You are not going to want to read this, but the difference in accuracy is probably due to your follow through/flinch. The faster bullet will leave the barrel before you push the pistol a greater distance. Slow bullets, if the follow through is not perfect, the flinch reaction will push the pistol further before the bullet leaves the barre. Flinch/trigger pull errors will move the bullet a surprising distance.
The 32 S&W Long was a well established Bullseye Pistol target round, and I have shot next to shooters who were using it in competition. The thing will cut clusters at twenty five yards, and will hold the X ring at 50 yards. It is an inherently accurate round when loaded to a velocity that keeps the bullet from tumbling. Pistol bullets are very susceptible to tumbling at low velocities.
In print writers used to fill magazines with accuracy tests of 38 Specials in 38 Special revolvers, and 38 Specials in 357 Magnum revolvers. They seldom shot statistically meaningful group sizes, but accuracy differences were primarily due to the mechanical ability of the pistol, not the round.
This is a discussion of this issue from a Bullseye Pistol Forum
Accuracy of 38 Special from 357/38 revolver vs 38
Even though a 327 bullet is a different size, and the cartridges are different, I am confident that the inherent accuracy between a 32 S&W Long fired in a 327 chamber, and a 327 fired in a 327 chamber, are negligible. Any differences will due to the shooter's reaction during hammer fall.
