Recoil Spring Buffer Idea

[Jim in Texas]

I have long been taught that:

1.         a properly-sized recoil spring will prevent a recoiling bolt from striking the back of the receiver;

2.         if you want to use ammunition with a higher recoil impulse, you should also change the recoil spring to match that new ammo;

3.         as a recoil spring wears, you should replace it before it allows the bolt to strike the receiver.

In the real world, people may change ammo without realizing that it has a different recoil impulse.  They also may not monitor their recoil spring wear closely enough to catch it before their bolt starts to contact the back of the receiver.  Thus, there may be a role for a fallback buffer that normally does nothing, but is there in case it is needed.

I think that such a fallback buffer should be thin so it does not excessively shorten the distance available for the bolt to travel.  It should also have an OD the same size as the OD of the bolt so it has the best chance of diffusing any impact energy.  It should be oil resistant so it holds up inside the firearm.  Finally, it should be hard enough that the recoil spring does not cut or tear the buffer.

The closest thing I can find commercially available are 1/2" rubber sealing washers, but they fall short in several respects.  First, they have a 1-1/16” OD, which is smaller than the OD of the bolt.  Those washers are available in either neoprene or Buna-N.  The Buna-N is oil resistant, but the neoprene is not.  Further, based on my early experiments, both the neoprene and Buna-N washers are too soft to avoid being cut or torn by the recoil spring, even though the bolt never touched them.

I have decided to try making a buffer made from UHMW (ultra-high molecular weight polyethylene).  UHMW shows to be oil resistant, impact resistant, and harder than either neoprene or Buna-N.  A photo of a couple of prototypes is below.  These experimental buffers are 0.10” thick, with an ID of 0.500”, and an OD of 1.125”.  

Has anyone else already tried something similar?  If so, what were the results?  Any other thoughts on the subject?

[BillinBama]

This being for the S&W 76?  Looks like a 87 recoil spring guide.  Yes, Navgunner has one for sale for $8 on his website.  https://navgunner.com/navgunner-llc/ols/products/xn--sw-76--mk760-smg-impact-washerbuffer-for-the-guide-rod-7d09a.  I bought one along with other things including his suppressor, great stuff.  Yours looks like it will work as well.  

[Rekraps]

17 hours ago, Jim in Texas said:

 

I have long been taught that:

1.         a properly-sized recoil spring will prevent a recoiling bolt from striking the back of the receiver;

2.         if you want to use ammunition with a higher recoil impulse, you should also change the recoil spring to match that new ammo;

3.         as a recoil spring wears, you should replace it before it allows the bolt to strike the receiver.

In the real world, people may change ammo without realizing that it has a different recoil impulse.  They also may not monitor their recoil spring wear closely enough to catch it before their bolt starts to contact the back of the receiver.  Thus, there may be a role for a fallback buffer that normally does nothing, but is there in case it is needed.

I think that such a fallback buffer should be thin so it does not excessively shorten the distance available for the bolt to travel.  It should also have an OD the same size as the OD of the bolt so it has the best chance of diffusing any impact energy.  It should be oil resistant so it holds up inside the firearm.  Finally, it should be hard enough that the recoil spring does not cut or tear the buffer.

The closest thing I can find commercially available are 1/2" rubber sealing washers, but they fall short in several respects.  First, they have a 1-1/16” OD, which is smaller than the OD of the bolt.  Those washers are available in either neoprene or Buna-N.  The Buna-N is oil resistant, but the neoprene is not.  Further, based on my early experiments, both the neoprene and Buna-N washers are too soft to avoid being cut or torn by the recoil spring, even though the bolt never touched them.

I have decided to try making a buffer made from UHMW (ultra-high molecular weight polyethylene).  UHMW shows to be oil resistant, impact resistant, and harder than either neoprene or Buna-N.  A photo of a couple of prototypes is below.  These experimental buffers are 0.10” thick, with an ID of 0.500”, and an OD of 1.125”.  

Has anyone else already tried something similar?  If so, what were the results?  Any other thoughts on the subject?

As always you guys are light years more advanced than I.  I just went to HD and found a rubber washer that fit. Seems to work just fine. 

[Jim in Texas]

Bill -

Yes, this is for the 76/760.  Just based on appearances, Navgunner's buffer looks thicker and softer than what I had in mind.  I am trying for something with a longer lifespan and less shortening of the distance available for bolt travel.  

Related question - What effect, if any, does his suppressor have on the recoil impulse?  All else being equal, adding a suppressor to an existing barrel tends to increase the recoil impulse.  I am wondering if his shortened and ported barrel completely compensates for that tendency.

[Rekraps]

14 hours ago, Jim in Texas said:

Bill -

Yes, this is for the 76/760.  Just based on appearances, Navgunner's buffer looks thicker and softer than what I had in mind.  I am trying for something with a longer lifespan and less shortening of the distance available for bolt travel.  

Related question - What effect, if any, does his suppressor have on the recoil impulse?  All else being equal, adding a suppressor to an existing barrel tends to increase the recoil impulse.  I am wondering if his shortened and ported barrel completely compensates for that tendency.

Great question as I run an integral on my 76. Note that it matters if you use super or subs... which by all accounts should run subs with the suppressor. In that case the natural tendency for the can to increase recoil impulse means that the lighter load of subs does not impact the ability of the gun to shoot. It's an offset. 

Now if you use supers with a can (why?) then I imagine there could be an issue.