I wanted to benchmark some performance data for various .223 / 5.56 factory match loads. Sharing my results.
Test rifle is a custom build with 20" Rainier UltraMatch .223 Wylde, shot suppressed with Griffin Armament Recce 5. Trigger is Geissele SD-E. Optic is Vortex HS-LR at 10x mag, shooting at 100 yards. Muzzle velocity data was collected with a MagnetoSpeed v3.
Six different factory loads where tested. Three were variation on IMI 77gr "RazorCore" with the others being Black Hills 77gr OTM, Fiocchi 77gr MatchKing, and PPU 75gr HPBT-M. One of the catalysts for this exercise was to examine differences between commercial and "brown" boxings of the IMI, as well as later production vs new production. Black Hills is supposed to be the commercial equivalent of the Mk262 Mod 1 ammo, so should theoretically set the benchmark for 5.56 military loadings, whereas the Fiocchi represents a typical commercial .223 match load using the popular Sierra MatchKing bullet.
Two, 5-round strings were shot for each load in a round robin (e.g., 5rds of A, 5rds of B, and so on). I started late morning on a very pleasant day so the temperature warmed up a few degrees and humidity dropped quite a bit by the time I was finished. Generally speaking, I did not consistently let the barrel cool between strings and had done some shooting to re-zero my scope before this test so there are no "cold bore" shots in the data. Bottom line: I wasn't super rigid and scientific on how I shot my strings.
The summary results of the velocity data are shown below:
The results on paper are below. Shooting was from a bench, seated, with a bipod and rear bag. Note that I had a few fliers, including one that was just off the paper and, I hate to admit this, was closer to an ND than a flier - be careful with those light triggers! So, if you can't find all the holes, that is why. I was more concerned about velocity data than group sizes since I had the chrono hanging off the suppressor, so don't read too much into the group sizes. I'm fairly confident I could get a sub-moa 10-shot group from any of these. Shots from the first string are circled with a sharpie.
Observations: Yes, it looks like the older boxings of IMI are hotter than my more recent lot, which aligns with some internet chatter. The recent lot of IMI 77gr OTM LR Mod 1 is very close in performance to the BH so I'm comfortable assuming that IMI is an appropriate substitute for Mk262 mod 1. Given the variation from IMI lots, I don't think I can really draw any firm conclusions on whether the commercial or brown boxes are the same, but I'm going to assume they are just from a business/industrialization perspective (why would IMI go through the trouble to make a different load for the commercial market?). Also, the military loadings are giving me about 200-ish fps over the commercial loads but the vertical stringing on the Fiochhi suggests the lower velocity is a more accurate node for at least this barrel. Also, given the typical price of the PPU, that's an attractive option for factory match ammo, plus I personally like the brass for reloading.
I'll keep relying on IMI for my factory loadings but I think I'm going to develop two handload recipes: one to clone the IMI / Mk 262, and a slower load that comes closer to the Fiocchi but maximizes accuracy out of the barrel. I suspect I can achieve the results for the latter using Varget, but I'm pretty sure I'll need to use a different powder, perhaps TAC, to get the Mk262 velocities.
(cross-posted on Weapon Evolution)