Unusual velocities from 185 vs 200's.

I am getting slower velocities with the 185 than I am from the 200 LSWC.  Both are Penn brand and yes I am sure I did not mix up the loads.  I actually repeated the test and got the same results; 715 f/s with 185's and 740 f/s with 200's.  Additional evidence - the 185's would not cycle the gun (Colt 1911 with slide-mounted rail and a Sightron tube style dot mounted), while the 200's would.  Same medium taper crimp on all loads.  The second trip out, I bumped up the charge by .2 grains and again the same results; this time the 185's ran 730 f/s and the 200's were 755 f/s and again the 185's did not cycle reliably and the 200's did. 
How can this be ? 
If it happened all jn a single day I would just think it was "opposite day" and not worry, but two separate occasions?

The greater mass of the 200's allows pressure to build quicker. Hence better cycling.

Put a 10lbs recoil spring in and they will cycle down to 660 or so

If loaded to the same OAL, then the 200's base will be deeper into the case, thus causing more pressure. More pressure is quite simply more pressure to squirt the bullet out and to cycle the gun. Simple fix, add 2 - 4/10ths more powder, maybe a different powder. A firmer crimp may help too.

185's do not seat as deep as a 200 typically so case volume is greater with 185. In my opinion this builds less pressure than the 200's. I know some people argue its because its lighter, but no matter how you slice it its got less felt recoil and lower velocites. I have some 45's that will function 3.4 BE with 185 and some that require 200 for same powder charge. At that light powder charge you can really feel the difference between the two bullets.
Jon
Jon

231 powder & 180 gr  needs  .6 grs more powder to get the same velocity as a 200 gr .  Hodgdon data. But there is .001" difference in bullet diameter.

This is not unusual. See Table 2 at this link:

https://www.shootingtimes.com/editorial/power-factor-recoil-bullet-weight-gives-edge/99399

Reduced case volume with the 200.
Uhhhhhhh.
I'm an idiot !!!!
Thanks guys.