OAL and barrel length factors.

[WidowsSon683]

I finally got everything I needed to start running some test loads for my 40. Im using IMR PB, 180 gr TCFP FMJ, WSR primers. My initial loads are at 4.8 grains (website says to start at 4.7 w/ OAL 1.125). My loads are a little long at 1.135 and will be shot from an XDM 5.25. My question is will the longer OAL and barrel ( 5.25 compared to most sites using a 4" for their tests.) affect velocity and how much. The Hogdon site says that 4.7 loaded to 1.125 will make 907 fps. Im only looking for about 925-950.

Edited August 9, 2013 by WidowsSon683

[kamikaze1a]

Not saying that it won't work but that load data you referencing is for Berry plated bullets and is over published max for fmj. Their data list 4.5 as max for fmj. Personally, I start low and work my way up...just to be safe.

[Dirty Rod]

A longer barrel will give you a little more velocity but not the OAL. OAL should really be geared towards making sure the round feeds reliably.

[Steve L]

A longer barrel will give you a little more velocity but not the OAL. OAL should really be geared towards making sure the round feeds reliably.

COAL will absolutely effect pressure which will directly relate to a change in velocity!!!

[bigedp51]

Your proposed start load with your bullet will be approximately 43,000 psi and 8,000 psi over max pressure of 35,000 psi for the 40 S&W.

You might want to invest in the Quickload software computer program, seating depth effects case capacity and chamber pressure.

Your proposed load at a OAL of 1.135 is 43,000 psi and at 1.125 the pressure would be 46,000 psi.

Jacketed bullets are harder than plated or lead pullets and require more pressure to push them down the barrel. Even with five reloading manuals and Quickload I spent a little time last night with my impact hammer because my dyslexic finger read the wrong bullet OAL. (chronologically gifted eyesight and late night reloading will get you every time)

[kneelingatlas]

A longer barrel will give you a little more velocity but not the OAL. OAL should really be geared towards making sure the round feeds reliably.

COAL will absolutely effect pressure which will directly relate to a change in velocity!!!

I tested the same load (9 Major) with different OALs and found that I lost 5 fps (0.4%) for every .01" I lengthened the load.

However a barrel 1" shorter lost 61 fps! That's 5%

[Dirty Rod]

A longer barrel will give you a little more velocity but not the OAL. OAL should really be geared towards making sure the round feeds reliably.

COAL will absolutely effect pressure which will directly relate to a change in velocity!!!

You are absolutely right. It does have some impact but my testing has shown a minor impact unless I was loading close to max. As was stated above, barrel length makes a bigger impact on my midrange loads and I would not advise anyone to shorten the OAL to get more velocity versus adjusting the charge weight.

[MesaAndy]

IMR PB burns too fast for 180gr bullets to make any decent velocity. At max loads you might make a power factor of 170 and the kick is going to be excessive. Start off with much less powder and see what the velocity is. The 5.25 XDm will give you better velocity since the powder has more time to burn. I usually notice 80 - 100 ft/sec increase with Power Pistol over what the book says. With a 16" Barrel I went from 1110 ft/sec to 1320 ft/sec with the same load. A full power load of 8.9gr and 155 JHP went from 1310 ft/sec on the 5.25 to 1530 ft/sec on the 16" barrel.

CLICK HERE FOR LOAD DATA>>> http://data.hodgdon.com/cartridge_load.asp

Edited August 16, 2013 by MesaAndy

[mjohn]

^^^^^^^^^^^^

Thank you for sharing the data.

However, it is not in a very easy to read and comprehend format.

[kneelingatlas]

+1 when I want to share load data I take a screen shot of the spreadsheet.

[MesaAndy]

Click on the link that is above the data. I tried to format it a little better... still not great.

Edited August 16, 2013 by MesaAndy