Hammer of Thor AR-10

[Mosinwolf762]

I have building AR-15s for a couple of years now, but this is my 2nd AR-10 build. My first of course was a .308. This time I want to build a powerhouse! My first choice was .338 RCM. On paper it looks like it would be awesome in an AR10 platform. The main issue is no ammo or brass available. Now I'm looking very closely at .325 wsm. It shows a lot of promise in performance and there seems to be hope for ammo and components because Winchester is still building rifles chambered in it. Has anyone tried to build a .325 wsm AR10? What are your thoughts about this build idea?

 

[Armed Eye Doc]

Have you tried to source a barrel and bolt for it?  Or would you have a barrel made for it?  I am not all-knowing as far as calibers available.  However, that is not one that I can easily say is available in the AR platform.

[Mosinwolf762]

Kak industries offers a magnum complete bcg for the Ar-10 and I can have McGowan make a barrel for it, so I can find all of the parts I would need to make the build happen

[Sisco]

Do it and start a thread documenting it. It would be interesting.

[98Z5V]

I've done a .338 Federal and a .358 Winchester.  Easy peasy, because it's just necked up .308 Win cases, so stardard bolts/BCGs work, as well as .308 Win Go/No Go gauges.  Wilson Combat makes the barrels already, and they're not bad at all. 

What do you want this gun to do for you?  How are you planning on using it.

Edited January 6, 2023 by 98Z5V

[JMJ]

1 hour ago, 98Z5V said:

I've done a .338 Federal and a .358 Winchester.  Easy peasy, because it's just necked up .308 Win cases, so stardard bolts/BCGs work, as well as .308 Win Go/No Go gauges.  Wilson Combat makes the barrels already, and they're not bad at all. 

What do you want this gun to do for you?  How are you planning on using it.

Out of those two which is your favorite? I’ve shot a 358win from a bolt action and was immediately a fan of the round. 
 

 

8 hours ago, Mosinwolf762 said:

Kak industries offers a magnum complete bcg for the Ar-10 and I can have McGowan make a barrel for it, so I can find all of the parts I would need to make the build happen

I had seen their BCG option when I was looking up info on what it would take to build an upper in .458x2” American(basically a 450 Marlin using any belted magnum cases instead of the wider belted cases Marlin/Hornady designed since I own a 7mmRM). It can be loaded to the same levels as 450 Marlin and the magnum level Buffalo Bore 45/70 loads. This one will eventually happen when I’ve got the time to handload again and money to put it together. 

[98Z5V]

48 minutes ago, JMJ said:

Out of those two which is your favorite? I’ve shot a 358win from a bolt action and was immediately a fan of the round. 

I don't have that .358 Win fully sorted out yet.  16" Wilson Combat barrel, midlength gas.  It kicked the living shiit out of me the first time I shot it, with a 5.4oz buffer.  I immediately ordered up a Heavybuffers.com, the XH Carbine, weighing in at 8.5oz.  That solved alot of the "keel you" aspect of the round, but my initial rounds were way too hot.  I pierced 16 primers.  Bottom line, running the Hornady 250gr SP-RP in it, I need to work way more on the load development on it before I can really enjoy shooting it and see what it can do.  I know it's gonna be great - I just need to put more work into it.

Now, that .338 Fed...  DAMN!  That is a great gun!  16" Wilson Combat barrel.  Right out of the gate, everything worked great with the 5.4oz buffer (AR-10 Carbine system), I didn't need to drill out the gas port, I DID have to run the Armalie AR-10 Carbine gas tube.  Loaded with 225gr Hornady SSTs...   That thing shoots softer than the gun I compare it to, and built it against.  I built it identical to the 16" .308 Win gun, for the purpose of comparing - that .338 Fed build blows that same-almost-identical .308 Win gun straight out of the water.

So, until I can sort out the load on the .358 Win, and resolve that whole gun - I'd have to say the .338 Fed is the best short .308AR that I've built. It's just ridiculous, fun to shoot, easy to shoot, and it's delivering 225 grains onto target. 

Edited January 6, 2023 by 98Z5V

[JMJ]

5 hours ago, 98Z5V said:

I don't have that .358 Win fully sorted out yet.  16" Wilson Combat barrel, midlength gas.  It kicked the living shiit out of me the first time I shot it, with a 5.4oz buffer.  I immediately ordered up a Heavybuffers.com, the XH Carbine, weighing in at 8.5oz.  That solved alot of the "keel you" aspect of the round, but my initial rounds were way too hot.  I pierced 16 primers.  Bottom line, running the Hornady 250gr SP-RP in it, I need to work way more on the load development on it before I can really enjoy shooting it and see what it can do.  I know it's gonna be great - I just need to put more work into it.

Now, that .338 Fed...  DAMN!  That is a great gun!  16" Wilson Combat barrel.  Right out of the gate, everything worked great with the 5.4oz buffer (AR-10 Carbine system), I didn't need to drill out the gas port, I DID have to run the Armalie AR-10 Carbine gas tube.  Loaded with 225gr Hornady SSTs...   That thing shoots softer than the gun I compare it to, and built it against.  I built it identical to the 16" .308 Win gun, for the purpose of comparing - that .338 Fed build blows that same-almost-identical .308 Win gun straight out of the water.

So, until I can sort out the load on the .358 Win, and resolve that whole gun - I'd have to say the .338 Fed is the best short .308AR that I've built. It's just ridiculous, fun to shoot, easy to shoot, and it's delivering 225 grains onto target. 

I bet that .358 Win could kick the donkey snot out of you LoL! That one really perks my interest cause the round would qualify for “primitive” deer season here if it’s chambered in a single shot rifle. I’ve had a hankering for a tandem of a semi and a single shot in the same round for all aspects of deer season here. Primitive season used to be our muzzleloader deer season then in the mid 2000’s they changed our regs to include single shot hammer fired rifles that shot cartridges .45cal and larger, I picked up a 45/70 handirifle then two years later they changed the regs again to .35cal and larger so everyone jumped to .35 Whelen. Since I built my Aero 308 I’ve wanted something in a big bore upper for the large frame gun. 
 

The .338 Fed has been an interesting round since it came out, but I don’t know anyone that has/hunts with one around here to get feedback from or try shooting one. In my mind I’d think it’d be more popular here since it has the same kE numbers as 7mmRM and that one is probably in the top 5 deer cartridges in Louisiana for decades. 
 

Thanks for the info!

[Mosinwolf762]

10 hours ago, 98Z5V said:

I've done a .338 Federal and a .358 Winchester.  Easy peasy, because it's just necked up .308 Win cases, so stardard bolts/BCGs work, as well as .308 Win Go/No Go gauges.  Wilson Combat makes the barrels already, and they're not bad at all. 

What do you want this gun to do for you?  How are you planning on using it.

I am building it partially to have something different, but it is going to be used for hunting. Honestly, nothing big enough to really need  the caliber chosen, but I already have one in .308 so why not lol. I will primarily use it for black bear here in Michigan and I might throw it in on an elk hunt in Colorado we're taking next fall but I'm primarily using my my 300 win mag. Funny you mentioned the .358 win, that is my backup plan if I couldn't put together a magnum AR10.