How slow (and heavy) can you go?

T

TXAZ

New member
We were at the range yesterday were another shooter was experimenting with a wide diversity of loads. Caliber might not matter, but let's assume 9mm if it does make any difference.

The ultimate question is about the process: Are their calculations you can go through first to get close, or is it all empirical trial and error to determine how heavy a bullet you could use, and determining the maximum safe velocity of the round, and still get the action to cycle?

I believe there are 9mm rounds from 65gr up to 165gr. Process wise, could you come up with a very speedy 45gr round or a very slow 300gr round?
 
The free ballistics calculator PointBlank includes a function for calculating recoil. You might find that's close enough to at least get some idea of what loads might or might not cycle the action.
 
Aguila Blanca said:
The free ballistics calculator PointBlank includes a function for calculating recoil. You might find that's close enough to at least get some idea of what loads might or might not cycle the action.
Click to expand...

But you still need to know how much recoil is required to cycle the action. Without that information, the numbers it spits out are meaningless.

Some guns will cycle with squib loads even when the bullet gets stuck in the barrel. And some guns won't cycle with light loads until you get to some ill-defined velocity/recoil force. Here again, the numbers a calculator puts out are meaningless.
 
Caliber might not matter, but let's assume 9mm if it does make any difference.
Click to expand...

Caliber might not make any difference but the pistol you are shooting it from DOES.

Since this is in General handguns, one is not limited to semi auto actions, but I understand that seems to be your focus.

So, how heavy a bullet you can use in a semi auto is limited by what will physically fit in the chamber and allow the gun to lock shut. TO FEED it would have to also fit through the magazine, and if your length is limited, then heavier bullets, being longer would have to be seated deeper, and that means an adjustment to the powder charge.

What is the lowest level that will cycle the action? There is no calculation that will tell you for certain for any specific pistol. General ballpark, yes but actual valid number for YOUR gun, no. That depends on multiple factors unique to YOUR gun, that cannot be plugged into a standard formula.

AS an example, I had a low power target load .45acp that would cycle the Sig P220 I had, (no idea if it would cycle a different P220), empties didn't seem to eject as much as slowly roll out of the ejection port. Same ammo, loaded in a Colt Government Model did not cycle the action at all. would move the slide back far enough to recock the hammer but not eject the empty, and the slide went back forward with the fired case in the chamber.

Every semi auto can be an individual about where it will cease cycling, and only testing with your gun and your ammo will tell you where that point is, for THAT gun.
 
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