View Full Version : Testing reliability with low round count?
I've looked for a regimented procedure to test reliability but couldn't find such a thing.
Basic function testing I understand but I'm looking for a little more.
Lets say you want to use 100 rds to test your rifle. For that low round count, you should probably use whatever ammo you'd use for defense or hunting or whatever you plan to use.
Fire 100 rds from 3 1/3 30 rd mags and call it good? Or perhaps load 5 mags with 30 rds but only fire four rounds to test full mag operation? Then unload mags to only having 4 rds each then fire those? Is seems doing that you learn more with fewer rounds.
Is firing rapidly a required test? Firing with the rifle off your shoulder to see if it cycles? Put a few rounds through it with no lube? Inspect case ejection or marks? inspect fed bullets?
It would be cool for a battery of tests like this to be put together to at least say, "the rifle appears to be off to a good start". I'm sure it's been done but darn if I can find it.
Thats the kind of thing I'm looking for.
Not exactly what you had in mind, but the SOTAR tests and measurements are precisely for this purpose. Not a round fired either.
What kind of rifle is it? What ammo to you intend to shoot? What buffer came in it? Do you have different buffer weights to work with?
The quality of the gun will make a big difference here. As will the mags. I good gun, should be pretty good to go.
So I would take your ammo and load mags of two rounds. Find a safe way to shoot the gun into the ground pointing down, this is not 100% necasary but a good added extra. Luckily it’s December so cold is good for this test.
So fire 10 rounds. 5 msg of two each. Make sure it locks back on every empty mag.
Now keep changing to the next heaviest buffer and redo the test. When you get to a buffer weight were it fails to lock back on some mags go out the next lightest buffer back in.
If you get to an H3 and it still locks back it’s probably an over gassed gun. Keep the H3 in there and hope for the best. Maybe shoot crap ammo out of it.
Lastly if you have a bunch of ammo types tailed this test to the least powerful ammo you want the gun to feed reliably.
Out side of this test I think you have to wait for failures or odd wear and evaluate them on a case by case basis.
Personally I want 1000rnds through something before I feel like I know it’s temperament .
For an AR? I'd shoot a mag or two with 10 rounds in it and call it good if it cycles normally and locks back.
Thanks.
One vote for 20 rds and one for 1k. 😄😎
Really though the answers were helpful.
Each of the rifles I have are past the 150 rd mark already. (DEF-10, Mini-14 .223W) the DEF10 had one stoppage and that's because I let it get dry, firing 7.62 NATO ammo, and it came off my shoulder while walking at an angle, firing. I forgave it for that. That rifle is still only at about 300 rds maybe.
I just dont shoot rifles much and was looking for the easiest way to determine if they were GTG.
I feel like I need to fire them more with the JSP theyve only seen a mag or so of.
What if a certain defensive round has a 3% failure to feed rate in your gun and you've only fired 40 of them with no problems? You'd be trusting ammo that you shouldn't. That's my concern.
If you get to an H3 and it still locks back it’s probably an over gassed gun. Keep the H3 in there and hope for the best. Maybe shoot crap ammo out of it.
The H3 is about the same weight as an A5H1 and a rifle buffer. If an upper runs with a rifle buffer, is it over gassed? No.
I like to run a few single rounds loaded in the mag for lock back checks. Then I'll run a few mags with 3 rounds to check function and zero the sights. Once that's done, I load up a full 30 round mag and make sure all rounds feed smoothly. Then, it's off to the races!
Thanks.
One vote for 20 rds and one for 1k. ����
You can pretty much tell if a gun is running/cycling correctly in the beginning. More rounds than that and you're going to find out if there's a part that could break prematurely... that's highly unlikely on a decent brand gun.
The H3 is about the same weight as an A5H1 and a rifle buffer. If an upper runs with a rifle buffer, is it over gassed? No.
H3 carbine weight does not directly translate to the weights on A5 and Rifle because the different springs.
h2 on a carbine most closely matches a standard rifle or A5 system. Every upper should work correctly with the rifle buffer system.
I've looked for a regimented procedure to test reliability but couldn't find such a thing.
TOP 3-2-045 - Test Operations Procedure- Small Arms, Hand and Shoulder Weapons and Machine Guns, paragraph 4.3.
Shoot about 6,000 round and keep count of the number of Class I malfunctions (less than 10 seconds to clear), Class II malfunctions (more than 10 seconds, but clearable with issued equipment), Class III malfunctions (not clearable in the field) , and the number of broken parts.
Then you will have some good solid data on how reliable and durable your rifle was.
-OR-
You can just buy a rifle and magazines from a quality manufacturer, zero it and be done.
H3 carbine weight does not directly translate to the weights on A5 and Rifle because the different springs.
h2 on a carbine most closely matches a standard rifle or A5 system. Every upper should work correctly with the rifle buffer system.
I made a mistake in my previous post. The A5H2 is about the weight of a rifle buffer, not the A5H1. The A5H1 is about the weight of an H2 buffer.
In any case, I still disagree that a short barreled AR that will lock back on an H3 buffer is over gassed.
I do agree with you that every (5.56) upper from 10 inches to 20 inches should run with a rifle buffer system. They should also run with an A5H2.
My notes have the following buffer weights-
H2 4.6 oz
A5H1 4.56 oz
H3 5.5 oz
A5H2 5.33 oz
Rifle 5.2 oz
Thanks.
Regarding the buffer, I have Armalite DEF-10's that came with H3 buffers.
The only changes I've made is furniture, and a charging handle & trigger on one of them.
In any case, I still disagree that a short barreled AR that will lock back on an H3 buffer is over gassed.
It could be, I suppose. And believe me... I think EVERYTHING is over gassed. I don't think I have an H3 anymore, but I bet my 10.5 that's choked down with an insertable port would still run an H3 carbine set up. (just a guess)
It could be, I suppose. And believe me... I think EVERYTHING is over gassed.
Have you considered the possibility of being under buffered?
I don't think I have an H3 anymore, but I bet my 10.5 that's choked down with an insertable port would still run an H3 carbine set up. (just a guess)
I think we've discussed this before- I restricted the gas on an 11.5 upper until it ejected but didn't lock back, then opened the gas one click. The upper then ejected and locked back. The same setting gave full operation with an A5H2 and rifle buffer. It should operate with an H3.
If anyone has first hand experience with an upper operating with a rifle buffer but not an H3 and standard carbine spring, please share.
Without at least 500 rounds (fired in a proscribed manner with known quality ammo) I don’t think you can say much about a weapon’s projected reliability.
Take a class with said rifle. Pronounce it good or not depending on results.
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Try these, not exhaustive but it will give you a snapshot.
Chamber a round over an empty magazine and fire, verify lock back a few times.
Chamber a round over a mag with 1 round, fire, verify gun completes cycle of operations.
Mount gun loosely in shoulder pocket, fire a a few rounds.
Rest gun in hands, no mounting, fire a few rounds.
Try these, not exhaustive but it will give you a snapshot.
Chamber a round over an empty magazine and fire, verify lock back a few times.
Chamber a round over a mag with 1 round, fire, verify gun completes cycle of operations.
Mount gun loosely in shoulder pocket, fire a a few rounds.
Rest gun in hands, no mounting, fire a few rounds.Those are good checks, and I use them myself.
Afterwards(!) I would also verify that things work with a full mag: mag seats ok, and bolt strips first round ok.
Have you considered the possibility of being under buffered?
Never. I dial the gas to the correct buffer. I no longer dial the buffer to the wrong gas (with the exception of one 14.5 middy with an H buffer carbine)
I'm bitter at how badly "the industry" screwed us for years with shitily spec'd gas ports now that I've corrected several of them and seen how nicely the right gas works.
It could be, I suppose. And believe me... I think EVERYTHING is over gassed. I don't think I have an H3 anymore, but I bet my 10.5 that's choked down with an insertable port would still run an H3 carbine set up. (just a guess)
Does that include a 14.5 carbine with a 1/16" port? Or, a 16 inch middy with a .082 port?
I am of the opinion that most everything is undergassed. Tuned to just barely work at 0 to 25 C on level ground.
What ambient temperature range do you regularly shoot in?
Do you shoot at angles greater than -45 degrees?
Does that include a 14.5 carbine with a 1/16" port? Or, a 16 inch middy with a .082 port?
My 14.5 carbines are gassed pretty good. BCMs, etc... And I don't run cans on those as they're spec'd at, I believe, Mil port sizes. I ran a Bushy 14.5 carbine that definitely was over gassed.
For middies, yes, a .082 was too rich for me. The .076 (I think) that I have on my BCM 14.5 middy is a little lean. And as I mentioned above, I put an H buffer in that instead of the H2 carbine buffer.
We're in the AZ desert so we shoot between 40 and 115 degree temps. Not too much high angle shooting for safety reasons of knowing where the bullets are going.
Actually, lysander... if I was (for whatever reason) taking a 14.5 middy into adverse battle conditions... yes... I'd take the .080-.082 port for a little more aggressive bolt speed.
fedupflyer
12-14-21, 23:36
I guess it depends on what your definition of what low round count is.
Me, that is at least 1000 rnds for reliability and zero malfunctions.
We're in the AZ desert so we shoot between 40 and 115 degree temps. Not too much high angle shooting for safety reasons of knowing where the bullets are going.
Actually, it's the low angle shooting that will give problems.
A 0.078" port on a mid-length will not lock back when depressed below 45 degrees.
A 0.078" port on a mid-length will not lock back when depressed below 45 degrees.
Thats good to know. Didn’t Crane use a 0.076” port in the midlength vs carbine thing?
Thats good to know. Didn’t Crane use a 0.076” port in the midlength vs carbine thing?
I am not sure what they used.
And, let me qualify that statement with "reliably".
I am not sure what they used.
And, let me qualify that statement with "reliably".
That's interesting. I'd guess that there'd be lots of factors including ammo. Hot 5.56 might get more lock backs than .223 pressure ammo.
It seems like I hear more about midlengths being more finicky about ammo pressure than carbine or rifle length gas.
It seems like I hear more about midlengths being more finicky about ammo pressure than carbine or rifle length gas.
None of my middies are finicky with any good ammo, and I don't shoot 5.56 pressure ammo very often at all. The only troubles I've had years ago (and someone else here also observed) was some of the middy gas tubes would wear prematurely on the carrier end. The diameter would wear down to where a bunch of gas would bleed out and cause weak cycling.
When new, my 14.5 BCM middy would lock back with an H3 carbine buffer. When the gas tube wore down, it became very fussy.
ViperTwoSix
12-23-21, 21:35
For an “off to a good start” on a new build I like the following live fire test with both a PMag and a good quality aluminum mag:
.223 = something like PMC bronze or something else that is generally regarded as a lower power .223 load.
5.56 = full power or hotter 5.56 load like M855.
1 round .223 lock back test
1 round 5.56 lock back test
3 round .223 slow fire feed test
3 round 5.56 slow fire feed test
(Work towards zeroing sights with these 6 rounds)
5 round .223 rapid fire feed test
5 round 5.56 rapid fire feed test
(Work towards zeroing)
20 round .223 rapid fire
20 round 5.56 rapid fire
(As fast as I can while keeping rounds on target)
Total rounds using two types of mags = 116. Then I final zero with intended ammo. I also then check the rifle to ensure everything is still as it should be.
You could cut that round count in half by only using your intended magazine and intended ammo.
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