Inaccurate handloads

[thesheepdog]

I just re-loaded some .357 Sigs and shot all of them this weekend. I came to find out that the bullets are tumbling at 25 yards. I couldn't hit a 2X2 target with about half of the rounds. My 1911 was doing about 3" groups same day.

Here's my load data

CC1 500 primer
Hornady 124gr XTP
AA no. 9 12.3 grains
cases were cleaned, de-burred, chamfered, re-sized and the bullet seating was correct to load specs.

[Brian Pfleuger]

What gun are you shooting them with?

XTPs shoot just fine in my G33, with the stock barrel or Lone Wolf barrels.

I also use CCI primers, but I've shot XTPs with Power Pistol using federal magnum and regular primers too, and they're all fine.

Is that 12.3 your first load? That's pretty near max, if not over, depending on your exact case capacity and seating depth...

[thesheepdog]

SA XD Service model.

AA powder says 13.1 is the max.

[Brian Pfleuger]

I assume that this gun shoots factory loads just fine?

Have you measured the bullet diameter and barrel?

[thesheepdog]

Yeah factory ammo is "acceptable". I have not measured the bore.

[thesheepdog]

I will say that the first few rounds out of the batch were pretty darn accurate. But then i notcied that one bullet made a hole in the paper the size of my thumb (indicative of a bullet tumble)

All of the loads functioned flawlessly, but, they just didn't cut the accuracy requirements.

[Don P]

Possible the bullets are seated too deep. I have found you need to have your rounds as long as the chamber and mag will allow.

[Brian Pfleuger]

Originally Posted by Don P

I have found you need to have your rounds as long as the chamber and mag will allow.

Interesting observation. I can not say the same about my gun.

I've fired the XTPs at 1.135 and 1.140, and a couple of my earliest rounds at 1.150 IIRC, and I saw no difference in their accuracy.

I have also tried different headspacing options and saw no performance difference.

I also tried sizing the case so as to headspace on the shoulder rather than the extractor (the only two options in most "cases"). I found that it made no difference in accuracy but shortened the neck enough to cause setback issues, so I gave up on that too.

Through all these changes there has been no discernible effect on accuracy.


The only thing I can think of is if there is a setback issue that is causing erratic pressure. Beyond that guess, I have no idea.

[thesheepdog]

Thanks guys. I am going to try re-loading these again this weekend. We'll see what happens. My brother and I loaded some .50 Beowulfs this weekend and they are stinking accurate. So, maybe with my succesful load on the .50's, i'll be able to transfer that knowledge to my .357's and maybe get some better results in accuracy.