Garand Barrel testing/ammo

[Clancy]

Gentlemen,
Here are the questions and answers to test on the M1 Garand using 2-groove Barrels. NOTICE: DATE ON THESE FILES!! You might find some of this data of interest.

What do you think they are setting up for ??

Some data has been posted before others have not.
Thanks again
Clancy
NRA Life Endowment
NRA Training Counselor
NRA Instructor
FSS 90% / BW X Speed Div by 1000 = PF
THA 63

 

[Dimitri]

If I get that velocity drop readings right, they are comparing the start velocity with the one after the number of rounds. If so the 2 grove 1903 went done quite abit.

The M1 with 4 grove went up in speed but only shot half the amount of ammo. I wonder why is that.

Dimitri

 

[Tyler]

The M1 with 4 grove went up in speed but only shot half the amount of ammo. I wonder why is that.

Dimitri

My guess would be that the rifle is 'standard' and would have been tested prior to adoption by the U.S. military in years before, so they would already know the standard velocity and would therefore need fewer rounds to get an average.

As for the lower velocity, my guess would be the larger total surface area of the lands would cause more friction and slow the bullet down a little.

 

[Dimitri]

A 4 grove barrel has more area that a bullet contacts then a 2 grove though.

The lands and the major ID have the same area, execpt on a 4 grove you have 4 extra flat parts that make the rifle lands "stick out" from the major ID.

Unless ofcourse its simply friction, the smaller lands of the 4 grove allow the bullet to bend and form better then a 2 grove's bigger lands which require more force for the bullet to be bent into shape so it slows the bullet down.

Dimitri