Hi Pete,
Excellent point. I have not done any comprehensive testing to determine the extent and rate of leading in my factory Glock or other OEM barrel using a similar rifling type. My range and casting time is limited and I would rather spend it on something a much more fun to shoot and capable of a higher level of accuracy than a carry gun with a barrel not much longer than my middle finger. My LW barrel is used for cast/lead and the OEM barrel I fed only factory ammo when carrying. My input is based the scores of other posts both here on at CBA, Cast Boolits and other sites that I read over, drawing on the experience (or lack there of) and range time of others.
In summarizing what I came up with regarding the different opinions on the subject, 3 main things seemed to stand out over the coarse of the research.
1. No unusual problems were reported with after market barrels with conventional rifling when shooting cast and leading did sometimes occur.
2. The rifling type used in Glock and similar OEM barrels had a general tendency to lead up with use to varying degrees in regard to caliber, shots fired, alloy type/bullet hardness, etc., due to the rounded shape and configuration of the rifling. Leading cropped up sometimes with less than a box, other times well into the hundreds.
3. There was not any hard fast advise or recommendations that no problems would arise by using cast in a factory Glock or similar OEM barrel. Those shooters who chose to do so accepted the extra vigilance in keeping on top of any leading and/or accepted any potential ill side effects of doing so. To be honest, several hundred rounds of cast were put through mine without a hitch. However I eventually decided my piece of mind was worth more and opted for the LW barrel.
In regards to the old SS rifles, their mainstay was a steady diet of paper patch bullets which do have a more abrasive action than lead alone. Coupled with burning BP and likely less than optimal barrel care over time the lands and grooves made the transition into dips and rises. I once had an 43 Egyptian rolling block with “Glock” rifling.
In the end each of us makes the choice for what we feel the most comfortable with based upon our own individual research. I doubt anyone here expects another to take their advice at face value, especially mine. More than likely you have begun to read through other posts here on the subject, along with other sites that you trust. Have fun sifting the fly turds from the pepper.
All the best. Michael.