broken, the buffer block isn't one of them :p:D.

BTW I once looked into the MCARBO and Tacticool buffer devices. I opted to simply use a silicone grommet that I had a bunch of.
 

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I know replacing the piston spring on an air rifle with a pneumatic cylinder really smooths out the firing impulse and makes cocking a lot smoother. So i wonder how a properly spec'd one would work to replace the buffer tube springs on AR type rifles. or maybe the options already exist? I saw an olympic arms one but the site no longer list it. Users seemed to like it
 

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So...what is the verdict? Do recoil buffers in the form of somesort of plastic ot whatever soften recoil or not?
 

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So...what is the verdict? Do recoil buffers in the form of somesort of plastic ot whatever soften recoil or not?
i noticed the most difference with the MCARBO buttstock pad and the heavy-weight bolt from KelTec
 

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Ok, i have the brass weight, and the sumo. Im on my second sumo, as the normal 115g rounds i use caused the pin sticking out of the sumo to crack against the "buffer tube?". Where the sumo slides back and forth, at the backside the thing that stopped the whole bolt was not spring or plastic. It was the rod attached to the sumo that slides into the bolt weight. It snapped clean off one day at the range. On looking at the pieces, it was clear the buffer tube had dented the crap out of that rod, to point of failure.
To be fair the springs main job is simply to return the bolt to charge. All else is coincidental. I could totaly see a longer weight with a micro piston in it. But more than likely you would also have to replace the buffer tube. That tube was not designed to hold the tailend against actual impact. Even if you made that buttstock out of aluminum. Now im all for a complete rebuild of the buffer tube. I dont think you need to replace too much weight with the piston in place, because the spring should have enough force to drive the bolt plus weight /piston back to battery.
My understanding of physics and rebound control is always questionable, so by all means tell me how wrong i am. If i didnt hate math so much id run some numbers to back my position. But i need to be paid to do math...
 

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To be fair the springs main job is simply to return the bolt to charge. All else is coincidental.
Umm, no.

Make a video for us... remove the spring and just cycle the gun manually to feed a cartridge into the chamber. You can let us know from the hospital bed how you made out and post the video.

The sub2k is a blowback gun. The mass of the bolt retards the uncorking of the chamber, and the spring contributes to that as well as bringing the bolt to a halt after it finally does get moving. Then and only then does it push the bolt forward to pick up another cartridge. Without that spring the bolt would need to be far more massive so as not to blow the shooter up. I think you have it bassackwards, the picking up of the cartridge is incidental, not blowing the user and the gun up would be the far more important function. But if you don't believe me make that video and prove it to yourself.
 
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