M4 Buffer spring length

[r2nailer]

Does a collapsible stock use a shorter spring than a pinned stock?
I'm having trouble determining the correct length
buffer spring for my M4.
I have 3 different length springs.

 

[jasons]

Does a collapsible stock use a shorter spring than a pinned stock?
I'm having trouble determining the correct length
buffer spring for my M4.
I have 3 different length springs.

As I recall they should be about 11 inches, give or take a 1/4. If it's shorter than about 10 1/2 or so it may be worn.

EDIT: From the technical manual:

CARBINE ONLY: Free length should be 10 1/16 in. (25.56 cm) minimum to 11 1/4 in. (28.58 cm) maximum.

 

[r2nailer]

The real problem is the bolt not striping off the next round.
It appears it doesn't retract enough after firing the previous round.
Using the charging handle works fine

 

[jasons]

Jeeze, there seem to be a lot of these recently.

What ammo are you using? If it's not the buffer or buffer spring it could be weak ammo or a gas issue.

 

[r2nailer]

milsurp and some green tip LC stuff

 

[jasons]

milsurp and some green tip LC stuff

OK, then gas system stuff. How old is the rifle (round count) and when did it start acting up? If its pretty old and started acting up slowly over time I'd look at the gas rings for excessive wear. If its new or just suddenly started acting up I'd probably start with the front sight base / gas block.


Just to eliminate the buffer stuff, how long is your buffer spring and which buffer are you using? (weigh it if you have a scale handy.)

 

[r2nailer]

I guess it started when I had 2 M4's apart for stock replacement.
One had an A2 stock, and one had a pinned stock. And I upgraded
them to non pinned.

 

[jasons]

I guess it started when I had 2 M4's apart for stock replacement.
One had an A2 stock, and one had a pinned stock. And I upgraded
them to non pinned.

OK, so back to the buffer.

Both are acting up or just one? You've verified that you're using M4 springs and buffers in both? (There is a difference.) Does the buffer travel smoothly in the buffer tube without any binding of the spring or anything like that? Are you sure the spring is properly seated over the buffer?

Pictures and specs (length, weight) would be helpful.

 

[r2nailer]

That was my first question. difference in springs?
Hey, your avatar, is that a Hawk?

 

[jasons]

That was my first question. difference in springs?
Hey, your avatar, is that a Hawk?

Yes, there's a difference in both springs and buffers. The M4 has an 11" spring (give or take) and the M16 has a 13" spring (give or take.)

Free length for rifle should be 11 3/4 inches (29.85 cm) minimum to13 1/2 inches (34.29 cm) maximum. Free length for carbine should be 10 1/16 inches (25.56 cm) minimum to 11 1/4 inches (28.58 cm) maximum. Do not attempt to adjust spring length.

The buffers are also different.

Carbine buffer:

Rifle buffer:

(Note that carbine buffers also have different weights.)


And yep, that's a HAWK. I was in 1st LAAM Bn back in the day. (Approximately 96-99.)

 

[r2nailer]

ok ill take a closer look tonight, tks.


I was 2/59 ADA Schwabach DDR (Germany), '76-'79
Vulcan aka Puff

 

[widnerkj]

I work in weymouth, and live in east bridgewater. I'd be willing to look at it for you. (and I think I have an extra carbine buffer spring, not positive, but I think I do)

 

[r2nailer]

perhaps I could convince you to come to my house in weymouth......

 

[widnerkj]

I'll be walking out of the office at 5:00 PM inbound

 

[r2nailer]

I did find a long spring and buffer in one of my M4's.
I'll get to the range this weekend to figure it all out.
Thanks for all the help.
Steve

 

[14paul]

The spring shouldn't be the problem. If you are using a rifle lenght buffer in a standard carbine buffer tube (like the ones for multi position stocks) you will have problems. The carbine style tube is shorter than the one that is on the fixed telescoping style/looking stock. Sounds like you need to just change to a carbine buffer.

If you can take a picture of both buffers & post it here.

 

[bpm990d]

Heavybuffers.com has a great reference chart with weight/sizes/lengths.

http://www.heavybuffers.com/reference.html

B

 

[stinx]

R2 the easiest way to check for a gas system issue is to do the following: Load 5-6 magazines with one round each. Fire each magazine,the bolt should lock open on each mag every time. IF the bolt doesnt,most likely you have an issue with the gas system.