Home Forums Reloading Big Game Rifles Been at this for 34 years...still going to the school of hard knocks

Got my son a brand new to him Browning A-Bolt II Stainless Stalker in .300 Winchester Magnum because he wanted to have a gun just like dads...to the point where he kept reminding me that he wanted mine when I die...real nice.

Anyway, having worked with four guns identical to his, and always finding (after I finally drank the Kook Aid) that a dose of Reloder 22 of between 74 and 76.5 grains under a 180 grain Nosler Accubond did the trick (m.o.a. or better in all of them consistently) I naturally started there. Not to mention I have 15 pounds of the stuff and I'm never going to burn it all at my stage of life.

So, out we go on the first evening range session and shoot 74.5, 75.0 and 75.5 grain loads with the bullet seated as far as the magazine would allow (not much longer than factory due to the constraints of a removable magazine). Here are the groups from those three powder charges. I was stoked as it looked like RL22 and 180 grain Accubonds were going to be the huckleberry again with a little tweaking of powder charge and seating depth.





So off we go. Decided that 75.0 grains was good middle ground to start refining with and loaded 3 each at various seating depths. Waited for a cool (relatively) morning with calm and headed for the range. Fired the first group of three that was an exact duplicate of the 75.0 grain load from the first night....uuuuuuuuuggh. Fired the next group of three that was seated .020 deeper.....uuuuuuuuuggh. Here is what those two groups were...along with a rough measurement of the combined group size.


One shot from each group through the same hole and then groups that you wouldn't want out of your favorite goose gun.

Pulled the gun off the rest and started racking my brain for all of the wisdom I've gained over the 30+ years of experience handloading and last night it hit me....you got taken for a fool by not looking at the entire picture. So I took the three targets and superimposed the groups on one. Keep in mind, I don't do scope adjustments during load workup. Here is what it looks like:



Out of nine shots this time there are two places where the bullets are touching, but again the overall is a shotgun pattern of rougly 3.7 inches....very close to the other composite...the only difference really being in group shape. This I attribute to a slight tightening in the action screws to an even 35 inch pounds (there were closer to 30 inch pounds on the first groups)

So, needless to say, I have learned that I can't just look at singular groups as an indicator of potential, but that the entire picture needs to be examined.

Now where to go from here as it doesn't appear that there is anything left to pursue with the tried and true in the other four guns. I guess I'll dig out my stash of 1990's vintage IMR 4831 and stick under the Accubonds, and then try the RL22 under a different bullet...the 178 grain Hornady ELDX perhaps.

I've got to get it worked out as he drew a controlled bull elk tag for the month of November...and that isn't far off.

Hope this thread helps someone else from having to travel the same road.

Cheers,

300winnie.

It's always tough when you have multiple variables. A new rifle that you don't really know the accuracy potential of and a load that has proven itself in other rifles but rifles are individuals.

Accubonds are popular, and usually shoot well. But not always. The closest thing to a "sure thing" first try for our .300 Wins and Roys has been the 150 gr
and 168 gr TTSX ahead of pretty much any powder. The 175 gr LRX has been finicky.

I've not got any of my rifles to shoot accubonds well. On the other hand Partitions are often very accurate.

I’ve found a strange, but repeatable, phenomenon with virtually every 300 Win Mag I’ve ever had/shot. I have noted that IF it doesn’t like a 180 grain bullet, it’ll probably like both 165 & 200 grain bullets. And vice versa. No idea why, but I always start with my 180 grain accuracy loads and don’t sweat it if she doesn’t show a preference for it.....I’ll just start loading 165’s or 200’s and she’ll probably like those two options. Never saw this in any other calibers I’ve owned.

My one exception is the Carolina Precision Rifles 300Win I had made over the summer. 700 action and a Bartlein 5R 10 twist barrel. So far this rifle loves everything I’ve shot. 0.2”-0.3” 4 shot groups at 100. Probably stick with 165 AB’s and see what happens.

My 257 Roberts loves 100 grain partitions.

If I was going to get a 300 mag of any kind I would go right to 200gr bullet's. But something you did not mention I wonder about, bedding. After I get a few shot's with a new rifle out of my system, I go through the bedding. I've found most rifle's can be improved with better bedding.
couple sheet's of typing paper need to go between the barrel and stock and touch no where. Then tighten the action screw's and slowly loosen the front screw watching the barrel in front of the action, no movement at all should be seen there. You can also see it at the front of the barrel channel, even more pronounced! See it, bed it.

Well, my .308 Win RPR absolutely hates 168s. No idea why... Tried TMKs, MKs, Nosler match - no dice. Probably the only .308 in world history to hate 168s.

OTOH, it likes 155s, 175s, 190s. Lots.

Sam_H,
If you assign any credit to Nathan Foster at Ballistics research...
His 300WM write up said not to waste your time with 168s.
I forget the basis...



Interesting I was thinking about 165s but I have been playing with harmonics analysis and it seems that 165s tend to be in a problem spot when 180s look good. Ever tried 220s?

Helped a buddy with his Browning AB3 300 Winny. I assumed that he'd need some 4831 or 7828 burn rate type powder for his 180 NBTs. Nope, IMR4350. 3000-ish and really accurate.

IMR4350 is and has always been the first powder I try in my new 300wm rifles. Load up near max with a good 180 and it's usually golden... Back when I only owned 1 rifle, it was a 300wm. I settled on the 200gr partition for both deer and elk. Its pretty hard to beat that combo. I tried Accubonds, when they first came out, but they were damned finicky, so I went back to partitions. Great bullet you know you can depend on. OP, you might also want to develop your loads closer to hunting season. I've had some RL22 produce some pretty sporadic results, depending on temperatures. You are also right to look at all of your groups. Superimposing the 3 3 shot groups on to one target for a better reference is smart. The composite of the 9 shots tells a better story. A lot of guys here will shoot 3 shot groups, pick their best one and post it here, thinking their gun is sub half moa, when in all reality it may only be a good 1.5 moa rifle. This is one reason I shoot 10 shot groups, it gives you a better idea of your rifles true accuracy, and precision along with true POI vs. POA.

Go back to square one and check everything especially the scope and bedding and all screws. Some little thing may be off and you could go through a whole bunch of rounds and not greatly better the patterns you have shot. Look at the muzzle crown for burrs or irregular carbon patterns.

Try some factory loads to establish a baseline of accuracy. Also check the run out of the rounds you have loaded and the dimensions of the fired case. This can get really anal and tedious, many times if I get groups that are about half the size you are getting but consistent I quit there and go hunting.

IMR4350 works very well in the 300 RUM. No speed demon, but works very well. In my 300 weatherby I run H4831 with plain Jane 180gr BTSP. When I start screwing around with 300 anything I try regular old hornady bullets. They always shoot for me.. recently I was chasing my ass with a 300 wsm, I finally grabbed some 178 ELD-X and switched to H4831 and it all came together.

J, have you tried H4350 in your WSM? In my 300WBY's, I always resort to 7828. That powder was made for that case. For things like 06, 300wm, 338wm, its always IMR4350 for starters. It usually ends with that powder as well. I've tried RL22, but its damn finicky when temps start to plummet...... Generally when I'm hunting big critters, the temps can be down below zero.

I tried h4350, Imr 4350, hv100, Rl17 and RL19 But not all of them with the 178. I tried 7828 with my 300 weatherby but groups weren’t that good. So switched to h4831 I’m getting 3092 with my current load shot a 5 shot group right at MOA. It might not be the best bullet but I would use that 180 hornady btsp in everything Alaska. Now that 178 ELD-X out the wsm Moose is where I draw the line for that bullet

I've tried H4831 as well. Its great powder. I left out my 308 Norma earlier in our discussion, but it loves H4831 and 200gr partitions:

This would make a damn good do anything load. Here or in AK (I'd imagine). However, I run IMR4350 in the Norma with Hornady bullets:


Most all of my 300wm's doted on the stuff...

Also iterate what BSA said this AB can be a bitch at times. With my RUM I lucked out. From what I saw with his groups the first 2 loads he could of seated little further out, maybe .005-.010 out. The 75.5gr load maybe seat it .005 deeper.

Good suggestion J. I've found the accubond to be a little finicky. I remember back in 2005, I had to load some up in my 300wm for an offhand competition. The rules suggested that the load could not be any faster than 2,700 fps because they didn't want us to damage the steel plates. I basically had to load my 300wm down to 30-06 levels. 200gr AB from a 300wm at 2,700 fps on the nose. I had to play with seating depth until the bullets went into a tiny cluster. I ended up walking away with 100+$ after that match. Shot the majority of the 4" steel plates offhand at 100 yards and 1 egg with 3 shots, offhand. That was one of the only times I got the damn AB to shoot in my favor. I pretty much gave up on them after that and went right to the 200gr partition, which was much easier to work up a good fast accurate load with..

I've not got any of my rifles to shoot Partitions well. On the other hand Accubonds are often very accurate.

My .375 R Guide and .243 WBY UL agree with Bugger.

Most my .308" rifles agree with you. Except for the .300 Roys - they agree with Bugger.

No one size fits all answer.