View Full Version : Which SR15 E3 extractor spring to replace?
After a good five years of running flawlessly my KAC SR15 E3 is finally having issues. I've been getting failure to eject problems. The bolt will not eject the spent case, and it'll try to feed the next cartridge; resulting in a jam. I suspect it may be the extractor springs. My question is: How do I know which one to replace? Is there a more effective way than replacing each spring at a time?
Additionally, I was on Operation Parts and noticed that they have Heavy Extractor Springs for the SR15 bolts. When would heavy springs be applicable? Are they meant for a specific type of ammo?
steyrman13
12-02-15, 16:37
If one is worn out then the other is probably not far behind. Replace them all at once.
turnburglar
12-02-15, 17:00
Id do all the PM at the same time. Extractor, extractor springs, buffer spring, ect. Springs are so cheap you'd waste more in ammo trying to chase the problem.
Last I knew, they came in a set when purchased. I can think of ZERO reason to replace one and not the other.
I think TB has a great point that it may be worth it just to replace everything. That way you know everything is GTG and you don't have to wonder any more.
If one is worn out then the other is probably not far behind. Replace them all at once.
Id do all the PM at the same time. Extractor, extractor springs, buffer spring, ect. Springs are so cheap you'd waste more in ammo trying to chase the problem.
Last I knew, they came in a set when purchased. I can think of ZERO reason to replace one and not the other.
I think TB has a great point that it may be worth it just to replace everything. That way you know everything is GTG and you don't have to wonder any more.
I didn't think of it that way. Pretty logical and makes sense. I will be replacing both at the same time.
What about the heavy extractor springs for the SR15 bolt? What are the advantages and disadvantages of those? Are they made for a specific type of ammo load??
The KAC E3 field repair kit comes with most all of the common parts to replace in time. The extractor springs are color coded. I would tend to lean towards the higher tension in 11.5" in use for some. For the longer guns, the extractor spring tension can depend on what the end use actually is. More extraction tension could be preferred than others, what is the serious use ammo? Going with more tension without need can induce other issues.
I would tend to use a system with less issues than others.
The ejector spring is a normal Colt spring.
I'd replace the extractor and buffer springs, along with the gas rings.
SeriousStudent
12-02-15, 21:01
Have you had a chance to call or email KAC, and pick their brains? I bet they might be able to offer some solid advice.
You may also want to reach out to one of the mods/IP's here, Failure2Stop. He works for KAC.
Hope that helps.
Failure2Stop
12-02-15, 22:20
Failure to eject will not come from worn extractor springs.
Recommend replacement of the ejector spring.
Standard parts will work, recommend a high quality spring.
Feel free to contact me directly if I can be of assistance.
From Tapatalk:
Jack Leuba
Knight's Armament Company: Military/Govt Product Liaison
F2S Consulting: Director of Shooting Stuff
What is the round count?
Man, wish I knew. Lost count a long time ago. If I had to guess, it'd be somewhere between 3000-5000 rounds.
Failure to eject will not come from worn extractor springs.
Recommend replacement of the ejector spring.
Standard parts will work, recommend a high quality spring.
Feel free to contact me directly if I can be of assistance.
Okay, I will try the ejector spring first. Thanks
Man, wish I knew. Lost count a long time ago. If I had to guess, it'd be somewhere between 3000-5000 rounds.
With the E3 bolt design, I have a hard time believing the dual extractor springs are even remotely worn. Even the ejector spring should be fine too.
Have you inserted a cartridge, by hand into the bolt to test the functioning of the ejector? Insert cartridge rim under extractor, and rock the cartridge into the bolt to compress the ejector, so that the bolt and cartridge are in alignment. Do it a few times and see how it feels. I should have strong, smooth tension. If there is resistance or doesn't feel right, your problem could simply be a brass shaving or some debris restricting it's movement. I would try disassembling the ejector, cleaning it real well and re-assembling.
Failure to eject will not come from worn extractor springs.
Recommend replacement of the ejector spring.
Standard parts will work, recommend a high quality spring.
Feel free to contact me directly if I can be of assistance.
From Tapatalk:
Jack Leuba
Knight's Armament Company: Military/Govt Product Liaison
F2S Consulting: Director of Shooting Stuff
This.^^
Ejector Springs are the same as Safety Selector springs. They are cheap. Just remember to source a new roll pin and the ejector removal tool from Young Manufacturing is a gift from God. if you need a good spring and roll pin, feel free to contact me at work this week.
bigjack7440
12-03-15, 08:49
I've got over 9000 rounds on a sr-15 MOD2 E3 and hardly ever clean anything . I went 5000 round before I even looked at the bolt (E3) and even then didn't clean it. With that said I've only ran Brass . After watching those guys go 20K+ and never EVER cleaned it I can't imagine why the bolt would need anything but KAC can't get 100% EVERY TIME
I'd look at other things like brass shavings ect and give it a good cleaning . I only just this week field stripped my Mod2 and whipped the bolt off and used a little froglube . Not trying to run it 20k and pour sand in it like the guys at ballistic radio http://youtu.be/UvPmJYcgBSo
But I do what to see how tuff this sob is.
Good luck
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My cell'y
What the other two said about the ejector. The only way an extractor spring prevents ejection is by not pulling the case from the chamber. If the case clears the chamber you have a bad ejector spring which is causing your ejection issues.
There was a thread on TOS about some of these uppers having weak ejector springs.
I use two Mod 1 uppers that show signs of it.
Replace the spring with a Colt and see what it does.
I'll swap mine this weekend and report back....
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