.300 Weatherby surprising velocity?

[DanielLudwig]

Tried a different load in my .300 today, and to be honest I'm shocked by the velocity! Load is 88.5gr RL 25 under a 180 gr. Nosler BT, WLRM primed. Rifle barrel is 28.5" Krieger 1-10".
Shot 4 through the Chrony Beta @ 8'
1:3453
2:3472
3:3473
4:3449
I guess i was just kinda shocked by the velocity! Are there any conditions that would adversely effect velocity readings through a chronograph? Temp was in the low 30's, not sure on pressure. Has anyone produced results close to these with a 180 gr. bullet in a .300 Weatherby?


Daniel

 

[ICANHITHIMMAN]

Your up there with the RUM and 338-378 speeds when you should be just over max win mag speeds.

I checked 3 reloading manuals Seirra, Barnes and Speer they all list 87g of R25 as MAX load and with a 180g bullet and an avarage MV of 3200 FPS out of 24" test barrels.

Now you are shooting 1.5g more and you barrel is 4 1/2" longer so, your speeds might be right on. As long as you dont have any pressure signs I say have at it.

 

[Trickymissfit]

Your up there with the RUM and 338-378 speeds when you should be just over max win mag speeds.

I checked 3 reloading manuals Seirra, Barnes and Speer they all list 87g of R25 as MAX load and with a 180g bullet and an avarage MV of 3200 FPS out of 24" test barrels.

Now you are shooting 1.5g more and you barrel is 4 1/2" longer so, your speeds might be right on. As long as you dont have any pressure signs I say have at it.

I think I'd back off about a grain and a half. I bet your seeing 80K psi pressure spikes. I'm getting ready to try MagPro and 8700 in a Weatherby, but the book says 3100 and 7828
Gary

 

[DanielLudwig]

I would like to think that if i was seeing in excess of 80k psi I would see some kind of pressure signs in the brass, but I'm not, no sticky bolt, no flattened primers, nothing. Still not too sure what to think...


Daniel

 

[Broz]

I think I would try a second chronograph to be sure and move it out to 15 feet so you are not affected by the muzzle blast.

 

[Long Time Long Ranger]

Your chrono may be correct. I have a 300 wby that thinks it is a 300 RUM. It shoots the exact velocities you are shooting with the 180 and 3210 fps is my accuracy load with the 200 accubond. All my other 300 wby's shoot the 180 near 3300 fps with a 26" barrel and the 200 grain at 3100 fps. Usually the 300 wby falls exactly between the 300 winchester and 300 RUM but some do shoot 300 RUM velocities. The 300 wby shoots on average 100 fps faster than the 300 winchester. Same with the 340 wby. It shoots on average 100 fps slower than the 338-300 RUM, 338 RUM and 338 Lapua.

 

[Trickymissfit]

I would like to think that if i was seeing in excess of 80k psi I would see some kind of pressure signs in the brass, but I'm not, no sticky bolt, no flattened primers, nothing. Still not too sure what to think...


Daniel

a pressure spike is not the samething as continous pressure. 80K would only be for a microsecond, but still exceed the max working pressure of the action. (most will proof around 100K psi these days). Bob Greanleaf and Fred Barker wrote a very good article on this in Precision Shooting, and it should be a must read for every reloader.
gary