.350 Legend - Latest Project

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Ultimate Predator

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Hi all. New to this site but I found it while looking for load data and information for the 350 Legend. I thought I'd pass along what I've learned so far and maybe learn from others here regarding what research you have done.
The rifle is a Stoner upper, 16" AR that I bought from Midwayusa. I work part time at Sportsman's Warehouse where I bought a Spikes Tactical lower receiver frame. I also bought the parts to put in the lower from Sportsman's, including a Timney trigger. On top of all this I mounted a Leupold VX III 3.5-10X.
As many of you know, there is not a lot of load data - yet. If others like the chambering as much as I have come to, I suspect there will be more data coming. I found an article by Layne Simpson from a couple of years ago. I later found out that Hornady has up-to-date info on the Legend, using more proplellants than the Simpson article.
I have tried 28 handloads and five factory loads so far. I have found the biggest problem with my rifle is feeding. I'm using CMMG magazines in both 10 and 20 round configurations. The 10 round mags definitely feed better than the 20s and two of the factory rounds have trouble with one of them refusing to feed at all in the 20 round magazines. If someone has input on how to handle feeding issues, I surely would like to hear from you! Can you remove some of the spring from the 10 or 20?
I was amazed at the groups some of these loads turn in and am still trying to handload something as good as the Winchester factory 180gr Power Point (#X3501). At 100 yards these print a 0.327" five-shot group from the bench (measured center-to-center). The best handload I've come up with so far uses Accurate Arms #9 with the Hornady 165gr FTX bullet (#3502). This load prints 0.575" for five shots at 100 yards. I have four hand loads that result in under MOA at 100 yards and three factory loads: In addition to the aforementioned loads, the handloads include the same AA9 but with the Hornday Inter-Lok 170gr SP (#3501) and Enforcer with the Hornady 165gr FTX bullets. The last handload is the AA9 and 165gr previously listed using a reduced charge. The two other factory loads are Winchester Deer Season XP 150gr (#X350DS) but these must be loaded individually as they will not flow through any magazine I have (severe stovepipes) and the Winchester 145gr FMJ Target (USA3501) which feeds well. Federal American Whitetail managed a 1.8" group but won't work in a 20 round mag.
I've tried seven different propellants so far and used mostly Winchester brass from firing factory loads. I recently found some Starline brass and really like it. I haven't yet tried my fired Hornady brass nor have I used primers other than Winchester WSP.
Regarding the Layne Simpson data, I had one load from it that resulted in extreme pressure. I did not measure the cases with my blade micrometer before firing so I don't know how much they expanded but I had a devil of a time getting the fired cases to pull out of the chamber. When I did get them out, two of them had the primers fall out on the bench - thankfully I had loaded only five rounds with this data and it wasn't even the maximum load Layne had suggested. There were two other HOT loads from Layne's data but not quite as bad. Propellants were Winchester 296 and Lil' Gun; neither of which were maximum loads. So be careful!
I full length resize all these loads and trim to 1.700". I also taper crimp to less than 0.001" tighter than straight.
Sorry this is so long but I sure appreciate you reading and I hope I help others experimenting with this chambering. I'm still working on mine but am also waiting for new data!
Many thanks - mj
 
Welcome to THR

I can't help you with the 350 Legend, since I don't have one in that caliber (My big bore is a 458 SOCOM). Sticking in the chamber is bad as it indicates extreme high pressure.

As far as AR function I can help you with but it would be best to start a thread on the Gunsmithing thread.
A couple of questions.
Does the slide lock back on the last round?
Will if feed a single round off of the magazine?
Are you using an adj gas block or heavy buffer/bolt combo. All this impacts timing.
 
I haven't gotten around to handloading for my 350 upper, but I find the Wilson combat mags to be the best as far as feeding goes.
 
Thanks, guys. I really appreciate your replies.
Slide locks back properly.
Will not feed using a single round in mag. Also tried feeding first round by hand hoping others in mag will follow - nope.
Using Odin AR-15 Adjustable Heavy Buffer with heaviest weights installed.
I'll check out the Wilson mags, if I can find any.
Two reasons I built this rifle: First is I was drawn in by the 350 Legend. Second was because they started acting like they wouldn't allow (they being marxists). I wasn't that thrilled with the M-16 in the service (50+ years ago) anyway. Have to admit the AR-15 is fun to shoot though. Don't know much about buffers, etc.
 
OK. Found 'em at the Wilson site. Ordered and on the way. All five-star reviews except one who said they work after you grind 1/8" off the lip. I don't know enough about AR-15s to question him so I'll keep his suggestion in mind when I test them. He also says they are not made by Wilson (Lancer?) but again, I don't know and don't care as long as they work! Thanks again - mj
 
I now what you mean, Blue. My ammo gets quite a dent about 1/4" below the case mouth when I try to feed them using my CMMG mags. I have a CMMG mag that has volunteered to be ground down. More later.
 
Ultimate Predator said:
OK. Found 'em at the Wilson site. Ordered and on the way. All five-star reviews except one who said they work after you grind 1/8" off the lip. I don't know enough about AR-15s to question him so I'll keep his suggestion in mind when I test them. He also says they are not made by Wilson (Lancer?) but again, I don't know and don't care as long as they work! Thanks again - mj
Click to expand...

They are lancer mags that Wilson has custom fitted. Work the best on my legends.
 
OK. I ground the front of a 20 round CMMG mag down. No change in feeding. Afterward I wondered if I ground the correct place. When folks are saying to "grind 1/8" off the front of the mag" I took that literally. I ground down the horizontal, front edge of the mag. I doubt they meant grinding 1/8" off the lips. Anyone else try this? In mine it makes no difference in feeding. mj
 
I thought I'd give an update on my .350 Legend project. I had spotty feeding problems, that is certain ammo would not feed at all whereas some fed with CMMG 10 round mags, some with their 20 round mags, and some fed with the Lancer (Wilson Combat) mags. I found some Starline brass and handloaded some of that but still had the problems. I wanted this rifle to be dependable with all ammo, not just selected factory loads and my handloads. I have a friend, an accomplished gunsmith, who has built literally hundreds of AR15s and AR10s and I finally asked him to look into this. He polished everywhere ammo could come in contact with the rifle and feeding is just fine now - with one exception: The Lancer mags are too short to feed anythning but 145gr Winchester ammo. I cannot load 150 grain nor 170 grain nor 180 grain Winchester and Hornady ammo in these mags; all but 145 grain are too long. I see where the mags are marked: 300 Blackout. Does anyone know if Lancer merely uses Blackout mags for the legend? Do they modify them in any way?
Some other things the gunsmith recommended are to install MagPul self-leveling followers (the yellow ones) in the mags and to cut a coil off of the Lancer mags to straighten out the mag springs (apparently the springs are twisted and cramped up in the housing). When I told him someone recommended cutting the front of the CMMG mag down about 1/8", he tested the mag I had done that to and declared it unnecessary. He did, however, trim (maintaining the curvature) both feed lips back about 1/4" to 3/8". I tested all my mags with four different factory loads and with my handloads and they all feed reliably now, except for the aforementioned limitations on the Lancer mags. I have not trimmed any of my mags' lips as he did to one of the CMMG mags... didn't need to... so far...
One other thing he brought up was the recoil and the gas force. He noted that the brass cases were ejecting at about 1 o'clock, almost straight in front of him. He even said this 350 Legend recoils more than an AR10 in .308. Never bothered me; in fact, I thought the rifle recoiled similarly to a 5.56. I hadn't noticed the forward-ejecting cases because I had always used a Caldwell brass catcher. He recommended installing an adjustable gas block, which I did. The one I put in (Superlative Arms "Bleed-Off") also vents a bit of gas forward so it reduces recoil too. After buying a new crush washer and a MagPul Bev Block, changing the gas block took less than 25 minutes. I had to find a nine-inch long 3/32" hex wrench (I actually made one) since the one that came with the gas block was only six inches long and couldn't reach the adjusting screw. I followed the directions for initial adjustment (4 1/2 clicks) and can't wait to go to the range to test this set-up. The instructions say to adjust for brass ejecting at between 3 and 4 o'clock. I hope I don't have to mess with the weights in the buffer system. I am waiting to go to the range until after the holidays because we are so busy at the store where I work part time...
New to this stuff but having a whole lot of fun! Prior to this the only thing I did to an AR15 was to change for forestock on an old A-2. Thanks to all here who have responded and helped my learning and I hope, in some way, this helps others who are pursuing this chambering.
mj
 
Following with great anticipation. I just built my latest AR in 350 Legend with a Sanders Armory 13.5" SS barrel. Where I ran into problems was finding a muzzle device to fit 5/8x24 threads. Seem pretty had to find. Settled, for now, on the A2 flash hider I removed from my first .300BO, 8.5" upper from PSA. Subs always tumbled, so I swapped it out...turns out the flash hider bore is .375". Don't know how that would affect the exiting .300 Blk round, but for certain, my subs quit tumbling after I swapped out the A2.
Next issue was with one of the CMMG mags I bought. Too big...it had to be pulled out of the mag well, while it's brother dropped freely. This is all just in dry testing as I haven't had it out to the range as yet. Thankfully, CMMG replaced the sticking mag under warranty, and gave me a freebie for my woe. Gotta love 2A companies.
So I'll keep following your thread to see what I can glean. Have everything to start loading except brass, but my factory ammo should provide seed stock for the reloads.
 
At first I couldn't find any brass except that from Winchester factory loads. Thankfully the store shelves are continuously stocked with Winchester 145, 150, and 180 grain ammo and later on with Hornaday 170 grain ammo. This allowed me to test using Winchester brass. I finally lucked out with Midwayusa and ordered a bunch of Starline cases. Oh, by the way, they had "blemished" bullets, 170gr, that I believe are Hornady. Five hundred for a really good price and they are very accurate. As much as I like Starline, I have to say that so far I haven't seen any difference in performance between the Winchester and the Starline. Still, if there is a chance where I might lose some brass while testing loads, or the gas block, I'm gonna use the Winchester brass! Thanks - mj
 
Apologies: Make that blemished bullets from Midway that are 165 grain. I suspect they are Hornady 165 grain FTX #3502.
mj
 
Your AR Stoner upper is a Bear Creek Arsenal upper thats simply rebranded. They are known to have feeding issues with the 350L and they do seem to be accurate though.

My 350 Legend is a Bear Creek Arsenal also and its been very accurate but I also had the feeding issues. After doing some extensive polishing, feed ramp modifications, and magazine "fondling" I've got it to feed 100% reliably with Hornady 170SP factory loads and my reloads using the same bullet.

I have found that the 10 round Magpul .223 mags feed the smoothest for me. All I did was grind down the front of the mag some and also dremeled out the strengthening ribs on both sides. I put 7 rounds in it and go hunting. Works well on the one deer I got with mine. I even have a thread on it here.
 
GatorHunter: I teach handloading classes and I published a book on the subject, broken down in three sections (Introduction to Metallic Handloading; Handloading for AR Platforms; and Advanced Handloading) and in order to sell in stores I had to not only get a business license but I had to open a liability insurance account. Not that any of that matters to you but I have to adhere to my long-term practice of never giving out handloading data. First, I am not a lab; second, I might commit a typo; and third, there are businesses who publish reliable data. I know it's a bit difficult to obtain 350 Legend data but I have found some. In order to help as much as I can, I will list bullets, propellants, advertised muzzle velocity, and data sources in the hope that it will help you. You should be able to find the exact same loads as I used. Where I list advertised MV, that is what the data book said and if I list "estimated" that is somewhere in between listed data for MV. I have tested 33 different loads in my rifle; what follows are the best 9, all of which turned in 5 each, 5-shot groups of under one inch at 100 yards (with Leupold 3.5-10 VariX II scope). Al loads were seated to fit in my CMMG mags and all used Winchester WSR primers and previously fired Winchester cases (I had not yet bought my Starline brass). All handloads were taper-crimped at 0.025" taper. Best to, well, least best, they are as follows:
1. Winchester Factory 180gr Power Point #X3501. 2100 advertised MV. (Note: This load consistently produces less than 1/2" at 100 yards in my rifle)
2. Hornady 165gr FTX bullet #3502 with AA9 for estimated MV of 2100fps. Source: Hornady's latest book. (This load produced a 5-shot group of 0.27")
3. Hornady InterLok 170gr SP #3501 with the same amount of AA9 as item 2 above. Same Hornady source. (This load produced a 5-shot group of 0.15")
4. Hornady 165gr FTX bullet #3502 with Enforcer for estimated MV of 2150fps. Same Hornady source. (This load turned in 5-shot a group of 0.6")
5. Winchester Factory Deer Season XP #350DS. 2325 advertised MV. (This load would not feed until I polished chamber, etc.)
6. Midway USA 165gr seconds #697153, probably Hornady SSP with W296 for estimated MV of 2050. Source: Loaddata.com
7. Factory Winchester 145gr FMJ Target #USA350. 2250 advertised MV. (This load turned in a 5-shot group of 0.8")
8. Hornady 165gr FTX #3502 with AA9 for advertised MV of 2150. (This load had several shots going into the same hole on most of the groups)
9. Hornday InterLok 170gr SP #3501 with AA9 at 2150 advertised MV. (This load had one 5-shot group that measure 0.8")
I also tried LilGun, CFEBLK, 2400, and IMR 4227, all of which shot under 1.5" at 100 yards. Loads for these can be found at Loaddata.com and in the newest Hornady book. As you can see, I was somewhat limited by bullet selection. I hope there will be more variety in the future. The Midway bullets were a good deal at 500 each for not much money.
I just got back from the range where I tested the adjustable gas block I recently installed. Superlative Arms. It also acts as a sort of brake by venting gas to soften recoil... but I don't think the rifle is that bad to begin with. The factory-recommended setting for initial trials with this block worked fine - I did not have to adjust further as all brass ejected at 4 o'clock in lieu of 1 o'clock as was prior to the Superlative Arms adjustable block.
I'm going to put a Leupold VX5 on this rifle. 30mm tube with 3-9X firedot. This scope currently resides on my Springfield M1a; I want a higher power for that rifle but love the scope!
Take care - Hope this helps! mj
 
Ultimate Predator said:
GatorHunter: I teach handloading classes and I published a book on the subject, broken down in three sections (Introduction to Metallic Handloading; Handloading for AR Platforms; and Advanced Handloading) and in order to sell in stores I had to not only get a business license but I had to open a liability insurance account. Not that any of that matters to you but I have to adhere to my long-term practice of never giving out handloading data. First, I am not a lab; second, I might commit a typo; and third, there are businesses who publish reliable data. I know it's a bit difficult to obtain 350 Legend data but I have found some. In order to help as much as I can, I will list bullets, propellants, advertised muzzle velocity, and data sources in the hope that it will help you. You should be able to find the exact same loads as I used. Where I list advertised MV, that is what the data book said and if I list "estimated" that is somewhere in between listed data for MV. I have tested 33 different loads in my rifle; what follows are the best 9, all of which turned in 5 each, 5-shot groups of under one inch at 100 yards (with Leupold 3.5-10 VariX II scope). Al loads were seated to fit in my CMMG mags and all used Winchester WSR primers and previously fired Winchester cases (I had not yet bought my Starline brass). All handloads were taper-crimped at 0.025" taper. Best to, well, least best, they are as follows:
1. Winchester Factory 180gr Power Point #X3501. 2100 advertised MV. (Note: This load consistently produces less than 1/2" at 100 yards in my rifle)
2. Hornady 165gr FTX bullet #3502 with AA9 for estimated MV of 2100fps. Source: Hornady's latest book. (This load produced a 5-shot group of 0.27")
3. Hornady InterLok 170gr SP #3501 with the same amount of AA9 as item 2 above. Same Hornady source. (This load produced a 5-shot group of 0.15")
4. Hornady 165gr FTX bullet #3502 with Enforcer for estimated MV of 2150fps. Same Hornady source. (This load turned in 5-shot a group of 0.6")
5. Winchester Factory Deer Season XP #350DS. 2325 advertised MV. (This load would not feed until I polished chamber, etc.)
6. Midway USA 165gr seconds #697153, probably Hornady SSP with W296 for estimated MV of 2050. Source: Loaddata.com
7. Factory Winchester 145gr FMJ Target #USA350. 2250 advertised MV. (This load turned in a 5-shot group of 0.8")
8. Hornady 165gr FTX #3502 with AA9 for advertised MV of 2150. (This load had several shots going into the same hole on most of the groups)
9. Hornday InterLok 170gr SP #3501 with AA9 at 2150 advertised MV. (This load had one 5-shot group that measure 0.8")
I also tried LilGun, CFEBLK, 2400, and IMR 4227, all of which shot under 1.5" at 100 yards. Loads for these can be found at Loaddata.com and in the newest Hornady book. As you can see, I was somewhat limited by bullet selection. I hope there will be more variety in the future. The Midway bullets were a good deal at 500 each for not much money.
I just got back from the range where I tested the adjustable gas block I recently installed. Superlative Arms. It also acts as a sort of brake by venting gas to soften recoil... but I don't think the rifle is that bad to begin with. The factory-recommended setting for initial trials with this block worked fine - I did not have to adjust further as all brass ejected at 4 o'clock in lieu of 1 o'clock as was prior to the Superlative Arms adjustable block.
I'm going to put a Leupold VX5 on this rifle. 30mm tube with 3-9X firedot. This scope currently resides on my Springfield M1a; I want a higher power for that rifle but love the scope!
Take care - Hope this helps! mj
Click to expand...


Thank you for all of that. I will do more research and find a good starting point and go from there
 
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