I never said Gain twist barrels didn't shoot well. You apparently misread my post. What I said is that exhaustive testing in government labs, and ranges, as well on civilian ranges has shown that Gain Twist does NOT produce better accuracy than uniform rifling does.
Back When Harry Pope was first making Gain Twist rifle barrels, they were still loading the conical bullet down the muzzle, in order to protect the all important base of the bullet. BY loading from the muzzle, the scoring of the rifling on the soft lead pushed any lead towards the OGIVE, not back to stick out behind the base of the bullet like a fin. Harry did some impressive shooting of these Muzzle loading guns with a gain twist, using the increased rate of pitch to slowly turn the bullet faster.
If you look up Harry's tooling for loading target rifles, you will find pictures of equipment that is still being used, and copies for use with the Slug Gun Shooters, and their big bench guns. The Slug gun shooters don't use Gain Twist in their long range guns, either. Many have tested this kind of rifling in the past, and are a great source of information about its performance. They may not have their notebooks full of notes on their Gain Twist experience with them At Friendship, but if you go to their homes, they can pull out their notes, and save you lots of trouble, and money showing you their records which convinced them that Gain Twist provided no better accuracy.
POPE feared that a fast ROT would strip lead from a bullet because of the Torque put on the lead bullet when its first pushed from its dead rest. We now know that this does NOT happen, although lead bullets do Obturate to fill the bore and grooves when fired. Harry"s concern was almost understandable because MLers were The target guns before the Civil War, with their deep grooved rifling. But after breechloaders came into prominence, after the Civil War, the rifling was much less deep- very shallow in comparison, and folks who had worked up target loads with MLers were suspicious of what might happen to a bullet fired in a shallow groove, fast twist barrel. Paper patching of bullets came into vogue to make up the difference between the diameters of cast bullets and bore diameters, as the tolerances of the existing machine equipment was in the order of Plus or minus .002-.005"! Even bullet swaging dies could not be cut to plus or minus .001" until late in the 19th century.
Once those dies became available, however, paper patched bullets began to slowly disappear from the firing lines. What everyone understand about accuracy and bullets is that you have to have a good seal at the base of a bullet, to get good accuracy. Any gas cutting, or blow-by, will destroy that accuracy.
Modern jacketed bullets, fired at much higher velocities, are much harder than bare lead bullets, and they show no deformation, other than the rifling lands and grooves, when fired. Tolerance on a modern rifle bullet is held to .0001"!, something not even dreamed about in the 19th century. With CNC equipment now being used to cut the barrels, tolerances on rifle barrels are now approaching that same degree of accuracy. Gain Twist for such bullets is unnecessary, and provides no better accuracy.
