working up a new load, what increaments to use?

[Mike in CT]

I want to get the most out of my Sig 9mm in terms of accuracy. I have reloaded a few thousand rounds and made my way through all of the start up problems, now I want to dial in a load. I just bought a Chrono so I can record velocity and accuracy by shooting from a rest.

So lets say I am using mixed range brass, Remington Primers, 147gr Montana Gold FMJ on top of WSF Powder. Hodgdon website shows a range of 3.9 to 4.3gr witha 1.169 OAL

I have loaded rounds and safely fired them from one end of this load range to the other. Knowing that accuracy can come from speed, do I start mid point and then go up in .1 or .2 gr of powder for each test batch? There is only a .4 range to work with. Do I change OAL, or something else?

Seems like I am missing something. I do have some Titegroup Powder on hand to use as a 2nd option in powder if needed.

Any advice is appreciated.

Mike

[blind bat]

Usually, I default to finding 'power floor +10' then play around with a loads to see if increasing or decreasing the load impacts accuracy. For example, I'll find a load that gets me to 135pf then tweak the charge from there but staying in the 130's.

[Kyle O]

Which sig 9mm? As long as the sights are adjusted correctly, I don't worry too much on groups, if it's over 3 inches at 20 yds, I may do something, but usually it's the bullet type/weight, and not little adjustments that I might make.

[Joe4d]

accuracy doesnt come from speed, it comes from consistency. It also generally will come from a bullet that matches the rifling, Sooooo, ditch the mixed brass, I'd also be surprised if 147's are best in your gun. Most 9's generally prefer a 124. For max accuracy out f a 9mm a good quality 124 gr hollowpoint will probably be best. Load to power factor with amainstream powder, you'll see more change adjusting the OAL than the powder charge.

[G-ManBart]

Are you using these for USPSA/IDPA matches, or something else? If so, you have Power Factor considerations. If not, it's just what works best in your gun. Until we know whether you need to make a specific PF, it's sort of hard to give a good answer. The general idea is to find the bullet/velocity/OAL combination your gun likes best. If you've got .4gr to play with, I'd shoot groups with the Min load, +.2gr and +.4gr, at a standard OAL. I'd see which of those was the best, then vary the OAL +/- something like start at 1.120", then try 1.110" and 1.130" (assuming all will chamber in your gun). Realistically, that's probably enough to get the load as accurate as you're going to get without really working hard. The easiest thing you can do immediately is to used cases that are sorted by headstamp, and even better, by number of times fired. New cases will give the best accuracy, and highest velocity in almost every situation. Even once-fired show a lower velocity, and bigger spread in velocity (SD and ES). R,

[shooting for M]

What kind of accuracy are you looking for? If you are shooting a stock Sig, I will assume "acceptable" for IDPA/USPSA. It has already been said here, velocity numbers aren't as important as your consistency or in Chrono terms, SD (standard deviation). As usual, G-man brought up a great point, OAL will probably make a bigger difference than velocity. And like Joe stated, try different bullets, again much more important to accuracy, MGs are great, but maybe your gun just doesn't like 'em.

Oh, and +1 on getting rid of the mixed headstamp brass, and use it for practice.

Just my $.02

ETA: I can't spell.

Edited January 23, 2011 by shooting for M

[arsoncop9]

mike,

I have a sig 226 9mm. mine loves 147gr. bullets. i cam currently working up a load as well. i went to the range with 147gr. hornady xtp's with mixed brass and federal primers. i am using titegroup with 3.3g,3.4g,.3.5g with 1.100 OAL. the 3.4g did the best but all the others grouped well. I also tested factory loaded Remington 147g golden sabres, factory Federal 147g Hydroshocks, factory Federal American eagle 147g FMJ. All these grouped about the same as my reloads with the golden sabres being the most accurate. I first tried 124FMJ and my target looked like i shot it with a shotgun at 15 yards. I tried titegroup and WSF with the 124. i plan to try my 147g with wsf just to see what happens. I also plan to get some Montana golds in 147g.

I also did a search on the forums while i was working up a load and noticed all the sig shooters that posted information was shooting 147g. Sig uses a 1-10" twist rate in the barrels and i think (Not Sure) this is why the gun likes 147g bullets over the lighter ones.

PS. i also shot WWB 115gr. FMJs and they also did not pattern as well as any of the 147grs. i shot.

Hope this info helps you.

[Bello]

.1 to .2 every 5 rounds to test

[Duane Thomas]

I test in .2 grain increments. In my experience .1 grain doesn't give you enough difference to even be worth testing.

[Erik S.]

If you're using a Dillon, you might be hardpressed to load within .1gr EVERY TIME. Even with ball powder, I've found SLIGHT incosistencies with the powder measure...especially in 9mm that uses small charges. Ususally +-.1gr is good enough. That said, load up what you think will make PF in your gun and run it through the chrono to be sure. Seat a bullet and drop check the cartridge in your chamber till it just fits and allows the slide to close (i.e. max OAL possible). I usually load up an empty case with just a bullet and no primer to check this if I'm reloading at home (residential area). I recommend discarding the dummy cartridge after checking your chamber since it looks like a live round. You do not want to end up with that round in your chamber when you arrive at a match, or anywhere else for that matter. Seating the bullet close to the lands will cause your pressures to be at their highest levels allowing you to find the TRUE max load in your gun as well as give you more freedom to play with seating depth later. If you start with the bullet way off the lands and a max charge works best in your gun, when you seat the bullet LONGER (closer to the rifling), you may experience pressure issues....this process of working BACK will eliminate that. Find your powder floor that keeps you comfortably above PF then work up in .2gr increments till you reach max or near max keeping an eye out for pressure signs along the way. Shoot 5-8rnds each at 20yds off a rest noting ANY feed issues. Pick your best group and play with seating depth from there. You won't have to worry about pressure since you already started with your bullets very close to the lands. Try seating in .005" increments working back until you reach min COAL. Load up another 8 rounds of each of those also noting any feed issues. Pick your best group out of that set of groups and load at least 50 cartridges for feed checking. Load up all your mags with the 50 rounds and make sure they all feed flawlessly. If you have a FTF, document, in detail, the type of jam as it might be related to bullet seating.

Edited to add that if you discover a load very close to PF works well, if you seat your bullets further in (i.e. shorter COAL), you will likely experience a decrease in MV that could cause you to drop below PF. Just keep an eye out for that.

Edited January 24, 2011 by Erik S.

[Duane Thomas]

Edited to add that if you discover a load very close to PF works well, if you seat your bullets further in (i.e. shorter COAL), you will likely experience a decrease in MV that could cause you to drop below PF. Just keep an eye out for that.

Why would that be? I've never tried it so I don't know, but it would seem to me that a shorter COL would lead to higher pressures would lead to higher velocities, yes?

[ima45dv8]

Edited to add that if you discover a load very close to PF works well, if you seat your bullets further in (i.e. shorter COAL), you will likely experience a decrease in MV that could cause you to drop below PF. Just keep an eye out for that.

Why would that be? I've never tried it so I don't know, but it would seem to me that a shorter COL would lead to higher pressures would lead to higher velocities, yes?

That's been my experience.

[G-ManBart]

Edited to add that if you discover a load very close to PF works well, if you seat your bullets further in (i.e. shorter COAL), you will likely experience a decrease in MV that could cause you to drop below PF. Just keep an eye out for that.

Why would that be? I've never tried it so I don't know, but it would seem to me that a shorter COL would lead to higher pressures would lead to higher velocities, yes?

Absolutely, shorter COAL equals more case volume used and higher pressures and velocity. R,

[Erik S.]

Perhaps I am wrong in this I was always under the impression that more pressure results when the bullet is touching the rifling not allowing the bullet to pick up speed before going down the barrel. The coefficient of static friction is greater than the coefficient of kinetic friction. My math could be failing me here. After reading your responses I can see how the pressure could increase with lower case volume but that seems less significant than the frictional effects of the bullet being up agains a "wall" (being the rifling).

If there is another thread than can clarify this for me, please advise. I have always used this method in rifle shooting and carried it over to pistol. Perhaps the theory CANNOT be used for both cartridge types

[Gregory_k]

i just load for power factor then adjust sightes if need be. USPSA does not require 1" groups at 25 yards.

[Sarge]

In these games I think the general school of thought is to load as long as your mags and gun will allow. But you don't want anything touching the lands when chambered. With fluctuations inherent to our loading machines you will end up with rounds too long that won't chamber. Been there done that.

Also the less case capacity(IE shorter OAL)the higher the pressure and typically the higher the velocity.

Totally different school of thought compared to the rifle experience quoted.

FWIW I load 124 CMJ MG to 1.13. I could probably go much longer in my G34 but the 1.13 was far more accurate than 1.14 or 1.15.

[larryflew]

I also thank you guys. A LOT of useful info there that I have not seen elsewhere re 147 loads.