What is the ballistic data for Lake City M72 .30 cal match?
BC?
MZ?
Trajectory?
Also can anyone provide reloading data for the M1 Garand to duplicate the M2Ball and M72 match performance?
Thanks in advance
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What is the ballistic data for Lake City M72 .30 cal match?
BC?
MZ?
Trajectory?
Also can anyone provide reloading data for the M1 Garand to duplicate the M2Ball and M72 match performance?
Thanks in advance
The information I have from years ago is that the BC of the 30M72 bullet is 0.53.
On the boxes of FA 60 and LC 62 Match ammo the MV is given as 2650 fps which coincides with the info in the 1963 National Rifle Matches booklet. In the Rifle Marksmanship Manual this is indicated as the MV for a temp of 70 degrees F. As the temperature rises the velocity rises to 2750 at 100 degrees F according to the manual.
Formerly the BC was computed from data measured by measuring the velocity difference between screes placed at fixed distance. In recent years this has been replaced by measuring continuious velocity data using a Doppler radar technique which provides a steady flow of velocity at different ranges. Some revision of previously quoted BC's have been made based upon this later data.
A good essay on exterior ballistics is contained in "Hatcher's Notebook" (the later editions.) Mine is the Third Edition of 1962
Hope this helps.
The ballistics data for the M72 Match should fairly well duplicate that for the old M1 ball ammo.
My info concurs that the M72/M118 bullet's BC is .530. Remember, that the 2640fps listed velocity was obtained at 78', and velocities at the 10' - 15' typically used by civilians is likely to be 2680fps or more.
Don
The army publishes data on MV at 78 feet for the following reason. In the early days measuring the short intervals of time required to measure bullet velocities was not as easy as today with our modern electronics. The chronograph screens were placed 150 feet apart and the velocity was computed as decreasing linearly across the screens so that the actual velocity measured was the average for 75 feet. The 150 feet was a compromise between accurate time measurement and the assumption that velocity decreased linearly. To avoid the effect of the muzzle blast, the first screen was placed three feet from the muzzle, ergo the velocity was the average of that measured at 75 feet + 3 feet.
Once the practice became established it became the standard for stating velocity, and one something becomes standard in the Army it is difficult to change. Besides it was easy to measure relative velocity against the same standard for all types of ammo during all eras. The comparison of Krag ammo, M1903 ammo, M1906 ammo, or even M1 ammo was against the same standard.
http://masterpostemple.bravepages.com/M1load.htmQuote:
Originally Posted by ARCHER 9505