What was proven? bds stated he has super accurate calipers and probably thousands of bullets measured. I think a high quality micrometer would be better .You did not indicate how your measurements were taken.
I built racing engines for 20 years, and have a full array of 'high quality' calipers, depth gauges, micrometers and dial bore gauges along with more experience using them than you'll ever glimpse. But It would be great if you would drop this agenda..
What does posting the Hodgdon reloading data have to do with anything? No, you can't compare the bullets so why post it?. Sierra is listed at .355 and Hornady at .356. Not down to 5/10,000. Sure, diameter will make a difference in pressure, but that all depends on the EXACT bore diameter and even if there is any fouling in the bore to make such a minuscule difference. Plus you have no way to measure the actual pressure.
The precise point is the bullets aren't comparable, and what effect that has on pressure. Whatever your bore diameter is you will have a tighter fit with a bigger bullet, leak less pressure, have greater friction and make more pressure.
I also said "seating depth" not just OAL Bullet companies give diameters to thousands of an inch not ten one thousandths
The OP didn't have seating depth, but we were supposed to so concerned because his OAL compared to that listed for a bullet with a completely different, and largely unknown profile.
Of course it will be different as you can not duplicate the test or any test done by someplace else.. Plus factor into the equation the powder(s) and primer(s) used and all the other different test parameters. Your velocity even though related to pressure means little as you can not compare it to Hodgdons test data.
I've used the RMR bullets with a variety of powders and primers in a variety of calibers. As you are probably aware it's generally difficult to achieve the max velocities given in published handgun data without exceeding their listed charge. But in all cases with the RMR bullets velocity has come easy even at long OALs, so easy it's only smart to stop at the max velocities given even though that's happening 0.2-0.4gr. under the max charge given. The bullets aren't comparable. I'd say judging pressure by velocity is better than not judging it.
So yes, I have a different view on dealing with insignificant factors.
It's not necessarily insignificant. Take Jake's Mini MPR load for example. He saw fit to stop at 6.1gr of BE86 at an OAL of 1.135". When you don't have any leade in the barrel, you have to go all the way to ~1.032" OAL with the MPR nose profile to clear the edge of the bore, due to the profile of the bullet. The Alliant data show max charges of 6.1-6.3 grains for generically categorized 115gr. jacketed bullets. But whatever they are, they are likely to clear in a no leade situation or at worst be much closer to it than 100 thou. Jake's seating his stuff a lot longer and even at that length 6.1gr. is a wise point to stop. I was recommending the OP stop at 6.0 for safety's sake based on my experience and what I make of it. That was my point in posting not in meeting your approval or explaining why I can measure...
Why does pressure and velocity come so easy? I'd say Jake's load shows there's pressure aplenty regardless of the OAL. I think these are terrific bullets, but they built to different priorities, with absolute performance being key. I think sizing a little larger helps accuracy and ignition consistency, even if were are only talking about 0.5-0.7 thousandths. And the blunt nose of the MPR makes for a long bearing surface at the same time as it makes 'normal' OALs heavily leade-dependent. Having loaded a lot of these using different calibers, powders, primers and OALs from no-leade to whatever the barrel will allow, I don't find it's smart to get closer than 0.2gr. to the max charge given in published load data for even remotely similar bullets. If I had run into just one case where pressure and velocity came hard rather than super easy I'd be more apt to believe diameter is not materially related. Believe what you will, just stop at 6 grains (or 6.1 if you
really stretch the OAL
)
