Let's discuss 350 Legend

[steve123]

Over at my friends shooting range, and he's thumping steel with his 30 carbine, my other friend is wacking steel hard with 7.62x39, and my pesky 5.7x28 seemed anemic. It got me thinking I'd like me some kind of thumper. Hmm what to get???

I know what you're thinking, why not just shoot my 223?! I have and do but I prefer to use it farther out and it can be hard on some of the steel we have.

Had a 300BO, it's fine for this kind of stuff but....

Plus it's fun to try out different chamberings, right?!
Anyway, I like the 350L's non rebated rim that's the same size as 223, and that it double stacks, and in the future some Co should come out with high cap mags.

So I got on youtube and found BCA uppers for cheap, ordered a 350L 16", which hopefully will be reliable???, and for hitting steel with authority! I kinda expect some tuning will be required so here "it goes".
Ordered a CMMG 10 round 350L mag too.

I 'think' I have some crappy AR mags somewhere that I will probably modify just to experiment. May get some use out of them after all??

It'd be fun to reload some heavies like 220 grain but for now I'll just buy some of the Winchester 145gr to start out with.

Do you or anyone you know have a AR in 350L, comments and advice welcome?

 

[TonyTheTiger]

This is the first I've heard of 30 Carbine thumping anything...

Something about the 350L makes me want one, even though I have no use for it.

 

[The DFC]

Interesting caliber no doubt.

 

[steve123]

30 carbine has some sort of charm to it?! 110's at 1950 fps make a decent thwack and make the steel move around a little.

I want to out thwack him, lol.

 

[Strykervet]

I'm interested in one of these... Not sure if it's the one you mention. BTW, I have a Beowulf, you wanna hit shit hard that'll do it too. It's a unique weapon to say the least, limited uses though. Due to it only holding ten rounds in a 30rd mag, I installed a boonie packer my buddy toted all over Iraq and back and it's sort of a solution to the low cap mag problem.

What is the .35 round that uses 7.62 brass, loads into standard AR mags, and loads 15rds. into a 30rd. mag? Reaper? Raptor? I can't keep up with 'em and last thing I need is a wildcat but since it's formed from 7.62 that changes things. That a mag will hold 15 is a big plus, and IIRC, the round I'm thinking of has better all around ballistics than does the Beowulf (which is really just a close range anti-material weapon).

Also wanna say Krieger makes these barrels? Or Satern maybe? So the one I'm thinking of has cut rifling as an option in addition to holding 15 rounds. I really think I want one.

What's the difference in ballistics between these different cartridges? Which .350 is best?

What we could use is a more definitive thread on .350's and .338's as well come to think of it. Why not start here?

 

[TonyTheTiger]

I want to out thwack him, lol.

You're on the right track!

 

[Cheyenne Bodie]

Maybe 6.5G 110's at ~2500 would do the trick as well.

 

[TonyTheTiger]

I'm interested in one of these... Not sure if it's the one you mention. BTW, I have a Beowulf, you wanna hit shit hard that'll do it too. It's a unique weapon to say the least, limited uses though. Due to it only holding ten rounds in a 30rd mag, I installed a boonie packer my buddy toted all over Iraq and back and it's sort of a solution to the low cap mag problem.

What is the .35 round that uses 7.62 brass, loads into standard AR mags, and loads 15rds. into a 30rd. mag? Reaper? Raptor? I can't keep up with 'em and last thing I need is a wildcat but since it's formed from 7.62 that changes things. That a mag will hold 15 is a big plus, and IIRC, the round I'm thinking of has better all around ballistics than does the Beowulf (which is really just a close range anti-material weapon).

Also wanna say Krieger makes these barrels? Or Satern maybe? So the one I'm thinking of has cut rifling as an option in addition to holding 15 rounds. I really think I want one.

What's the difference in ballistics between these different cartridges? Which .350 is best?

What we could use is a more definitive thread on .350's and .338's as well come to think of it. Why not start here?

Short answer is its a 223 case where they pulled brass off the line before the shoulder/neck was formed and threw a 35 caliber bullet in it. So it won't compare to any 308 based wildcats but should smoke 300BO easily.

 

[steve123]

Maybe 6.5G 110's at ~2500 would do the trick as well.

I have a 6mmFatRat upper that would work but I want to preserve the barrel life for long range applications.

I thought of 6.8SPC but 350L won out.

Thought about 450 and 50 but want higher capacity and less recoil.

 

[Strykervet]

Short answer is its a 223 case where they pulled brass off the line before the shoulder/neck was formed and threw a 35 caliber bullet in it. So it won't compare to any 308 based wildcats but should smoke 300BO easily.

Okay, then what's the deal with 10rd mags? Sounds like it would just double stack like regular 5.56 no?

If that's the case then I'd like to compare the ballistics to that of the one modeled off the 7.62 brass yet designed for small frame AR's. if the difference is negligible and handloading .350L isn't an MOS, then it seems like no contest.

 

[steve123]

Stry, regular AR mags won't work because of the rib depression that's closest to the front of the mag.

I just want easy, as in not a wildcat cartridge this time, by using factory brass, and occasionally factory ammo.

 

[mcfred]

It's sort of weird. It's not actually a .350, and if you assumed the groove to be .357" or .358" you'd be wrong. SAAMI groove diameters are actually .355" or 9mm. Loading stubby/heavy .358" projectiles may push out the web and prevent the cartridge from chambering at mag-length. Some people have gotten Lee cast bullet sizers to squeeze .358"s down to .357-355 as a work around.

While the .350L's based on the .223 Rem case, it's .013" fat at the web/case head (SAAMI Drawing), so once you get past 10 it might start doing something weird in the mag. Standard 30-round .223 mags have a rib down each side at the shoulder that would have to be removed for the shoulder-less .350L.

Initial release Winchester brass was all over the place in overall length and some lots of loaded ammo had a pretty severe crimp that cause mild loads to be overpressure blowing out primers due to inappropriate headspace. They've probably got it sorted out now.

This guy uses a lot of words if you like reading:
https://www.realguns.com/articles/1106.htm
https://www.realguns.com/articles/1111.htm
https://www.realguns.com/articles/1124.htm

Retrirees with a lot of time to fiddle are playing with the .350L here:

350 Legend and Cast Boolits

THIS IS A STORY OF THE DEVELOPMENT OF A LOW PRESSURE CAST BULLET CASE, A SET OF CAST BULLET LOADS AND A GUN THAT SHOOTS THE ABOVE. IT DOES NOT GIVE YOU LICENSE TO EXPAND THE INFORMATION HERE TO ALL GUNS AND ALL LOADS, ESPECIALLY NOT TO HOT LOADS USING JACKETED BULLETS. YOU ARE...

castboolits.gunloads.com

An alternative if you don't mind a wildcat search for ".357 Max Rimless" and related data produced my a user named "Moleman" and others. It uses .358" projectiles, Starline .223 Remngton Basic brass and is same/same but different precursor to the .350L.

 

[steve123]

Just got back to the house with 2 boxes of Winchester 145gr ammo.

 

[steve123]

Just got back to the house with 2 boxes of Winchester 145gr ammo.

Got the BCA upper, it's a nice looking unit. Got the 10 round mag too.

Damn, those 145gr Winchester's didn't work well in this upper! You can read about that in my other thread.

https://www.snipershide.com/shootin...-priority-do-i-troubleshoot-problems.6978530/

The 180gr Winchester hunting ammo worked fine so far and was significantly more powerful! I'll report back about it when I've fired all 40 rounds. Just shooting off the truck hood with no rear support I got a 3" 10 shot group at 100Y.

Got dies, brass, and more 180's coming soon....

 

[Codiekfx400]

Somebody needs to make a high bc deer slaying bullet for the legend.

 

[steve123]

Got the BCA upper, it's a nice looking unit. Got the 10 round mag too.

Damn, those 145gr Winchester's didn't work well in this upper! You can read about that in my other thread.

https://www.snipershide.com/shootin...-priority-do-i-troubleshoot-problems.6978530/

The 180gr Winchester hunting ammo worked fine so far and was significantly more powerful! I'll report back about it when I've fired all 40 rounds. Just shooting off the truck hood with no rear support I got a 3" 10 shot group at 100Y.

Got dies, brass, and more 180's coming soon....

All 40 rounds of the 180gr ammo worked perfectly! 1940-ish fps.

Tried a few of the 145's in my friends lower and they didn't function in that either??? Faulty ammo!

Pretty accurate, the 200M chicken silhouette was no challenge, stopped after 3 hits with a 2.5" group because I wanted to let my friends shoot at the other steel and I didn't have much ammo left.

Hits the 50Y to 136Y steel hard but the recoil is slight, ETA (more than a 223 though), I liked these attributes a lot!

Very glad I bought the BCA upper, and in 350 Legend, it's perfect for the type of medium distance steel shooting my friends and I do which is mostly offhand and on generously sized targets.

 

[steve123]

I got my new Winchester brass and 180gr bullets in. Dies weren't in yet so I used a 357 mag seater die.

Attempted loading some Alliant 2400 powder I have for the 357 mag. That was a no go, started to get pressure before my AR would function, that idea was out.

So I went down to the GS and bought some Hodgdon Lilgun. I was short on time before I was due out at my friends shooting range so I took .3 grains off max load which was 25.2 grains and seated 25 180's to try.
The pressure signs were normal, no ejector smear and the Federal primers were not quite flat. Man these loads were powerful!!! Darn near like shooting a 308!!! I didn't have a chrono with me but I'm guessing the velocity was 200 or more fps faster than the factory load I shot last week! Smacked the steel very hard and loudly!

Definitely slowing it down to the level that the factory load was, which was much more pleasant to shoot.

 

[srt-4_uk]

Somebody needs to make a high bc deer slaying bullet for the legend.

Kinda defeats the purpose

 

[Codiekfx400]

Kinda defeats the purpose

I am not following.

 

[srt-4_uk]

The whole point of 350 legend is that its fast-ish and fits in an AR mag. High BC bullets will negate both of those really quickly.

 

[roostercogburn98]

Gonna use CFE Black when I finally set the dies up. They have been collecting dust for a hot minute now. If I want to put thwack anyone, I second then 50 Beowulf. Some 350g hollow points make terrible messes out of rocks and sing up a bowling ball pretty good. The 7.5 inch 7.62x39 ar makes some noise in a small package as well. The 350 has impressed me so far in my shootings. The 180s are pretty dang hard hitting for sure.

 

[steve123]

Gonna use CFE Black when I finally set the dies up. They have been collecting dust for a hot minute now. If I want to put thwack anyone, I second then 50 Beowulf. Some 350g hollow points make terrible messes out of rocks and sing up a bowling ball pretty good. The 7.5 inch 7.62x39 ar makes some noise in a small package as well. The 350 has impressed me so far in my shootings. The 180s are pretty dang hard hitting for sure.

It would be fun to try a 50Beo! Maybe a project for next winter.

The 200M full size chicken silhouette I've been mentioning is on a swinger, when I hit it yesterday with the warm 350L load it would go almost halfway around then go back. We have it set up the hill, and angled down, so gravity will keep it facing us all the time. A 308 with 175's will swing it all the way, and so will a 45-70 with 535gr cast bullets going 1100 fps.
Maybe a 220gr bullet in the 350L would swing it all the way??

We have a 300Y 7" diamond I'll try, a 400M turkey to try, and the 500M ram. I don't plan on seeing much success but what the heck, no guts no glory.

 

[roostercogburn98]

Not sure I’ll load anything past 180 honestly. I think they could be pushed just a little faster, I was averaging 2115fps if my old memory serves me right. The 150s have been shooting very well for me I just want to tinker with that load some. All I have shot from it so far is factory ammo. I also have a 16in bolt gun so my experience might vary slightly from yours. The Beowulf is fun but haven’t shot it in ages. I have a couple hundred cases primed and and ready to load just never got to it.

 

[XLR308]

One of the guys I'm going hunting with in a couple of weeks will be using a 350 legend on Texas hogs.
He upgraded to this since he and a couple others had hogs shot with 300BO super loads just soak them up and trot off.
Should be able to add some info on terminal performance in a couple of weeks, I will be using my old faithfull hog medicine of 68spc with either 85tsx or 120sst loads to compare it to.

 

[TxTrout]

One of the guys I'm going hunting with in a couple of weeks will be using a 350 legend on Texas hogs.
He upgraded to this since he and a couple others had hogs shot with 300BO super loads just soak them up and trot off.
Should be able to add some info on terminal performance in a couple of weeks, I will be using my old faithfull hog medicine of 68spc with either 85tsx or 120sst loads to compare it to.

I’d be interested in this report. I’m considering building a .350L thermal hog machine. Just got the thermal in the mail...now I need something that goes bang.

 

[Greg Langelius *]

My thinking has it as something like a 9mm Mag, or a .357/180XTP sub; either in an AR upper.

I'm not thinking of any great distances with either, neither,

 

[steve123]

I loaded some test rounds, 3 of each grain weight, in .3 grain increments, using the lilgun powder, and the Winchester 180 grain bullets. Six 3 shot groups tested, starting high at 25 grains and ending at 23.5 grains.
The distance I shot at was 75Y using 1" paisters to aim at, I chose that distance because I was using my 1-8x Burris XTR2 and wanted to see the aiming point easier.

Except for a couple of the test loads in the 1.25" range the rifle averaged 1" and the lightest load/2.3.5gr shot a 3/4" group with almost no vertical, so I will load up more of those to try. That lightest load had about the same recoil impulse as the factory 180 grain ammo which was what I'm after. I'll do a little seating depth testing and after that I'll call it good since I never intended this cheap upper to shoot moa anyway.

 

[roostercogburn98]

Seeing an update to this thread got me thinking I forgot about the 350 lol. Been sidetracked with the 22LR lately and been dedicating lots of time to stretching its legs out. Will set my dues up this week and start a load I guess

 

[steve123]

Seeing an update to this thread got me thinking I forgot about the 350 lol. Been sidetracked with the 22LR lately and been dedicating lots of time to stretching its legs out. Will set my dues up this week and start a load I guess

Any gun related sidetracks are worthy ones!

 

[Healy]

a 458 qualifies as a real thumper

 

[TACC]

I thought I read that the 180 grain bullets were supposed to be the ticket for hogs and deer out to anything less than 200 yards.

 

[357Max]

I hate typing on this phone, but out of town. So all you grammer Natzi's can suck it.​

As my screen name implies, I've long been a fan of the 357maximum.​

Got pretty exited when 350L was anounced and been following for a while. Waiting for them to get the primer popping factory ammo sorted etc. So around Christmass I went looking for a barrel. They all sucked. Either a stupid M4 profile (AR stoner, CMMG, Bear creek) or they had 1/2" 28 muzzle theeads (Kak) WTF leaves about .075 wall going through muzzle threads.​

X caliber was having a sale so I just ordered what I wanted. Just got email today from x caliber that it shipped.​

11" Heavy .950 to carbine length .875 gas block with 5/8" x 24 muzzle thread. Going to wrap this with a 12" m lock HG with a SLR blast forward comp.​

Should be a fun pistol.​

I'll report back qhen I get it together.​

It will be set up very sim to my 300BO pistol pictured​

 

[black5.3]

Just my $ .02 opinion but im not really seeing a huge benefit of going down the 350L rabbit hole when i already have a 300blk. From my limited research... i can lob 125gr bullets even bulk 147gr or higher subsonic stuff at distances the 350L was designed for with higher bc bullets ect for hunting or even smacking steel in a smaller suppressed package.. my 8” 300blk sends everything from 110gr vmaxs to the 150’s class bullets to 400-500 easily with respectable accuracy. Isn’t the 350L kind of on the same page as a 30-30 im terms or ballistics?

Im not criticizing anyone for taking on the 350L and trying it out because it definitely appears to be a cool new cartridge to try. Im just trying to understand what it may offer over a already proven 300blk.

 

[lash]

I hate typing on this phone, but out of town. So all you grammer Natzi's can suck it.​

As my screen name implies, I've long been a fan of the 357maximum.​

Got pretty exited when 350L was anounced and been following for a while. Waiting for them to get the primer popping factory ammo sorted etc. So around Christmass I went looking for a barrel. They all sucked. Either a stupid M4 profile (AR stoner, CMMG, Bear creek) or they had 1/2" 28 muzzle theeads (Kak) WTF leaves about .075 wall going through muzzle threads.​

X caliber was having a sale so I just ordered what I wanted. Just got email today from x caliber that it shipped.​

11" Heavy .950 to carbine length .875 gas block with 5/8" x 24 muzzle thread. Going to wrap this with a 12" m lock HG with a SLR blast forward comp.​

Should be a fun pistol.​

I'll report back qhen I get it together.​

It will be set up very sim to my 300BO pistol pictured​

View attachment 7242828​

Hey. I’ve also always been a big 357 Maximum fan. Similarly, I’m interested in it’s big brother out of an AR. At some point I’ll pick up a 350 Legend barrel from Craddock and put together an upper for it. His stuff always hammers.

 

[srt-4_uk]

300blk is almost 500fps slower with 147-150gr bullets per Hodgdon.
Getting ammo to reliably expand and penetrate is another plus. I've read a lot of people switching to then away from 300blk because it wasnt the hunting round they were expecting.
And yes, bullet placement > everything. But I'm not taking a 32ACP into bear country.

 

[lash]

Just my $ .02 opinion but im not really seeing a huge benefit of going down the 350L rabbit hole when i already have a 300blk. From my limited research... i can lob 125gr bullets even bulk 147gr or higher subsonic stuff at distances the 350L was designed for with higher bc bullets ect for hunting or even smacking steel in a smaller suppressed package.. my 8” 300blk sends everything from 110gr vmaxs to the 150’s class bullets to 400-500 easily with respectable accuracy. Isn’t the 350L kind of on the same page as a 30-30 im terms or ballistics?

Im not criticizing anyone for taking on the 350L and trying it out because it definitely appears to be a cool new cartridge to try. Im just trying to understand what it may offer over a already proven 300blk.

There are whole threads discussing and answering this question.

here’s one:

https://www.snipershide.com/shooting/threads/350-legend.6958950/#post-7933461

In addition to what @srt-4_uk just said above, this fits a niche in states that require straight walled cartridges of .35 nominal caliber and above for hunting. It essentially offers a lower recoiling effective hunting round for those that might otherwise choose 450 bushmaster, in a handy AR platform.

 

[MarinePMI]

I thought the whole point of the 350L was for the guys/gals that live in states that require a straight walled case to hunt deer(?)...still, it's a neat cartridge.

 

[lash]

I thought the whole point of the 350L was for the guys/gals that live in states that require a straight walled case to hunt deer(?)...still, it's a neat cartridge.

Yup.

 

[black5.3]

There are whole threads discussing and answering this question.

here’s one:

https://www.snipershide.com/shooting/threads/350-legend.6958950/#post-7933461

In addition to what @srt-4_uk just said above, this fits a niche in states that require straight walled cartridges of .35 nominal caliber and above for hunting. It essentially offers a lower recoiling effective hunting round for those that might otherwise choose 450 bushmaster, in a handy AR platform.

I thought the whole point of the 350L was for the guys/gals that live in states that require a straight walled case to hunt deer(?)...still, it's a neat cartridge.

Aahhhh ok that makes more since to me now.. I live in a most part “free” state so i totally over looked the strick hunting regulations aspect. Thats a big positive.

 

[Greg Langelius *]

I keep seeing this cartridge in a bunch of applications and firearm. I see it as a 9mm Mag/Rimless 357 Mag-ish cartridge.

Put it in a .350 Legend Automag-ish Handgun, .350 Legend Lever Gun, Ruger 350 Legend PC Carbine, a Moon Clip Revolver. and yes, an AR.

Just wingin' it...

There is a decided lack of bullets that can expand at the expected velocities. That should change quickly, maybe even by factory sizing .358/35 caliber rifle bullets down to .355/.356. Some already available ones could work. New bullets, specifically configured, are already available.

I'd really like to see a .355 180gr Gold Dot with the right construction for the .350's velocities. I'm thinking PD with some whack!

What would be the downsides of seating a longer ogive deeper in a straight wall cartridge ala the 7.62 Nagant? Might any of those downsides be mitigated?

Many users of this caliber (7.62 Nagant) handload their own ammunition, though the proper brass cases are also expensive and difficult to come by. However, Starline has been developing and perfecting brass for the cartridge, and handloaders have had success using dies for the .32-20 and .30 Carbine to handload the rounds. 32-20 brass cases are inexpensive, readily available, and can be reformed and used safely in guns chambered for 7.62×38R, but the resulting cartridges are too short to achieve the gas seal. Cut down 223 brass reformed in 30 carbine dies can be utilized to load for the Nagant also. These will achieve the gas seal, but case rims will be undersized.

Three other cartridges—.32 S&W, .32 S&W Long, and .32 H&R Magnum—will also generally chamber and fire in the revolver, but will not achieve the gas seal. The case head of the .32 S&W/H&R is about the same size as the case diameter of the Nagant cartridge, so the case head will sometimes actually end up moving into the chamber, thus preventing an adequate primer strike. Due to the dimensional differences between these cartridges and the original 7.62×38R cartridge, this practice is done at the shooter's own risk. The .32 H&R Magnum in particular develops much higher pressures than the 7.62 Nagant or either of the .32 S&W cartridges, which are both late 19th century developments. The most common anomaly when firing these cartridges is bulged cases.[4]

Looks like Starline is doing something somewhat similar in .308 diameter. Would .355 be such a huge jump?

Not looking to achieve anything like a gas seal, but putting some taper into the case mouth might improve feeding. .350 Legend Auto, anyone? Forget about a Collet Puller...

Greg

 

[Yondering]

300blk is almost 500fps slower with 147-150gr bullets per Hodgdon.
Getting ammo to reliably expand and penetrate is another plus. I've read a lot of people switching to then away from 300blk because it wasnt the hunting round they were expecting.
And yes, bullet placement > everything. But I'm not taking a 32ACP into bear country.

Getting bullets to reliably expand and penetrate from the 300 Blk is easy. People having trouble with it and moving away from the 300 Blk is because a lot of people are stupid and try to use the wrong bullets. I can't list all the threads I've seen with people wanting to use a 150gr or 165gr for 300 Blk hunting rounds, along with all the dumb responses of "more grain weight can't hurt" and stuff like that. Or in the subsonic loads, guys insisting 300 Blk is only good for subs but wanting to hunt with SMKs, A-Max/ELD, and others like that.

Truth is, there are a lot more bullets that work well/correctly in the 300 Blk than their currently are for the 350 Legend. At Legend velocities, most of the pistol bullets are not constructed heavily enough, but most of the rifle bullets are intended for higher velocity. There are a couple exceptions of course, with a few Legend-specific bullets that seem to work well, and a couple others like the discontinued Hornady 180 SSPB, but the fact is the selection of good Legend bullets is pretty small right now.

Also, I've discovered that a lot of the pistol bullets don't feed well in an AR, although they're probably fine in a lever or bolt gun.

 

[Yondering]

Wrote this and then realized it's a long post. TL;DR is that the Legend has some growing pains with wonky dimensions, and I'm going to modify/improve mine to work better.
-------------------------------------------------------------

I picked up my Legend just to figure out what the deal is with this new round. I probably won't hunt with it since I've got a couple other 35 caliber AR15 options that work better, but I like 35/9mm caliber rifles and wanted to check it out.

Milling the ribs out of an aluminum GI magazine is working in my rifle for about 15 rounds or so. I could have milled out farther, but didn't want the cutouts exposed below the mag well. Might extend that and wrap it with something later on.

I chose a 20" barrel, partly to increase the dwell time in hopes of getting a subsonic load to cycle. No luck with the subsonic loads so far, and my 20" barrel seems to give about the same velocity as others are reporting from 16" barrels. That makes sense with this low-capacity case for that bore size; it's somewhat like the 300 Blk in that respect.

I've realized there are a few things Winchester should have done better with this cartridge. They gave the case head a larger diameter (.390") than the 223, but then didn't follow up with a larger bullet diameter. It's almost like they made a decision to go two different directions; the .355" bullets could have worked with the standard 223 case dimensions, but the .390" head was better for .357-.358" bullets. Instead they kept the .355" bullets and went with the oddball case head.

On top of that, chamber dimensions seem to be such that .358" bullets are too tight with some brass. That is certainly an issue in the chamber of my rifle.

The bore of my rifle is .355"; I slugged it to verify. Larger .357" and .358" bullets can be safely fired through the .358" bore, and is not as dangerous as some claim if it's done right. However, the chamber throat dimensions of the Legend are wrong for that as well, no surprise, so larger bullets have to be seated deep enough to stay out of the throat. The worst part of that is the throat and chamber dimensions are even too tight for proper sizing and seating of cast bullets, which the Legend would otherwise be perfect for.

I've also found that most of the 357 Mag bullets I have won't feed well in the Legend; the blunt flat noses jam in the feed ramp. My barrel has larger feed ramps already, but more work is in order there.

Use of 223 brass has been a question in some 350 Legend discussions, so I experimented with that. Short answer is that it doesn't really work well, but not for the reason most have claimed. The .390" case head is not the issue; 223/5.56 brass expands just in front of the web to fit the chamber, and is no more of an issue than any loosely chambered factory rifle. However, even the longest 5.56 brass is too short after being necked up to a straight wall case. After trimming the case lengths to eliminate uneven necks, my cases ended up about .050" short, which is just enough to cause issues with the extractor not catching the rim.


I intend to modify the chamber of my rifle to allow better bullet options, since I have the ability to make my own reamer. I'll open the chamber a few thousandths so that a .358" cast bullet can be seated with enough clearance for normal brass dimensions. More importantly, I'll open the throat to .358", with about a 1.5° taper to bore diameter. This will allow easier use of the wide variety of .357" pistol bullets as well as cast bullets.

I'm also going to change the carbine length gas system to pistol gas, with the goal of using this for heavy subsonic loads.

 

[sav338lapua]

all i needed to know is the 350L uses the cartridge mouth to headspace on. this to me is a big no-no as it pertains to higher presversion sure rifle rounds' in a bolt action rifle probably not to much of an issue, but in a semi-auto what happens whewn someone has to long of brass and the BCG slams it up into the throat??? maybe nothing or maybe a bulged barrel. ill stick with the 375 winchester-200gr sierra fp 2350 FPS and 250gr at 2200 FPS. its the modern version of the 38-55 win which is what the 30-30 win is made from so its easy to have a 30-30 win rebored to 375 win or 38-55 win since there basically same cartridge just a slight change in brass length and both shoot lead bullets extremely good very accurate. oh and don't even think of using in a handy light weight lever gun with a tube magazine, you cant crimp the bullet in which is a must in lever guns except for savage 99's.
just my 2 cents.

 

[lash]

It was designed for a specific purpose. There is no doubt the there are many bottleneck cartridges that perform better. I don’t think that anyone, including the designers of the cartridge, think that it beats or negates the purpose of your favorite bottleneck cartridge. However, your favorite .375, blackout, 35 rem, etc CANNOT be used in the midwestern states that require straight-walled cartridges of .30 caliber or larger to hunt deer. Oh, and it works in an AR.

Sheesh people! Pay attention! It’s a purpose built cartridge.

 

[sav338lapua]

uh lash where you been, 375 win is straight walled case as is the 38-55 win and have been straight wall cases. and in the 38-55 win has been around since 1889!!! you sir should look things up before you let your ignorance shine.
375 right 45/70 left

 

[Niles Coyote]

Straight walled is only part of our limitations. Max case length for michigan is 1.8"

 

[sav338lapua]

not a problem in ohio any straight walled case

 

[lash]

uh lash where you been, 375 win is straight walled case as is the 38-55 win and have been straight wall cases. and in the 38-55 win has been around since 1889!!! you sir should look things up before you let your ignorance shine.
375 right 45/70 left
View attachment 7252960

Hey, where you been? Obviously not reading the thread, that’s for sure. As said, there are length limitations. Oh, and I missed where you could stuff those rounds into an AR.

Try paying attention next time before showing your ignorance. ?

 

[lash]

Oh look! I found another straight walled cartridge that you can use for deer hunting in Ohio! Golly! I never knew there were other straight walled cartridges!

I guess that there is no no need to ever design another niche cartridge, since it’s all been done already. I feel so ignorant!

 

[Jerry m]

Straight walled is only part of our limitations. Max case length for michigan is 1.8"

& Delaware 2019, & possibly Maryland this year...