OK, finally got the two Grendels out to play for their first rounds, and they both show a definite tendency to start out with significant dispersion, then tighten up fairly quickly. I assigned the 20" to my Grandson Patrick to get the scope ontarget and put the first 100rd through the bore. He's an untrained shooter, and his performance will not be a part of this report.
He's got to start somewhere. I started with Elena by simply putting her behind the rifle after some safety and operational instruction, then letting her develop in her own most natural way. When she wanted to do better, we trained. Now she's very good. I'm trying to see of that approach will also work with Patrick.
At this stage, both the 20" and 24" tend to be unimpressive with both the AE 90 TNT load and the HDY Custom 123 SST load. The best the AE 90 TNT could deliver in either was about 1.5MOA, and the HDY Custom 123 SST was just plain dismal in the 24".
That's in my rifles, and with barrels that are not shot in much; I think they will do better after another 100rd or so down the pipes. I also think those bullets will do immensely better as handloads with diligent load development to conform the load harmonics better to these particular barrels.
Handloads with 90 TNT do better, I have yet to test 123 SST handloads, and the HDY 95 VMax is turning out to be the crowd pleaser. All handloads use W748, and the good 95gr VMax load is at 30.0gr, and may tighten up more (in the 24" barrel, only one with any load testing yet) with a tweak. Too few groups to make claims yet, but there will be more, but five rounds at 100yd (one group only) got covered completely with my thumb..
There is a major difference between the 20" AR Stoner Factory Upper and the 24" home assembled Upper. They both use Midway/AR Stoner components, but the 24" shoots a lot better. I experimented by lapping the 24" Upper Receiver face and bedding the extension with Red Loc-Tite. Too early for certainty, but it looks like the two extra tweaks may have had some actual benefit.
I will be putting this to a more stringent test by doing load development with the 20" in original format, and then doing the Lapping and Bedding to see if it brings any improvement.
Needless to say, there will be bore scoping, and chronographing too.
The underlying premise to this series of 6.5 Grendel Upper build and factory Upper test comparisons is to find out if some very basic and inexpensive rifle components can be reliably developed without huge expenditure into good shooters by a reasonably average hobbyist. At this early stage, it's starting to look like it may be possible. FWIW, the entire test day was completed with no (zero) failures of any kind.
The next upgrades to both rifles will be
Bolt Release Assist Levers (already in house),
PSA Nickel Boron Two Stage Triggers (already in house), and
Limbsaver snap on butt pads for the M4 stocks (one in house, three to go). I got 3 of the 4 triggers on sale for $59 and change. The mods are for a set of three PSA PA-15 M4 Classic Lowers, and a PA-10 Lower.
Eventually, the 24" will be converted to an A2 configuration with a Luth-AR MBA-1 Stock Assembly, and the Luth-AR Chubby Grip (both in house).
Yesterday was my first day back at the range after 10 months of Illness, hospitalizations, 160 mile appointments, specialists, and rehabs. Really good to have all that stuff in the rear view... Wonderful 70-75 degree, under 5mph range day. Some days are just golden.
Greg