40 s&w oal

[flrfh213]

i am trying to get into 40 S&W reloading, doing my first run as we speak, i am using a 165gn TMJ with 4.8 gn bullseye with book calling for 1.120 OAL how EXACT does OAL need to be i have it at 1.117 to 1.119. i cycled the first 10 rounds thru my M&P 40 and they run thru great.... i ASSUME the oal is close enough, how bout opinions from the more adept in the gallery....

thanks in advance

 

[rcmodel]

.002" or .003" will not change pressure or feeding, much.
But how hard can it be to just back the seating stem off a scooch and make them right?

As for book OAL?
The only true way to know if it is right for your gun is to take the barrel out and use it as a guage to chamber check them at the loading bench.

Seat just deep enough the bullet is not contacting the rifling leade before fully seating in the chamber.

They should drop in the chamber with a "thunk", and fall back out under their own weight.

rc

 

[NVMM]

Ah, The wisdom of rcmodel...

"But how hard can it be to just back the seating stem off a scooch and make them right?"

 

[aerod1]

scooch = .002" - .003"

Sorry rcmodel, I couldn't help myself
...but you are correct!!!

 

[flrfh213]

this is part of the reason i am on this forum. this way i can use all yalls knowledge and skills to better myself. thank you

 

[Shrinkmd]

How well does this work with lead bullets? They sometimes stick a bit compared to jacketed.

 

[MichaelK]

"How well does this work with lead bullets? They sometimes stick a bit compared to jacketed."

I find that developing a cast bullet load is slightly more fussy than jacketed. You need to pay attention to the cartridge mouth closely. You commonly make lead bullets a thousandth's larger than jacketed, and I suspect that displaced lube might bulge the cases slightly more. What happens is that the case mouth can be a few thousandths too large for the chamber. A factory 40 typically has a case mouth about .421". My cast 175 grain load measures .422". That's just big enough to chamber. Larger than that and the round will feed into the chamber, but stop just before lockup, jamming the slide slightly open. A light taper crimp will eliminate this problem completely!
Michael

 

[double d]

I load my .40 S&W 165 gr FMJ to 1.120" for a Glock 22. I recently
compared some 1.115-1.119" loads to the 1.120's, and found a
better grouping. I also compared some 1.125-1.127's to the 1.120's
and they were worse. I have found that an adjustment of "5 minutes"
(looking at a clock face) to the seeting die gets me about .002 in the
OAL. (For those with didgital watches--good luck)