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Discussion Starter #1
Quick question for some of the forum members with unfired or lightly used ACR's;

What is the length of you gas piston spring?

Trying to figure out if after 4200 rounds the spring has lost some of it's ommph.

:cool:
 

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Discussion Starter #3
3 and 7/16 of an inch.
Thanks for the quick reply, mine is only 3 5/16.

That might explain some things. Since around 3000 rounds my ejection pattern for XM193 has been getting erratic. Looks like I might have some spring set.

If more replies show springs more your length, I might just have to get a new spring.



ETA: My rifle is running fine, just trying to diagnose the change I am witnessing. (learning the platform)
 

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The used ACR has the same spring length as yours and all seems well with it.
 

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Discussion Starter #5
The used ACR has the same spring length as yours and all seems well with it.
Hmmmm, that might just blow my theory outta the water then.

Hopeful to get some more responses for a comparison.

Thanks again!
 

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Maybe some slight differences in this batch of ammo over the last batch?
 

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Discussion Starter #7
It's been different lot numbers. but maybe they changed something. I'm going to pickup some other 5.56 stuff and experiment.
 

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Discussion Starter #8
Anyone else been able to measure their piston spring length?

Just trying to eliminate all varibles before I call BFI and "try" and discuss the issue with them.

TIA
 

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my 10.5" acr's spring was mashed into/wrapped around the piston so it doesnt come out but still functions, i know it wasnt my sbr conversion that started it bc i had problems inserting the spring through the gas block before i did my conversion
 

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According to the calipers it is 3.441 inches. My acr is pretty new too so less than 20 rounds through it so far.

Sent from my Xoom using Tapatalk
 

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Discussion Starter #11
my 10.5" acr's spring was mashed into/wrapped around the piston so it doesnt come out but still functions, i know it wasnt my sbr conversion that started it bc i had problems inserting the spring through the gas block before i did my conversion
Ouch, thats not good...

Thanks for trying tho :cool:
 

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Bigdog, I'd look into that one. Or at least keep an eye on it. I've not had that problem. I can't currently get to my ACR to measure right now, but I haven't noticed any change.
 

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Discussion Starter #13
Bigdog, I'd look into that one. Or at least keep an eye on it. I've not had that problem. I can't currently get to my ACR to measure right now, but I haven't noticed any change.
Maybe next time you clean it, I would appreciate it.
 

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Maybe next time you clean it, I would appreciate it.
I'll do my best. I don't have calipers, but I work with what I have.
 

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Discussion Starter #15
I'll do my best. I don't have calipers, but I work with what I have.
Thanks, just laying on a ruler would be fine. Doesn't have to be that exact.
 

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Discussion Starter #18
Wow, such a difference between rifles,

I have seen 3 3/8, 3 1/4, 3 5/16, 3 7/16, watta mess, no consistancy. (interesting tho)

Thanks for the responses, keep 'em comming please
 

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Discussion Starter #20
Well, I guess I can throw the "spring set" theory out the window...........................:confused:
 
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