OAL question

[jballs918]

i have a quick question about OAL in the Lyman 48. is this the minimum that they are supposed to be set at or are they supposed to be dead on to the OAL in hte manual. the reason way i ask is becuase all my 38s are at 1.48 or 1.49 and the manual says 1.44 will this make a really big differance

[9.3X62AL]

A more involved question than it might first appear to be. Your longer (.050") OAL might yield slightly lower pressures than the "spec" length given in the Manual, and the 38 Special is pretty user-friendly when it comes to OAL issues with a given load. As long as the loaded round chambers OK and a leading drive band of the boolit fits into the cylinder throat without undue friction after several cylinder-fulls of firing, you should be all right.

A LOT of factors can influence a given OAL recommendation in a loading manual. In the 38 Special specifically, a given OAL might enable proper crimping of a designed-in crimp groove--or prevent a front drive band from contacting the throat (creating possible loading interference), or some other factor that boolit design dictates. What it boils down to at times is how a load fits and functions in your revolver/pistol/rifle and that platform's chambering quirks' interface with that given load. The easy answer is follow load manual recommendations closely until you gain sufficient experience to start the sort of experiments that Cranks Like Us delight in--and debate about--and sometimes disagree on.

Again, the 38 Special is pretty forgiving. Calibers like the 9mm Luger and 40 S&W are DEFINITELY NOT FORGIVING when it comes to OAL length issues, and close attention to data detail is HIGHLY recommended.

[versifier]

This is my general rule of thumb, but it does not apply to semi-auto pistol cartridges. You can seat to a greater OAL without pressure problems, the only concerns are if they will fit and function properly in cylanders and/or magazines. You can run into pressure problems, sometimes very serious ones, when you try to seat to a shorter OAL. Maybe not as big of a deal in rifle cartriges shooting reduced cast boolit loads, but one should still be aware and pay attention for pressure signs. You can still get pressure spikes with reduced loads, as there are still elements of interior ballistics that remain only educated guesswork. The biggest potential danger is with revolver loads, as we often load them as stiffly as we do with jacketed bullets. Max or near max loads with telescoping bullets or short OAL's can spell disaster.