Originally Posted by boomtube
The loading manuals are made by people who print the results they got in their rifles, etc. Some use sporting rifles, some use universal receivers but they all have different rigs so the "max" loads you see only reflect those differences. YOUR rig and mine are like none of their's so our MAX may or may not be the same as theirs, this is not chemistry class in which we do "exactly this to get exactly that" results.
I know one guy who got badly blown primer pockets in a still new Win 70/22-250 with Hodgdon book midrange charges of Varget. If he had started at a presumed dummied down max load he would have surely had a bad occurance. Meaning, anyone thinking the book makers fudge the results so we will be safe is wrong! Do what the books say, "start low and only work up if no pressure signs occur" or you may get a viscious surprise.
An old thread but I couldn't help but to comment on this because I see pressure signs in 2 guns, a 243 & 270 with loads well under max...With a 243Win...37 gr Varget behind a 85gr HPBT producing a very accurate load going out at 3040fps. Just what the book says it should be. 38gr is max and I load that with TSX 85gr because that was the most accurate, going out at 3200 fps. I get what Hogdon's manual says in terms of speed but I also get flattened primers in both cases (no pun intended)...no cratering, no sticky bolt. Same with a light load of Varget, 32.0 gr behind the 100gr Hdy Interlock producing only 2675 fps. Flattened primers only. To get more velocity in the 100 grainers I switched to IMR4831, and with that I get velocities higher than book for a given charge. With this I also get flattened primers well below book max but .actually tried a few at 1 gr over max to 43.9 gr giving 3120 fps. Now that seems fast for a 243 and 100 gr bullet and I know there's no free lunch. But still only flattened primers.
In a 270 BAR, I get flattened primers with only 54.0 gr H4350 driving a 130gr TSX at 2900 fps. So when you guys are talking about pushing 130 gr bullets 3100+ I don't know how you get there.
Any ideas of why I get "premature" pressure signs? As you say boomtube, I'm reluctant to go much hotter despite being under max, OR drive them faster than expected (in the case of the 100 gr bullet) even though I'm not seeing much overpressure sign.