I have been chrongraphing loads on my Oehler and find that my velocities are consistantly less than those in the Nos. Manual - some significantly less. For example:

.223 24 in barrel 25 gr. H-322 40 gr. bullet - Nos. shows 3567 ft/sec - my chron. shows average 3443

22/250 24 in. barrel 34 gr. IMR 4895 50 gr. bullet shows 3802 ft/sec - with 35 gr. H-4895 my Oehler indicates average of 3584

Swift 26 in barrel 42 grs of 760 55 gr. bullet - Nos. shows 3830 - chrono shows 3775

6BR 24 in. barrel 32 grs of 2015 55 gr. bullet Nos. shows 3649 - my 6BR with 26 in. barrel chronos. 3584

7 mm. Rem. Mag. 24 in. barrel 65 grs. of IMR 7828 175 gr. bullet Nos. shows 2950 - I get 2793.

Is this unusual? Do you think that I can safely get near book velocities by increasing powder charges over boook charges while carefully watching for pressure signs? Tell me what you think.

I believe you'll find that most Nosler books are the same, the velocities have, in my experience, been reported a little higher than I can achieve too!!

Don't worry about it or try to load to the velocity listed, what you have IS what you have.

Your results aren't unusual at all. Most manuals results are from pressure guns using "Universal Receivers" and a special barrel for each cartridge. These receivers and barrels are made to the tight, minimum chamber specs, and the barrels are frequently 25 or 26 inches long instead of the 22 or 24 inch barrels used in most rifles. With less energy used to expand the case and a longer barrel the result is a higher velocity in the manual than what you are going to get in your rifle.

It's even worse in cartridges for revolvers, where often a ten inch barrel is used without any venting to simulate the barrel/cylinder gap.

CM, Nos. includes barrel length for each cartridge tested and barrel maker.

You need to remember that every barrel is not the same plus every lot of powder and primers is at lest a little different than any other...to see the difference read the A-Square manual "Any Shot You Want".

This isnot unusual at all as velocities can vary greatly between rifles with a given load.Even loaded to the same pressure levels some rifles will produce more velocity than others.

Hey'
My buddy and I both had 7mmSTW's built by the same smith,at the same time.His was a Remington action,mine was a Sako action.Everything else was the same barrles,length,etc.We would work up the same loads.His velocities were quite a bit slower than mine.I still have mine,he doen't.
1geejay
www.shooting-hunting.com

Your velocities aren't that far off of the "book" in most instances and are well within the normal range.

However, since ALL of your velocities vary on the slow side, you might check you chronograph screen spacing. If you are using a 2-foot spacing with the Oehler and missed the measurement by, say, a quarter inch on the long side, an actual velocity of 3000 fps would register only 2969 fps. I doubt that this is your problem, but you might want to check.