I have an Ackley Improved 338-06, which is not to be confused with a standard 338-06. They're different animals. In data to follow, bullets are seated approx. .010 -.015" from the rifling in all loads. Velocity is instrumental at 10' not corrected to MV. All groups were 4 shot, rested from a bench. The rifle has a snug chamber which was throated short for 210 Ptns seated to 3.340". Speer 200s to the same OAL, & 200 CT BTs are at 3.360" OAL to fit the magazine & feed. WLR primers in all loads. Seating depth will make an accuracy difference. Note that Accubonds often seem to like some jump, but not always.
***Approach my loads with caution. My stuff is different than your stuff.***
My favorite load so far... H4350 poured slow, case tapped & settled as possible can fit 66 gr in my fireformed cases. It just gets to 3000fps out of my 25" barrel with 200 Speer Sptzr, the 200 CT Ball. Tip, & 210 Partitions. Except for OAL on the CT, these 3 bullets are virtually interchangeable in my rifle. Speers are used for development cuz they're the cheapest & I have a pile of them. All 3 shoot around an inch or less for 4 shot groups with a 1.5-5x scope. More magnification would likely shrink groups further. After 6 or 7 firings primer pockets remain snug.
Other loads...
Acc.2700 pressured out around 63gr @2850fps with Speer 200s.
RL19 filled cases with 66 gr @2821fps with the Speers.
With RL17 I've seen 2967fps @ 63.5 gr. with the Speers. Accuracy wasn't as good as H4350.
RL16 ran out of case capacity @ 65gr. for just over 2900fps with the Speers. Fair accuracy.
W760 pressured out with 66.5gr @2917fps. with the Speers at around one inch groups.
My lot of WW brass holds 72.6 gr of water full to the top after fully fireforming. 325 WSM is very similar in case capacity & bullet weights. Using Nosler starting loads & working upward 1/2gr at a time, the velocity/charge weight of the 2 cartridges is also very similar with the few loads I've done this way so far. Also, I'm now using reformed Hornady 35 Whelen brass for the loads below.
Initial tests show...
IMR4451 & 200 Speer reached 2828fps with 63.5gr. & a 3/4" group, Will continue upward with this powder as possible.
Big Game @65gr gets to 2987fps with the 200 Speer with what looks to be be good accuracy so far. Will test further.
Just today I tried Sierra 215 SBTs with Big Game which seemed to get a tad warm @63gr & 2886fps. Best accuracy seemed to be around 2850fps, but the wind was terrible at the range today.
Good luck with your Ackley. Mine all like to be run toward the higher side. When run warm with the above powders ES is usually in the teens or less with single digit SDs.
Edit... I forgot the 180 Accubond loads tried last week with Big Game to 66 @3102fps & c.1" to 1 1/4" groups. The bullets were .035" from touching the lands. No real reason to do much else with this load as I got the bullets for the 338 Federal that I dont have yet. Just wanted to see what they would do.
Last edited by 358WCF; 05/04/21.
