358 mgp

[JZdryfly]

For those who shoot cast bullets in the AR, there is a recently developed cartridge that I'm having success with. It's the 6.8 SPC opened to 35 caliber. Very nice development.

[Landy88]

Interesting round.

Do you have any velocities recorded, yet?

I'm such an easy mark for .35s.

[am44mag]

Any feeding issues from standard mags? I have an extra lower that I need to do something with. This seems right up my alley.

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[JZdryfly]

No, not yet, as I just now put this together. If you visit "MGPCUSTOMS.COM", you can read up on bullet weights and velocities. Also enter 358 MGP in reloads nest and there's more info from users. I just fire formed with 1680 as per Mike Pilkington's data and couldn't believe the performance and accuracy from just fire forming. 1" groups of 7 rounds at 100m. Today I got a 1.5" group of 5 rounds with the Lyman 358315 and 22gr of IMR 4227. I shoot cast in all my guns for silhouette shooting so am not looking for max, just power to knock over steel. This load should knock over rams at 200m. I'll see next week. If you go on FB, search "Bang and Clang Alaska" and you can see what I'm talking about

[JZdryfly]

Mike modifies 6.8 spc mags for use and I don't know how standard mags would work

[RU shooter]

Looks like skinny and short 35 Rem . ,Pretty impressive speeds from a little case ! What kind of operating pressures that running at ? 50-55k ?

[pull the trigger]

This is almost identical to a 35 Rem. I was so close to putting one of these together. I would if I lived in a different state. The bullet selection is huge too.

[hicard]

I have one and really enjoy shooting it. Not much recoil, 35 Rem velocity and very accurate. I am using the RCBS 200 gr and the Accurate mold in 35-235gr loads with a grin on my face. If I changed anything, I would try a little lighter barrel configuration for easier carry but that might have a negative result in the accuracy dept. I have that 360-280 mold also, might have to give that a try as it does look good in the photo.

[Texas by God]

How can this cartridge equal the .35 Rem? By hype and loading to very high pressures? It can't. Now we load the .35 Rem hot and claim it to be equal to the .358 Win?

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[JZdryfly]

Fun cartridge to shoot in an AR-15 with cast bullets. Efficient, extremely accurate, and did I mention, it's FUN- just what shooting is all about

[dragon813gt]

How can this cartridge equal the .35 Rem? By hype and loading to very high pressures? It can't. Now we load the .35 Rem hot and claim it to be equal to the .358 Win?

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If you want 358 Win in an AR15 then you want the 358 Yeti. Everyone knows that [emoji6]

To bad this doesn't feed from standard mags. There are so many wildcats it's ridiculous. But as soon as mags have to be modified I'm not interested. I'm waiting for a viable 35cal wildcat to come along.

[JZdryfly]

The Yeti is a nice cartridge, and it is amazing the number of wildcats created to fit the AR15 package. Choices choices, it's great to have so many options for what ever reason a person wants

[JZdryfly]

What I'm doing with the 358 MGP. Lyman 358315 204gr with 22gr of I4227 at 1668fps for 1258 ft/lbs. Lyman 358318 245gr with 22gr of I4198 at 1562 fps for 1325 ft/lbs. NOE 360-280 280gr with 19.5gr of I4198 at 1337 fps for 1176 ft/lbs. All burn clean and cycle the bolt and very accurate and do what I want-knock steel silhouettes over out to 200m

[Texas by God]

I'm sure it is a lot of fun and don't think I'm trashing your cartridge. It's just simply not a .35 Rem equivalent any more than a ,300 blackout is a 30-30 equivalent.
Case volume matters.

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[BK7saum]

I'm sure it is a lot of fun and don't think I'm trashing your cartridge. It's just simply not a .35 Rem equivalent any more than a ,300 blackout is a 30-30 equivalent.
Case volume matters.

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In this case (pun intended) it just might be. It is a shortened 30 remington case (6.8 is a modified 30 rem, 0.422 base.). The 35 rem runs at 34k psi. The 6.8 runs at 55k psi, and thus the 35mgp can also. Case volume does matter but so does the pressure of the cartridge. A 62% increase in pressure has got to make up for quite a bit of case volume.

And we're not talking about hotrodding into dangerous pressure here, just run of the mill 55k psi that just about all modern cartridges operate at.

Case volumes might not be as different as you'd think. The 35mgp has a very short neck in comparison to the longer neck of the 35 rem.

Anyone have water capacity data for the two cases?

[dverna]

If you want 358 Win in an AR15 then you want the 358 Yeti. Everyone knows that [emoji6]

To bad this doesn't feed from standard mags. There are so many wildcats it's ridiculous. But as soon as mags have to be modified I'm not interested. I'm waiting for a viable 35cal wildcat to come along.

Agree with that. If the cartridge will not run with standard AR magazines my interest is low. But for many others, if they can achieve their needs by simply altering magazines it certainly is viable.

I know it is not rocket surgery to mark magazines but Murphy and I seem to be the best of friends. If I can possibly screw it up...I will.

Still, a neat cartridge though. Nice for cast bullets and should be a good one for deer at medium ranges.

[dragon813gt]

This one would not be as bad since 6.8 already has its own mags. To bad you have to modify the mags. You're also dealing w/ a proprietary cartridge so costs go up dramatically. That's what makes conversion on 5.56 and 7.62 cartridges so appealing.

Don't get me wrong, I like the performance of this particular cartridge. It doesn't need a special bolt like the Yeti. Which at this point isn't being made as far as I know. So w/ a simple case conversion and mag modification you have a nice 35 caliber round for the AR15.

[Texas by God]

I should have said they are not equal if loaded to the same pressure. Bump the .35 Rem up to 55 k and see what's what.

[Landy88]

In this case (pun intended) it just might be. It is a shortened 35 remington case (6.8 is a modified 30 rem, 35 rem, etc.).

The .35R is a different and larger diameter case than the .30R and the rest of that family of old Remington cartridges.

[BK7saum]

The .35R is a different and larger diameter case than the .30R and the rest of that family of old Remington cartridges.

Absolutely correct. I mistakenly pulled 30 rem up when I was looking at 35 remington. 0.422vs o.460 base diameter.

[Landy88]

Absolutely correct. I mistakenly pulled 30 rem up when I was looking at 35 remington. 0.422vs o.460 base diameter.

Your MGP round, all of these quibbling details aside, is a very good solution to fitting a viable sporting and cast friendly round in AR15s and other actions that were designed for the diminutive .222R family.

With all of these AR rounds that would fit it too, maybe Sako will bring back the original Vixen -- Well, one can dream the impossible dream.

[Meatpuppet]

An option in an AR platform is the 358 SOCOM... Essentially a 458 SOCOM case necked down to .358.
Can shoot almost all 357/358 dia rounds from 115 to heavy 200+
- 110 gr. 357 XTP @ 3151 fps
- 125 gr. 357 XTP @ 3000 fps
- 180 gr. 358 Hornady TTSX @ 2290 fps
- 200 gr. 358 Hornady TSX @ 2200fps
Uses standard AR-15 Magazines
Dies available from CH4D
Available from Tromix Lead Delivery Systems (http://www.tromix.com)

Full disclosure: I am a 357 Maximum fanboy and the 358 SOCOM gives me the same performance (and then some) in an AR platform without much "wildcat" work. Just run 458 SOCOM brass into the 358 dies.

[dragon813gt]

Requires an upper w/ an enlarged ejection port. It's own mags, not a big deal since they're readily available. 458 brass is readily available but not cheap. And you need the 458 bolt. All in all not a big deal and I went and looked for the parts to buy now. But I can't find a barrel or full upper.

[Meatpuppet]

Sorry about that. You have to call Tony Rumore at Tromix to order (918-543-3456 or TONY.RUMORE@TROMIX.COM). I believe they are making another production run of barrels. I dont think it has taken off to the point where it is a stocked item on the web page. I ordered the complete upper in 358 last time. However, you can get just a barrel if you want.

And the 458 / 358 SOCOM use standard AR Mags (Lancer Mags seem to work the best). Tromix sells regular AR mags labeled 458 SOCOM for those states having restrictions or mag requirements.

[Texas by God]

What I'm doing with the 358 MGP. Lyman 358315 204gr with 22gr of I4227 at 1668fps for 1258 ft/lbs. Lyman 358318 245gr with 22gr of I4198 at 1562 fps for 1325 ft/lbs. NOE 360-280 280gr with 19.5gr of I4198 at 1337 fps for 1176 ft/lbs. All burn clean and cycle the bolt and very accurate and do what I want-knock steel silhouettes over out to 200mThis sounds more like I imagine a .35 caliber round based on the 6.8 case should deliver. And I would love to have one if the finished AR15 weighs 8# or less.

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[DDriller]

200 gr. FTX clocks 2015fps out of my 16" barrel ar15 358 MGP.

[hicard]

The MGP website is down. Anyone know how to contact MGP to order more magazines for the 358 MGP?