Ville28 Posted February 18, 2014 Report Share Posted February 18, 2014 Looking at the springs and actuators for a 21 and 28 buffer system I was wondering if the 21 or the 28 absorb more kinetic energy and rely less on impact with the rear of the receiver to retard bolt action given equivalent blish lock function? Also, is there any technical information available about the proportion of recoil that is retarded by the blish lock verses the recoil spring system? Thank you very much! Link to comment Share on other sites More sharing options...
mnshooter Posted February 18, 2014 Report Share Posted February 18, 2014 This has been debated for, oh, about 86 years or so. Still no scientifically proven answer, even though the physics would be relatively easy to test. Mythbusters never answers my letters. Link to comment Share on other sites More sharing options...
jim c 351 Posted February 18, 2014 Report Share Posted February 18, 2014 Ville28, I don't know the scientific answer to your question. However when the Blish is disabled the gun fires faster. Since the 21 system reciprocates faster, I would think this system hits the receiver rear harder. Jim C Link to comment Share on other sites More sharing options...
joseph12297 Posted February 18, 2014 Report Share Posted February 18, 2014 OK, engineer drinking coffee, so I'll bite on this one... I would think the energy upon the spring and buffer and rear of receiver on the 21 and 28 would be the same. Discounting the Blish lock, all of reaction is in direct line with the rear of the receiver.The back pressure energy from one 45ACP fired in the chamber would be working against the buffer assembly of the 21 or 28.The 28 has a larger mass in motion, and slower rate, but the energy should be the same as they both are opposing the exact same total force from the cartridge.I think the question of how much of the total force is actual impact on the rear of the receiver really does not matter,(unless your buffer disc was worn out and had metal to metal contact and cause damage) the total force on the rear of the receiver is the same. I could be missing something, I will need another cup of coffee to ponder further..... I have no thoughts on how much energy the Blish lock takes away from the reaction to the rear of the receiver, some I would guess because it travels at an angle. I think felt recoil from my 21 may be less than from my M1A1 (no Blish), but that might be partially because the Colts guns are fitted so nicely. Larry Link to comment Share on other sites More sharing options...
Ville28 Posted February 18, 2014 Author Report Share Posted February 18, 2014 Thanks for the caffeine induced insights! I guess all things equal the force seen by the rear of the receiver would be the same but if you looked at a graph of force vs. time would the 21 show a quicker spike? Also, with less buffer and less inertia would the 21 rely more on the fiber washer to abruptly stop the bolt than a 28? What really got me thinking about this were some of the previous discussions about the receivers in 28 Westies having a tendency to crack due to a variety of reasons. Just curious if a 21 configuration would be a little rougher on a receiver than a 28. Thanks! Link to comment Share on other sites More sharing options...
jim c 351 Posted February 18, 2014 Report Share Posted February 18, 2014 Thanks for the caffeine induced insights! I guess all things equal the force seen by the rear of the receiver would be the same but if you looked at a graph of force vs. time would the 21 show a quicker spike? Also, with less buffer and less inertia would the 21 rely more on the fiber washer to abruptly stop the bolt than a 28? What really got me thinking about this were some of the previous discussions about the receivers in 28 Westies having a tendency to crack due to a variety of reasons. Just curious if a 21 configuration would be a little rougher on a receiver than a 28. Thanks!Ville, I'm definitely in the camp that believe the 21 set up would be more stressful on the receiver rear end. If you are determined to follow thru on this then here's an experiment. Get a lead or copper BB pellet and figure out a way to fasten it to the rear of receiver where the bolt would strike. Scotch tape would probably work. Fire one shot using the 21 system and another with the 28 system. Using a micrometer measure each BB. The one that is the most compressed is the one most stressful to the receiver.. That's your homework assignment for today, and then report the results to us. Jim C Link to comment Share on other sites More sharing options...
joseph12297 Posted February 18, 2014 Report Share Posted February 18, 2014 Hi Men, I would agree with everything stated.But the total energy should be the same, obviously that force over the surface area that is spread over may be a variable... I may need to run some theoretical numbers on pieces parts Link to comment Share on other sites More sharing options...
mnshooter Posted February 19, 2014 Report Share Posted February 19, 2014 (edited) Thanks for the caffeine induced insights! I guess all things equal the force seen by the rear of the receiver would be the same but if you looked at a graph of force vs. time would the 21 show a quicker spike? Also, with less buffer and less inertia would the 21 rely more on the fiber washer to abruptly stop the bolt than a 28? What really got me thinking about this were some of the previous discussions about the receivers in 28 Westies having a tendency to crack due to a variety of reasons. Just curious if a 21 configuration would be a little rougher on a receiver than a 28. Thanks!Mass times velocity. Some things never change.The only thing you should use that fiber washer for is to level an uneven table leg. It is about worthless compared to the more recent neoprene buffers. Edited February 19, 2014 by mnshooter Link to comment Share on other sites More sharing options...
reconbob Posted February 19, 2014 Report Share Posted February 19, 2014 Here we are again. A couple of thoughts - - while the two recoil mechanisms are dealing with the same force - i.e. the recoil energy of .45 ACP, the power of the recoil springs and the weight of the recoiling parts is different. It might be that the impact force of the bolt on the back of the receiver is the same for M1921 and M1928A1, but then again it might not. If you had a VERY strong recoil spring the bolt would not recoil at all. So you can't say that because its the same cartridge the force on the back of the receiver is the same regardless of the weight of the actuator and strength of the recoil springs. - there is considerable scientific and engineering study of the Blish principle - its does exist. Recall that Auto-Ordnance experimented with hi-powered rifles using this principle. The patents were issued based on engineering study and test firing. Remember that one of the purposes of a patent is that anyone who follows the engineering data in the patent can make an identical working mechanism, or machine, or whatever it is. - Jim C. has a great idea. For a few years now I have wanted to make a receiver where the bolt would strike a rod in the back of the receiver which would transfer the force of impact to a sliding weight. The distance the weight would move would show the force and therefore the velocity of the recoiling bolt. Once set up it would be easy to fire and measure M1921 vs. M1928A1 vs. M1 and blish lock vs. no blish lock. Maybe someday.... Bob Link to comment Share on other sites More sharing options...
PK. Posted February 20, 2014 Report Share Posted February 20, 2014 I would point out that the 21 buffer pilot puts all the stress onto a very small shoulder and into the receiver. It should not be used without a breech oiler, which acts as a hardened washer to spread the load. I cannot recommend that the 21 style buffer system be used in any WH gun because of the unhardened material in the receiver; far better to use a system that mates the large diameter 28 disc with the 21 bolt parts and spring. Link to comment Share on other sites More sharing options...
Ville28 Posted February 20, 2014 Author Report Share Posted February 20, 2014 Thanks to all for their insights on this question! I have just a couple of other thoughts that I have been pondering: Even though the springs for the 21 and 28 system are dimensionally different, would anyone know if they are similar in terms of Hooke's law or are both springs compressed/extended an equivalent length for a given force? Finally, thinking about the differences in the mass of a 21 vs. 28 actuator and given a constant force, I would think acceleration of the bolt/actuator combination would be the only thing that would be different? Of course if the springs are similar as asked above. Thinking about F=ma and a=F/m, both scenarios would impart the same force on the rear of the receiver but the acceleration and cyclic rate of the 21 would be faster which is definitely what is observed. Thanks again and please let me know if I am missing something! Link to comment Share on other sites More sharing options...
gijive Posted February 20, 2014 Report Share Posted February 20, 2014 I think you missed the link to the Math, Physics and Engineering Forum Here it is for future reference: http://empforums.com Seriously, some very knowledgeable people here. Link to comment Share on other sites More sharing options...
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