View Full Version : XM193 under powered?
Hey guys, I took some xm193 to the range today along with some silver bear 62gr sp. When shooting the xm193, the bolt failed to lock back 4 out of 6 times after the last round was fired. I tested with silver bear and the bolt locked back 6 out of 6 times. Some things to note is that the casings were ejecting at around 2 o clock for the xm193 while the silver bear was ejecting at 3-4 o clock. The silver bear also felt more powerful. Is this just a case of under powered ammo? Is there something else that could cause the bolt to not lock back? This is a new build with just under 500 rds through it. My gear below...
LMT MRP 16" Piston Upper
Mega lower
DD LPK
POF Enhanced buffer tube
H2 Buffer and standard spring
Any input would be appreciated!
Highly unlikely that the XM193 is under powered. What's more likely is the hot ammo is making the bolt speed TOO FAST for the mag follower to engage the bolt stop.
I've had to trim coils off of the bolt catch plunger spring on a few guns to get the tension right. But with the piston in the equation, it's hard to say where the problem is.
Simple answer it's a piston gun! Under gased over gased who knows!
What your gas setting? And the difference in bullet wt/pressure ? Get some 55 gr Wolf/Silver bear an see if does the same thing! Probably will!:rolleyes:
Highly unlikely that the XM193 is under powered. What's more likely is the hot ammo is making the bolt speed TOO FAST for the mag follower to engage the bolt stop.
I've had to trim coils off of the bolt catch plunger spring on a few guns to get the tension right. But with the piston in the equation, it's hard to say where the problem is.
+1
definately NOT under powered. I have a rifle with an adjustable gas system, and when I start having problems with the bolt locking back, (with XM193 only) I turn it down (less gas hitting piston) and it works like it should. Lot of frustartion trying to figure that one out. I was thinking along the same lines as you and would turn up the gas system to the point brass was flying 40' away from the rifle. Then the light bulb went on :D
Ok, thanks guys. I read on ARF that someone else had the exact same problem with xm193 while his gun worked with wolf. He fixed it by using a stiffer buffer spring and now it works with both ammo. I think ill give that a try.
Ok, thanks guys. I read on ARF that someone else had the exact same problem with xm193 while his gun worked with wolf. He fixed it by using a stiffer buffer spring and now it works with both ammo. I think ill give that a try.
NO!!!!
Don't use a non standard buffer spring. Taking advice from those Mongoloids over on ARF will get you into trouble. Try a heavier buffer. Or switch to the A5 buffer system.
Thanks for the reply. What are the issues with a stiffer spring? Im looking for a happy medium where I can use silver bear and xm193.
Thanks for the reply. What are the issues with a stiffer spring? Im looking for a happy medium where I can use silver bear and xm193.
I know some people buy off on the aftermarket spring industry. But I personally thing you dial your guns cycle in with the buffer. You can find a buffer that runs both ammo, I'm sure.
Non standard action springs give me the creeps. I've had bad experiences with them.
What kind of bad experience? I thought about using aH3 buffer since my current setup seems close to running both without issues. Maybe ill try that first if i can find someone with a H3 buffer to let me test. There arent any good gun shops in orlando :(
I tried an aftermarket spring and it just induced malfs. Didn't blow up the gun or anything.... just pissed me off. I'd stick with the buffer approach.
Silver Bear is .223 Remington, XM193 is 5.56mm NATO.
If anything is underpowered, it is the .223 Remington Silver Bear, not the 5.56mm NATO round....
Simply adjust the regulator to match the ammunition being used. That's what the regulator is for. No need to change the buffer unless it's incompatible with the system
Yea it makes sense. I thought I got a bad batch of ammo or something. I'm just going to call LMT and see what they say about it.
Thomas M-4
05-10-11, 23:34
Yea it makes sense. I thought I got a bad batch of ammo or something. I'm just going to call LMT and see what they say about it.
What magazines were you using?
I had a 60+% failure to lock the bolt back with brownells magazines using xm-193 changed the followers out to magpul followers and they have been perfect. So far almost 4k rounds.
I tested with 6 fairly new pmags. They've each been used maybe 2 times. A Mix of 20 and 30 rds.
Thomas M-4
05-10-11, 23:59
I tested with 6 fairly new pmags. They've each been used maybe 2 times. A Mix of 20 and 30 rds.
The 20 p-mags had a reputation a while back of not being absolute reliable locking the bolt back IDK about newer ones . The 30 rounds which I own some 2nd gen and 3rd gen I never had a problem with. Could be a problem with the lower or the LPK. XM193 is not known to be under powered in fact most reports are the opposite .
It does sound like you [MIGHT] need to talk to LMT.
Hmmm, I dont remember if it was locking back on the 20 or 30 rd mags. Ill have to test it this weekend. Thanks for the tip!
30 cal slut
05-11-11, 07:43
For shits and giggles, I just clocked some this past weekend - average velocity coming out of a civilian length M4 carbine barrel was about 3,045 fps (ten rounds). I'm no expert, but I wouldn't consider that underpowered.
Thomas M-4
05-11-11, 08:18
Try the mags first if that doesn't isolate your problem then I would try to swap uppers. If it works with a different upper then most likely something is up with the upper. If it still fails to lock the bolt back with a different upper then I would be looking at the lower trying to find out whats up with it.
Will add I would do all of this while using one kind of ammo preferable full power 5.56 nato .
I went to the range yesterday and did more testing. This time the xm193 locked the bolt back 10 out of 10 times. The only thing I did was add more oil to the BCG. I guess it may not be an issue for me anymore. I was running both silver bear 62gr SP and Federal XM193 55gr with 0 malf's on the same mags that was giving me issues before.
Heavy Metal
05-16-11, 10:31
There should be a Gas Regulator on that LMT.
You do understand how it works and how to set it right?
The only thing I know how to set is "Fire" or "Suppressed". I have it set to "Fire". The manual doesnt mention any other gas setting.
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