I've shot 7 different kinds of factory ammo through our Sig P320 X5: CCI Blazer Brass 147gr, Speer TMJ 147gr, S&B 115gr, and a variety of 115gr ~17 CPR ammo from Walmart including Federal 115gr, Federal Aluminum 115gr, Remington UMC 115gr, and WWB 115gr. I tested groups freestyle, and the best grouping ammo was CCI Blazer Brass 147gr. Here's a couple pics I posted in the P320 X5 thread. This is a 5-shot group at 20y during zeroing with CCI Blazer Brass 147gr, it measures about 1.5": This is CCI Blazer Brass 147gr at various distances up to 25y to see what the bullet was doing at various distances. It measures about 2.5": The CCI was a little stout so I wanted to get some 115s that had less recoil but were also economical and easily available at Walmart. I tested the different 115's and settled on Remington UMC. It seemed to have the best balance of recoil and accuracy. The best 5-shot group at 25y was a little over 2" and the recoil impulse seemed OK. WWB shot a little bit better but it had a little more felt recoil to me. Also, Remington UMC had a closer POI to the 147gr load in case I wanted to go between both bullet weights for some reason (like shooting spinners). Sorry, I've only been able to shoot at an indoor range so I don't have actual timer data on the splits, just going off how the recoil felt. I also wanted to note how basically everything shot well except S&B 115gr and that I've had no malfunctions in about 1k rounds so far. That might not seem like much but most of the rounds were shot rapid fire if that matters at all.
Since the new P320 X5 is coming out with a new DPP slide cut, the older ones are being discounted. We picked one up for a decent deal along with a Sig Romeo 1 6 MOA and just wanted to add some data to everything else people have added. First, here it is: We added the Gray Guns competition trigger kit, which brought the trigger pull down from ~5.25# to almost 3#. We also added the GG stainless steel guide rod with 15# recoil spring, and Springer grip tape. We shot ~120 rounds, a mix of CCI Blazer Brass 147gr, Federal 115gr FMJ, and S&B 115gr FMJ. CCI Blazer Brass shot the best for us, here's a group while zeroing the red dot at 20y freestyle, and it measures about 1.5": Once I got it roughly zeroed at 20y, I shot 3 rounds from various distances freestyle to see what the POI looked like. The max size is about 2.5": Overall, I really like it. In my hands, accuracy freestyle is comparable to our STI Edge in 9mm but splits aren't as good. However, I shoot it much better than the various Glocks we own. I'm definitely considering moving from Glocks to the P320 platform because our X5 seems to shoot well. Does anyone know if you can expect comparable accuracy from other P320s? Will the different X-series guns shoot any better on average than "regular" P320s? Do X5s generally shoot better? Thanks!