9mm PF advice

[Sarge]

Hey all,

This weekend a fellow shooter has graciously offered to help me chrono some reloads.

The gun is M&P pro

The loads will be 124gr MG CMJ WSP Titegroup I want to load some 3.9,4.0, 4.1 gr loads for comparison.

My question is about temperature effects on PF. I want to stay close to minimum pf without crowding 125 too much once it warms up. This weekend it will most likely be in the 40's by the time I shoot. What are your suggestions/rules. I understand pf will if anything, go up with warm weather, correct. So what am I looking for number wise this weekend. Make sense?

I am sure someone at the range will have advice but I would like to hear it from you all most of all.

Thanks alot

[yoshidaex]

i'd suggest loading up test rounds in 0.2 grain increments. the majority of powder drops out there has a variance of +/- 0.1 grains. might be worse.

as for staying close to PF, getting closer to 130 would give you enough cushion in the instance the chrono station at a major match tends to read low.

for your cold chrono session maybe a target pf of 127 or 128 would be ideal if you're trying for 130.

IIRC titegroup goes up when it gets hotter and vice versa. how much, i don't know. though there are other powders out there that does the opposite. i think Sillhouette is one of them.

would you happen to know what brand of chrono you will be using?

along the same lines of using reduced pf loads, you may have to change your recoil spring accordingly.

Edited March 12, 2009 by yoshidaex

[Sarge]

No I did not get the brand of chrono. I was just grateful that he offered the use of it.

[tnichols]

My experience has been that temp. does effect velocity, but so does powder (meaning lot to lot), primers (lot to lot), seating depth, etc.... My point is, that unless you are working out of a LARGE single lot of powder, for example, you are better off to chrono anytime you change a variable (new lot of powder/primers, different case headstamp, etc...) just to be sure, especially if you want to run so close to the minimum power factor. If you aren't getting large lots of powder/primers or are using mixed brass, shoot for a power factor of 130 and you'll be golden.

[kevin c]

That's good advice from tnichols.

If you run your loads further away from the PF floor (I run about 135 PF through my Production Glocks), then it's less critical, but close to the floor, or if your gun is unusually picky, rechecking the load, not only velocity but function in the gun and POI, is the safest thing to do.

[JimInFL]

From the powder perspective, I've had experience twice now, with VV N320, and Silhouette. The N320 minor load was absolutely stable across 40 degree spread (chrono'd in 40 degrees, and in 80 degrees identical). Silhouette, on the other hand for my open load, went from 171PF to 176PF (colder morning was higher).

[G-ManBart]

My question is about temperature effects on PF. I want to stay close to minimum pf without crowding 125 too much once it warms up. This weekend it will most likely be in the 40's by the time I shoot. What are your suggestions/rules. I understand pf will if anything, go up with warm weather, correct. So what am I looking for number wise this weekend. Make sense?

With Titegroup, the velocity should increase as the termperature increases, but be warned that some powders work the exact opposite and cold temps increase the velocity.

Don't try to get too close to 125pf. You simply will not be able to tell the difference between a 125pf load and a 135pf load so it's a lot better to find something that's 130+ and not worry about it. Personally, I'd like a bit more....132pf or so. Why? My standard 38SC load, from one lot of powder, brass, bullets and primers, that was all loaded at the same time, went 172+PF at three big matches, but it went 166.1PF at Nationals. If you go sub-minor you're shooting for fun, which would totally suck. Some folks will run one load until they get ready for a big match and then bump up their load a couple of tenths for insurance for big matches which is counter-productive. Why practice with something softer than what you'll use in big matches? Worse, if they're really using milder ammo at local matches there's a good chance they're really sub-minor and cheating, but they don't know it....I doubt anybody wants to be that person. R,

[Sarge]

All great answers and thanks much. I guess I will shoot for very high 120's to 130 in the cold. I actually don't see myself shooting much more than local club matches this first year anyway. I just want to be able to get some data that will keep me safely above minimum pf so I can load for the upcoming season while the weather still sucks.

Thanks again all. I'll post some results after saturday.