Reloading the S&W 5.7

Been intrigued by the 5.7x28mm since its introduction. Have fired the FN version several times. Also an experienced reloader, and in fact helped a friend load for his FN FiveSeveN a couple years ago. But consistent reports of difficulties in loading for this cartridge have held me back. Brian Pearce's writings are especially concerning; the gun apparently begins to unlock and extract under pressure, resulting in case shoulders being blown forward considerably and visibly. Then there's that mysterious coating on the case, which FN continues to refuse to identify nor explain its reason.

So what are your thoughts on this new S&W version? My hope is that the gas-operated "Tempo" system might avoid the case distortion inherent in the FN's delayed blowback method. Internet "experts" are divided on the need for the coating. Does the Smith require it? I've got hundred or more once-fired cases, so the fate of the Western world hinges on your answers.

So have I and I have been reloading 5.7x28mm for the Five-seveN since 2005.

It is (was) an extremely difficult platform to reload for. Until the M&P5.7, all firearms chambered for this round have been straight blowback, no unlocking at all, and yes, their shoulders get blown quite far forward so after resizing and moving that shoulder back, the cases will crack at the shoulder and neck.

FN designed the round and then, after, built the firearms around it. I can’t state this as fact but I believe the coating was a sealant like most NATO rounds have around the case mouth and primer. I doubt that FN expected the lacquer/sealant to affect it but since militaries don’t reload and it is straight blowback, it did.
Originally a lot of us thought that it was very powder sensitive but after much trial and error (some not so good), it turned out to be the coating. I guess we can call the Five-seveN a “delayed blowback” but it would be a lacquer delayed blowback. Not knowing there was even a coating on the brass when I first started reloading this round, I media tumbled them like every other piece of brass. After having tried many things (like Loc-tite to delay the pulse), the most reliable results I had achieved (enough for it to cycle through a full mag) was to laod the rounds and them coat them with a spray metal laquer.


This S&W offering is awesome! The gas operated “Tempo” system eliminates the need (or want) of the coating and has functioned flawlessly for me. Since I have been reloading this round for awhile, my first outing with the S&W M&P5.7 was with my reloads for the Five-seveN. I did have to purchase a box of factory ammo just to compare results. So far I have only had one FTF and that was one of my reloads and it was the primer, not a failure to feed.
Since then I have been reloading the same 200 pieces of brass over and over trying to degrade/eliminate the coating and get a failure. No more FTFs yet, still 100% reliable, but due to the fully supported bolt face that doesn’t allow the rim to slip under the extractor, it has to jump the rim (and the extractor covers 9 to 12), it causes me to scrap some brass during resizing. No failure to feeds or cracked necks/shoulders but those tiny rims may only hold up long enough for…10 reloads?

Love this round, love the M&P5.7. Cheapest round I can reload, of ANY caliber, is the 5.7 with a 55gr surplus pull down and with 30-35gr varmint grenades, instantly eliminates the destructive critters that like to undermine structures and chew on wires and lines.

Thank you, snw19_357, excellent post.

Reading this gives me hope. The fact that you have successfully loaded for this cartridge is encouraging. I am an experienced rifle and pistol cartridge reloader but this is the first time I have encountered what I would consider major problems.
I purchased the M&P 5.7 a few months ago and fired two hundred or so rounds of factory ammo with no function problems. Extremely fun to shoot! Tried to work up some reloads, paying close attention to what has been said about the cartridge. The first thing I noticed was the coating on the brass is scraped off when the case is run through the sizing die (RCBS.) There is a collection of waxy material collecting around the shell holder. I made the mistake of tumbling the first 100 or so cases, which seems to have added to the removal of the coating. When I fired the first five of this batch the bullet went down range and hit the target in good order but I had to manually operate the slide in order to extract the case from the chamber. I stopped shooting after the sixth round because of the extraction problem and there was too much going on at the range for me to be able to collect all of my brass for examination.
My plan going forward is to process another batch without tumbling. I will wash them in a water and dish detergent solution and dry them for a couple of days to get rid of the case lube and try again. I did trim the cases to 1.130" +.002" - -0" but I don't think that would cause FE problems.
I will consider and appreciate any constructive suggestions.

What powder, etc. are you using?

I have not encountered any issues with any of my reloads in the M&P, regardless of the condition of the coating. I used to segregate by brass (once fired factory vs tumbled and reloaded) but no longer. I have even completely removed the coating with MEK and Scotch Brite so it's nice and shiny.
Perfect coating, ugly partially removed coating or shiny; no issues with the M&P.