358 Winchester AR-10 build

[Bliksem]

Finally pulled the trigger and ordered parts for a AR-10 build in this caliber. Of course I will need to get at least 1 mold as well... Being bored waiting for the aircon installation crew at the office is costing me but it is an early Xmas gift.

Upper is from Bear Creek but the 308 barrel will be switched out with a Wilson Combat 18" Ultimate Hunter in 358 (I like the WC stuff but the prices are a little rich so just the barrel). Lower is a kit I build a few years ago.

Anybody on this forum have experience or advice to share with such a combo?

 

[Ian]

NOW we're talking!

Mine, Poppers, and Winelover's are all .308. Lots of members have .358 bolt rifles.

I bought a PSA upper because I couldn't come up with the parts to put together a .358 any cheaper any other way. Plan was to buy a KAK 18"/midlength gas but the dang PSA lightweight stainless barrel shot so well with full-house powder-coated cast bullet loads (and keeps on shooting well over 500 rounds into the adventure) that I never bought the .358 barrel.

I highly recommend the Superlative Arms adjustable gas block (vent style rather than restriction style). Lots of members report good results with the Lee C-358-200-RF mould for anything .358, they make a six-cavity. My .35 Remington likes it, FWIW.

 

[Bliksem]

Ian, I'll look into the gas block you mentioned, thanks for the feedback. I've never owned any rifles in this caliber so it is a new adventure. The closest I came casting in this caliber was when I mistakenly ordered 1000 gas checks for 35cal. At least I still have those and can shortly recover my expense by using them...

 

[Ian]

The formula that has worked for me with all my gas-operated rifles is basically the same. Powder coat a gas-checked bullet, size to just about half to one thousandth smaller than the rifle's throat entrance diameter, use air-cooled wheelweight alloy with a pinch of tin or bump with lino or whatever to get about 14 bhn, (depends on your wheelweights of course), use a neck-sizing die to get about three thousandths under bullet diameter and then uniform the necks with an expanding/flaring spud to get about 1.5 to two thousandths neck tension on the bullet, use a published starting load for a jacketed bullet of the same weight you are using, and seat the bullet about .010 to .020 off the lands. I roll-crimp or "factory crimp" mouths just to eliminate feeding issues. A Forster benchrest seating die is expensive but a very important part of the equation for me, as is about .002" headspace. If you set the shoulder back too far it affects accuracy. This has gotten me to full-power jacketed bullet performance with 1.5 MOA or smaller 10-shot groups, with no cold-bore flyer, day in and day out in now four different calibers.

 

[fiver]

1.5 to two thousandths neck tension

use a published starting load for a jacketed bullet of the same weight you are using,

If you set the shoulder back too far it affects accuracy.

check.. check,,, check.
I mess with OAL and alloy some to tune things a bit more.

 

[Glaciers]

Got to say the 358 Win is about as good as it gets. Although I'm not modern enough for gas operated rifles, still in the bolt and lever rut. I like my rut. Going to stay there at this time in my life. But, you can't go wrong with 35 calibers. The 358 in the AR would be a respectable piece.

 

[popper]

Come on guys. I got a bunch of 308 brass and ar10 rifle upper. Don't need it but bore to 358?

 

[Missionary]

.308 brass is an easy transformation to .358.

 

[462]

still in the bolt and lever rut. I like my rut. Going to stay there at this time in my life.

Same-same.

 

[Bliksem]

Come on guys. I got a bunch of 308 brass and ar10 rifle upper. Don't need it but bore to 358?

Come on, you know you want one...

 

[Brother_Love]

I’m gonna be watching this. My favorite rifle is my 358.

 

[Joshua]

Hey, I thought we all decided that the next guy to build an AR-10 was gonna build an “Elmer Keith Commemorative in .338 Federal”!

But joking aside, I’m excited for you and your new project! The 358 is the sensible choice, so many more molds are available for it.

Josh

 

[CWLONGSHOT]

358Winchester was the first "DEER GUN" I bought myself. It was a Browning BLR used with a M8 3X Leupold and it was a deer killing machine!! I started loading for it right away too as those 200g Silver tips where not in stock all the time. The 200g Hornady sp was working well for me too!
I have had a few others thru the years. My most recent is a Grice commissioned Ruger American. She is quite the shooter too!! My bullet of choice is the Sierra 225 made for the 35 Whelen. But @ 2400+ its the hammer of thor!
My powder of choice now is TAC. Its the one "new powder" I have tried and like allot! Shoots right @ 1" and 2" high at 100 has be holding dead on out past 200.

I like 35's the best and instead of changing bullet weights I change calibers. My 356 shoots the 220 Speer the 35 Rem Bolt 200 FTX. While the 35 Rem levers get the 200 Sierra RN and the 357 Max the Hornady 180 SSP. Working on the 350 Legend still but the 357 Mag shoots my heavy cast HP. The 357 Sig likes a 135 RD cast and the 38 Super a Saeco 383 cast.
Going "up" the Whelen is awesome with the Nosler 225 Accubonds and my Big Lady 358 Norma tosses 250g Speers and Oryx bullets about 2850 fps. I think Im well healed in 35's.

CW

 

[Joshua]

I have a sporterized Arisaka that I have measured the barrel thickness on. I have just enough diameter behind the front sight that JES could rebore/chamber/recrown it in 35 Whelen. The chamber would still be sloppy unless I had it set back one thread.

I’ve looked at both the 338-06 and the 35 Whelen. I would want to shoot cast in it. So if I ever get around to this project I’m thinking that I would go with 35 Whelen.

However, the .358 Win has a much more efficient case capacity for shooting cast. So maybe I’ll keep thinking.

Josh

 

[Missionary]

Now Joshua .... Do not overlook the 375-06. I went through the same head rattling debate some years ago. No regrets getting the 375-06.
But then we already had many more 375 molds than 358 rifle molds. And we like caliber 38 rifles.
But a 345 FN grainer cast of range scrap and PC'd at 1950 fps under 50 yards will go through everything I have slammed it into.
The 270's at any speed are fantastic from steel plates to .....

 

[RBHarter]

Among others , in an A&B barreled Santa Barbara 98'M , I've shot several of the popular 38/9mm bullets the quick search for a load to baseline ended with the RCBS 35-250 . I'm sure I shot a bunch of 358-200 Lee's as I have 2 6c moulds which is its own story of CRS .

I don't recall data and it probably wouldn't be useful anyway but it amounts to a case full to the base of the neck of FC 308 necked up to 358 -10% plus .2 gr of IMR 4350 . 5 shots repeatable go into .9" @ 100 and run 2089-2110 fps . That's right in the heart of the 250gr jacketed data ....... except that 4350 isn't listed as it's about 1.5 full powder groups to slow for the 358 in jacketed .......

3031 maybe 4895 . My example didn't like anything in the H322/4198 range loads .

1-14 @ 24" .

 

[fiver]

4350 should be somewhere, I found data for RL-19 with a 250 running close to 2400 fps.
I backed it down for the Saeco [#248 iirc] 250gr. bullet a smidge to between 48.5 and 50grs.

 

[CWLONGSHOT]

That RCBS 250 is a nice bullet!

CW

 

[Bliksem]

So the adventure continues. A while ago the barrel arrived from Wilson Combat, a 18" Hunter Elite with 1/14 twist, but the plan changed as I acquired 2 x NIB uppers from Aero Precision. The first I'm keeping in 308Win but the time has come to convert the second to 358Win. I have gathered all the bits and pieces seen in the pic to start to process along with much researching on loads for this platform. There is not much info out there for this cartridge in the MSR platform but the experimentation is half the fun.

I have a box of Hornady 200gn Interlock bullets as well as the 200gn Lee mold for starters. I have a selection of powders to try as well from RL7 to RL15 and quite a few others in between. It seems that IMR3031 could be a contender for the most suited for 200gn cast in this rifle but only testing will answer this. If anyone reading this has gone down this path please share your outcomes.

I will probably be ordering another mold from Accurate once I have more experience with this platform and am leaning towards the 36-230D or 36-210BG. Let the adventure continue.

 

[Ian]

If I remember correctly you have Quickload. In my experience, the program has been quite accurate for predicting velocity (and, we can assume, pressure) with the Reloder series of powders and the .308 and .35 Remington with cast bullets and is invaluable for stitching together a more complete picture from fragments of published data.