new 350 legend barrel and tuning issues

[jbs27572]

It seems to be a good barrel. Groups with Winchester white box are clover leaves at 50 yards. I tried a few at 100 yards and groups opened up a bit but I think most of that was me rather than the rifle. I did have a few tuning issues. The barrel came with a free adjustable gas block. I started with the gas block closed and opened it up one full turn at a time but never could get the bolt to lock back reliably. Sub-X ammo doesn't even eject the case. I eventually had the set screw all the way out and put it back in 4 or 5 turns. Out of 40 shots, 3 locked back on the empty mag (with supersonic ammo). What do you think? A lighter buffer spring and or a lighter buffer weight? It fed flawlessly with the Winchester 145 gr fmj bullets but when I went to my reloads, I had feeding issues. The blunter nosed RMR bullets are getting jammed straight into the feed ramp. I am not sure what can be done to fix that.

I reloaded some 147 gr 9mm bullets from RMR in new Winchester cases. Previously, I had tried 25 gr H110 and it looked ok for the first 5 shots ( with the old barrel) but When I loaded up a mag wit them, I ended up with 3 blown primers and bulged cases. I pulled the rest and backed down to 24 gr. No pressure signs I can see but the speeds are still about 100 fps faster (with the new barrel) than the Winchester white box ammo.

 

[atblis]

There are no free lunches. If it’s still running faster than you’d expect, you’re likely over pressure. I suspect you’ll find loose primer pockets.

What mags are you using? I’ve had feeding issues with 350. Been meaning to try the Wilson Combat lancers.

MAGAZINE, AR-15, 350 Legend, 15 ROUND, POLYMER | LANCER

These Lancer 300 BLK L5AWM magazines have been carefully modified in our shop to allow the .350 Legend case to better clear the magazine during the feeding cycle.

wilsoncombat.com

 

[jbs27572]

A 5 round mag came with the rifle and I bought a 20 round duramag magazine. The commercial ammo feeds flawlessly. It is just the blunter profile bullets from RMR that have the feeding issue.

 

[outrider58]

If you're going to shoot subs unsuppressed, you'll probably need to lighten your action, spring or buffer or both.

Who made the upper?

Whose gas block is on it?

Where does the brass land(the Winchester)? If the muzzle points to 12 o'clock and the rifle but at 6 o'clock, where does the brass land?

The feeding issue could probably be solved with different mags.

 

[jbs27572]

The rifle is a Diamondback Carbon series The barrel and adjustable gas block came from OdinWorks. The brass lands at roughly 3:00 and about 4 to five feet away.

I will try the 5 round mag that came with the rifle but with the old barrel, the feeding issue didn't exist. It might be related to being undergased or a difference in the feed ramps between the two barrels; I am not sure right now.

 

[outrider58]

The rifle is a Diamondback Carbon series The barrel and adjustable gas block came from OdinWorks. The brass lands at roughly 3:00 and about 4 to five feet away.

I will try the 5 round mag that came with the rifle but with the old barrel, the feeding issue didn't exist. It might be related to being undergased or a difference in the feed ramps between the two barrels; I am not sure right now.

That's with the gas block all the way open?

I am not well versed in things 350 L, but as I read about it and their inherent feeding issues, there are all kinds of remedies out there. Due to my ignorance on the subject, I can not recommend any of them, for safety reasons.

When you fitted the new barrel to the receiver, did you make sure the feed ramps were properly shaped to the receiver? There should not be any kind of edge on the ramp that could catch, snag the rifle round the tip of the round travels up the ramp and into the chamber. You can test this by running a ballpoint pen up the feed ramp where barrel extension and the receiver meet. The should not be any hang-up there.

Gas block: Are you sure the GB is perfectly aligned with the gas port? If your brass is landing at 3 o'clock with the GB all the way open, that indicates the gun is a tad under gassed. That could be caused by any number of reasons including misaligned gas block, too heavy buffer, too heavy a buffer spring, etc. If I understand you right, this problem started with the new barrel/gas block, and the gun functioned fine beforehand as a 350L, or did you convert an existing gun of a different caliber to the 350L?

 

[atblis]

What’s the barrel length and gas system length?

 

[outrider58]

What’s the barrel length and gas system length?

I found this. The GB looks like crap...

350 Legend 16.1'' Mid Length | Shop Now

350 Legend 16.1' Mid Length barrel. Black Nitrided, 1:10 Twist, made from 416R stainless steel, hand lapped.

www.odinworks.com

 

[jbs27572]

That's with the gas block all the way open?

I am not well versed in things 350 L, but as I read about it and their inherent feeding issues, there are all kinds of remedies out there. Due to my ignorance on the subject, I can not recommend any of them, for safety reasons.

When you fitted the new barrel to the receiver, did you make sure the feed ramps were properly shaped to the receiver? There should not be any kind of edge on the ramp that could catch, snag the rifle round the tip of the round travels up the ramp and into the chamber. You can test this by running a ballpoint pen up the feed ramp where barrel extension and the receiver meet. The should not be any hang-up there.

Gas block: Are you sure the GB is perfectly aligned with the gas port? If your brass is landing at 3 o'clock with the GB all the way open, that indicates the gun is a tad under gassed. That could be caused by any number of reasons including misaligned gas block, too heavy buffer, too heavy a buffer spring, etc. If I understand you right, this problem started with the new barrel/gas block, and the gun functioned fine beforehand as a 350L, or did you convert an existing gun of a different caliber to the 350L?

I took it to a gunsmith to have the new barrel and gas block put on as I don't have a barrel wrench or a torque wrench. I also had him dimple the barrel for the gas block. Yes, the problem came up with the new barrel and gas block. There were no feeding issues with my reloads with the old barrel and gas block.

I have read that mil spec barrels often have gas ports drilled a little larger than they need to be to insure reliability but this can cause them to be over gassed. Also, the old barrel had a pistol length gas system and the new barrel has a midlength gas system. It may have needed the heavier buffer and spring to deal with the higher pressure from a pistol length gas system and/or the gas port is smaller diameter and I need a lighter buffer and spring. I have a 3 oz buffer and a lighter spring on order and should get them sometime this week. I also ordered a (very expensive) adjustable gas block from Riflespeed and will get that changed out when it comes in but that may take a little while since it is backordered.

 

[jbs27572]

I found this. The GB looks like crap...

350 Legend 16.1'' Mid Length | Shop Now

350 Legend 16.1' Mid Length barrel. Black Nitrided, 1:10 Twist, made from 416R stainless steel, hand lapped.

www.odinworks.com

How can you tell from a picture without an actual barrel to inspect?

 

[jbs27572]

What’s the barrel length and gas system length?

16" barrel with a midlength gas system.

 

[outrider58]

I took it to a gunsmith to have the new barrel and gas block put on as I don't have a barrel wrench or a torque wrench. I also had him dimple the barrel for the gas block. Yes, the problem came up with the new barrel and gas block. There were no feeding issues with my reloads with the old barrel and gas block.

I have read that mil spec barrels often have gas ports drilled a little larger than they need to be to insure reliability but this can cause them to be over gassed. Also, the old barrel had a pistol length gas system and the new barrel has a midlength gas system. It may have needed the heavier buffer and spring to deal with the higher pressure from a pistol length gas system and/or the gas port is smaller diameter and I need a lighter buffer and spring. I have a 3 oz buffer and a lighter spring on order and should get them sometime this week. I also ordered a (very expensive) adjustable gas block from Riflespeed and will get that changed out when it comes in but that may take a little while since it is backordered.

I don't think it is a problem of the gas port being too small, but rather, a matter of dwell time differential between the two different barrels.
Let's see what the new parts you ordered do. I prefer SLR and Superlative Arms blocks, they are both very user friendly if you get tired of waiting on the Riflespeed. Just as an alternative.

Did you understand my feed ramp inspection? You have to have the barrel and receiver to perform the inspection. It is best to do this before the barrel is mounted(bolted) on so that you can cut and polish the ramps prior to mounting the barrel 'permanently'. You do not want to reform the feed ramp(s) while the barrel is mounted to the receiver. That said, you should still perform the inspection and if a problem is found, removal of the barrel is necessary to correct the problem.

 

[jbs27572]

Yeah, I vacillated between the superlative arms gas block and the riflespeed one. It was the allure of being able to adjust the gas block by essentially twisting a knob to go from super and subsonic ammo that finally won out.

I will inspect the feed ramp as you said. If it has a problem, I can take it back to the gunsmith that mounted the barrel for me and request he cut and polish the feed ramp. I have no experience with doing something like that myself and don't want to ruin my new barrel.

 

[outrider58]

Yeah, I vacillated between the superlative arms gas block and the riflespeed one. It was the allure of being able to adjust the gas block by essentially twisting a knob to go from super and subsonic ammo that finally won out.

I will inspect the feed ramp as you said. If it has a problem, I can take it back to the gunsmith that mounted the barrel for me and request he cut and polish the feed ramp. I have no experience with doing something like that myself and don't want to ruin my new barrel.

That may or may not be part of your feed problem, but often times, working on AR problems is a matter of elimination.

 

[atblis]

I don’t know that 350 Legend is fully understood at this point, but I wouldn’t expect mid length to cycle subsonic. Supers, probably yes. However, I notice that pretty much everybody does a carbine length gas, even on 20”. Perhaps it’s the mid length gas system. I wouldn’t be so quick to condemn the gas block.

I’ve done lighter spring, and lighter buffers to get 300 blk working. Reliability is typically lower.

 

[jbs27572]

You may be right but I hope not. No fix for that but getting another barrel. I got my lighter spring and buffer so we will try that for now. I'll let you know what I find.

This was a pretty expensive barrel I got for free: The company I bought the rifle from screwed up in their add and advertised a rifle with a barrel that apparently doesn't exist. I jumped on it because of the (inaccurate) description. The company comped me the barrel to attempt to right their mistake. It would suck if I needed to get yet another one with the right length gas system for it to cycle properly.

I got the 3 oz buffer to try this time. I saw an add for as light as a 1.6 oz buffer that I could try if this 3 oz one isn't light enough.

 

[outrider58]

Before giving up completely with that barrel, your last option would be to open up the gas port a tad.
Nothing ventured, nothing gained.

Middy barrels can be a PIA. They are made to tame full power ammunition. People sometimes expect too much out of them. Not saying it's this case, at all. They just don't handle light/sub loads well, generally speaking.

And again, I claim no working knowledge of the 350 legend AR, so...