How do you judge reliability?

[cyclesteel]

I received my LMT back from LMT see this thread for the back story
https://www.m4carbine.net/showthread.php?t=46166
I headed to the range this afternoon and out of 200 rounds I had 1 malfunction.
The malfunction happened in the first magazine and was similar to what was going on before LMT replaced my bolt. Except this time more of the round was showing and there was a big dent in the neck area of the round. I did not have my phone on me so I could not take a picture. I was shooting from a sandbag so it is possible I was putting pressure on the magazine and caused a miss feed. I was not paying that much attention.

Back to my original question since my rifle was bad out of the box this one malfunction is sort of bothering me. How many rounds before I can really trust the rifle? I have had a Stag and Colt 6920 previously and never had a problem with either of them granted I probably put less the 2000 rounds through each AR was I just lucky ? Do you guys think I am good to go and I am being too picky?

[Cameron]

I have an all LMT rifle that has never had a failure and has fired several thousand rounds.

I had a Bushmaster that shot 5,000 rounds without a failure.

I would try the LMT again, make sure it is not a magazine issue, and if it has another failure I would send it back again, or have it corrected by a local gun smith.

Cameron

[ztf HITMAN]

I definitely wouldn't pick it up in an HD situation. LMT is a reputable company, I'm sure they don't want one of their carbines running (or not running) like that. I'm sure they'll make it right.

[HiggsBoson]

I work in automation. Many industrial processes are measured for reliability using a metric called MTBF (http://en.wikipedia.org/wiki/Mean_time_between_failures), or Mean Time Between Failures. There are other variations such as Mean Time Between Critical Failures, or in the case of a firearm, I would use something like Mean Rounds Between (or before) Failures. This simple metric of course leaves at least two things out of the equation: Rounds per unit of time, and the definition of "failure".

[RAM Engineer]

I work in automation. Many industrial processes are measured for reliability using a metric called MTBF (http://en.wikipedia.org/wiki/Mean_time_between_failures), or Mean Time Between Failures. There are other variations such as Mean Time Between Critical Failures, or in the case of a firearm, I would use something like Mean Rounds Between (or before) Failures. This simple metric of course leaves at least two things out of the equation: Rounds per unit of time, and the definition of "failure".

In MRBF, rounds IS your unit of time. The clock ticks each time you pull the trigger.

I'm a Reliability Engineer by training and trade and have been for 10 years. Like Higgs Boson says, there is more to "Reliability" than most people realize.

What most people want to know about reliability translates into: "how reliable is my gun?"

Well, by definition, true reliability failures are random and cannot be predicted. Only the rates of occurrence can be estimated by testing. If you've got a piece of crap, you don't have to test long to determine that. If you have a really good gun, it should get through 1000 rounds, no sweat (which is what I usually see recommended as a baseline for determining the acceptability of a CCW carry gun reliability). However, if you have occasional failures pop up, you really need to determine the cause if at all possible. Magazine issue? Get rid of that mag. Ammo issue? Discontinue that lot/brand/type of ammo. Operator Error? Stop F-ing up. Now that you are left with failures attributable to the gun, keep testing and see if they continue. See if the RATE of occurence changes.

The only problem with the approach is that it TAKES forever, and by the time you figure it out, your gun is worn out and the failure rate is increasing...

My suggestion is: Go back to the range. Control as many variables as possible and see what happens. If you have even one more failure that you can't trace to mags, ammo, lack of lube, etc., then send it back.

[cyclesteel]

Another 200 rounds down range today and no malfunctions. Hopefully it was just a fluke or possibly an underpowered round. I might put an h buffer in just for good measure though.

[Thomas M-4]

Another 200 rounds down range today and no malfunctions. Hopefully it was just a fluke or possibly an underpowered round. I might put an h buffer in just for good measure though.

Did you ever replace the buffer spring?

[cyclesteel]

Did you ever replace the buffer spring?

Not Yet . I did order a wolff XP buffer spring it should be getting here sometime this week along with my h buffer. I am not sure which one I am going to try first. Any recommendations? or should I just leave well enough alone.
Is running both the Wolff Xp buffer spring and the H buffer going to give me problems ?

[Thomas M-4]

Not Yet . I did order a wolff XP buffer spring it should be getting here sometime this week along with my h buffer. I am not sure which one I am going to try first. Any recommendations? or should I just leave well enough alone.
Is running both the Wolff Xp buffer spring and the H buffer going to give me problems ?

I replaced my buffer spring with a tactical cs buffer spring http://www.sprinco.com/tactical.html
I used the Blue one [standard rate], with a H-buffer, with 14.5'' LMT upper and LMT enhanced BCG. When my buffer spring got to 10 1/8'' I experienced 2 FTF malfunctions. 400 rounds later after changing the buffer spring no more FTF .

[ColdDeadHands]

i would shoot it some more and pay attention not to put any pressure on the mag. IMO they should have just sent you a new BCG in exchange for the old one.

[Robb Jensen]

I measure it in stoppages or lack there of.....

[cyclesteel]

i would shoot it some more and pay attention not to put any pressure on the mag. IMO they should have just sent you a new BCG in exchange for the old one.

I wish they also changed the BCG , I am also half tempted to either sell or trade in the LMT and pick up a 6920. I am trying hard not to but My OCD gets the best of me sometimes. But My luck the colt will also have issues.

[sgalbra76]

If we are comparing DI AR-15s, then my optimal measure of reliability is that the weapon be able to fire 1000rds with defense/duty ammo under normal conditions without any stoppages and without any additional cleaning/lubing. Most well maintained Colts that I've used can do this.

It's hard to say what my standard would be when the ammo is crappy, and the environment is nasty. Then again, that really isn't the fault of the rifle so much as the fault of the ammo and your maintenance skills. If we were comparing different rifle designs(SCAR vs M4), then you could blame it on the rifle.

[Iraqgunz]

Until you have fixed all the issues I would wait before I render a verdict. Also remember that most weapons will have a small break in period. Lube the weapon, get some good ammo and fire it up.

[Belmont31R]

Sounds like you have lost confidence in the gun.




The stock LMT spring should be fine. A quality and in spec standard USGI recoil spring is JUST FINE. No need for any fancy springs.


An H-buffer is a good idea in a carbine. It will help the gun run a little smoother, and lower recoil a bit.


I give any new gun a 200rd freebie range. Some people think they should work right out of the box. Ive had more than 1 have a couple problems in the first 200 rounds and then work fine after that.

[dcollect]

You judge reliability in the brand name, how else??

:D

[ztf HITMAN]

Is this becoming a problem with LMT? I saw on another forum someone else having similar problems with an LMT...Man, I'm glad I went with BCM

[C4IGrant]

I received my LMT back from LMT see this thread for the back story
https://www.m4carbine.net/showthread.php?t=46166
I headed to the range this afternoon and out of 200 rounds I had 1 malfunction.
The malfunction happened in the first magazine and was similar to what was going on before LMT replaced my bolt. Except this time more of the round was showing and there was a big dent in the neck area of the round. I did not have my phone on me so I could not take a picture. I was shooting from a sandbag so it is possible I was putting pressure on the magazine and caused a miss feed. I was not paying that much attention.

Back to my original question since my rifle was bad out of the box this one malfunction is sort of bothering me. How many rounds before I can really trust the rifle? I have had a Stag and Colt 6920 previously and never had a problem with either of them granted I probably put less the 2000 rounds through each AR was I just lucky ? Do you guys think I am good to go and I am being too picky?


There are many things that can cause a malfunction in a gun (especially an AR) that have ZERO to do with the weapon itself.

Magazines are big culprit as is crappy ammo, poor lubrication and maintenance.


C4

[cyclesteel]

Magazines are big culprit as is crappy ammo, poor lubrication and maintenance.


C4

It was probably one of the above.. I emailed Gene again over at LMT and explained what happened. He assured me my ejector was definitely the issue and was fixed ( he replaced the bolt) He suggested it could have been ammo or the magazine. It could also have been break in. Prior to getting the gun back from LMT. I only put a little over 40 rounds through the rifle not including how many LMT used to test fire and check it out when I sent it in.

Thanks for all the input guys. I think I am just going to shoot the crap out of it and see what happens.

[spamsammich]

Is this becoming a problem with LMT? I saw on another forum someone else having similar problems with an LMT...Man, I'm glad I went with BCM

All manufacturers have QC issues at some point. Don't declare that the sky is falling just yet.