..But seriously, of course he can. He can schit in his own shoes if he wants to. Is it safe to load over-pressure? Likely. But the question becomes, "When does it become unsafe?" A few thousand PSI, say to 68K PSI MAP on a very consistent load velocity-wise, likely isn't going to be noticed, let alone likely unsafe.
Again, I have to look at all the companies who publish manuals. They have to assume that their readers will follow their instructions. It's never wise to ignore your manual unless you know what you are doing. Publishers cannot make that assumption, so not having a chrono won't put you in harm's way. Follow the manual's advice and everything will be fine.
Hi Steve;
I've been a handloader for four decades at least, and have handloaded most common cartridges from the .22 Hornet to the .458 Win Mag, and in some of those it's been multiple versions. (never the .303 Brit, though). In starting out, I went by "the book" cautiously. Over time, as I purchased more manuals and rifles, I learned there were discrepancies, not only in rifles but manuals, and sometimes in new publications of manuals by the same company, or near extreme results from similar cartridges testing near identical bullets from the same length test barrels. I'm quite sure that by now I have enough experience and know how to be aware when "something is rotten in Denmark". Internal "politics" is involved, such as "who did the testing on cartridge A?" It's not always the same member of the "team". I know that from conversations with some of the chief ballisticians. For now, just two examples:
Example 1: A number of years ago, I was doing a lot of firing handloads from several .300 Win Mags. I got to know pretty much what each could give me (safely) considering brand and barrel length -- which varied by as much as 200 fps by the same bullet fired from 24" or 26" barrels. The 26" was a Browning and had a "fast" barrel. But over the course of time, I purchased the latest Hornady manual that seemed OK until I read the data for their 220gr. It consistently showed a max of 2500 fps for that bullet. I knew better, so contacted Hornady using their "help" service. I knew it was late in the day (right on their closing time) but was hopeful. It turned out that the head ballistics guy had just turned out the lights and was heading for the door when the phone rang. He went back to the phone and I was on the other end. I asked why a max of ONLY 2500 fps for that 220gr. He was straightforward and apologetic: "We had a young man do those tests and when recoil got to be too much for him (shooting a REAL rifle) he cut it off and that's what went into the computer. When pulled for printing it included "2500 fps maximum" for all loads for the 220gr." To my knowledge that was never officially corrected until the following edition that included some at 2700 fps. It was the 4th edition that showed five "maximum loads-use with caution" and two maximum at 2400 fps. I told him "Those are .30-06 loads", and he agreed.
Example 2: Recently in my blog writing, the theme was "What are Mediums?" Among those the .338 Win Mag and .358 Norma Mag were included and compared. There's minimal difference in capacity and shape -- in fact, .358 Norma cases can be fireformed from .338 Win cases and necked-up. Nosler #6 manual had used data for two equal-length test barrels (24") from two sources (Lilja and Wiseman). Since the larger bore of the two would be expected to, at the very least, equal or slightly outperform the smaller bore due to a better expansion ratio, a better MV should be expected from the .358 Norma over the .338 Win from 250gr Partition bullets fired froim each... assuming equal PSI. Right? Instead of getting similar results, or better, from the Norma, my "unprofessional" knowledge of ballistics was insulted from these results: 2628 fps from the .358 Norma as "max", and 2780 fps from the .338 Win! I knew from experience that the .338 Win number was believable whereas those for the .358 Norma were well below par even though I'd never owned, used or even seen a .358 Norma to this day at age 85! Those are a couple of examples only, but there's a multitude of others scattered in manuals over the years! Yeah, I still use 'em but only consider them for what they're worth, and usually NOT $50 Cdn! I use my judgment based on experience and have never "blown up" a rifle nor been harmed by one, nor had to pound open an action with a mallet! A few loose primers?Yep -- blown primers? 5 that I can recall, and those caused mostly by "book loads".
And, despite ideas that come from "somewhere", ALL manuals have this disclaimer: "Approach maximum loads with caution. If there are SIGNS of excess pressure, reduce loads by a couple of grains." And we have this myth "out there" --- "don't trust signs of excess pressure", yet ALL pros do or they wouldn't include such a disclaimer in their manuals.
With all due respect...
Bob
www.bigbores.ca 
