Buffer bumper material

[Disciple]

From a most interesting but very long thread I do not wish to lengthen further with ancillary digression:

Possibly, but probably not.

People don't know a good portion of the forward velocity comes from the buffer tip rebounding off the end of the RE.

The action spring can't really deliver much energy during the 1/4" of over travel, but the buffer tip returns some % of the rearward velocity nearly instantly.

Assuming this rebound is undesirable, as I understand it to be, is there no material with greater hysteresis that is sufficiently rigid and durable? Polymer science has likely improved since the original material was specified.

[markm]

I'm no engineer, but it strikes me that you're searching for a problem with the buffer system that doesn't seem to exist. I mean... in my years of running this platform, I've found the WAY bigger problem is incompetence from those who've set specs for gas ports.

"We" shot the AR for decades with over gassed ports that lead to all kinds of functionality issues and false hysteria on the system's reliability; and also all kinds of ridiculous aftermarket gizmos (pig tail gas tube, for example) to treat the symptoms of these over gassed nightmares.

I'm not trying to be argumentative, but it seems that the buffer system in place is just fine.

[Clint]

It's not necessarily undesirable.

It just means the closing velocity during the normal cycle is higher than the closing velocity of the first round chambered when using the bolt catch or charging handle.

BTW, one of the other things that pesky little A5 biasing spring does is reduce the rebound energy.

From a most interesting but very long thread I do not wish to lengthen further with ancillary digression:



Assuming this rebound is undesirable, as I understand it to be, is there no material with greater hysteresis that is sufficiently rigid and durable? Polymer science has likely improved since the original material was specified.

[Disciple]

markm, I cannot disagree. I find the exploration of the physical properties of the system interesting in itself. I read the entire exchange between lysander and StainlessSlide for example.

Clint, thank you.

[99HMC4]

We tested a lot of different designs and materials for the LARB tail cap for those reasons...

[Disciple]

Interesting product. The conical contact face makes sense to me. How does the thermal and chemical stability of your material compare to the original? What is its fatigue life? Have you measured energy return for the two bumper types?

Magnetic eddy current braking should be excellent here, if damping is desired, and searching for that I found the Omni Robusta LLC M.A.R.R.S. Buffer. It doesn't appear quite ready for market to me—I don't like the abrupt ledge between the body and the tail—however with development I think the concept could become the reference design.

[99HMC4]

Interesting product. The conical contact face makes sense to me. How does the thermal and chemical stability of your material compare to the original? What is its fatigue life? Have you measured energy return for the two bumper types?

Magnetic eddy current braking should be excellent here, if damping is desired, and searching for that I found the Omni Robusta LLC M.A.R.R.S. Buffer. It doesn't appear quite ready for market to me—I don't like the abrupt ledge between the body and the tail—however with development I think the concept could become the reference design.

The material we use will last the life of the weapon, we have yet to wear one out and every been trying for the last 4 years. Unless you’re cleaning your weapon with aircraft paint stripper, we haven’t had any chemical issue whatsoever ever. We did energy absorption testing by way of bolt velocity/ rate of fire.

[Disciple]

We did energy absorption testing by way of bolt velocity/ rate of fire.

Do you publish those values?

[99HMC4]

Do you publish those values?

No, only thing we released was a percentage, which was around 20% reduction. You don’t let everyone see all your cards. ��

[lysander]

From a most interesting but very long thread I do not wish to lengthen further with ancillary digression:



Assuming this rebound is undesirable, as I understand it to be, is there no material with greater hysteresis that is sufficiently rigid and durable? Polymer science has likely improved since the original material was specified.

Rebound on the back end IS desirable. It allows for a greater velocity when closing than the spring can deliver without becoming difficult to open.

It's rebound off the barrel extension that is undesirable.

OH, and the original material was a polyether urethane with a hardness of 95 Shore A. It was chosen because of its good rebound properties. Remember the original buffer design was a stiff spring.