9mm COL question

[crashguy]

Does 1.03 COL using Lee 9mm 124gr tumble lube truncated cone seem too short? I used my Storm Lake barrel as a gauge and that is the length that results in a "plunk" and drop free, it is also the place where the top band is covered by the case. I have been running this boolit sized .357 in cases sized with the lyman .38 M-die, at 1.05 COL ( the top band is showing and rests against the rifling , the boolit does not "plunk" nor drop free) over 3-3.5 gr IMR 700x with good results( little leading, OK accuracy and no feeding/ extraction/cycling issues in a G19). Should I be re-working my load to incorporate the shorter COL?

[williamwaco]

Does 1.03 COL using Lee 9mm 124gr tumble lube truncated cone seem too short? I used my Storm Lake barrel as a gauge and that is the length that results in a "plunk" and drop free, it is also the place where the top band is covered by the case. I have been running this boolit sized .357 in cases sized with the lyman .38 M-die, at 1.05 COL ( the top band is showing and rests against the rifling , the boolit does not "plunk" nor drop free) over 3-3.5 gr IMR 700x with good results( little leading, OK accuracy and no feeding/ extraction/cycling issues in a G19). Should I be re-working my load to incorporate the shorter COL?


Seems to me you answered your own question.

[Shiloh]

When going shorter and I have, I back off the powder charge a bit. I have used a start load a few tenths below the given start load for this purpose.
Then I work back up. As you have found, your boolits need to drop in and fall out.

Shiloh

[crashguy]

Yes William I thought I did too.....it's just that there is just alot of boolit in that case.... I am gonna have to trust my instruments on this .

Shiloh- I will no doubt heed your advise to lower the powder charge.

So back to the beginning on this for me.


Ed

[Dannix]

1.03 COL... that is the length that results in a "plunk" and drop free, it is also the place where the top band is covered by the case... at 1.05 COL, the top band is showing and rests against the rifling , the boolit does not "plunk" nor drop free
Ergo use 1.03. :mrgreen: As already mentioned, tweak your powder charge and use due caution.