Originally Posted by TOM H
I've been reading your post and just what barrel contour are you talking about. Also the test you talk about breaking down sniper ammo for the 300mag was that done thru the military and why was it done?
The barrel contours I'm referring to that held zero after several shots in succession were five different ones used in accuracy testing. They all held 1000 yard zeros within 1/4 MOA for at least 30 shots fired in less than 20 miinutes.
First three .30-.338 Win Mag barrels, 1.2" at the receiver, .9" at the muzzle, 28 inches long. One Douglas, one Obermeyer and one Kreiger. Win. 70 post '64 action with face squared to barrel tenon axis, squared bolt face and lapped lugs.
Fourth, a cut off and rechambered 30" Palma .308 Win. barrel (with about 2800 rounds through it) retapered to 1.2" at the receiver, 1" out about 3 inches past the reinforce then to .7" at the muzzle; total length 26 inches. New chamber was a .300 Win. Mag. Same action type and truing the bolt and receiver face up and lapped lugs.
Fifth barrel was a 30" Kreiger medium Palma taper fit to a single shot Paramount action with squared up receiver and bolt faces and lapped locking lugs. Only 20 shots were fired in under 10 minutes into 3.2 inches at 800 yards.
Ten or so .308 Win. barrels made by Hart and the military armory in Springfield, MA, were shot at 600 through 1000 yards with all sorts of ammo. Up to 25 or 26 shots would be fired in about 20 minutes and no stringing of shots happened in the matches they were shot in. Same for those other barrels above used for testing that were shot in many matches and they never changed point of impact while they heated up. I've seen more than a few folks shooting M1's and M14's in special rapid fire matches putting 24 rounds into a 600 yard target in 50 seconds; 1 foot groups or thereabouts which is pretty good considering precice sight alignment and picture are not attained. Those barrels were the hottest I've ever touched or fired myself.
The .300 Win Mag ammo was USN issued stuff given to me that I broke down to measure bullet release force and weigh the powder charge. I had called Crane, Indiana, ammo depot and asked them what powder was in the ammo by its lot number.