Lost on OAL ????????9mm

B

BCboy

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OK I have 115JHP's & 115FMJ's and 231 Powder . In the winchester guide it lists everything at 1.169" with this powder . If you look in other manuals you get 1.125",1.110",1.050" etc..... with the JHPs and 1.135",1.130",1.125"....etc with the FMJ's
How do you know what to use ????? all the powder charges are the same but all different OAL? SO what to do ? Stick with one manual and go for it?
want to try some 124's as well
 
Hi

I load all my 9mm at 1.168, it works flawlessly in my glock and both sigs, this is the maximum OAL according to the Speer Manual, It also seems to be close to most factory as well.

Steve
 
Max OAL depends on your mag first, then the bullet shape and throat length, and finally on how well the loaded bullet feeds.

Mag OAL is easy - how long a bullet can be loaded?

OAL for throat length (for a given bullet) is easy - remove the barrel, start with the longest your mag will load and see if it will drop in without pressure. If not, reduce OAL until it will and you have the bullet lying right against the lands.

OAL for feeding is easy - try to feed the longest bullet your mag and throat can accomodate. If it doesn't, reduce OAL until it does.

Reducing OAL length increases pressure, but might to a point might increase accuracy and ease of feeding.
 
The OAL of any given cartridge is determined by the shape of it's nose (Olgive) and the tightness of your chamber.

A long nosed 9MM bullet may seat shallower and hence the cartrdge OAL might be longer as the Olgive does not engage the rifling by virtue of it's narrower nose. The same weight of bullet with a blunt nose but wider olgive may have to be seated deeper into the case in order for it to chamber properly. There are various turns to the same theme but from that you should get the idea. You should try to load your rounds as close to manual recomendations as possible, If your bullet is not listed match weight and design and you should be close. For a guage remove your barrel from your gun and place the loaded cartridges in the chamber. If they seat flush then they should load and shoot ok.

Using lead truncated 125 gr boolits I load my 9MM to 1.115" as I do for my 125 gr RN. They feed properly at that length in the six 9MM I own.

Take Care

Bob
 
Good point, I also use a cartridge checker which not only lets you know if the loading process was flawed but also checks for OAL by placing it on a flat surface. Worth every penny.
 
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