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M014 vs. M4S90 Recoil Spring Question.


Unobtanium

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I have an M1014.

I ordered an "M4S90/Common Parts" recoil spring from Brownells. It is the only one they offer for the M4.

 

I measured the new spring against my M1014 spring (has had a few rounds through it by now). Surprise. My M1014 spring is still noticeably longer. It has 64 coils while the one from Brownells has 65.

 

Further, I mic'ed the diameter. M1014=0.47", M4=0.45".

 

My M1014 cycles loads as light as 2.75 dram. However, based on posts I have read, the M1014 is historically the most finicky, and indeed my M1014 did eject light loads rather weakly when I first got it, although it never had any failures.

 

If anyone has a micrometer or is curious, I would be interested to see how your M1014 or M4S90 spring OEM compares. It will be a good chance for you to clean and lubricate the tube. I recommend TW25B for this process. Less friction in the recoil tube= better reliability, especially with light loads.

 

I also noted that my recoil "buffer" is chrome-plated. I don't remember if the M4S90s I had were or not.

 

aa7mo5.jpg

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Where did you find that spring on Brownells? I've been looking for those for a while. It doesn't show up as a stocked part in the schematics.

 

In my 11703, I replaced the spring with a 11707 spring and noticed the difference in spring length as well. I had assumed that the spring had just taken a set since it had about 10,000 rounds on it at that time. By then, the action was extremely sluggish, the weak spring failed to return the bolt to battery on weak loads quite often.

 

When I transitioned to a new 11707 receiver extension, it came equipped with a newer production plunger and spring as well. The action cycled with authority and returned the bolt to battery much faster than the original. Perhaps this was a 'feature' of the crappy four port barrels?

 

This extension should be disassembled and cleaned periodically. A lot of crap builds up in there. Sometimes finding the right tool to remove the stock mounting screw can be a real pain though.

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Where did you find that spring on Brownells? I've been looking for those for a while. It doesn't show up as a stocked part in the schematics.

 

In my 11703, I replaced the spring with a 11707 spring and noticed the difference in spring length as well. I had assumed that the spring had just taken a set since it had about 10,000 rounds on it at that time. By then, the action was extremely sluggish, the weak spring failed to return the bolt to battery on weak loads quite often.

 

When I transitioned to a new 11707 receiver extension, it came equipped with a newer production plunger and spring as well. The action cycled with authority and returned the bolt to battery much faster than the original. Perhaps this was a 'feature' of the crappy four port barrels?

 

This extension should be disassembled and cleaned periodically. A lot of crap builds up in there. Sometimes finding the right tool to remove the stock mounting screw can be a real pain though.

 

The small spring is from Brownells. Are you saying your 11703 spring was smaller yet?

http://www.brownells.com/.aspx/pid=6248/Product/RECOIL-SPRING-STANDARD-AFTER-S-N-M293830

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  • 2 years later...

Hate to drag this up, but I found a legit source for M1014 springs. The mic'ed 0.045", but I had since re-calibrated my calipers, and re-measured that same Brownell's spring, and it mic'ed 0.043". They are a hair over 19" in length (keep in mind, I had a few hundred rounds on my M1014 spring when I measured it, and these are new in the box), and have a phosphate type finish. Sadly...my source is currently sold out. I'll re-post when they come back in stock, but just wanted this on a few people's radar.

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willy_nilly.gifI bought several of the M1014 receiver extensions (non-collapsing, because of California) with the original spring and assembly inside; never knew there was something special about them except that it was a little longer.

 

Would you mind measuring one to verify?

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