Ok, I went and bought some CFEBLK and 125gn Sierra Pro-Hunters. Friday, Started at 26gn and worked my way up to 27.5gn. I liked my results of 27.2, so I loaded up 20 @ 27.2 and went out this morning. I'm hearing the sweet spot is around 2600 FPS. I shot just 2 groups and both are "minute of deer", I was just hoping for a little better results. On Wilson Combats website, it states the the temperature was 90-100*. I'm in Nebraska and this morning when I chronographed my leads, it was 18* feel like 8*. My results: Ave 2331 FPS, ES 40, SD 17. I was .5 away from maximum
charge weight. So my questions are, could my low velocities be because of the temperatures here? How much velocity am I giving up because of said difference? If I did nothing more than wait for warmer temperatures, will my groups tighten up? Am I wasting resources by doing load development in such cold temperatures? Shat are your thoughts?

Hello Gentlemen,

First post here. I feel extremely lucky to have come across your forum and this thread. I would consider myself an early adopter of the 300 HAM'R and have already assembled a few builds. The 1st was an 8" Pistol with SLR Rifleworks linear compensator. I have used four different factory loads and have settled in on the 130 FNHC per Bill's recommendations. I was surprised the find that all four rounds had points of aim within an inch of each other at 50 yards. Also, I should have just stuck a coffee can where the brass was ejecting due to its amazing consistency, a testament to Wilson Combat's quality control. Bill or anyone assembling HAM'R AR's my question for you is this... can you please tell me if you are using standard buffers and springs with the the 300 HAM'R? I have to say the 8-inch barrel with pistol gas was hitting me pretty hard compared to standard 5.56 ammo. I was running a flat wire spring and H2 buffer. All brass was ejecting at 4 o'clock, with 125 TNT, 130 HP, 130 FNHC and 150 SST, so I felt like I didn't want to go to a higher power spring or H3 and chance the bolt not locking on an empty mag. Due to my previous law enforcement experience I have never been a big fan of adjustable gas blocks for a "duty" gun.

I am going to try the upper this weekend on my SBR lower with Maxim Defense stock and JP captured spring with (2) tungsten weights to see how it performs. That is if I can get the lower completed today. I also have a 16-inch lightweight 300 HAM'R build that I can't get to run due to what seems like being undergassed, but I was running a titanium bolt carrier group and ran out of time to drop a standard one to try and eliminate the carrier. I used a bunch of VSeven parts and got the rifle without optic in at 5 lbs even.

I also just got a WC 11.3 inch HAM'R barrel for my truck gun but I just have to find time to assemble it.