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37rangemaster
Member Posts: 235 ✭✭✭
I got around to putting a few rounds over the chronograph today...remington model 700 .300 win-mag...now i was going off of a hornaday load which uses winchester brass winchester magnum primers and 180 grain hornaday bullets....shooting 73.5 grains of R22 its supposed to be clocking 2900fps (in the manual they worked up the loads using the same model rifle) i was getting 3100 fps shooting the SST's and the normal 180 grain spire points...the manual said they were getting 3000fps with the max indicated load of 76 grains of R22...i dont have any pressure signs...the only difference from the manual is the seating depth which i have set to the rifle...any opinions?
Comments
With a 180 grain pill, the Nosler reloading manual says 73.5 grains of RL-22 will push 3023 fps, with a max load of 75.5 grains pushing 3118. You may want to double check your manual.
ECC...the temp was nice and cool roughly 55* so i dont think that caused high pressure...the manual i am using is called "the complete reloading manual for the .300 win-mag...it has that exact load you were talking about in the nosler section...looking at the powder section of the manual it says that using a full load of R22 "76 grains" should push a 180 grain pill at 2870 fps with a pressure of 54,500 psi...pressure seems to jump up when using less powder 72.3 grains has an indicated pressure of 55,700 psi...maybe the chronograph is off?
I think your chrono is on and your book data is off. You will find many variations or discrepencies in published velocities from various manuals. The Nosler Reloading manual is right in line with your numbers. One of my rifles shoots a little faster than the Nosler published data. Nosler is one of the best reloading manual IMO. The higher pressures from less powder can be caused by not having enough powder in the cartridge (although I doubt this would be the case with 72.3 grains). The powder lays flat in the cartridge and is less than half full when laying horizontally. When the primer ignights, it causes all of the powder to ignight simultaneously rather than from the back of the cartridge to the front. This can cause pressure spikes...it can blow up your rifle as well. Someone else can probably explain it better than I.
Just some other things to consider:
Some barrels are just plain faster than others and you will record higher velocities from them.
Some lots of powder (especially Re-22) run very inconsistant and you can notice wider swings in velocities.
The incorrect spacing between the sky screens can have a big effect on velocities.
The inexpensive chronographs are notorious for inaccurate data and can record higher or lower velocities than actual.
Dirty barrels or clean but not fouled barrels can provide differentials in velocities.
Brass by different manufacturers have different volumes and this too can show a change in velocities.
Your load technically is on the lower end of the scale for this cartridge, so I wouldn't expect to see signs of pressure yet.
Borrow another chronograph and do some more tests.
Best.