Home Forums Reloading Big Game Rifles Old Partition Accuracy

For the past year, I've been playing with a .243 (1972 600 Mohawk) and a 6mm Rem (1978 700 BDL). The .243 is one of those guns that just shoots everything incredibly well. Hornady 100 gr BTSPs behind a healthy dose of H4831SC consistently shoot 5-shot groups of 5/8" or better. The 6mm is a little fussier when bullets are seated to fit the short action magazine. But the 6mm still shoots under an inch with the Hornady and H4831SC.

Then, I acquired on the Campfire, a partial box of 95 grain Partitions in a black and gold box with metal corners and marked as "Nosler Bullets a subsidiary of Leupold". Leupold sold Nosler in 1988. So, the bullets are at least that old. With a limited supply of the 95 grain Partitions, I tried a simple substitution using the same load as the 100 grain Hornadys. In the .243, the 3-shot Partition groups was 1.5". The 6mm ran 3". So, groups with the Partitions basically tripled in size. Is this a case of the lesser accuracy that the old Partitions were reputed to have? Or, am I missing a trick?

If this is not your current load, try H4831 or H4350 and CCI 200's.
Yes, the old NPT's are not as accurate, but in general the groups only open up about an additional half inch. Never had them shoot 3 inch groups in a good rifle.

Both rifles normally love H4831sc and CCI 200s, just not with the old NPT.

I’d try a bit more H4831 to give them a little more kick in the rear. Might not be getting full pressure to get the skirt to bump up. The old ones have shot well for me. They just wanna kick in the rear.

I'm at 46 grains in the .243 and 49 in the 6mm, which I'm sure will give some fits because it's over max in some of the newer manuals...

I don't have a comparison target to show for the 6mm. But, these are 3-shot .243 groups shot back-to-back after cooling.

I would feel really lucky if I got the same accuracy when switching just the bullets. I would back down a bit and work back up to the previous charge or possibly a bit higher if you were working below maximum.
My old 243 likes IMR4350 with the 95 Partition even with the old lathe turned bullets. IIRC It’s with 42.5 grs.

I had very good luck with the old partitions.

And this is why you "work up a load". Why do you guys not get it? Its idiotic to think you can just pop a similar bullet in and be right back to sub moa or what ever your rifle was shooting before. You change anything in the recipe, you better work up a load. I don't give a schidt if you are just switching primers or going to a different lot of powder. As far as "old" partitions. They have shot incredibly well for me. Just as well, if not better, as the new ones. There's no flies on the partition of any vintage... And where do you get that older partitions have a reputation for poor accuracy? That's bs as well...

Without a chronograph it’s hard to go further but speed is the best judge of safety mostly. Looking at the PT group I’d try a little more powder and or seat them a bit longer.

Thanks. Seating out farther might be worth a shot - or three... Unfortunately, with only a partial box of 35 year-old bullets, a normal, full work up isn't possible. I was hoping the proven loads with the 100 grain would give reasonable accuracy with the 95 grain substitution, but I was surprised they grew that much. You're right about maybe tweaking the powder load considering the lighter bullet is going to give less pressure.

Did you check bullet alignment after they were seated? In my experience, excessive run-out. tends to affect Partitions more than other bullets

That said, I first handloaded Nosler Partitions around 1976-77, when they were still lathe-turned with "relief grooves" around the middle. The two rifles I tried them in were a Remington 700 .270 Winchester, and a "sporterized" 1903 Springfield. The bullets were the 130 .270 spitzer and the 200-grain .30 "semi-spitzer," and despite knowing nothing about bullet alignment back then I got 1", 3-shot groups with both bullets in both rifles.

Good to know. I didn't realize that the Partitions were more prone to the effects of runout. Actually, a concentricity gauge is at the top of my wishlist! I now have had two 6mm Remingtons that were finicky and I'm starting to wonder if it's the dies instead (70s RCBS). From your writings, it seems like a smart way to help isolate accuracy problems. The groups got bigger with both the .243 and 6mm. But, far more so with the 6mm.

Ive had better luck in the accuracy department with older partitions than new ones.

Like others have said, work up a new load since you are changing bullet. Shortcut didn’t work is all.

msquared,

I would definitely get a concentricity gauge, as they can make as much difference as any variable-testing, maybe more. Have had a bunch of them, but the one I ended up with is the first I tried, 30 years ago, the RCBS Casemaster. Others may be "smoother," but the measurements come out the same--and the CM also includes an effective neck-thickness gauge, which also can make a big difference.

MD,

Thanks for the recommendation. I've been trying to sort through reviews of the different models of concentricity gauges and each seems to have advantages and weakness. I was leaning towards the RCBS and appreciate the confirmation. I've been reloading for 35+ years, too many of them at an enthusiastic yet more basic and functional level. However, I have lucked into several exceptionally accurate rifles in recent years and am trying to get more into the "nitty-grity" of things trying to reach their true accuracy potential. Your input is very helpful!