OAL for M&P Pro

[fiddler]

M&P Pro 9mm

147gr MG

WSF

I'm new to reloading and I'm setting up my press. I'm trying to figure out what OAL to start with. Many posts in this forum recommend an OAL of 1.125 - 1.130 for this pistol/bullet/powder combination however the Winchester reloading data website recommends an OAL of 1.169. To further complicate things the Atlanta Arms ammo that runs fine in my gun measures 1.142 to 1.148.

I believe that too short an OAL risks pressure spikes and too long won't feed reliably. Where should I start?

Roy

[chuck s]

I go with 1.14-1.145 in my Pro and it always feds well

[atbarr]

I load to a OAL of 1.140. The bottom line is, start out low and Chrono.

[polizei1]

I like 1.140-1.150. I've had great success with that length. I like to load my ammo long, just seems to work!

[AS350Driver]

I use 124's but also load them to 1.140. I had some factory ammo when I first got the gun that was about 1.110, and experienced feed problems.

[reichebrown]

124s @ 1.15

[superdude]

M&P Pro 9mm

147gr MG

WSF

I'm new to reloading and I'm setting up my press. I'm trying to figure out what OAL to start with. Many posts in this forum recommend an OAL of 1.125 - 1.130 for this pistol/bullet/powder combination however the Winchester reloading data website recommends an OAL of 1.169. To further complicate things the Atlanta Arms ammo that runs fine in my gun measures 1.142 to 1.148.

I believe that too short an OAL risks pressure spikes and too long won't feed reliably. Where should I start?

Roy

the winchester (Hodgdon) website is quoting the maximum overall length for the 9mm Luger cartridge (1.169 inches). Round nose bullets can often be seated that long and work fine, depending on the length of their nose. Flat nose bullet often cannot be seated that long because they might not fit in the magazine or chamber. see the link below for practical information on determining overall length.

http://38super.net/Pages/Overall%20Length.html

[mcracco]

I believe that too short an OAL risks pressure spikes and too long won't feed reliably. Where should I start?

Roy

Start by pulling the barrel out of your gun and seating the bullet .005-.010" off the lands! You can't use an OAL dimension from someone else because they have a different barrel with different bullet.

[reptoid]

I believe that too short an OAL risks pressure spikes and too long won't feed reliably. Where should I start?

Roy

Start by pulling the barrel out of your gun and seating the bullet .005-.010" off the lands! You can't use an OAL dimension from someone else because they have a different barrel with different bullet.

Amen

[fiddler]

Good advice. Thanks all.

[freakshow10mm]

My standard advice is to load to the longest OAL that will fit your chamber and feed reliably from your magazine. Start with a dummy round at the SAAMI max 1.169 and drop it in the chamber. Shorten the OAL until it fits. Then load 3 dummy rounds at that OAL. Put them in the magazine and hand cycle them in your weapon. If they feed and eject fine, use that OAL. Then start at the start charge and work up using the established OAL. You may need to fine tune a bit here and there once you are shooting live ammunition, but this method is the equivalent of bore sighting your scoped rifle.

Winchester always uses the SAAMI OAL max for their pistol data.