The Firing Line Forums - View Single Post

P Flados · January 31, 2019, 11:37 PM

The 350 legend is the fastest straight wall only if you are talking about only factory straight wall ammo and rounds that are legal in all the straight wall states (1.8" max case length).

It is designed by Winchester with details that make me think that the sole purpose is the selling Winchester bolt guns, primarily in straight wall states or in locations where the 35 cal (35 Remington) has a traditional following.

It will work in the AR-15 platform (check out CMMG), but is not optimized for this platform.

The 357AR (I have one) is the real 357 Max rimless. It is a better choice for those that like the AR and have no need for factory ammo.

The 357 Max, 357AR and 350 all can be loaded to essentially the same performance levels in comparable guns. These guns are all very comparable to traditional 35 Remington performance. All 4 rounds will do better than traditional 35 Remington performance when used with the right plastic tip bullet.

The SAAMI specs are out. The rifle bore, 0.355, is strange, but it is not a total disaster. People need to relax a little.

With the 0.357 min freebore, A 0.357 bullet will chamber ok and will size down in the barrel fine with no problems. They actually seem to call for 0.357 bullets in the factory ammo. If they allow 0.357 bullets, the chamber freebore really needs to be above min (0.357), the middle of the SAAMI tolerance or 0.358 should really be minimum target for actual guns.

0.358 bullets can be used, but for most they will need to be seated very deep to avoid jamming into an undersized freebore.

The 0.355 bore makes a mess of the supply chain for new bullets. Regardless of the factory choice, some will want 0.355 bullets. Although 0.357 will be best for any new bullets from general bullet makers (this size will work fine for all three choices), they know that some will be too paranoid to use 0.357 in a 0.355 gun and 0.357 will also not sell to many with 0.358 guns. They also know that there will be a very limited market for true 9mm rifle bullets. It really messes the most with those wanting new/better 0.358 bullets (basically you can forget it).

A 0.357" bore size and 0.359 freebore would have been just so much better.

I did some test conversions of 223 brass. The taper will be no big deal for the conversion (it will fire form), the bigger concern is the length. Converted cases came out 1.700 +/- 0.005. With the min/max of 1.71/1.72 on the 350 chamber length, some should work for most, but do not expect anything close to a 100% success rate. If your chamber is close to spec max, success rate will probably be very low.

And then there are the real issues with the taper. The 0.012" taper is much more than we use for the 357AR. I expect some will reload the 350 with standard 38/357 dies. They will be working their brass a lot. The standard 38/357 sizer might make a reasonable neck sizer, but most 350 reloaders will probably need to pop for a set of all steel 350 dies (that I assume will become available).

For custom guns, some may want to go for a "tweaked" 350. Stick with enough standard 350 dimensions to allow factory ammo to shoot, but use a 0.357 blank (at max per the spec), open the freebore up to the max (0.359) and make sure the chamber length is real close to the min (1.710).

January 31, 2019, 11:37 PM	#10
P Flados Senior Member Join Date: January 8, 2017 Location: Wilmington NC Posts: 243	The 350 legend is the fastest straight wall only if you are talking about only factory straight wall ammo and rounds that are legal in all the straight wall states (1.8" max case length). It is designed by Winchester with details that make me think that the sole purpose is the selling Winchester bolt guns, primarily in straight wall states or in locations where the 35 cal (35 Remington) has a traditional following. It will work in the AR-15 platform (check out CMMG), but is not optimized for this platform. The 357AR (I have one) is the real 357 Max rimless. It is a better choice for those that like the AR and have no need for factory ammo. The 357 Max, 357AR and 350 all can be loaded to essentially the same performance levels in comparable guns. These guns are all very comparable to traditional 35 Remington performance. All 4 rounds will do better than traditional 35 Remington performance when used with the right plastic tip bullet. The SAAMI specs are out. The rifle bore, 0.355, is strange, but it is not a total disaster. People need to relax a little. With the 0.357 min freebore, A 0.357 bullet will chamber ok and will size down in the barrel fine with no problems. They actually seem to call for 0.357 bullets in the factory ammo. If they allow 0.357 bullets, the chamber freebore really needs to be above min (0.357), the middle of the SAAMI tolerance or 0.358 should really be minimum target for actual guns. 0.358 bullets can be used, but for most they will need to be seated very deep to avoid jamming into an undersized freebore. The 0.355 bore makes a mess of the supply chain for new bullets. Regardless of the factory choice, some will want 0.355 bullets. Although 0.357 will be best for any new bullets from general bullet makers (this size will work fine for all three choices), they know that some will be too paranoid to use 0.357 in a 0.355 gun and 0.357 will also not sell to many with 0.358 guns. They also know that there will be a very limited market for true 9mm rifle bullets. It really messes the most with those wanting new/better 0.358 bullets (basically you can forget it). A 0.357" bore size and 0.359 freebore would have been just so much better. I did some test conversions of 223 brass. The taper will be no big deal for the conversion (it will fire form), the bigger concern is the length. Converted cases came out 1.700 +/- 0.005. With the min/max of 1.71/1.72 on the 350 chamber length, some should work for most, but do not expect anything close to a 100% success rate. If your chamber is close to spec max, success rate will probably be very low. And then there are the real issues with the taper. The 0.012" taper is much more than we use for the 357AR. I expect some will reload the 350 with standard 38/357 dies. They will be working their brass a lot. The standard 38/357 sizer might make a reasonable neck sizer, but most 350 reloaders will probably need to pop for a set of all steel 350 dies (that I assume will become available). For custom guns, some may want to go for a "tweaked" 350. Stick with enough standard 350 dimensions to allow factory ammo to shoot, but use a 0.357 blank (at max per the spec), open the freebore up to the max (0.359) and make sure the chamber length is real close to the min (1.710). Last edited by P Flados; January 31, 2019 at 11:52 PM.