Nylon buffers for Semi Auto Historic Arms

[AmEngRifles]

I have located and modified a nylon “ spacer” as sold by Home Depot. The original model is 1” long x 1/2” diameter, with a .257 bore down the center. I trim 3/8” off as the full 1” length does shorten a complete recoil cycle. So with a 5/8” length piece, the bolt, piston extension and striker seem to maintain their full recoil. Will test as I get time and update. This is particular to the Historic Arms Guns as Len builds them with the original recoil buffer removed, due to his striker spring design. This piece sits over the recoil rod, inside the striker spring, and should provide some buffering between the striker, et all, bolt and piston extension and the rear of the trigger frame.

Will post a pic of said product soon. But if you go to Home Depot website and search for “ nylon spacer” look at the 1”x1/2”x .257 ID version.

Information

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[AmEngRifles]

Here is the part, as bagged. Bought this at Home Depot for .48 cents each. I trim 3/8" off the length, so the piston extension and striker recoil approximately the same amount as before the nylon buffer is installed. It may work without trimming, but the buffer appears that it will definitely be taking the full force of the reciprocating parts. I actually think the striker spring column pretty much buffers the striker, but doesn't hurt to have a little extra insurance.

Carbine top cover used to give some contrast to the white spacer on my white work bench.

[tr63]

Any updates on your buffer ?

[AmEngRifles]

No, sorry tr63. I have not been able to get to the range lately. I am hoping today possibly. if I can't get there today or tomorrow, it will be a few weeks.

[AmEngRifles]

OK, went to the range yesterday. I felt there was NO recoil reduction with the buffer in place to my shoulder. That may have been from me cutting to a length that may have been too short?? I did feel like it was acting as a dead blow and absorbing some of the recoil energy, in that I was experiencing more BOB stoppages once again. It MAY have had nothing to do with that? But I just removed it anyway to reduce the prospect. It did stand up to 30 rounds with little deterioration. But I feel like it was all for not. No real advantage.

If at some future date, I get the rifle running at a reasonably reliable cadence, I may try a longer one, just to see what effect it has.

A quick reaction to my statement in first paragraph. It should not be a product to reduce what I feel to my shoulder, but it should be a product to reduce metal on metal battering. It may not translate to any felt recoil to me, but it could provide the beneficial service of keeping the metal parts from beating on each other. Like a shock buff on a 1911. It won't reduce the recoil I feel through my hand and wrist. but it does help keep the dust cover from battering into the frame.

I will approach it again after I resolve the issue with my L4. Or try it out in my .303. That one is running well.

[WallyG.]

Is there enough room to place a coil spring in this location... possibly with a sacrificial nylon impact pad in front of the coil? All riding along the return spring rod like your buffer in this post. Length established so that only light engagement occurs routinely.. but in the event of a hot round being present to sufficiently dampen the recoiling parts from a hard impact with the rear wall of the slide/lower. This idea seems to have great merit in light of the function of the original parts removed in the HA design.

[AmEngRifles]

WallyG, I had not thought of it in that fashion, but yes, I suppose if the spring was the same diameter (1/2") as the nylon bushing, than yes,. It should be short and stout. Like a tea pot! lol

If you have not seen the inside of the Historic Arms trigger frame/striker set up let me know and I can try to take a few pictures.

Thankfully, on my Project Guns Bren, the original buffer is all there and the Mighty Lime striker system is working very nicely. So this discussion mainly revolves around the Historic Arms Brens, and in particular, my L4A4.

[TactAdv]

WallyG, I had not thought of it in that fashion, but yes, I suppose if the spring was the same diameter (1/2") as the nylon bushing, than yes,.

NO!!! Absolutely the wrong direction of thought for a buffering action! Do NOT add in any more springs. A spring will simply store MORE kinetic energy and impart it back into the system in the counter-recoil stroke adding in potentially harmful increased velocities and momentum to the counter stroke. That is what springs are intended to do- store potential energy and release it in the direction counter to compression or tension. Bad ju-ju.

A true firearm "buffer" is designed to do one thing- convert excess/unneeded potential/kinetic energy into HEAT. It is this conversion of unwanted energy into heat, without STORING any of it to be added back into the dynamic system as counter recoil energies that effectively buffers the system.

The "dead blow" effect is indeed what you want to see happen, you just aren't noticing the "dead blow" is a conversion of the recoil energies into the buffer material or mechanism into a heat energy value.

The tried and true old time material that works stupendously are the ages old phenolic resin compositions....."bakelite".....or just "phenolics". They work by absorbing an impact blow of kinetic energy and force the material to compress almost imperceptibly thereby generating a heat rise in the material. By the fact that the conversion is so efficient and the material has a super low value of what is known as the "coefficient of restitution", i.e., its ability to not perceptibly "spring back into shape" it imparts no real restorative energy value in counter recoil.

Modern buffers substitute, usually, a form of hydraulic mechanism where the recoil blow forces a small quantity of in-compressible fluid through a tightly orificed metered opening slowing the impact movement of the piston as the fluid transitions through the opening, which dramatically raises its temperature. A simple counter balance spring forces the hydraulic piston back the other way once the force is removed but has no part in adding into the total system counter recoil energies.

The phenolic discs are extremely effective and can last a very, very long time. I am still using original phenolic discs in various of my WWII MG's.....M1/M1A1 TSMG's, M1919A4/6 BMG's, and others. If not exposed to physical damages they last well.

My advice would be to obtain some M1919 BMG buffer stack discs and bore a suitable center hole through them to allow the needed semi-auto Bren rod to pass through and allow a short stack of 1-3 of the discs to be added at the rear of full recoil travel. Some places to look for them:

1919a4 30 cal buffer rebuild set of 22 buffer discs | eBay

Disk Buffer | Gun Parts Corp.

Electronics supply stores also usually have sheets of phenolic material as it is still the go-to material for insulating PCB Boards.

1/8" x 24" x 48" Grade X Phenolic Sheet | U.S. Plastic Corp.


With anything you do here, you will need to make sure you are not overly shortening the original allowed recoil length of the dynamic parts, any shortening of the ORIGINAL designed in recoil distance will cause a noticeable increase in ROF. (As an effective example, adding in a 1/2" rubber block into the rear of the fullauto Uzi SMG will increase ROF from about 550rpm to well over 800rpm!! Doesn't take much!)

No springs! No "rubber" type blocks.
-TomH

[Bruce_in_Oz]

Like most small weapon parts, "buffers" are generally a consumable / "expense" item. In a big ordnance system, they, like springs are changed regularly to maintain reliable function. I recall with some amusement my reaction when first confronted with the "yellow-spring" buffer in our initial FN Minimi issue. As I understand it, those were supposed to be fitted ONLY in the "folding butt" variant. In the butt of these guns there was an alloy thing shaped like the real buffer that was only there as a spindle to locate the plastic butt and its retaining bolt. They were a bit "parts-hungry" in service.

How many "private" users swap out the little coil springs in the feed covers of their belt-fed toys after "X" amount of rounds? How often do civilian M-60 GMPG drivers replace the extractor and ejector springs? It's not just compression that kills those last two, but the accumulated crud buildup that reduces travel efficiency AND which collects moisture that mixes with the crud to cause corrosion and collapse of the springs.

"Run 'til fail" is not exactly a good idea with small arms, artillery, aircraft, etc..

[WallyG.]

Correct me if I'm wrong here.. but wasn't the key component of the original Bren buffer that was removed in the Historic Arms builds a big coil spring? A sacrificial nylon buffer as proposed is intended to be disposable after some quantity of cycles... I just thought that adding a few coils might prolong the wear interval.