my old rifle had loose bore and longthroat...so loads had plenty of room to releave pressure before projectile enguaged rifling.....my reloads for it were at hot end of scale.....
also I partial length resized...so in effect the shoulder COULDVE been up to ????1mm longer than normal......
IF new rifle has tight chamber,they wouldnt fit in.....the case would be too long......and if short throated,a hot load could well become a bomb...nowhere for pressure to go....shorter throat=shorter pressure curve=lower pressure tolerance=lighter loading.......
if you take it to the extreme,look at how Roy Weatherby made his rifles chambers....big long lead into rifling so when primer goes off and powder starts to ignite the projectile starts moving forwards,in effect giving a bigger case...this I believe is the theory behing Remington Hypersonic shot shell loads too....1700fps Vs 1500 in others.
my good mate just around corner also owns a .270 the loads his rifle tolerates are 2-3grns BELOW book maximum before he starts getting pressure signs...my old girl was 2-3 ABOVE .
hope that makes sense.
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