The "old" style mags are a no go. The feed angle is perfect, but the 358 neck jams down in the body of the mag. I'd open it up a bit but there is not much meat to begin with. I might give Ruger another call and see if they'll send me a 450 Bushmaster mag. I saw where someone was having good luck with it in a 308. Only downside is that it is not a flush fit.
So I played with the "old" style mags a bit more and it was obvious that the 358 neck was getting stuck in the channel designed for a 308 neck. I borrowed one of the wife's emory boards and opened the feed lips just a hair in the neck area until one round could pop up smoothly and feed when the bolt was cycled from a closed position. Loading more than one round jams the necks deeper in the body of the mag in an area that is difficult to get to and very thin plastic, not something I want to file away on. I certainly wouldn't trust it for hunting until well proven, but it looks like I might have a reliable 1+1 solution.
Just figured out I could induce a jam on the top of the chamber by placing pressure on the bottom of the modified magazine.
Bushmaster mag inbound.
The Bushmaster mag seems to work perfectly! I haven't been able to jam a round yet. It's not flush fit, and while it holds 4 rounds, I can't get it to seat with a closed bolt unless only loaded with 3 rounds. Not an issue for me. Ruger sent mine for free. PM me for the customer service contact if you have any trouble.
got out for a bit this weekend with the 358 american and chronographed a few loads, here is the chronograph info from yesterday:
NOE 230gr RD bullet with 1.6cc of IMR 4227 (right around 20grs) did 1640fps, this is an accurate load
125gr Missouri bullet, powder coated, with 12.5gr of Bluedot did 1640fps
the 200gr hollow point with 2.2cc Trailboss did 1180fps and had an SD of 13, extremely accurate
NOE 230gr bullet with 47.5 gr Data 85 did 1980fps and had an SD of 13.2 (this load showed some promise and i think if the bullets were harder it would have shot really good) Could probably stuff a bit more powder in there to get around 2100 with this powder, it is slow for the case but i got a lot of it and it seems to do well with cast bullets.
230gr bullet with 36gr of 3031 averaged 2026fps and had an SD of 65
I did discover that my alloy is softer than i thought, i shot the 3031 load at an old wet 6x6 around 80 yards and the bullet never exited, took it home and split it and the bullet went about 4" and was completely flattened out. After thinking about it i realized that my usual hunting alloy of water dropped 50/50 pure&WW with a touch of tin is no longer that hard after powder coating @ 400 degrees. I am going to have to start quenching when removing bullets from the PC oven, hopefully the rapid temp changed doesn't affect the powder coating. I believe the softer alloy accounted for the larger groups i was seeing with the heavier loads, averaged around 2" for the 3031 and the D85 loads. That little rifle begins to get lively with the heavier loads, not painful but certainly know you are shooting a 230gr bullet, also noticed a huge difference in impact between the 4227 load @ 1640fps and the same bullet @ 2000fps, like about 9" higher with the heavier loads.
This is one of the NOE 230gr bullets fired into soft saltwater ice at 1600fps impact speed, this powder coating continues to amaze me how well it stays intact.
haven't had a chance to do much more shooting with the new 358 but i did install a new trigger spring from Mcarbo, easy to install and made a huge difference. I don't have a trigger pull scale but the difference is very impressive, a worth while addition to any Ruger American.
This is making me miss the .358 badly.
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Originally Posted by jwhite
Nice, I'll have to look into it!
No 358 shooting for me either. Seems like everything exploded with spring...been running like crazy...
That's the way to go, he did a Howa 243 to 358 win for me that's a hammer!
Semper Fidelis, to God, Country and Corps!
When I had a .358, I luckily found an old CH fl set of dies. They would form .358 from LC 7.62 in one pass. I’ve become a fan of that brand, I’ve had .250 Savage dies from CH for decades and I recently found some 8x57 CH dies.
I have formed a lot of .358 win from .308 with my RCBS die. One pass. The expander ball has a nice taper.
Last edited by White Oak; 05-07-2019 at 02:26 PM.
Finally got a chance to shoot the 358 a bit. Tried some Promo under the Lee boolit for practice boolit, but it felt too light for a valid practice load so I moved to Blue Dot. Things were looking promising around 1850 fps, then it started shooting patterns. Loose scope base. I'll get it lock tighted down and try again when I get the time. Might be September!
Didn't feel like I was getting enough neck tension, as my M die was hardly touching the neck and boolits were seating very easily. I subbed out the expander rod in the Lee sizing die for a universal decapping rod. Afterwards, the M die made much better contact with the neck, a test boolit seated with a little more "grab" and I was not able to set the boolit back by pushing the test round into my workbench even with no crimp. Fingers crossed that this will help settle down the ES on my RL-7 loads.
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