BP I was trying to keep others from jumping on the pistol bandwagon and starting a discussion not  directly related to ours on Mann's findings. 

When you look at the bullets out of Mann's short test barrels one can really get a visual on the base of the bullet trying to pass up the nose and the accordion effect as well as the nose slump affect. Also while looking at the those test bullets one will also notice that the nose always slumped to a different position from test to test. This is exactly what is happening to our breach seated bullets within the constraints of the barrel. My 32-40 bullet at 1450fps in a 15 twist barrel is spinning at 69,600 RPM's and that pointed unsupported spitzer nose is trying its best to not slump over to one side by the centrifugal forces being applied to it and it takes allot of alloy strength to help it hang in there. If it just can't hang in there and slumps over it becomes just like an unbalanced drive shaft and use that as an example because use ole folks have likely experienced those results. 

J.Louis

J Louis I understand what you are saying about the handguns and I wasn't trying to jump on the handgun bandwagon "BP I was trying to keep others from jumping on the pistol bandwagon and starting a discussion not directly related to ours on Mann's findings." Since short barrel rifles are not legal under the present laws, only a ballistics lab with an exemption could now perform those Mann tests, I have a XP-100 that can have as short a barrel as I want on it legally &  I will be receiving a damaged 30BR barrel for it  sometime late winter early spring, I know it’s not a 32-40 or 32 miller short but a soft cast bullet will never know the difference where the pressure comes from, and I have the 185gr P. Jones 30001 plain base spitzer mould to use with different alloys, if time allows and depending on where the damage is located in the barrel {if salvageable I will use it to build a unlimited pistol for CBA competition} I may perform some tests using it and a Chronograph plus the  Pressure Trace II system which will be my Christmas present to myself this year. It could provide some interesting insights into the short barrel, soft bullet/muzzle pressure base expanding noted in Mann’s book and relate to spire pointed soft bullet nose slump, do not have the funds to try the different twist barrels but it would also be an interesting project to try a super fast twist versus the ideal? Twist barrel with soft pointed cast bullets, would need someone to provide a stop or super slow motion digital camera, some different twist barrels to actually see bullet nose slump in flight, as I have never seen a correctly recovered bullet showing the slump (I would like to have a member or anyone if they have one to please post a photo of a recovered bullet with nose slump) or a video showing it in flight.

See next post: Mike