Zero weight buffer with strong spring?

[Shobbles]

This may be just a theoretical question as I cannot find much about spring tension. Why not reduce the weight of the buffer to be a light as possible and use a heavy spring? That should result in softer recoil, but may shove the carrier too hard forward. The AK and the like don’t have a weight, but they do have alot more moving mass as part of the bolt and piston group.
It just seems like, especially for ultra lightweight builds, adding mass because the carrier is too light is an odd solution when you could just strengthen the spring a bit.

 

[FrommerStop]

This may be just a theoretical question as I cannot find much about spring tension. Why not reduce the weight of the buffer to be a light as possible and use a heavy spring? That should result in softer recoil, but may shove the carrier too hard forward. The AK and the like don’t have a weight, but they do have alot more moving mass as part of the bolt and piston group.
It just seems like, especially for ultra lightweight builds, adding mass because the carrier is too light is an odd solution when you could just strengthen the spring a bit.

IF what you suggest is doable, someone likely has done it. I am not sure what your objective is.

 

[Duckyou]

From my understanding (which could be lacking here) you need the moving mass to function correctly - it is not just the bolt to move back and forth. There are more movement involved.

 

[Shobbles]

From my understanding (which could be lacking here) you need the moving mass to function correctly - it is not just the bolt to move back and forth. There are more movement involved.

I was just curious to see if anyone knew the “real” answer. I figure if there’s a weight in it after how ever many million$ were spent on development, it must be important. It just seems like a strong spring should be an equivalent solution.
Full auto presents unintended behaviors (I’ve read), and bolt bounce is a big issue that weight apparently is the only solution.

 

[OverEngineer]

Null

 

[Shobbles]

Just found an answer while reading about bolt bounce. The weights inside the buffer move (I thought that was just a cheap buffer and was annoyed by it). The moving weights slap the bolt back forward when it bounces. So the buffer is a separate moving piece which makes my engineering enthusiast side happier.

 

[FrommerStop]

Just found an answer while reading about bolt bounce. The weights inside the buffer move (I thought that was just a cheap buffer and was annoyed by it). The moving weights slap the bolt back forward when it bounces. So the buffer is a separate moving piece which makes my engineering enthusiast side happier.

I it was my understanding that the loosely held weights in the buffer was to facilitate full auto fire by prevent bolt bounce or rebound. If the bolt bounces back at the same time that the hammer is tripped by the auto sear, the gun may not fire.
What I am not sure of is if there is a necessity for loose buffer wts for semiauto fire. It only in the last year or so that I have gotten serious about learning the AR platform.
Anyone here know more about that? I was thinking of asking that fellow on small arms solutions about that. He seems to know more about the colt M16 and following M4 rifles than anyone else that is available. He used to work for colt.

 

[FrommerStop]

There are all sorts special buffers. Here is one. https://www.midwayusa.com/product/1003373611
How and Why to Change Buffer Weight on AR-15 Rifles

How and Why to Change Buffer Weight on AR-15 Rifles

If you have an adjustable gas system on your AR-15 rifle, changing the buffer weight can do some wonderful things; here's how to get it done.

www.rifleshootermag.com

 

[Shobbles]

Wonder how the captured spring “silent” buffers perform. I don’t recall anyone mentioning bounce when I was researching them.

 

[FrommerStop]

Wonder how the captured spring “silent” buffers perform. I don’t recall anyone mentioning bounce when I was researching them.

A worse case scenario of bolt bounce in the AR. Bolt bounce occurs most reciprocating semiauto bolt designs.

To clarify, the internal weights have been removed from the carbine buffer, so it now weighs .8oz instead of 2.9oz. There is nothing to counteract the hammer/anvil action of the bolt carrier impacting the barrel extension - the "hang time" is 39 milliseconds. This video demonstrates the importance of the action spring. The bolt carrier comes to a complete stop for about 12 milliseconds. Interestingly, bolt carrier group speed during the rearward phase is almost identical to the same weapon with a standard 2.9oz carbine buffer.

 

[SAWMAN]

I have several of the JP's in my AR's. They work GREAT !!
You can change the springs in them if needed. With the "normal" spring,it will cycle a 6.8SPCII hot loads,mile loads,223/5.56 hot and book low loads. I have not tried them in conjunction with sub loads,and/or a surpressor.
And they are super quiet and extremely smooth. Especially if you give them a little lube. ---- SAWMAN

 

[Shobbles]

I just shot my bolt with my iPhone camera at 240 fps. I locked the bolt back, then released it. 240 is definitely too slow to get accurate, but after a few iterations, it bounced for 4 to 5 frames, which is 16 to 20ms If my math is correct.

 

[oneshot]

Not such how this worked , but there were some one making weight that fit in the bolt carrier. one time. Just my 5 cents jj I can see a couple of problems with this.

 

[FrommerStop]

Not such how this worked , but there were some one making weight that fit in the bolt carrier. one time. Just my 5 cents jj I can see a couple of problems with this.

I have been looking at lot of youtubes and some carriers are built heavier. This is for blow back ARs that in are pistol calibers. It seems you can get a 9x19 to work, but going up in power there is not really enough wt and CMMG is using their radial delayed blow for more powerful pistol calibers.
The back of the bolt lug locking surfaces are angled so they will move under pressure, but with a delay

https://cmmginc.com/wp-content/uploads/2019/06/RDB-Animation3-1024x576.gif

 

[Dan1612]

OR, we can leave it be to run how it was designed by professional engineers.
Low mass, yes, if tuned properly (JP comes to mind). Again, being an engineer helps.
No mass, not so much.
But even if bubba gunsmith’s kitchen table is too clear and he wants a new project: It begs to question, why?

 

[OverEngineer]

Null

 

[Shobbles]

I have been looking at lot of youtubes and some carriers are built heavier. This is for blow back ARs that in are pistol calibers. It seems you can get a 9x19 to work, but going up in power there is not really enough wt and CMMG is using their radial delayed blow for more powerful pistol calibers.
The back of the bolt lug locking surfaces are angled so they will move under pressure, but with a delay

https://cmmginc.com/wp-content/uploads/2019/06/RDB-Animation3-1024x576.gif

View attachment 89401

That’s pretty nifty. I read a forum where someone went through the calculations and found that 223 would need something like a 20lb bolt for blowback operation.

 

[SAWMAN]

Yeah,there is a good reason why you will not find a 454Casull offered in a Win94 action but IN a 92 action. It's called working pressure (60K psi) and case head thrust. --- SAWMAN

 

[FrommerStop]

OR, we can leave it be to run how it was designed by professional engineers.
Low mass, yes, if tuned properly (JP comes to mind). Again, being an engineer helps.
No mass, not so much.
But even if bubba gunsmith’s kitchen table is too clear and he wants a new project: It begs to question, why?

Some engineers are very clever and others have experience that they can also rely on. One can set the gas on an AR so that with the perfect weighted buffer it will give the most manageable felt recoil. Works well on the range. In the world of real life having more gas than is needed is what the experienced engineer will consider for when things are not optimal like with fouling, dirt, and with less than optimal ammo.
Several of my AR uppers came over gassed; that is normal for economy uppers. That is done to ensure function if something is not optimum. I Simply upped the buffer wt and they function fine with any brand of mag and the ejection is to behind and not forward. A down side is that the BCG components might wear or fail sooner. But such parts are cheap and I keep spare parts.

The more gas, the more rapid the BCG speed. The more rapid the BCG speed, the more to the right front will be the ejection pattern. A faster moving bolt will be extracting while chamber pressure is higher. Means more wear on the extractor for example. Everything should be adjusted from what I have read to eject from 3-4:30.

 

[Dan1612]

Several of my AR uppers came over gassed; that is normal for economy uppers. That is done to ensure function if something is not optimum. I Simply upped the buffer wt and they function fine with any brand of mag and the ejection is to behind and not forward. A down side is that the BCG components might wear or fail sooner. But such parts are cheap and I keep spare parts.

I don’t buy garbage rifles, but if I did, I’d do the same thing.
That’s a great pic, it’s what I use when adjusting a gas block after suppressing.