In my 243 Sako AII (22" 10 twist barrel) bullets up to 87gr have been very accurate indeed. They work fine for fallow. But gaining some more open country side with really BIG fallow I wanted to try some 105gr speer spitzers.

Loading some under Norma MRP (can't remember but I think 46gr max) I checked they were on the target by shooting at 50yards. 2 printed quite nicely so I went back to 150 yards for testing.

Patterns of 6-8"! This is the first time this has happened to me with this rifle. As far as I could see the holes were round but I wonder if stabilisation is an issue. I thought 105gr was OK in 10 twist?

Anyone any experience of this bullet in 243?

I never had any success with 105gn pills in my 243 but it handled 100gners OK. 85>90 gns were far and away the most accurate and efficient.
Rifles chambered for 6mm Rem appear to handle 105 gn pills very well.

Many years ago I had a Browning Safari 243, Belgium made. The most accurate bullet for that rifle was Speer 105 spitzer and the 105 round nose. The round nose was pure hell on deer.
Jim
PS
The two powders that served best was IMR 4350 and IMR 4831/H4831

I have an older Savage 110 in .243Win. It has a 1 in 10" twist, and a 22" barrel. It will print Sierra 100gr SBTs into .722" (5 at 100yds) on occasion, but not always. 1.0" is closer to the norm. Even though it's a sporter barrel, .565" at the muzzle, it will shoot the Sierra 70gr. HPBT and the Nosler 70gr. Bal.Tips into .5". It's also quite accurate with the Sierra 85gr. HPBT. While the .243Win. is supposed to be a dual purpose caliber it seems to do much better with the lighter bullets. I don't think the larger group size with the 100gr. bullets makes much difference really because we are usually shooting it at larger animals so we don't require the same degree of accuracy. Just one mans opinion. Best wishes.

Cal - Montreal

Sorry, something I meant to mention in the post above but forgot was how well a bullet will shoot is not merely a function of bullet weight vs. barrel twist. It also has to take into consideration the shape, configuration of the bullet.
I have a 6.5x55 with a 1 in 9" twist that simply does not shoot
most bullets above 129gr. very accurately. Yet this rifle is very accurate with the Lapua Scenar 139gr. bullet (very long, streamlined bullet), and the Sierra 160gr. SPSP (round nose to me). You'd play merry olde hell trying to plug this data into any kind of formula. It's enough to make you ill at times. Best wishes.

Cal - Montreal

1894mk2: My Browning BLR, with a 1 in 10" twist, shoots the 105 gr Speers quite well, using a modest load of 37.0 grains of RL19. Yesterday it also shot well with IMR 4064 behind the same bullet, again producing good groups with a light loading (I believe 31.0 grains, but don't use that without checking). Both of these loads are quite light, on the low end of the manual's recommendations. The BLR did not like a light load of IMR 4350 with this bullet.
I also shot the RL19 load in a Model 70 yesterday and it shot a 1" group at 100 yards - it is a 1957 model which I am guessing also has a 1 in 10" twist.

I load the 105 grain Speers in several 243s with a 1 in 10 twist behind a load of H 414. I redline it sometimes with a load of 44 grains of H 414, for an MV of 3250 fps. Workup on that load if you try it.

I find my 1 in 10 twists will shoot the 105 grain Speer, but not the 105GR Hornady A Max.

Rugers and Remingtons, now have a 1 in 9.25 twist, and will shoot it just fine.

cheers
thunderbolt