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To critically access available information:

The stellite material is good- it is vastly superior to 300 series stainless steels as a suppressor baffle material.  The link discusses hardness and a higher melting temperature (among other things).  Barrel liners and 80% greater life in a barrel is not really a great comparison as chrome is .0004" thick and subject to cracking and peeling and chrome moly is not wear resistant.  17-4 has also been regarded as the holy grail of barrel materials by people like John Noveske, it is known to provide 2-3 times greater barrel life than other materials also, but is cost prohibitive to work with in terms of tool life with resulting barrels costing 3-4 times that of 416SS.  The 17-4 we use has nearly identical hardness to stellite 6 (most commonly used) and 21 (actual alloy used for M2 barrel liners) and 17-4's melting point is ~100F hotter.  It is 10% lighter than stellite also, because it is not cobalt based.  

Silencer co brought stellite to suppressors- probably for marketing reasons to compete with AAC's 718 inconel marketing.  The companies using stellite are all related by associated founder origin to silencer co partners and employees. Silencer Co casts and finish machines the baffles probably because this reduces the per pound cost of material used to manufacture parts, and minimizes machining time.  These offshoot companies probably also do because machining wrought would mean ~$40-$60 worth of cobalt material alone without considering cost to form it into a bar, all of which is substantial.  Casting means that stellite is as much as 60% weaker than billet 17-4 and also shares the process attributes of cast parts. That means possible internal voids and grain structure that is not ideal, like that found in wrought materials.  When you talk to a casting person about pressurized parts they immediately tell you casting is not ideal for pressurized parts.  For reasons of economy some pressurized parts are cast, but those are financial decisions primarily.

Stellite obviously is erosion resistant and that is the property category where it is probably the best material available- but that is coming with 10% more weight to material thickness, and up to 60% lower material strength so it comes at a price when you have to use more of a heavier material to get a similar strength component.

The best baffle materials are 718 inconel, stellite familiy alloys and 17-4, and we feel 17-4s high strength to weight ratio makes it obviously better than 718 inconel which is softer and substantially weaker, and in our opinion also better than stellite which is weaker and heavier - two property categories that are very hard to compromise in the sound suppressor product category.

In the end, engineering involves making a decision based on an overview and study of available materials. That is why you will get different answers to the same question. KAC for example used 625 inconel - they considered it ideal.  It is softer than all of the above, it is weaker than all of the above with exception of 300series stainless- probably its sole positive attributes are high temp strength retention (less noteworthy when your room temperature strength is so comparatively low)  and corrosion resistance- something inconel 625 does a superlative job of- and that is why you find it in nuke plant piping.  AAC founder Kevin went to SIG and they now offer titanium and 17-4 suppressors.

Quoted:


To critically access available information:

The stellite material is good- it is vastly superior to 300 series stainless steels as a suppressor baffle material.  The link discusses hardness and a higher melting temperature (among other things).  Barrel liners and 80% greater life in a barrel is not really a great comparison as chrome is .0004" thick and subject to cracking and peeling and chrome moly is not wear resistant.  17-4 has also been regarded as the holy grail of barrel materials by people like John Noveske, it is known to provide 2-3 times greater barrel life than other materials also, but is cost prohibitive to work with in terms of tool life with resulting barrels costing 3-4 times that of 416SS.  The 17-4 we use has nearly identical hardness to stellite 6 (most commonly used) and 21 (actual alloy used for M2 barrel liners) and 17-4's melting point is ~100F hotter.  It is 10% lighter than stellite also, because it is not cobalt based.  

Silencer co brought stellite to suppressors- probably for marketing reasons to compete with AAC's 718 inconel marketing.  The companies using stellite are all related by associated founder origin to silencer co partners and employees. Silencer Co casts and finish machines the baffles probably because this reduces the per pound cost of material used to manufacture parts, and minimizes machining time.  These offshoot companies probably also do because machining wrought would mean ~$40-$60 worth of cobalt material alone without considering cost to form it into a bar, all of which is substantial.  Casting means that stellite is as much as 60% weaker than billet 17-4 and also shares the process attributes of cast parts. That means possible internal voids and grain structure that is not ideal, like that found in wrought materials.  When you talk to a casting person about pressurized parts they immediately tell you casting is not ideal for pressurized parts.  For reasons of economy some pressurized parts are cast, but those are financial decisions primarily.

Stellite obviously is erosion resistant and that is the property category where it is probably the best material available- but that is coming with 10% more weight to material thickness, and up to 60% lower material strength so it comes at a price when you have to use more of a heavier material to get a similar strength component.

The best baffle materials are 718 inconel, stellite familiy alloys and 17-4, and we feel 17-4s high strength to weight ratio makes it obviously better than 718 inconel which is softer and substantially weaker, and in our opinion also better than stellite which is weaker and heavier - two property categories that are very hard to compromise in the sound suppressor product category.

In the end, engineering involves making a decision based on an overview and study of available materials. That is why you will get different answers to the same question. KAC for example used 625 inconel - they considered it ideal.  It is softer than all of the above, it is weaker than all of the above with exception of 300series stainless- probably its sole positive attributes are high temp strength retention (less noteworthy when your room temperature strength is so comparatively low)  and corrosion resistance- something inconel 625 does a superlative job of- and that is why you find it in nuke plant piping.  AAC founder Kevin went to SIG and they now offer titanium and 17-4 suppressors.

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Thanks man!  Fun stuff is in the works.

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