Buffer tubes and springs.

[1986s4]

I am trying to finalize my first build from stripped lower. So far a LMT lower with a Colt LPK and Mag pull grip. Just need the buffer tube, buffer and spring. My question is mostly about buffer tubes and one spring question.
A tube made of 7075 aluminum, mil-spec dimensions is my minimum. Is there an appreciable difference in quality in these tubes beyond those specs? Does one need Colt, LMT, BCM, Geissele tubes? If there is I'll just save up and get the better part. I decided before I started that this would be a simple but high quality build. Which is why I got the lower first last year and waited until recently for a good price on a LPK. Which leads to my next question; a Geissele multiple stranded buffer spring. Is the juice worth the squeeze for one of these?
Thanks in advance.

[GH41]

I am trying to finalize my first build from stripped lower. So far a LMT lower with a Colt LPK and Mag pull grip. Just need the buffer tube, buffer and spring. My question is mostly about buffer tubes and one spring question.
A tube made of 7075 aluminum, mil-spec dimensions is my minimum. Is there an appreciable difference in quality in these tubes beyond those specs? Does one need Colt, LMT, BCM, Geissele tubes? If there is I'll just save up and get the better part. I decided before I started that this would be a simple but high quality build. Which is why I got the lower first last year and waited until recently for a good price on a LPK. Which leads to my next question; a Geissele multiple stranded buffer spring. Is the juice worth the squeeze for one of these?
Thanks in advance.

You are a perfect candidate for the A5 system.

[1986s4]

I am rather unfamiliar with the A5 system. What advantages does it hold?

[1986s4]

I should add that my upper has a Colt 14.5 SOCOM barrel with Colt BCG.

[titsonritz]

You are a perfect candidate for the A5 system.

My thought as well, I'm not going to change out anymore carbine RE but I won't do anymore builds without an A5.


I am rather unfamiliar with the A5 system. What advantages does it hold?

The A5 is a buffer system consisting a receiver extension 3/4" longer than a standard carbine tube, a proprietary buffer by Vltor and rifle length action spring. There are multiple threads on the subject, the search button is your friend.


Start here:
https://www.m4carbine.net/showthread.php?207340-Buffer-question&p=2632292#post2632292

[GH41]

My thought as well, I'm not going to change out anymore carbine RE but I won't do anymore builds without an A5.



The A5 is a buffer system consisting a receiver extension 3/4" longer than a standard carbine tube, a proprietary buffer by Vltor and rifle length action spring. There are multiple threads on the subject, the search button is your friend.


Start here:
https://www.m4carbine.net/showthread.php?207340-Buffer-question&p=2632292#post2632292

With you. I won't change anything that is working but won't start from scratch without the A5.

[26 Inf]

1986s4: As the last couple of guys have alluded to, if you are building from scratch, it isn't a bad idea to go with the A5 extension tube tube and buffer. In essence it is a rifle buffer system on a carbine.

It uses an intermediate receiver extension/buffer tube which is longer than a carbine tube and slightly shorter than a rifle tube. The spring is a rifle length spring and the buffer is specially made to fit the system, in essence it is a short rifle buffer. Most folks say the a5 system smooths out recoil impulse, removing whatever snap there is to the recoil of the carbine. Because of the slightly larger buffer length, the buffers can be made heavier than carbine buffers. That, compared with the addition length of the rifle spring, can be a big deal when shooting suppressed, or, if you simply have an over-gassed rifle.

There have been several information threads on here, just search 'A5.'

You can get the kit from Vltor, the originator, but they are almost always out of stock. The BCM kit is less expensive, and generally in stock:

https://www.bravocompanyusa.com/BCM-Intermediate-Buffer-System-A5-Kit-p/bcm-intermediate-shk.htm $99.50

The BCM kit comes with the A5H0 buffer, which weights 3.8 oz. Which is the equivalent of a carbine system H buffer (the H buffers are often also called H1 buffers). It is a good starting point for most projects.

[AndyLate]

The BCM kit frustrates me (I still bought one) because it includes the A5H0 buffer, not the A5H2 buffer the system was designed around. I really wish that BCM would offer a choice of buffers with the A5 kit, just like they do (did?) with the carbine RE kit.

To answer the original question; if you are buying a carbine spec receiver extension you should get one from any of the companies you listed, and I would add Sionics to the list.

I bought a cheaper RE before I learned better and the inside looks like it was machined with a broken bit by someone coming off a seven day bender. The manufacturer assured me it was fine and it would "wear in". Kinda sounds like "That will buff right out".

LMT's RE has a grayish dry film lubricant on the outside, but I don't understand why that is advantageous.

Some of the REs offer more positions than the original 4, but again I don't see a practical difference. I really only use a couple of positions - your requirements may be different than mine.

[17K]

LMT tubes are my favorite.

Six position, drain holes, a lip to hold the buffer retainer. Their castle nuts have round notches to work better with staking with a punch.

A standard spring and H2 buffer would be my choice with that barrel.

[everready73]

If you dont go with A5 system quality buffer tubes are not really that expensive. BCM can be had for under $40. They sale the kit (RE, buffer, spring) for $58 but you would be wasting the carbine buffer as you should be running an h/h2(h2 IMO). I would buy the parts separate after you determine buffer to use. Primary Arms has had the LMT tubes on sale before so might want to check with them. Sionics and Sons of Liberty have quality tubes that are under $40 as well.

I would just go with a standard carbine spring from a reputable company. G&R tactical has the BCM carbine spring for $5, the tube for $37, and you would just need to buy h2 buffer for around $25 depending on where you get it. Thats under $70 for a quality set up. Aero would be the cheapest i would go. Spicetac has the kit for $30 that includes everything i believe. The tubes are usually $20 or so by themselves

[1986s4]

My thought as well, I'm not going to change out anymore carbine RE but I won't do anymore builds without an A5.



The A5 is a buffer system consisting a receiver extension 3/4" longer than a standard carbine tube, a proprietary buffer by Vltor and rifle length action spring. There are multiple threads on the subject, the search button is your friend.


Start here:
https://www.m4carbine.net/showthread.php?207340-Buffer-question&p=2632292#post2632292

I have since done some research on the A5 system and it seems good. If I go with a standard recoil system the advice here seems to be and H or H2 buffer with my Colt 14.5 SOCOM barrel.
Thanks to all for your advice.
Regards, 1986s4