Concerned about OAL in 9mm


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PodPeople
June 23, 2013, 03:33 PM
I loaded up some Friendswood 115gr LRN bullets for my S&W Shield 9mm. I found that due to the shape of the bullets and the Shield's chamber size I had to seat them to 1.070 in order for them to properly chamber. I used 4.4 to 4.5 grs of W231. The Lee and Hogden manuals show a minimum OAL of 1.100 and loads of 4.3 to 4.8 grs. I shot a string of 11 of these bullets and measured the velocities. They ranged from 1039 to 1074 with an average of 1054. For this bullet/powder combination the Lee and Hogden manuals show a starting load velocity and a "never exceed" velocity of 1079 and 1135. Can I assume that the chamber pressures are not dangerously high and that these bullets are safe to shoot? Or could the short barrel length of the Shield result in acceptable bullet velocity even though the chamber pressure may be dangerously high? Is acceptable bullet velocity a sufficient indicator of safe chamber pressure regardless of barrel length? :confused:

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stavman11
June 23, 2013, 03:46 PM
Did ya do the Plunk test for the Bullets...

Pull the barrel and determine the best OAL need for that Gun...

here is a youtube of it
http://www.youtube.com/watch?v=cdJLNox1hpk


My XDM9 had a similar issue...had some loaded at 1.14 and i couldnt unchamber a loaded round... they shot fine...

So ended up at 1.10 to 1.11 and they work great... was a similar Bullet size issue... cuz 2 other types work fine at 1.13 or so

Walkalong
June 23, 2013, 04:05 PM
and a "never exceed" velocity of 1079 and 1135.There is no such thing as a "never exceed" velocity. There are velocities listed for a certain barrel length to go along with the "never exceed" (Max) powder charge, and these listed velocities, taking barrel length/type into consideration, can be helpful in determining if we are pushing our luck.
I had to seat them to 1.070 in order for them to properly chamber. I used 4.4 to 4.5 grs of W231. The Lee and Hogden manuals show a minimum OAL of 1.100 and loads of 4.3 to 4.8 grs. I shot a string of 11 of these bullets and measured the velocities. They ranged from 1039 to 1074 with an average of 1054Assuming this is accurate, you sound like you are probably OK.

What barrel length were the velocities listed for vs what you shot them in?

PodPeople
June 23, 2013, 04:09 PM
Yes, they passed the plunk test in both my max cartridge guage and the barrel.

PodPeople
June 23, 2013, 04:13 PM
What barrel length were the velocities listed for vs what you shot them in?

The manuals didn't specify what barrel length was used in the tests. I assume they were longer than the Shield's barrel.

rcmodel
June 23, 2013, 04:17 PM
Hodgdon manual says they used a 4" barrel.

rc

PodPeople
June 23, 2013, 05:49 PM
Hodgdon manual says they used a 4" barrel.

I stand corrected. Lee's data is the same as Hogdon's so that's probably where they got it.

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