Barrel Weights & Recoil Control

[David M]

Many pistols use barrel weights to help control recoil and movement.
A number of pistols use moving weights (spring loaded) i.e. Pardini, MG2, FWB, Hammerli RRS etc.
The movements needed to be controled are. ...
1/ Bullet acceleration down the barrel
2/ Gas discharge out the end of the barrel (muzzle blast).
3/ Slide movement backwards and stop.
4/ Slide movement forward with next round and breach close.
Typical pistol barrel movement is up and torque to the right.
Now the million dollar question (this was well argued on a german pistol site with no apparent answer).

Does the spring on a moving weight go in front of the weight or should it go behind ?
Seems both work but on different phases of the recoil.
Also how heavy should the springs be (relative to the weight) ?

[Gwhite]

I've tried both arrangements. I could never tell that either did much of anything...

If it does work, I think Cesare Morini has the best idea. His MatchGun weights are at an angle.

The only way you will really tell is to strap accelerometers to the pistol.

[David M]

With movement being up and back, angled may be the way to go.
Also it can be radial movement i.e.
The Tesro TS22-3 Pro has a pivoted weight (aft near the trigger guard) that is spring loaded.
The weight moves front end down and the spring pushes against the weight (from behind).
The holder has number of holes to alter the weight and the spring is adjustable for resistance.

[-TT-]

Typical pistol barrel movement is up and torque to the right.

In general, torque will be coming from your hand and wrist. These will rotate upward under recoil, but not in a perfectly vertical orientation. For me, the muzzle will generally rise and move *left*, but I can alter the lateral movement by modifying my grip and stance. It really doesn't matter, as long as it's predictable and controlled.

Now the million dollar question (this was well argued on a german pistol site with no apparent answer).

Does the spring on a moving weight go in front of the weight or should it go behind ?
Seems both work but on different phases of the recoil.
Also how heavy should the springs be (relative to the weight) ?

In my opinion, both. Both recoil and rebound are important to recovery. I have found that I prefer about twice as much recoil (spring in front of weight) movement as rebound (spring behind weight). There's no single answer however, it depends on the geometry of the pistol, the size of the weight(s), the pistol's recoil spring rate, the mass of the bolt, and of course the ammo itself. You have to experiment.

I made a recoil absorber for my Benelli and was very impressed with the results. viewtopic.php?f=4&t=60199

[Gwhite]

I'd love to see real data on how much all the pivots, springs and such add, as opposed to just increasing the mass & moment of inertia.

The mechanical engineering students on the college team I help coach all have to take an "instrumentation" course. They have a final project where they have to instrument & measure some phenomenon. I'll have to see if I can enlist one to look into this. Tiny 3-axis accelerometers from phones are easy to get now, but I'm not sure how well they will react to the jolt of firing. They may just saturate.

I think the course is in the spring, so it may be a while.

[-TT-]

The Mantis 3 is a commercial livefire accelerometer with a Bluetooth LE connection. I bet you could convince them to give the students access to their API and get some interesting data.

I strongly feel it's not just the weight. The difference between rearranging springs, removing the springs, and even un-damping by drilling holes so the air could escape the chambers the weights move in, all greatly affected it. The end result is quite remarkable.

[KDZ]

Sounds like an interesting project. How would you isolate the pistol to measure only pistol-generated movements? Suspend from wires? Then how would you fire without touching the pistol?

Maybe some kind of remote trigger-activating mechanism, which seems feasible with electronic trigger.

The mechanical engineering students on the college team I help coach all have to take an "instrumentation" course. They have a final project where they have to instrument & measure some phenomenon. I'll have to see if I can enlist one to look into this. Tiny 3-axis accelerometers from phones are easy to get now, but I'm not sure how well they will react to the jolt of firing. They may just saturate.

I think the course is in the spring, so it may be a while.

[Gwhite]

You want to duplicate the damping effects of the hand, so I figured you'd shoot it normally.