Go Back   CMP Forums > CMP General > Ask Each Other > Reloading
Register FAQ Members List Calendar Mark Forums Read

Reply
 
Thread Tools Display Modes
  #11  
Old 07-15-2019, 08:02 AM
Unclenick Unclenick is offline
 
Join Date: Nov 2010
Posts: 1,044
Default

M2 Ball was loaded so the average round from a 24" test barrel with tight chamber tolerances ran about 2800 fps at the muzzle (as a Magnetospeed would measure it) and just under 2790 at 15 ft from the muzzle (as SAAMI standard practice would measure it) and 2740 fps at 78 ft from the muzzle (as the military spec has it measured; start screen at 6 feet and stop screen at 150 feet for the old vacuum tube detector coil type portable chronographs). These numbers are faster than most folks load for the Garand today. They were also measured with the cartridge handled so the powder was back over the flash hole, which maximizes peak pressure and velocity in the test gun (worst case pressure for someone firing uphill). You may get close to test barrel velocity with a new Criterion barrel or another match-grade barrel with a minimum length chamber. Worn chambers and throats won't.

The Garand typically throws powder forward against the bullet in flat firing and then has vibration settle it some. 25 years ago I intentionally fired some 1964 M72 NM ammo in several club Garands so the powder was at the back of the case. I fired them again with powder at the front of the case and they averaged about 80 fps slower. So keep powder position in mind when testing: only compare powder-over-flash hole velocities to the military velocity spec.

Incidentally, those old club guns had very worn barrels. The old NM ammo gave average powder-over-flash hole velocities of anywhere from 2495 fps to 2611 fps at 15 feet in the old guns (Oehler 35P) which would be about 2506 fps and 2622 fps extrapolated back to the muzzle. The NM ammo records show the 1964 load was 46 grains of IMR4895 and was rated 2669 fps MV from a test barrel (presumably extrapolated back to the muzzle from a lower 78-foot measurement). Still, it gives you some idea just how much difference the gun can make. I don't know what to allow for the age of the powder. Maybe nothing.
__________________
--------------
Nick

Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Instructor
NRA Patron Member
ORPA Life Member

Last edited by Unclenick; 07-15-2019 at 08:38 AM.
Reply With Quote
  #12  
Old 07-15-2019, 06:36 PM
.22shooter .22shooter is offline
 
Join Date: Mar 2010
Location: VA
Posts: 2,214
Default

I used it fairly extensively with 110s around 2012/2013 during the panic buying. Worked just fine and produced 2MOA on average

Bill

Sent from my SM-J700T using Tapatalk
Reply With Quote
  #13  
Old 08-13-2019, 08:00 PM
AllenGill AllenGill is offline
 
Join Date: Jul 2012
Posts: 50
Default

Here are some data with Greek GI to compare:

M1 40.5 gr. AA2495
Mean 2343.4
Standard Deviation 45.9

Avg. Group Inches 4.125




M1 44.5 gr. AA2495
Mean 2532.7
Standard Deviation 24.6

Avg. Group Inches 4.25

M1 45.5 gr.IMR 4895
Mean 2648.5
Standard Deviation 28.8

Avg. Group Inches 6.25

M1 49.5 gr. IMR 4895
Mean 2832.1
Standard Deviation 38.4

Avg. Group Inches 3.5


M1 Greek
Mean 2715.5
Standard Deviation 31.0

Avg. Group Inches 2.5



The M1A liked it the best. It shot a 1.75 inch group at 100 yds using 168 gr. HPBT and a 6X scope. I misplaced the chronograph data, but it was very close to the chart velocity ~ 2700 fps range
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 02:08 AM.