Recently a friend of mine was having issues…we thought we traced it to the action spring so I pulled mine and loaned it to him since he had a class coming up and needed a functional gun. I stuck his weakened and slightly short spring in my gun in the meantime. It measures 10 1/8". I have a bunch of known quality good action springs coming and will replace it soon.
A day or two later I went to the range and as I was firing from the prone and the rifle was occasionally failing to eject. Spent cartridge was completely extracted from the chamber, but did not leave the action before the next round began to feed causing what would otherwise look like a double feed.
When I got home I oiled the ejector and cleaned the rifle real well, as soon as I get these action springs in I will return and try again.
So I suppose the question is can the action spring have an effect on proper ejection? Is it simply coincidence that my problems cropped up that shortly after putting a possibly weak action spring in? Other known causes of failures to eject?
The upper/bcg are top quality and this one is rather new. Ejector doesn’t seem sluggish, extractor is sharp and springs/insert are new.
Yes it can cause function issues. Which is why they are supposed to be measured as part of the inspection process. Carbine springs are supposed to measure between 10 1/16 and 11 1/4 inches. So you are right on the border. I replace them at around 10 1/4.
My experience is that a brand new buffer spring really only last a couple thousand rounds before it gets in that 10 1/2 or 10 1/4 area. They really don’t last very long. I think we have a tendency of putting up with the buffer springs past their useful life.
In my Noveskes’ and others that will handle them, I use the Sprinco Blue spring with worry free shooting.
OK thanks alot… and yeah the carbine spring does make sense as it’s same length receiver extension - hey i’ve been up all nite so my mind is a bit slow.
Only if it is preventing the bolt group from traveling its full range. This apparently isn’t the case as you stated above that the bolt group was stripping a new round from the magazine with out ejecting the spent cartridge case. The battle buddies (extractor/ejector) are the culprit here.
Don’t let top quality or new fool you. Every manufacturer at one time or another has released a bad part from go (except Colt :dirol:). If the bolt group is traveling its full range of motion, your next step is to install a known good bolt assembly and head back to the range.
I recognize that, I thought the title of the thread would indicate that. It “looked” like a double feed, with the exception that one of the cartridges had no bullet or powder.
My springs should be here today or tomorrow, I’ll be off to the range with a new one in the gun and a spare LMT or BCM bcg.
Good topic. I have never payed attention to the buffer spring length. I just measured three of mine in three different lowers.
Factory LMT lower with 14.5 colt upper and H Buffer with 2000rounds on it (mild suppressor use): Spring length 10 3/4
Factory LMT lower with 12.5 BCM upper and mix of H buffer and H2 buffer and 2500 rounds (some mild suppressor use): Spring length 10 1/4
Noveske Lower with 16" midlenth and standard car buffer with BCM stock kit and spring aprox 100 rouns (all suppressed): Spring 11 1/4
My 12.5 SBR has been feeling “slugish” on the trigger, almost like I’m faster than the trigger and ready to fire another round before the trigger resests, could this be the buffer spring causing this? I notice it more when shooting anemic 223 and not as bad when shooting m193. Function has been 100% and copious amounts of slip 2000 is used. It has been cleaned etc…
Also, for you AR armorers out there that manage dept guns etc…is there a log you can share that you use to track the history of the guns…some sort of chart that shows rounds fired, BCG replacement, and other maintance issues? I understand if you can’t share it just curious.
I assume that you are going to replace the ejector spring. If so, I highly recommend that you do not reuse the roll pin that is used to secure it. Also, you may want a second set of hands unless you have an ejector removal tool.
Not an armorer, but your 12.5 SBR’s action spring is on the shorter side of the recommended length for a carbine-length receiver extension. I forgot where I read it (it was here, I know that much), but the minimal length for an action spring in a carbine-length receiver extension is 10.0625 (10 1/16) inches. I would replace that action spring.
I wasn’t, but you have me wondering if I should. I was going to put in a new action spring and see if it went away. If I need to change the ejector spring I’ll will go ahead and buy the tool, do it properly, and be set up next time.
Grant has the parts listed…I wonder if an envelope is a shipping method…
I assumed you read MK18’s post. What you are describing sounds like an ejector issue. Either that or there is a ton of shit in there, or the spring is worn. When you depress it, it should be stiff.
It’s stiff, or at least it feels as stiff as my other rifles. Holding the bcg vertically in my hands at chest height, it’ll throw an empty piece of brass about two paces(I’m 5’9’'.) It’s possible that I hadn’t put a drop of lube on the bolt face and worked the ejector in a long time. I suppose I misread your reply earlier.
Try the action spring first, since it’s already on order. If that doesn’t work then have the ejector spring on stand by. BTW- It’s the same spring as the selector lever so if you have one then you are already GTG.
Will do, and I do have some on hand…I did not know that. I may still order some because I’ll still need a roll pin, they’re cheap, and I’m trying to finally get a spares box going.
