In the last year I have been working with the 7828. It was better than previous powders I'd used, but the problem appeared to be the heating of, what I considered, a very thin barrel. As I said, if I let the barrel cool for 30 minutes between shots, one minute groups were possible.
I tried bedding the factory stock. Later tried an overmould stock and now have it mounted in a Choate Tactical which is free floating (and this stock handles the recoil very well). The OEM stock had a intentional lump in the fore-end that put upward pressure on the barrel. Removing that and later re-creating it with the glass bed made no difference.
I am really looking to create a rifle with the 1000-1200 yard reach and accuracy of a 338 Lapua Tactical rifle. I tried the 8mm Mag on a thousand yard course a couple of years ago. No one at the range, including another fellow shooting the same OEM Remington 700 as mine in an H-S Precision stock, could understand the poor accuracy. He checked chamber alignment and head space (an awesomely equipped, for being on the range, long range shooter) then tried his ammo in my rifle. His rifle shot -1/2 minute. Mine shot 3-5 minutes with him shooting it. He was truly puzzled.
I'm loading 180gr nosler E Tips in my 8mm mag.
75 gr IMR 4350
250 cci primers
my remington 700 Bdl loves this recipe.Less than 1 in groups at 100.
I'm a fan of the accubonds,but my 8 didn't like them.My 7 mag loves the 140s.
Back to the 8,the E tips are very accurate and hold there weight at high speeds.
Caught the bullet at 50 yards(in 5 gallon water jugs),lost only the weight of the plastic tip.The E tip stopped at over 48inches of water.
I know I'm seriously late to the party, hope I'm even later to my funeral, but here's my thoughts. I bought an 8mm mag soon after Remington put them in production, never did anything special to it but normal cleaning and care, and it has shot like a charm, 3/8" group at 100 last time. Factory loads SUCK so have to load your own, my choice is the Sierra 220 bt, been using H4831sc. Was at 81 grains but dropped it back to 80.9 and got 50 fps more and a tighter group. 5 shot average was 2978 with those, lowest at 2976. The Sierra tech has recommended trying reloader 22, says it has better accuracy and more speed but no one carries that around here lately. But I've hunted with this rifle for 35 years now, with a few years of trying others, only to come back to the 8. I have loaded some nosler 180ballistic tips too, 85 grains H4831sc, the chronographed at 3220. Only shot one muley with it, at 20 yards....too close, could put a softball through the hole, but he sure went down. Awesome gun. Sorry about the inaccuracy of some, dunno why it would do so poorly. Mine's been great, no heating problems either.
OK, I had the Douglas barrel installed by Douglas. Figured they would do it correctly.
First trip to the range was shooting loads I'd worked up in the old factory barrel. Accuracy was phenomenal. Half minute groups at 200 yds. But, way too hot for the new rifle. Ten rounds fired and the brass from all were trashed. This was all new brass. Primers did not appear to be excessively flattened, but the brass extruded into the ejector button leaving a "polished" spot on the head stamp.
After depriming, the primer pockets would not hold a new primer. With the rarity of 8mm RM brass this was a costly loss. Recoil had been tamed with the medium target barrel and the cases extracted smoothly with normal operation of the bolt. I was paying too much attention to the group rather than looking at the cases.
Oddly new loads with the reduced powder charge are not as accurate as the over pressure stuff. I am looking for new powder and bullet combinations to extract that full accuracy. Some of the suggestions in this forum will be tried.
Let me clarify, the rifle is accurate to 1 minute with which any fool should be satisfied...just not seeing the >1/2 minute of those over pressure rounds. BTW, I have broken down all the remaining box of that high pressure loads so's to remove the chance of using one again.
according to the Sierra tech I have talked to, the reloader 22 is faster and more accurate at max suggested load. He hadn't tried the 7828 but planned on it, and thought it should be similar to the RL-22 as well. Hope you find something that works and gets that 1/2" I have found I can get a 1/2" with the H4831 but intend on trying the other two as well, when I can get more Sierra 220's to test.
I'm loading H450 behind the 200 gr Partition in a Rock Creek barreled stainless 700. I can't remember the exact charge so I won't list it here but when I chronographed the load this spring I was getting 3150 fps from a 25.5" barrel. I plan to back off 2 grains of powder to lessen recol a bit. Accuracy has been sub moa and the last group I shot went 0.42" for 3 shots at 100 yds.
The critters have to win every time, I only have to win once.