Human vs Vice

[toddinjax]

So I had a discussion yesterday concerning "one ragged hole" results via putting a pistol in a vice. It got me wondering if manufacturers testing their guns from a vice is really the best or most accurate test simply by the nature of a vice to hold perfectly still vs. what our (imperfect) humans bodies. Is it at least possible that with a gun held in a vice, setting the velocity to create the smallest one hole group may produce an amount of recoil that the vice can easily overcome, but a human can not so easily or completely overcome? Are we doing ourselves a disservice by "setting up" a gun to produce great results in a machine and then expecting our bodies to behave in a way that we know is impossible?

[fc60]

Greetings,

Years ago, I had a Hämmerli SP20 in 32 S&W Long. The barrel is easily removed from the shroud without special tools.

I mounted the barrel only in a mechanical fixture and fired 3 ten shot groups at 50 yards.

Next, I returned the barrel to the shroud and assembled the pistol. Using a Burris 7X scope and sandbags I fired 3 ten shot groups at 50 yards.

Placing all six targets side by side you could not determine which method was used.

The above is only valid for a blow back design pistol in which the barrel and frame are one unit.

Testing the barrel from a fixture ensures all the machined features are correct. i.e. chamber is aligned and crown is cut uniform.

Also, the major European manufacturers use CIP approved ammunition designed for the pistol.

Interesting side comment, Pardini does not include a test target with their 22 SP nor 32 HP pistols? (I have tested several Pardini 22, 32 Long, and 32 ACP barrels in the mechanical fixture and never had one fail to hold the X-ring at 50 yards with good ammunition.)

Cheers,

Dave

[Dcforman]

Your post reminded me of this thread. Might not be exactly what you are looking for, but any gunsmith should be aware of how a gun shoots from the hand, not just how it performs in a rest...

https://www.bullseyeforum.net/t16145-ha ... it-pistols

Dave

[brent375hh]

If I could shoot into one hole hand held, and adjust from there, I certainly would. I can't, so maybe it doesn't make a difference.
I have have met people that say it doesn't matter. Their rationale was if you missed a 10 with an inaccurate load, perhaps it would have gone in the right direction to break a 10. Extrapolation of that theory doesn't make sense to me.

[David M]

The more interesting question is,
"Are you testing the barrel in the machine rest or the ammo ?"
because most of the time we may test many ammo's but only one barrel.

[toddinjax]

I was more wondering if a manufacturer shoots and tests from a vice and comes to results of say 535fps gives the most accuracy. But a person holding and firing the same pistol has trouble holding still at such a setting and they actually get better accuracy (from gun and man working together) at 500fps. The 535fpt being "theoretically best" while in actual practice a world class competitor performs best with it tuned to 500fps.
You can build a bicycle frame that is extremely rigid with minimal flex; more energy goes to propelling the rider forward (and that's what they use on a smooth velodrome for fairly short races). But to ride that bike 125 miles on open roads will beat the stuffing out of a rider's body in short order and he will tire quickly and his body will not be able to perform his task. He likely won't perform too well next day either.

[fc60]

The more interesting question is,
"Are you testing the barrel in the machine rest or the ammo ?"
because most of the time we may test many ammo's but only one barrel.

Greetings,

A good question. I have found that, for example, in the 32 S&W Long WadCutter loaded with the 0.314" H&N bullet, Lapua cases, and 1.70 grains of Alliant Bullseye it shot very close to X-ring at 50 yards in a variety of barrels.

i.e. Pardini, Hämmerli, MatchGun, Benelli, FAS, and custom machined barrels.

The mechanical fixture started out life as a "barrel tester". We were trying to sort out 1911 45 caliber Match barrels for best accuracy.

Turns out, what we discovered was that if the barrel was machined correctly they all shot pretty much the same, including off the rack standard barrels. One barrel did shoot poorly and a trip to the lathe and a new crown returned that particular barrel to the Match status.

What we did learn was ammunition varied greatly. Some lots of the Military issued ammo shot solid X-ring. Back then, we could still buy the Winchester 185 grain FMJWC bullets and with careful reloading practice we came very close to duplicating the accuracy of the "good" factory ammo.

So, in my humble opinion, it is value added to test your ammo in the most repetitive way possible at the distance you plan on shooting. Chronographs are good tools to have. Along with keeping notes for future review.

Cheers,

Dave

[brent375hh]

The OP has provided enough information to conclude that they are interested in air pistol velocity.
I did a fair amount of testing with this. Shooting an air pistol at 480 or 550 fps is not going to wear out a shooter. You can tune your pistol within that range to produce the best one hole group. Every velocity I tried produced one hole groups with R10 pellets, just some were rounder that others. I doubt that manufacturers have the manpower to do anything but set them to their own specifications.

[brent375hh]

The following website has similar information as my own testing.

https://www.tenrings.co.uk/pellet-testing/

[David M]

Testing a Morini 162 prior to the 2000 Olympics in a machine rest with a chronograph inline.
Pistol was grip mounted and barrel free floated.
I tested various pellets (weight/diameter) and various velocities with interesting results.
It was found that the group was nodal as the velocity increased.
Starting around 140m/s, up to 155m/s. The group would open and close then open/close again.
The tight groups were at 148m/s then at 154m/s. Small but subtle group size change.
The best 3 shot group would suspend a unfired pellet in the single hole of card target.
I went with 148m/s as when hand shot it felt better.

[JamesH]

IIRC The Hammerli 280 was shot for the sample target by removing the shroud and clamping the barrel - a bit of a cheat considering the frame was relatively flexible.

Probably the effect of ammunition will be greater, especially shooting centrefire.
In a clamped barrel shots of different velocity and even different bullet mass will likely land in the same hole.
In a moving frictional damped, eg ransom, rest different loads will land in different spots
Off-hand they'll be different again.

[rmca]

Is it at least possible that with a gun held in a vice, setting the velocity to create the smallest one hole group may produce an amount of recoil that the vice can easily overcome, but a human can not so easily or completely overcome?

In air pistol, the amount of recoil (if any, depends on the pistol) is so low, that if you can't handle it, you can't hold the gun either.

Are we doing ourselves a disservice by "setting up" a gun to produce great results in a machine and then expecting our bodies to behave in a way that we know is impossible?

No. The group done by an human is the sum of his/her hold PLUS the machine accuracy of the gun. So the smaller each part is, the smaller the group. Recoil is felt after the projectile is out of the barrel, so if you are not anticipating it, your hold shouldn't get any larger. (I know Newton's 3rd law, but it takes more time to move the gun than the projectile, due to the difference in weight ..)

Hope this helps

[Rover]

Back in the day, I was concerned with stuff like this.

I put a S&W 41 frame in a Ransom Rest and tested all the ammo I could find using four different barrels (two long, two short).

No two barrels were most accurate with the same ammo (some widely varying) and one (not the other three) would jam repeatedly with one brand (only).

Have fun!