I had a buffer bushing fail on one of my Heckler & Koch 270 and since these are no longer available from HK, I tried one of the silicone buffers available on ebay and gunbroker.
Here is a photo of an original HK buffer under heavy pressure from the bolt. Notice the space between the bolt and the buffer retainer plate:
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Here is the aftermarket silicone buffer under very mild pressure. Note how the buffer is compressed and the bolt is in full contact with the buffer retainer plate:
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The original buffer was made from a hard material and at the end of the bolt stroke would buffer the recoil forces. The new buffer is made from silicone and its a much too soft of a material to do the job of buffering the bolt. With only slight pressure the buffer collapses and the bolt makes direct contact with the buffer retainer plate. The original buffer on the other hand is much harder and I could not get it to collapse no matter how much force I applied to the bolt for the photos above. What that means is that the bolt never contacts the buffer retainer plate with the original buffer and there is never metal on metal contact, this reduces the stress on the bolt. With the silicone aftermarket buffer the bolt is only stopped when it hits the metal buffer retainer plate.
What effect will running a silicone buffer have? Well I wanted to test that and I put around 700 round of ammo through an HK270. The result was this:
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That is a firing pin retainer roll pin. Becasue the silicone buffer would not do its job and stop the bolt, the bolt would contact the metal buffer retainer plate at full speed and with high force. The sudden deceleration of the bolt caused high G forces. The momentum of firing pin inside the bolt was stopped by the retaining pin. Becasue of the high G force the firing pin bore right through the retaining roll pin (the FP retaining pin was inspected and in perfect condition before testing as the FP was changed recently, that is when the failing buffer was noticed). I noticed the rifle malfunction and after disassembly found the problem. If I did not catch it right away there was always a chance to break the firing pin (no longer available from HK either) as it was no longer captive inside the bolt.
To summarize, running the silicone buffer is like not running a buffer at all as it does not do the job of stopping the bolt and reducing the forces that are transfered to the firing pin and retainer. If you run your rifle with the silicone buffer or no buffer this will happen eventually. DO NOT SHOOT AN HK270 WITH THE SILICONE BUFFER OR WITHOUT A BUFFER. You will break the firing pin retaining pin and then the firing pin, and maybe others parts like the bolt, buffer plate retaining pin as well as cracking the receiver. If you have been running the silicone buffer (or no buffer) I suggest you inspect the FP retention roll pin. Until someone makes aftermarket buffers from an appropriate material it is not safe to shoot your HK270 with anything except an OEM HK buffer.
Here is a photo of an original HK buffer under heavy pressure from the bolt. Notice the space between the bolt and the buffer retainer plate:
Here is the aftermarket silicone buffer under very mild pressure. Note how the buffer is compressed and the bolt is in full contact with the buffer retainer plate:
The original buffer was made from a hard material and at the end of the bolt stroke would buffer the recoil forces. The new buffer is made from silicone and its a much too soft of a material to do the job of buffering the bolt. With only slight pressure the buffer collapses and the bolt makes direct contact with the buffer retainer plate. The original buffer on the other hand is much harder and I could not get it to collapse no matter how much force I applied to the bolt for the photos above. What that means is that the bolt never contacts the buffer retainer plate with the original buffer and there is never metal on metal contact, this reduces the stress on the bolt. With the silicone aftermarket buffer the bolt is only stopped when it hits the metal buffer retainer plate.
What effect will running a silicone buffer have? Well I wanted to test that and I put around 700 round of ammo through an HK270. The result was this:
That is a firing pin retainer roll pin. Becasue the silicone buffer would not do its job and stop the bolt, the bolt would contact the metal buffer retainer plate at full speed and with high force. The sudden deceleration of the bolt caused high G forces. The momentum of firing pin inside the bolt was stopped by the retaining pin. Becasue of the high G force the firing pin bore right through the retaining roll pin (the FP retaining pin was inspected and in perfect condition before testing as the FP was changed recently, that is when the failing buffer was noticed). I noticed the rifle malfunction and after disassembly found the problem. If I did not catch it right away there was always a chance to break the firing pin (no longer available from HK either) as it was no longer captive inside the bolt.
To summarize, running the silicone buffer is like not running a buffer at all as it does not do the job of stopping the bolt and reducing the forces that are transfered to the firing pin and retainer. If you run your rifle with the silicone buffer or no buffer this will happen eventually. DO NOT SHOOT AN HK270 WITH THE SILICONE BUFFER OR WITHOUT A BUFFER. You will break the firing pin retaining pin and then the firing pin, and maybe others parts like the bolt, buffer plate retaining pin as well as cracking the receiver. If you have been running the silicone buffer (or no buffer) I suggest you inspect the FP retention roll pin. Until someone makes aftermarket buffers from an appropriate material it is not safe to shoot your HK270 with anything except an OEM HK buffer.