Speeds in a manual ?
11-09-2017, 10:23 AM
#2
Typical Buck
Join Date: Apr 2017
Posts: 820
I've found them to be reasonably close. Most of the testing labs have high dollar equipment for measuring all the data where we usually have okay stuff so there of course will be variances. Not to mention the actual shooting equipment they use to test pressures and speeds. Rarely will you find exact speeds but you will find relatively close "in the same ball park" speeds. Or at least I have. About the only one I found some pretty high differences in was my Speer manual, I think it was #13, where I found some pretty major speed differences in both my 7mm-08 loads and my .300WM loads. Speeds weren't even on the same block as the ball park. The 7mm-08 load was almost 120fps faster than the published and the .300WM was over 100fps slower. Now this was back in 2005 or so and they may have been some powder differences or something.
11-12-2017, 05:18 AM
#3
Nontypical Buck
Join Date: Dec 2009
Posts: 1,780
The current manuals are fairly close in some of my rifles. The only one current manual that has not been remotely close in any of my rifles is the Barnes book. They have somehow been wildly optimistic compared to the numbers from my chronographs.
I do have some rifles that are faster or slower than the test barrels but most are reasonable after making adjustment for barrel lengths and temperatures. However I have found more wildly inconsistent rifle-to-rifle results in the fine 7mm RM than any other cartridge with seemingly identical rifles, so it would be hard to blame a manual for not matching closely in that case.
I do have some rifles that are faster or slower than the test barrels but most are reasonable after making adjustment for barrel lengths and temperatures. However I have found more wildly inconsistent rifle-to-rifle results in the fine 7mm RM than any other cartridge with seemingly identical rifles, so it would be hard to blame a manual for not matching closely in that case.
11-12-2017, 06:01 AM
#4
Nontypical Buck
Join Date: Feb 2003
Location: Eastern wv
Posts: 3,413
depends on your chamber, every time a reamer is sharpened it gets smaller, so takes less powder in a tighter chamber to make the same mv. I don't pay much attention to manuals except the charge weights. if I'm not making the mv that its supposed to I keep upping the charge till I either get there or have signs of high pressure, then back it off till its safe. faster twists make less velocity at the same pressure as does cut rifling vs. button rifling, the manual is just a guide, the numbers are not etched in stone.
RR
RR
11-12-2017, 03:23 PM
#5
Nontypical Buck
Join Date: Oct 2009
Location: Kansas
Posts: 3,872
Yup - your rifle and your brass will tell you when to stop. We really don't have any idea where the pressure of our loads line up compared to book data, so if you want more speed, listening to your brass and your rifle will tell you more than the reloading manual.
If a guy is really going after speed, he can work up a dummy round which matches their mag length, or be happy loading single shot style, and then have a smith throat their chamber for that seating depth. Gives about as much powder capacity as possible with their given chamber, before going to something like an improved shoulder or larger case.
Sometimes the manuals are right on the money, sometimes they're slow, sometimes fast, sometimes real world rifles start crying uncle before we even hit a max load, and sometimes a "max load" in the book is a few whole grains below anything which would give any pressure signs... Just gotta know your rifle and cartridge, and listen when your bolt or brass tell you to stop.
If a guy is really going after speed, he can work up a dummy round which matches their mag length, or be happy loading single shot style, and then have a smith throat their chamber for that seating depth. Gives about as much powder capacity as possible with their given chamber, before going to something like an improved shoulder or larger case.
Sometimes the manuals are right on the money, sometimes they're slow, sometimes fast, sometimes real world rifles start crying uncle before we even hit a max load, and sometimes a "max load" in the book is a few whole grains below anything which would give any pressure signs... Just gotta know your rifle and cartridge, and listen when your bolt or brass tell you to stop.
