308 Recoil system

[Cameron]

I purchased a PA10 in 308 this last fall.  It's the usual over gassed model.  After studying here, I toned it down with an adjustable gas block, heavier buffer and 50¢ behind the buffer spring.

It was almost perfect.  So I just added a Tubbs flat wire buffer spring.  Do I keep the quarters in there or can I leave them out?  My inner engineer says they are not needed anymore.

[98Z5V]

Measure the internal depth of the receiver extension, please.

[jtallen83]

2 hours ago, Cameron said:

Do I keep the quarters in there or can I leave them out?  My inner engineer says they are not needed anymore.

Quarters are to stop the carrier from hitting the receiver before it bottoms out and to keep it closer to the bolt catch so it is not slamming the catch hard. If you need them with a standard spring then you still need them with the Tubb's spring.

[Cameron]

7.75"

[survivalshop]

Quarters should never be needed in a properly set up AR Buffer system . the Tubb's 308 Flat Wire Spring will not need them in any length Buffer system .The Spring will work as designed in a Rifle or Carbine system , be it Ar 10 or DPMS .

 

 From his sight .

High Performance Tubb Precision Flatwire Buffer Spring for AR-10, SR-25 Rifles & Carbines. This Tubb Precision AR-10, SR-25 Flatwire Buffer Spring fits both carbine and standard length stocks.

Why should you use Tubb Precision Flatwire Buffer Springs?

-Extended life at optimum performance! Many conventional buffer springs are constructed from music wire or non post winding processed stainless steel. Their performance becomes suspect in as little as 500 rounds and can cause rifle performance to degrade to the point that rifle function will change. We fielded many questions from people complaining about "mystery malfunctions" when their rifles get past that round count , and we've found installation of a Tubb Precision Flatwire Buffer Spring cures nearly all of them, and it cures them for good.

-Tubb Precision Flatwire Buffer Springs are unique in the fact that their load and compression rates fluctuate significantly less than a standard buffer spring.

Standard buffer spring load
Bolt in battery: 7.2 lbs
Bolt locked open: 16.5 lbs

Standard buffer spring variation: 7.5 lbs
Tubb Precision Flatwire Buffer Spring
Bolt in battery: 11.1 lbs
Bolt locked open: 15.0 lbs

Tubb Precision Flatwire Buffer Spring variation: 3.9 lbs
The Tubb Precision Flatwire Buffer Spring provides a more positive lock up when the bolt is in battery while providing the user with a linear pull when locking the bolt back instead of the clunky progressive feel of a standard mil spec buffer spring

This is the last Buffer Spring you'll ever need for your 308 AR! Tubb Precision springs are duty rated for 500,000 compression cycles at maximum performance.

Enhanced rifle performance - Due to the superior nature of its material, Tubb Precision Flatwire Buffer Springs have the same power as conventionally constructed "extra power" springs, yet provide that extra energy using a lighter spring weight. Correct timing and resistance on the recoil stroke and a controlled rebound ensures reliable feeding with consistent forward thrust. The result is that the rifle functions flawlessly and stays on target better.

With the Tubb Precision Flatwire Buffer Spring, the bolt will remain locked a little longer, allowing pressures more time to subside. This means getting those heavy bullets to needed velocities can be more readily accomplished.

Tubb Precision Springs cure spring induced malfunctions for the life of the rifle.

Unaffected by temperature - Music wire and carbon steel springs are adversely affected by temperatures as low as only 175° F. TubbSprings perform flawlessly in excess of 700° F. Performance and function will not change during rapid fire conditions.

Perfect consistency - Tubb Precision Flatwire Buffer Springs are made to Stringent 9002 Quality Control Standards. Certified materials use, and our exclusive post-winding processing guarantees true, consistent performance. Conventional AR-10, SR-25 buffer springs are notorious for exhibiting wide variances in installed load height, compression and rebound performance, and even length.

Unless you're using Tubb Precision springs in your rifle, not only are you frequently replacing springs, but rifle performance may be continually changing with each replacement.

MADE IN THE USA

 

[jtallen83]

My Aero extension was too deep, required quarters even with the Tubb’s spring. 

[Armed Eye Doc]

It is dependent on having the proper length receiver extension with the proper  length buffer.   As @jtallen83 said, a RE that is too long with a standard spring will still be too long with a Tubbs.

[308kiwi]

3 hours ago, jtallen83 said:

Quarters are to stop the carrier from hitting the receiver before it bottoms out and to keep it closer to the bolt catch so it is not slamming the catch hard. If you need them with a standard spring then you still need them with the Tubb's spring.

^^^^^^^^^^^^^^what he said.

The quarters , effectively a spacer, are to compensate for a buffer tube that is too deep or a buffer that is  too short and also gives you the opportunity to tune the travel of the buffer so as to not hammer the living crap out of your bolt catch and/or to prevent the carrier contacting the lower.

Regardless of what spring you use, (assuming said spring doesn't go into coil bind in compression), the relationship of the buffer to the tube will not change so yes you should keep them in place.

[308kiwi]

 

[98Z5V]

2 hours ago, Cameron said:

7.75"

It should be 7 5/8" internal depth, and 7 3/4" internal depth is 1/8" too much. That's 0.1250".   One quarter is 0.069" thick.

You need both of them - but you better verify the length of your buffer - it must be 3.250" long.

Edited January 3, 2019 by 98Z5V

[98Z5V]

1 hour ago, survivalshop said:

Quarters should never be needed in a properly set up AR Buffer system .

Well, that would be the key point here.  "Properly set up AR buffer system" is not what he's working with.

[Cameron]

Buffer length verified at 3.250

[98Z5V]

You're gonna need those two quarters, then.  No more, no less, to make that out-of-spec receiver extension work.  Keep 'em in there. 

[DNP]

....and on the bright side, someday when the zombies attack....you'll have change for a candy bar when you stumble across a vending machine. 

[survivalshop]

On 1/2/2019 at 9:05 PM, 98Z5V said:

Well, that would be the key point here.  "Properly set up AR buffer system" is not what he's working with.

Exactly , many out of spec components being made , be it for the Armalite system (copies ) or the 308 AR systems using out of spec AR 15 Receiver Extensions  , you need the correct components for the system to work . 

Has the OP tried the system with out the spacer Quarters ?  Was the BC hitting the Lower Receiver ? I didn't read that ins post .  There are too many factors involved to say what happened in one Rifle to another , we are talking about 308AR's .

 I also want to see a photo of the Receiver Extension in the Lower Receiver, does it have the anti tilt type Receiver Extension , measurement could be a little different . 3/4 " is a lot though.

Thats also a DPMS type Buffer length & I don't believe that Buffer will ever hit the end of the Extension Tube , with a Tubb"s FW Spring in there , with or with out the Spacer quarters, the Tubb's spring is about a 1/4" longer when completely compressed , so the spring would be the stop , not the bottom of the Receiver Extension  . The BC may hit the Threaded area of the Lower Receiver , but thats not because the Spring is not stoping the Buffer , it's because the Receiver Extension is too deep or an odd fitment Or the Lower Receiver is not made correctly , we have seen that before .

 

[98Z5V]

13 minutes ago, survivalshop said:

Exactly , many out of spec components being made , be it for the Armalite system (copies ) or the 308 AR systems using out of spec AR 15 Receiver Extensions  , you need the correct components for the system to work . 

Has the OP tried the system with out the spacer Quarters ?  Was the BC hitting the Lower Receiver ? I didn't read that ins post .  There are too many factors involved to say what happened in one Rifle to another , we are talking about 308AR's .

 I also want to see a photo of the Receiver Extension in the Lower Receiver, does it have the anti tilt type Receiver Extension , measurement could be a little different . 3/4 " is a lot though.

Thats also a DPMS type Buffer length & I don't believe that Buffer will ever hit the end of the Extension Tube , with a Tubb"s FW Spring in there , with or with out the Spacer quarters, the Tubb's spring is about a 1/4" longer when completely compressed , so the spring would be the stop , not the bottom of the Receiver Extension  . The BC may hit the Threaded area of the Lower Receiver , but thats not because the Spring is not stoping the Buffer , it's because the Receiver Extension is too deep or an odd fitment Or the Lower Receiver is not made correctly , we have seen that before .

 

^^^  This right here is why I recommend real Armalite AR-10 Carbine recoil system parts.  What you stated just proved my point for me, brother. 

You always measure a receiver extension at the top of the receiver extension - so if there is a flare at the bottom to help retain the buffer retainer, that doesn't count for internal depth.  I've stated this exact thing before here, numerous times.

1/4" is 0.250" - if a receiver extension is 1/4" too long, I can guarantee you that the BCG will hit the ears on the lower receiver, and start tearing up parts.

[Cameron]

Thank you all for your help and input.  I'm considering my next move.

 

[98Z5V]

^^^   SEE?!!?  See those marks on the ears of your lower?  That's damn sure not 0.250" of impact right there.  0.250"worth if impact would have been WAY WORSE on your lower, for sure.

You seeing this @survivalshop?

That receiver extension if flared at the bottom, too, to better hold the buffer retainer - that's why we don't measure at the bottom of the receiver extension, and only at the top...

There's also no way that receiver extension can go in another turn, either - which has been a problem in the past - one more turn, into the proper position, can stop impact damage - that's not the case here.  I've documented cases of it before.

[survivalshop]

Oh , now I see this has an ongoing thread about this & it snot mentioned in this one ? geez !?

[98Z5V]

21 hours ago, 98Z5V said:

There's also no way that receiver extension can go in another turn, either - which has been a problem in the past - one more turn, into the proper position, can stop impact damage - that's not the case here.  I've documented cases of it before.

 

2 hours ago, survivalshop said:

Oh , now I see this has an ongoing thread about this & it snot mentioned in this one ? geez !?

Not for this guy - it's been about a year ago that someone needed to turn their receiver extension in another turn...   But, it has come up in the past, and it's something I always watch for and ask for pics of - just to see...  

[Cameron]

I shot five rounds yesterday without the two quarters in the receiver extension.   The buffer was still nicking the ears of the receiver.  The buffer was still being marked by the retainer pin.

Cleaned and repainted the buffer head and the receiver ear marks last night.

Five shots today with two quarters in.  No new carrier marks on the ears of the receiver.  Still slight marks on the buffer head from the retainer pin.

One thing I failed to state in my first post was the gas tube is the typical PSA short tube.  Approximately 1/4" .

[98Z5V]

19 minutes ago, Cameron said:

  Still slight marks on the buffer head from the retainer pin.

As far as we've been able to trace down - that's an upper receiver dimensional issue.  As of right now, there is no cure for it.  The Tubb Carrier Weight System used to cure this very thing, but that product is discontinued.  

When you close your receivers, the back of the BCG should push the buffer off the buffer retainer, right when those receivers close.  The buffer should never, ever touch the buffer retainer when the receivers are closed, and due to that, it will never contact the retainer during cycling. The only time the retainer "stops" the buffer, is when you open the receivers.

The Tubb CWS added 0.080" to the back of the BCG body - thus, eliminating this issue.

 

[Cameron]

Fortunately the marks on the buffer face are much less.  Only marking the paint I added to see new the marks.  Originally the buffer face had hash marks into the aluminum.

[Cameron]

Well the simple answer is to weld a quarter onto the back of the BCG.  lol

[jtallen83]

25 minutes ago, 98Z5V said:

As of right now, there is no cure for it.

Wouldn't the offset buffer retainer handle the issue?

http://commonbullets.com/wp/archives/1727

https://truenortharms.com/ar15_default_store_view/offset-buffer-retainer.html