Having some major headaches with my 338 Edge
and finding a new load with H1000… I wanted to share my results to reinforce the warning that newer H1000 appears to be hotter, and get some feedback on a couple points…
When I first had the rifle made it had a little longer throat, around 3.970” COAL to touch the lands with a 300 SMK. At that time, and with older lots of H1000, I was loading 93.5 grains of H1000 with really no pressure signs. At 150 rounds I had the barrel set back just enough to rechamber with a shorter throat. It is now about 3.920” COAL to the lands with a 300 SMK (.098” freebore I’m told).
Got the rifle back, read all over about the newer lots of H1000 being hotter. Went and bought some, and loaded one round each at 90, 91, 92, 93, 94 of H1000 (should have loaded more at each, oh well). The rest of the load specs: Rem brass, 300 SMK, CCI 250, 3.890” COAL (about .030” jump) . My chrono gave me the following velocities:
90 – 2802, 91 – 2810, 92 – 2856, 93 – 2898, 94 – 2909
I noted some pressure signs at 93 and 94. I don’t recall any stiff bolt lift, just some primer flattening and ejector marks. The one round of 92.0 looked good, and 2850 was more or less my goal so I loaded 20 more at that. Shot those with ½ MOA 5 round groups and no major pressure signs that I recall now. Some partial primer flattening but no stiff bolt or ejector marks that I remember seeing. Conditions that day were: temp – 48, humid – 72, baro – 29.90, dens alt – 600.
Thinking I was good to go with that load, I loaded 40 more and went out a week later to shoot at distance. I didn’t record exact conditions that day (damn it), but it was about 15 degrees warmer and 1500 feet higher in elevation. At around round 9 or 10 or so I had a stiff bolt. Looked at it and noticed the primer pierced. “Huh, that’s weird” I thought. Looked at the first 8 or so cases and saw some ejector marks. Decided to go ahead and shoot the rest of that batch of 20, and pull the remaining 20 I had loaded at 92.0. In doing so I had another pierced primer. I really doubt the temp / conditions had much to do with it, as H1000 is supposed to be pretty stable…? None of these were chronied and as I recall they weren’t matching up very well with the 2850 number I had put into Shooter based off the initial pressure test rounds.
Dropped the load two whole grains to 90.0, loaded 20 more and went to the range. Still had some ejector marks, partially flat primers, and one pierced primer. Conditions: temp - 64, baro – 29.83, dens alt – 560. None of these were chronied.
Due to the continued pressure signs I dropped the load another two whole grains, to 88.0. Loaded 50 up and went to shoot at distance, thinking there’s no way I could still have pressure there. I ended up still having somewhat flattened primers, some shiny but not raised ejector marks, and on the very last round a pierced primer. Conditions were: temp – 55, baro – 27.82, humid – 90, dens alt – 2500.
Now for what really has me scratching my head at this point. Shooting the 50 rounds at 88.0 yesterday… I put three rounds over the chrony first thing and got: 2733, 2781, 2788. I put 2775 into Shooter and was almost 2 IPHY (NOT MOA) low at just about every range all the way to 1000 yards. In the end the dope I got was: 535 – 9.0 IPHY, 760 – 15.75 IPHY, 870 – 19.0 IPHY, 965 – 22.75 IPHY. Given the conditions I have to put roughly 2875 into Shooter / JBM to get those numbers to line up. I tend to trust the numbers / ballistic programs over my chrony. That velocity would also better explain the continued pressure to me. I read the H1000 got hotter, but damn… 88.0 and 2875 out of an Edge with the 300 SMK???
I’m not sure how to reconcile the results of the first five pressure test rounds and the first 20 at 92.0, with the subsequent pressure at 92, 90, and even 88. It was using the same H1000 (newer stuff), so maybe I just wasn’t paying enough attention on the first 25 (but I sure thought I was). I’m well aware working down from pressure isn’t ideal, and I probably should have dropped WAY down and done ladder testing back up on the first signs of pressure. Normally I do that when developing a load but I already had data for this rifle, albeit with a little longer throat / jump and older lots of H1000. It is what it is…
92: Partially flattened primers, some cratering, some bolt “click”, partially raised ejector marks. Two pierced primers out of 20.
90: Partially flattened primers, partially raised ejector marks. One pierced primer out of 20.
88: Partially flattened primers, shiny but not raised ejector marks. One pierced primer out of 50.
Even at 88.0 of H1000 I’m thinking the load density is getting on the low side. There’s lots of room left in there with the 300 SMK at 3.890”. At this point I’m really leaning towards ditching H1000 altogether and going to Retumbo. I know H1000 used to be nearly the universal favorite for the Edge, but it seems to have become far faster than when everyone was so happy with it for this application.
In the end, my questions are:
Would you trust the chronograph or the real world dope couple with ballistics programs? Which velocity figure better matches up with data of newer lots of H1000 in the Edge?
Ditch the H1000 and go to Retumbo? (seems to be logical to me given all the wasted case capacity with below 88 of H1000) Is Retumbo any more temp sensitive in your experience?
Anyone else had this dramatic of a jump from the old lots / new lots of H1000? Again, I read it got hotter, but I had no idea the jump would be that large. Have the new lots been consistent after the jump?
Here’s a picture at the 88.0 grain load (note the partially flattened primer and the shiny ejector mark over MAG), and a fresh one for reference: