At what point does the pellet exit the barrel?

[mikeyb]

I found the slowmo video of a springer doing its dance. It was related to AOA testing the Diana ZR mount. You can watch the entire video normal speed but I suggest watching from the time linked at 0.25 speed. 

Michael;

That video is flawed in many ways.

If you look closely to the times annotated in the video, you will note that the gun starts to move back at ms -408.8
Then the maximum excursion OF THE MOUNT is achieved at ms -398.1
Then the MOUNT bounces at ms 393.5 and then bounces again later at an undisclosed time.

Compare that shot cycle with the one in this video:



And you will see that the gun actually completes the shot cycle before the ZR mount can catch up with it.

;-)

Keep well and shoot straight!

HM

Sorry Hector, I don't understand the point you are trying make.

I referenced the video to show how much a springer jumps and dances before the pellet leaves the barrel. The clear and time-stamped AOA video at 10000 frames per second looks spot-on to me. Shot cycle duration approximately 10ms (-408ms to -398ms) with pellet likely leaving the muzzle around -396ms(?). What is interesting to me in the AOA video is the all the additional movements (dancing & flexing) of the action, the end cap, and the safety lever that highlight how violent a springer shot cycle really is.

The Diana ZR mount in the AOA video looks to me like it is doing its job exceptionally WELL!. Scope appears to be almost completely isolated from the LARGE springer movements. Yes the scope is slowly moving/recovering its "zero" position after the initial shot/rifle-dance. The scope may even bounce a little in the mount but that is what I would expect to see from a slightly underdamped vibration/shock isolation system.


Anyone watching the AOA video should see confirming evidence of at least three things we "thought we knew" about springers and scopes.

1) Springers jump and vibrate A LOT during/after a shot.
2) A ~10ms shot cycle time calculated/simulated/measured for major piston/rifle movements is very close.
3) A Diana ZR mount can isolate a scope VERY WELL from the most violent springer motions.

I see essentially the same thing in the low res video clip. The rifle jumps while the scope slowly reacts and lags behind the rifle movements as the ZR mount does its isolation thing.

Are you suggesting that the ZR mount in the AOA video is too underdamped and needs to be better adjusted or "tuned"?

[HectorMedina]

Sorry Hector, I don't understand the point you are trying make.

I referenced the video to show how much a springer jumps and dances before the pellet leaves the barrel. The clear and time-stamped AOA video at 10000 frames per second looks spot-on to me. Shot cycle duration approximately 10ms (-408ms to -398ms) with pellet likely leaving the muzzle around -396ms(?). What is interesting to me in the AOA video is the all the additional movements (dancing & flexing) of the action, the end cap, and the safety lever that highlight how violent a springer shot cycle really is.

The Diana ZR mount in the AOA video looks to me like it is doing its job exceptionally WELL!. Scope appears to be almost completely isolated from the LARGE springer movements. Yes the scope is slowly moving/recovering its "zero" position after the initial shot/rifle-dance. The scope may even bounce a little in the mount but that is what I would expect to see from a slightly underdamped vibration/shock isolation system.


Anyone watching the AOA video should see confirming evidence of at least three things we "thought we knew" about springers and scopes.

1) Springers jump and vibrate A LOT during/after a shot.
2) A ~10ms shot cycle time calculated/simulated/measured for major piston/rifle movements is very close.
3) A Diana ZR mount can isolate a scope VERY WELL from the most violent springer motions.

I see essentially the same thing in the low res video clip. The rifle jumps while the scope slowly reacts and lags behind the rifle movements as the ZR mount does its isolation thing.

Are you suggesting that the ZR mount in the AOA video is too underdamped and needs to be better adjusted or "tuned"?

Michael;

Sorry for not making myself clear.

First off, the video was not commissioned by AoA, it was commissioned by DIANA. It was made with Gen I  mounts i a German spec gun.

You are right in that the spring in the mount in the video is OVER reacting, it makes the scope close on the mount before the shot cycle finishes.
And then it separates and closes again.

ZR Mounts do not "dampen" anything, they are supposed to "FLOAT" the scope while the shot cycle is going on. Once the shot cycle is done, THEN the mount should return to battery. For that we need the excursion of the mount to be at least 6-8 mm's to the rear. Which is not the case in the video.

What we discovered in the video you showed as "AoA" was that the mount did not work too well in rifles of less than 13 ft-lbs yield (the rifle in the video had a 7 ft-lbs yield), and that the return spring had to be "weakened" a bit to make the mounts work well in the 12 ft-lbs region.
STILL, the mounts are not recommended for less than 8-9 ft-lbs (exception being those guns with sleds).

For guns with a yield of around 12 ft-lbs and using heavy scopes, I still prefer the higher return force of the Gen I mounts spec.

That spring guns jump and buck like wild bull at a rodeo has been made evident in many other videos, and what we have learned, after some years of ZR mounts in existence and operation is that the  MAIN problem for scopes is not the (in)famous "double recoil" but the vibrations transmitted to the erector group/tube during the shot cycle.
Therefore current Gen III or IV ZR mounts DO work exceptionally well because we learned a lot from that video and from the thousands of mounts currently in circulation.

ZR Mounts do work well and, yet, there are always things that can be improved.

The "chase" that's still going on is how to make the pellet exit the barrel ASAP. Before harmonics can flow to the muzzle and before the piston bounce jacks up to 11 the vibrations.

Again, apologies for not making myself clear.

Keep well and shoot straight!





HM

[mikeyb]

Thank you Hector for the detailed explanation!

I suspected the mounts might need some rifle specific tuning and your response will be very helpful when I finally install the ZR mount I have still new in box.

Cheers :-)