I’ve been perusing this fine forum for quite awhile and I’ve read most of the technical stickies. What I mean by extra power is something like a SpringCo blue spring. I’ve read the Tuning 101 and other discussions, but I didn’t see a clear (to me answer to this). So I’ll pose 3 questions.
How does one know when an extra power spring is necessary or preferable?
How does the spring tension interact with the BCG and buffer weight to impact the operation and performance of the rifle?
In what case would it be preferable to run a lighter carrier and buffer?
I hope these questions make sense to you guys, because it almost seems like an art to determine the best setup for each of my rifles and I want to understand what I’m doing as I tweak them.
It is really more theoretical. And it has been bugging me for a long time. I’m trying to understand the proper use for an extra power spring. IF there is one. How does it impact the operating system?
I could see the extra power spring being used incorrectly to offset over gassed systems, but what is the use of this spring?
Also, what is the purpose of lightweight carriers?
That’s why I put this in tech discussions. I was hoping the M4 Carbine Wizards could explain it fairly plainly.
I have my thoughts, but I would like to hear from someone knowledgeable.
What would be the most cost effective way to fix an overgassed carbine barrel? I’ve been using the Blue Springco spring and H2 buffer as a bandaid in my M&P15. Even with that in it, it feels like there’s gas to spare with shooting PMC Bronze, which is certainly no 5.56. I thought the idea was to use the heaviest spring/buffer setup your carbine will lock the bolt back on while shooting the weakest ammo you plan on using.
That’d sound advice for a properly ported barrel. Yours is over gassed.
If you want to stick with the carbine receiver extension, grab an H3 buffer. That gun wood run a Vltor A5H4 buffer with the std Vltor spring. If you don’t want to mess with the gas block by getting an adjustable one, the Vltor A5 system is the easy way to go.
Thanks, but I was trying to start what Clint called a “theoretical discussion” because I want to understand how an under or over powered spring affects the operating system.
I’ve seen a lot of discussion about the gas system, and the effect of various buffer weights on the operating system, but I’ve not seen a discussion on the effect of the spring rates on the system.
I dont consider a springco blue “extra power”. A real extra power spring is something a like a springco red, wolff extra power of a tubbs extra power. If anything a springco blue should be the STANDARD as it works with pretty much every setup run in a normal range.
Not enough to be meaningful. Possibly not enough to be measurable, unless it’s an absurdly heavy buffer spring. Slowing extraction is better achieved using additional buffer weight and/or an LMT enhanced carrier.
Or, better yet, curtailing the amount of gas in the system.
The point of reduced weight carriers is to reduce the reciprocating mass in order to reduce recoil and muzzle movement, goals valued in the competition community, hence Markem’s satin shirt comment. This is done as a system, not in isolation. Reducing the mass without reducing the gas via a smaller gas port or an adjustable gas block will not be as effective as in combination. Believe the springs are left alone, that is, stock. A major part of tuning is the muzzle device, which the OP did not ask about so will leave out.
Problem with reduced mass and gas is the operating spectrum is likely to be reduced, so reliability with cold weather or a very dirty firearm is likely to suffer.
Hope that helps.
hi there, been working through these things to understand the operating system myself.
i think the biggest reason people look at aftermarket springs is the chrome silicon aftermarkets make a much better spring steel, but are quick to corrode vs the standard stainless. the sprinco jobs use some trick coating and i take a handful of grease and run the spring through it as an extra measure. you get more cycles and less OAL shortening with a CS spring before rate degradation. this is helpful when tuning gas ports and cycling mass, your spring rate is not going to change in 2 or 3 thousand rounds like you would get with a stainless spring. if i am not mistaken, magpul has switched to a coated CS spring in their magazines.
a heavier spring will send the bolt into battery faster and theoretically be able to overcome more friction to complete it’s travel. i would guess this makes for more wear on the bolt in most cases, but should aid in reliability unless your cyclic speed is exceeding 600+ rpm. i think thats the sweet spot! (<600RPM)
a low mass system will never be as reliable regardless of proper gassing. it is my opinion that you want as much mass as you can get towards the face of the bolt.
One thing I didn’t see any touch on is bolt bounce. The heavier a buffer/spring, the less bolt bounce you should have (theoretically). The more mass you have to move, the more resistance there should be to accelerate the BCG. This goes for spring resistance as well. A heavier spring should provide more resistance to move the BCG when it slams forward into battery.
FWIW, my M&P carbine gas barrel with a Sprinco Green and an A5H4 cycled with 0 failures until it got hot. Then I would have regular FTE’s. Other than that, it was 100%. In general though, it was heavily over-gassed.
IMO, heavier springs/buffers are band-aid fixes for over-gassed carbines. The proper fix is to reduce the amount of gas. An adjustable gas block did A LOT more than any spring or buffer in my experience. The Sprinco Green was only for more life/reliability out of the spring.
I am interested in this. On the one hand I see how a stiffer spring would reduce the bounce GIVEN the speed of the bolt hitting the barrel extension. However, and this is the important part, a stiffer spring will make the bolt (and carrier) faster slam into the barrel extension harder than a softer spring.
I would guess that the harder the collision between bolt and extension, the more the bolt will rebound.
All in all, it seems to me (theoretically speaking) that these 2 pro’s and con’s of a stiffer spring would cancel each other out.
More resistance to the bolt bounce once it happens
More velocity, harder collision, more bolt bounce
I hope this makes sense. Does reality reflect what I just wrote? I am interested to know. I would love to see some kind of scientific, controlled experiment. Probably not too hard to do. Just need a high speed camera, an AR, and 2 springs of different stiffness.
I think there are two different benefits to the spring, and maybe you arent seeing both?
First, what do you mean by bolt bounce?
Initial thing affected: movement from BCG rearwards into the RE. Heavier buffer and stiffer spring used to compensate for over gassing. This slows the acceleration, and probable percieved recoil, of the BCG.
Second would be increased return of the BCG into battery due to the stiff spring re expanding. I would assume this ensures more reliable return to battery.
Any SMEs, feel free to let me know if I’m blowing hot air out of my keister.
No SME here, but suspect the solution to bolt bounce is not simply more mass as in heavier buffers for the sake of added mass but a smarter approach such a spring loaded weight such as is used in the A5 system, where a a slug inside the buffer is held back by a spring so it travels forward when the buffer stop it’s forward motion, thus actively countering the carrier bounce, without adding additional mass or using stronger springs.