Chance cycle Dynamics in 3 or more Spring-Piston Airguns Chap seven

Does a higher energy springtime decrease accuracy in a springer air rifle?

​ In this particular chapter we explore what goes on when higher power suspension springs are used in my FWB 124 and LGU air guns. I’ ve heard these rifles are optimized intended for 12 ft-lbs, but they do quite well with higher power springs. Let’ s begin with the FWB 124. After i lubricated my FWB 124 with Krytox, the snout velocity dropped dramatically, therefore i decided to put an older, increased power spring to get the snout velocity back up. This offered me the opportunity to test how the FWB 124 performs with reduced and higher energy suspension systems. The lower energy spring was obviously a Maccari Slightly Softer springtime, which produced muzzle powers around 11. 2 ft-lb. The higher energy spring was obviously a Maccari Pro-Mac, which created muzzle energies around thirteen. 3 ft-lb.   I might expect that the weaker springtime would result in more bright recoil and therefore better precision. Figure 7. 1 facilitates this assumption, with the typical of eight 10-shot organizations for the weaker spring within Fig. 7. 1a) as being a bit smaller (although inside the error bars) of the typical of eight 10-shot groupings for the stronger spring within Fig. 7. 1b).
​ The conventional deviation and extreme distribute of the muzzle velocities had been pretty much the same for each springs.  
Picture

Fig. 7. 1 FWB 124 10-shot groups away bench at 20 back yards with a) Maccari Somewhat Softer mainspring (red rectangle) and b) Maccari Pro-Mac mainspring.
​ A 2 ft-lb (19%) increase in muzzle power is significant, so I had been curious to see how that will increase would affect the recoil traces. I looked at the particular recoil of the FWB 124 with the two springs more than longer times in Fig. 7. 2a) and smaller times in Fig. seven. 2b). Figure 7. 2b) also shows when the pellets exited the muzzle. Amazingly, the position, velocity, and speeding traces are nearly similar over the first 0. 015s! The main difference is that the later oscillations are shifted slightly towards the right (later times) for your weaker Slightly Softer springtime (purple traces). These take place well after the pellet leaves the barrel, so I question that they had much impact on the accuracy or snout velocity. Maybe they are simply due to the different springs sloshing around differently once the pellet has left the barrel?
Picture

Fig. 7. two FWB 124 recoil remnants showing the position, velocity, plus acceleration of the sled-mounted gun for the Maccari Slightly Smoother and the Maccari Pro-Mac mainsprings. a) looks at longer occasions and b) focuses on shorter times and displays the pellets leaving the particular barrel (vertical red lines).
​ Now let’ s have a look at my LGU.   Within the past year, I’ ve already been the only competitor in the World Industry Target piston class in the monthly Rochester Brooks matches  (https://www.rbgunclub.com/field-target/), so I decided to try out the hunter field focus on piston class. HFT includes a muzzle energy limit associated with 20 ft lbs, therefore i replaced the 12 FT-LB (16 J) factory springtime with a 20 J (15 ft-lb) spring that included the rifle. The higher snout energy produces a slimmer trajectory that should really assist with accuracy and ranging with longer distances.  
Figure seven. 3a) shows some focuses on at 20 yards from the bench with both springs plus Fig. 7. 3b) displays three targets at fifty two yards off the bench using the 20 J spring. In 20 yards, the precision was pretty much the same with springs despite the fact that recoil has been significantly stronger with the twenty J spring, which improved the muzzle energy through 11. 1 ft-lb in order to 14. 4 ft-lb.
The variation within muzzle velocity was comparable for both springs. I used to be very excited by the precision that the 20 J springtime produced at 52 back yards. The three 10-shot groups with 52 yards are the best I’ ve ever shot using a spring piston air gun past 50 yards. I used to be especially pleased that the groupings drifted only slightly, using the third group back along with the first group. All the groupings had ctc distances below 0. 9”, with the very first and third groups below 0. 75”. Remember, they are 10-shot groups!
​ The higher snout velocity also took off regarding an inch of pellet drop at 52 back yards, which will help reduce misses because of ranging errors. For assessment with 10-shot groups on 52 yards using the sixteen J spring, please take a look at Fig. 5. 6 within Ch. 5.
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Fig. 7. 3 LGU 10-shot groups off along with at a) 20 back yards with 16J (top) plus 20J (bottom, red rectangle) mainspring and b) with 52 yards with 20J mainspring.
​ Figure 7. four shows the recoil remnants from my LGU using the 16 J and twenty J springs. Unlike the particular FWB 124, where raising the muzzle energy with a couple of ft-lbs didn’ capital t make much difference within the recoil traces, with the LGU a similar increase in muzzle power made a big difference in the recoil. I aligned the sixteen J and 20 L traces using the pellet get out of signals (bottom curves within middle plot). The amplitudes of the velocity and velocity peaks and dips had been clearly bigger with twenty J spring. These highs and dips also had been shifted to longer periods, suggesting that the shot period took a bit longer using the 20 J spring. This really is opposite to the behavior within the FWB 124, where the less strong spring shifted the recoil traces to slightly lengthier times (to the right). Ideally, the traces ought to be aligned according to when the piston was released, but this is difficult to nail down very specifically, so I had to use the pellet exit time, which will be somewhat different due to differences in snout velocity.
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Fig. 7. 4 LGU recoil traces showing the position, speed, and acceleration of the sled-mounted rifle for the factory sixteen J and 20 M mainsprings. Vertical red ranges show the when pellets leave the barrel. Remember that for the 20 J springtime only a single light door was used, so there’ s only one pulse within the bottom orange trace in the centre graph.
​ Finally, I examined to see to if the effectiveness changes when going to a far more powerful spring. Figure seven. 5 shows that the more powerful spring required more function to cock for both the FWB 124 and LGU, however for the FWB 124 the particular resultant increase in muzzle power actually increased the performance, while the stronger spring within the LGU decreased efficiency. One particular difference with the FWB 124 is that the weaker spring had been lubricated with moly/Superlube as well as the stronger spring was oiled with Krytox. For the LGU, both springs were lubed with Krytox. The embrace efficiency with the stronger springtime in the FWB 124 isn’ t very dramatic, yet at least one can conclude that will efficiency in this case did not drop when a stronger spring improved the muzzle energy simply by 19%. I’ m prepared to live with the decrease in effectiveness of the LGU with the more powerful spring if it can preserve better accuracy at lengthier distances.
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Fig. 7. 5 Efficiency associated with FWB 124 and LGU with lower and increased energy springs.
So designed for my FWB 124, maximizing the muzzle energy through 11. 2 ft-lb in order to 13. 3 ft-lb might have hurt accuracy slightly with 20 yards, but not considerably, without affecting the standard change nor the extreme distribute in the muzzle velocity. The particular shot cycle at brief times was pretty much exactly the same for these two springs, however it looks like the oscillations using the weaker spring were somewhat delayed well after the pellet exited the barrel. The particular efficiency with the stronger springtime was slightly better. It might really help to check the precision at longer distance to find out if the higher muzzle speed produced by the stronger springtime can result in better accuracy in longer distances. The higher snout velocity of the stronger thread will produce a flatter flight, which also will help from longer distances.
​ For those of you who would like to maximize the muzzle speed of your FWB 124, I would recommend that you try the manufacturing plant piston seal. I was usually getting up to 50 frames per second greater muzzle velocity with all the factory piston seal more than any aftermarket seal which i tried using a variety of mainsprings.
For the LGU, the stronger spring reduced efficiency a bit and didn’ t change accuracy from 20 yards. However , from 52 yards the precision looks very promising (personal best! ) and the slimmer trajectory will certainly help varying and hitting targets from longer distances. The recoil felt stronger, which is supported by the recoil traces, yet that didn’ t appear to hurt accuracy. If it weren’ t for the 12 ft-lb limit in the World Field Focus on piston class, I would certainly use the stronger 20 L spring in those fits. Since the muzzle energy restrict in the American Airgun Industry Target Association’ s Seeker piston division is twenty ft-lbs, I’ m looking towards trying the stronger spring within my LGU for hunter FEET matches. I wonder if there’ s anything that can get us a few more foot lbs out of the LGU?!
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