99c .243 twist rate

What is the rate of twist of a '69 99c .243? I have read the forums on the 99 and also the reloading forum and didn't find out the twist rate. There is gads of info on the .250-3000 but I didn't see a whole lot on the .243. I need to know which bullet weights this barrel twist will stabilize best. A "one bullet does it all" scenario would be great. I intend on shooting groundhogs, coyotes, deer and whatever despicable vermin that shows itself on the farm. Something in the 90 grain class is what I am thinking. Powders I have on hand are IMR 4831, IMR 4895, IMR 4320 and Hodgdon's BLC2. I use the 4895 in .222, the BLC2 in .22-250, the 4320 in a 7.7 Jap that I sporterized back in '69.

I was curious myself, so I tried to measure it on my barrel. No dice. I could not come up with a jag or brush that took a reliable bite on the rifling, or a rod with a smooth enough swivel, to get a reliable, repeatable measurement. I'm hoping somebody with this info surfaces.

My old Speer manual show the twists for all the calibers in the mid 60s. It lists the 99 243 as 1 in 10.

Thanks!

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Originally Posted by bushrat

My old Speer manual show the twists for all the calibers in the mid 60s. It lists the 99 243 as 1 in 10.

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Bushrat, does your manual give the twist rate for a 99 in 284 Win.?

The 243 and 284 have the same twist, 1 in 10".