147gr load question

[Xscream]

I loaded up a test batch of 9mm, 147 gr. zero bullets with 3.6 gr of Win231, COL 1.160 with WIN SSP primers.

25 degree day, sunny with a light wind I got the following chrono results.

910 avg over 10 shot string, S&W MP Pro 5"

860 avg over 10 shot string, Berettta 92FS

876 avg over 10 shot string, Sig P226

The Lyman manual states max load is 960FSP. My two other manuals don't list Win231 w/ 147gr. Will I see an increase in volocity when shooting in 80 degree weather? Knowing I won't see 80 until next May, any predicitons? There were no signs of overpressure, which was to be exspected.

[Hi-Power Jack]

I haven't heard that WW231 is particularly temp sensitive, but it could change a bit.

But, I think that firing only 10 shots is insufficient to accurately measure your Avg Speed -

I'd be willing to bet that if you fired 25 shots at 25 F., you would get different numbers than you're

showing above. Just random distribution.

[Justsomeguy]

See... this is why I don't do much testing in the winter. You may or may not have a significant swing in velocity on warmer days which you can or cannot attribute to the cold weather when last you tested. Certain powders are temperature sensitive, and others are "reverse temperature sensitive", in which case they would go much faster in the cold. I have not tested 231 in the cold to document its particular sensitivity, but I will tell you that even powders not known for large temperature variance WILL exhibit SOME difference in velocities at your reported temperatures. The difference between 910 and 960fps, for instance, could well be attributable to a 25 degree outdoor test vs. indoor data at a likely 70-75 degrees from a manufacturer (in a minimum spec chamber too), and could indeed be somewhat larger in some guns.

Edited November 26, 2013 by Justsomeguy

[Xscream]

Thanks for the feedback. Shooting indoors is on the list, but I'm a couple weeks away yet. I'll be curious to see the differences in tempature.

Specifically speaking to the M&P Pro, I had over 50 rounds thorugh it yesterday (30ish out) and had an average of 908, High was 937 and low was 892.

[bajadudes]

I load 4.0g under a 147 MG JHP @ an OAL of 1.120 +/- .004 and get about 893 fps out of a Beretta 92fs @ 10' from the chrono. PF=131.29

@3.9 grains it was 863.5 fps

@ 4.1 grains it was 924.35 fps

Mixed HS brass CCI SP primers.

That was this summer @ approx 80 - 90 degrees, I'll try it again tonight in a cold warehouse ( about 40 deg.) and see what happens.

Sorry, I have no Zero bullet data to offer.

[Xscream]

Thanks for the info, I'll be curious to see what you come up with tonight. I was about 5' from the chrono.

[Hi-Power Jack]

I was about 5' from the chrono.

I'm surprised you didn't have trouble that close to the chrono.

Usually recommend about 10 feet to prevent muzzle blast

from interfering with the chrono results.

[Xscream]

I had limited space and backed up as far as I could while not shooting behind others on the firing line. I'll be re-chrono'ing on Friday.

[ZombieHunter]

I have a "winter load" and a "summer load". Depending on how your powder reacts to hot/cold, will depend on how you adjust your load. Any single base powder is going to have some sort of sensitivity to it, while double base powders are less susceptible (basic chemistry dictates you will see a velocity change as the temp. changes). And, as some have already mentioned, some powders are reverse sensitive, meaning the velocity will drop as it gets hotter and faster when its colder.

Whatever load you have now, will most likely need to be adjusted in the summer; especially if you're on the upper end during the winter. 231 is pretty sensitive if I recall, and will increase in pressure/velocity quite a bit in the summer. From your readings, it sounds like you're nearing the upper end. However, different gun barrels produce difference results - so keep that in mind as well.

[bajadudes]

Didn't get a chance to chrono last night sorry. Hopefully I will be able to try tonight and report back.

[bajadudes]

Outside it's 22 deg. warehouse is unheated. loaded a mag with 15 rounds that are stored in said warehouse and put it in the freezer for 15 min. for extra cold test.

same 4.0 grain 147 spec as above with WC231 which gave me 893 fps out of a Beretta 92fs @ 10' from the chrono. PF=131.29 in 80 to 90 degree weather.

This time in the cold avg was 880.6 fps for a PF of 129.4

Happy Thanksgiving to all.

[mjohn]

Thanks for the testing. I was expecting a larger spread between the warm and cold temps.

[bajadudes]

My experience has always been that 231 is very versatile and stable. Never really experienced much seasonal variation.