450Bushmaster.net

I'll go back and measure all of the bullets. Then maybe try and reshoot them with the CCI450s and 1680.

I shot some Lil-gun with the Speer 350s seated to 2.305", 32, 33 and 34gns. The 34gn load was way too hot, don't go there.
the 33gn load gave 1911fps and I believe is too hot also. I think I'll give up on Lilgun for the 350s.

It's supposed to rain all day, so I'm waiting for a clear weather day to re test loads...

With it being all wet, I thought I'd try shooting some into the clay bank of my berm. It's mostly clay with some shale pieces in it. I fired 3 rounds, but was only able to dig 1 out. I was at from about 5' from the berm and the bullets were travelling 1911fps. It expanded to .740" and weighed 301gns.
I think that they'll work on hogs.

Nothing wrong with that.

The .458 Speer 350 in the 450 Bushmaster.
I have gone through three boxes of these Speer 350s, and several powders in search of the magic load for my Ruger AR 450 Bushmaster. First off the bullets were lubed with Imperial Sizing Die Wax and stuffed through a Lee .451” cast bullet sizing die. After sizing, the Speer 350s measured .452” and lengthened to .990”. I checked the distance to the lands and it was at 2.322”, but they wouldn't fit the magazine. When seated to 2.300” the round would fit in the magazines, feed and cycle the action just fine. I couldn't find any published load data for a 350gn bullet in the 450 Bushmaster, so I used Quickload and compared that to starting loads for the 460 S&W from the Hodgdon.com site that listed pressure data also.
With looking at Quickload, I was hoping to get to 1800fps and set that as my target velocity. I loaded all of the ammo with Starline brass and Hornady dies. I taper crimped to .475” and then used a LEE FCD.
I first tried CFE BLK with a charge that was way too light and the action got fouled with piles of unburnt powder. After scrubbing everything out, I switched to Lil-Gun. I tried a couple of loads and accidentally got to 1911fps and pressure signs on the case heads.
IMR 4227 topped out at 1640fps with35gns.
A1680 never would burn consistently. I tried standard and magnum primers, but got wide velocity ranges. At 41gns of A1680 I got an average velocity of 1746fps, but in the five shot string got a low of 1622 and a high of 1834.
IMR4198 gave 1739fps with 38gns and burned clean. 39Gns was too hot.
RL7 burned real clean and gave some acceptible groups. 42 gns gave 1765fps.

Lastly I went back to CFE BLK and tried some heavier charges. I used CCI 450 primers. 43Gns gave an average of 1792fps, but the cases were covered in soot.

So I think that I will go with 42gns of RL7. The cases came out clean, it gave good accuracy and the action cycled fine. For accuracy testing, I put on a Vortex 3.5x10X scope, but will be switching it out for a 1-4X Vortex with lighted reticle to take it Hog hunting in a couple of weeks.

Update on the 350 Speers.
I finally connected on a couple of hogs, the biggest was 185#, the range was 50yds-ish and I put it right in the left eye. It traveled through about 2 feet of bone and tissue only to exit. I would have loved to have recovered it to see if it mushroomed at all, but it did the job. After I shot the big one, the group of hogs started running around and a smaller 80# hog stopped for a second, I put one through both shoulders and he dropped.
I've got 2 deer and 5 hogs so far this season, the others were taken with a 300Win...

I'm surprised you went in the direction of slower powders after your experience with 1680. No surprise from your experience with Lil Gun but just a little slower like H110 / W296 / 300MP would have been whear I would have put a lot of effort. That having been said, I was also surprised with your 1680 experience. I resized .458 325gr Speer's (I think) and they really shined with plain old A1680.

Good Results at the range with your recipe as well. Because of the straight wall, if you're not already doing so, change the start pressure in QL to zero with cup and core bullets in this caliber. It'll give you better velocity predictions.

Job well done and a beautiful Range Report. I'd like to see more like yours submitted by the gang here.

Hoot