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Another Aol Question


TruStreet

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At our weekly match last night a shooter new to reloading asked me the following question. I couldn't give him a good answer, but I told him that I would get back with him. So please help me out

If you load a 40 S&W 180 JHP with the same load, but

Lets say you very the OAL; to 1.125 another to 1.130 and 1.135.

What effect will the different OAL have on the load?

TIA

Manny

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The length, in and of itself, may change feeding. Some pistols are touchy about aol, others don't care.

Greater aol, with the same powder charge, will decrease velocity. The longer ammo will be slower.

Thanks, I'll pass the info on.

Edited by TruStreet
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That...and this is an important safety point...doesn't mean a shooter should just load shorter in an attempt to get the same velocity with less powder.

Loading shorter also increase case pressure...not to be confused with velocity.

40 is a fairly high pressure round to begin with (at major power factor). Many like to increase the OAL a bit in hopes of keeping the pressure down. Of course, there is something to watch out for here too. If you get the OAL too long, then the bullet could engage the rifling...causing other types of pressure issues.

So, there is a window that the OAL of a round should be set within.

(Patrick can probably explain that better than me.)

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At our weekly match last night a shooter new to reloading asked me the following question. I couldn't give him a good answer, but I told him that I would get back with him. So please help me out

If you load a 40 S&W 180 JHP with the same load, but

Lets say you very the OAL; to 1.125 another to 1.130 and 1.135.

What effect will the different OAL have on the load?

TIA

Manny

To add a little bit to the excellent advice already given...once you go beyond the SAAMI spec maximum overall length (1.135" for 40 S&W), you're in uncharted territory. Loads that you find in books won't match up with what you'll be getting out of your gun, or seeing on your chronograph. In fact, when you load .40 long, like many do for major loads in STI/SVI guns (among others) it's getting close to the max overall for 10mm (1.260") so it's a pretty different animal from what you'll find in reloading guides.

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  • 4 weeks later...

Hey I changed bullets and had to reset my Dillon so I varied my OAL and shot some loads.

I used, 1.115, 1.125, and finally 1.135 and the velocity only changed from 816 down to 815. I thought it would chnge down more as the oal increased, but it did not??

T

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