9mm Setback Max?


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bg226
April 4, 2010, 02:08 PM
What is the maximum bullet setback that is still safe for the 9mm Luger cartridge? If the bullet type matters it is 124GR Ball.

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bds
April 4, 2010, 02:30 PM
That depends on the combination of powder type, charge amount and OAL.

I normally start a dummy round (no powder/primer) for 9mm at 1.125" OAL and see if that length will feed/chamber well from the magazine and hand racking the slide. If not, gradually decrease the OAL until I have good feeding/chambering (i.e. 1.12", 1.115", 1.11" etc.) - For some 115gr FMJ profile, you essentially cannot seat the bullet deeper than 1.12" without exposed bullet diameter getting smaller than the inside case neck diameter.

For some lead bullet profile types, I have gone as short as 1.08" - 1.10" OAL, but keep in mind deeper you seat the bullet, you will need to decrease the powder charge as well - so do your testing in small increments. (I normally keep my 9mm FMJ/plated bullet OAL to 1.125" and lead bullet OAL between 1.10" - 1.125" depending on the bullet profile).

I am assuming your 124gr "ball" is either FMJ/TMJ/CMJ or plated - should be fine around 1.12" - 1.125" OAL, but do your own feed/chamber check and decrease as necessary in small increments.

YMMV

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