1911Tuner
Moderator Emeritus
Control subject: 5-shot RG .38 Special revolver with 2.1 inch barrel. (Rifled length)
Test subject. 5-Shot RG .38 Special revolver with 5/8ths inch of forcing cone only. All rifling in the cone was honed to provide .001 inch land/groove depth in order to prevent bullet tumbling across chronograph skyscreens.
Bores slugged and measured. .002 inch difference, with the tighter bore diameter belonging to the test gun.
Barrel/cylinder gap adjusted to within .001 inch. Adjusted barrel was lightly countersunk to remove burrs and toolmarks. Average BC gap...approximately .028 inch. (Ouch!)
Ammunition: Standard velocity 158-grain lead RN. 5 rounds per gun chronographed.
Control subject: Average 586 fps
1. 593
2. 578
3. 582
4. 588
5. 587
Test subject: Average 557 fps
1. 568
2. 546
3. 551
4. 553
5. 545
A disinterested 3rd party was employed to fire the two revolvers blind, in a back-to-back test to see if there was any discernible difference in felt recoil. He reported that there was very little difference, and indicated that the test gun's recoil may have been slightly sharper. The test was repeated three times, and he picked the test gun as producing sharper recoil all three times. He emphasized that the difference was slight...but that there was a detectable difference.
Phase two of the experiment will entail another chronograph test of 10 rounds in the control gun, followed by a second 10-round chronograph test of the same gun with barrel parted off to 5/8ths inch of forcing cone w/ full depth of rifling intact...lightly countersunk to remove toolmarks.
Stand by...
Test subject. 5-Shot RG .38 Special revolver with 5/8ths inch of forcing cone only. All rifling in the cone was honed to provide .001 inch land/groove depth in order to prevent bullet tumbling across chronograph skyscreens.
Bores slugged and measured. .002 inch difference, with the tighter bore diameter belonging to the test gun.
Barrel/cylinder gap adjusted to within .001 inch. Adjusted barrel was lightly countersunk to remove burrs and toolmarks. Average BC gap...approximately .028 inch. (Ouch!)
Ammunition: Standard velocity 158-grain lead RN. 5 rounds per gun chronographed.
Control subject: Average 586 fps
1. 593
2. 578
3. 582
4. 588
5. 587
Test subject: Average 557 fps
1. 568
2. 546
3. 551
4. 553
5. 545
A disinterested 3rd party was employed to fire the two revolvers blind, in a back-to-back test to see if there was any discernible difference in felt recoil. He reported that there was very little difference, and indicated that the test gun's recoil may have been slightly sharper. The test was repeated three times, and he picked the test gun as producing sharper recoil all three times. He emphasized that the difference was slight...but that there was a detectable difference.
Phase two of the experiment will entail another chronograph test of 10 rounds in the control gun, followed by a second 10-round chronograph test of the same gun with barrel parted off to 5/8ths inch of forcing cone w/ full depth of rifling intact...lightly countersunk to remove toolmarks.
Stand by...