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+ for the FN 5.7x28mm

Discussion in 'Handguns: Autoloaders' started by HKGuns, Jan 1, 2013.

  1. HKGuns

    HKGuns Well-Known Member

    I took the Five-seveN to the range today and the thing that strikes me most about this pistol is probably not what you would think.

    I took around 5 other pistols as well and cleaned them all when I got home. The Five-seveN was last to go and was immaculate.

    It is by a very wide margin, the cleanest shooting pistol I have ever shot or owned. I don't know if it is the the round, the powder or the design of the cartridge, but I had to look real hard to find anything to clean.

    What is your cleanest shooting pistol?
  2. wally

    wally Well-Known Member

    CMMG .22LR pistol converted into a SBR 600 rounds of Federal Bulk Pack and next time I won't even open it up until twice that.
  3. rcmodel

    rcmodel Member in memoriam

    Maybe its the relevately high pressure round, operating in a blow-back operated firearm.

    That high pressure gas escaping at high velocity when the slide blows open should keep the dirt moving right on along, instead of sticking around in the action.

  4. usp9

    usp9 Well-Known Member

    I've said the same thing. I don't know why it's so clean, but it is apparent when field stripped after shooting.

    Not as clean as the FN, but my HK slides are clean and easy to wipe down after shooting. Easier than any other duty style pistols I own at least.
    Last edited: Jan 2, 2013
  5. Orion8472

    Orion8472 Well-Known Member

    I have noticed this as well. Could be clean powder? High pressure? Design of the chamber? Whatever it is, . . . it is clear that it runs cleaner than other calibers.
  6. HKGuns

    HKGuns Well-Known Member

    Glad i am not the only one who has noticed.

    After giving it more thought I think it may be the shoulder on the case that prevents powder and residue from being blown back into the pistol. Most other pistol cartridges are straight walled. It is very much like a bolt action rifle to clean up.........
  7. barnbwt

    barnbwt Well-Known Member

    The pressure spike in the 5.7 is over so fast I don't know if the cartridge still has any "poof" left after the delayed-blowback mechanism allows the chamber to separate from the slide; it may just be slide momentum by that point (which would also explain why the cartridge is so touchy to load for). If that's the case, the 5.7 would experience sooting more like high-pressure locked-breech actions that don't allow much, if any powder gas to vent into the gun's interior (unlike the HK roller-delayed blowback filth-machine :p). The ammo itself is very clean, too, since it is coated with teflon (I don't know if this somehow keeps the chamber clean, too). I'll bet FNH went with a really clean-burning powder as well, since the NATO requirements specified a really reliable action, and the round is, again, quite touchy to load for and time for a blowback.

  8. usp9

    usp9 Well-Known Member

    What is this delayed-blowback mechanism? :confused:
  9. Pete D.

    Pete D. Well-Known Member

    The delayed blowback used in the 5-7 is effected by a coating on each of the cartridge cases. You cannot see the coating but it is there. When the round is fired and the case expands against the chamber walls, the coating causes the case to "stick" in the chamber slightly longer than it otherwise would before starting its rearward journey and ejection.
    The coating starts to wear, especially around the shoulder, after a few reloads. The relative burn speed of the propellant is an important factor in effective and safe reloading...the choices are fairly limited.
  10. Hit_Factor

    Hit_Factor Well-Known Member

    That doesn't make sense. The 5.7 is reloaded by some people and restoring an invisible coating is going to be tricky. The delay has got to be a mechanical function of the firearm.
  11. Pete D.

    Pete D. Well-Known Member


    I have been unable to find a source for the idea. My apologies. I picked it up on the early Fiveseven forum (no longer exists....all data lost in a crash some years ago.)
    The cases are coated. After a few firings, it starts to wear off and can be seen.
    You are correct in thinking that replacing the coating is tricky. Mostly it cannot be done by the average reloader.
    Now you have me second guessing the idea. I will have to do some research.
  12. usp9

    usp9 Well-Known Member

    Usually in delayed blowback pistols there is either a slot cut into the chamber that allows the expanded case to "grab" the chamber or a mechanical device, (such as the gas piston on a HK P7), used to retard the rearward movement of the case until after the pressure drops. There is nothing like that in the 5.7.

    I've never heard of this case coating either. I've owned my 5.7 for about five years and have read a good bit about the gun. I'm not a reloader, so it isn't something I'd look into especially, but this is the first instance I've read that a coating is responsible for delayed recoil. Not saying it isn't the truth, but I am skeptical.

    Without some authoritative source, I'd have to say that the 5.7 is a straight blowback. The only caviat to that statement is that it does appear that the barrel has a small amount of travel, just a few milimeters, before it hits the pin used to hold the barrel. Perhaps that small joint movement of both the slide and barrel together is enough for pressure to drop. However it works, it is a great gun, accurate, reliable and definitely clean.
    Last edited: Jan 4, 2013
  13. RX-178

    RX-178 Well-Known Member

    I'd call the Five Seven a hybrid blowback-recoil operation, since the barrel and slide recoil back together, but are not actually locked together like in a traditional recoil-operated mechanism.

    In a traditional delayed blowback action, the barrel is usually fixed, where in this case, the barrel moves along with the slide.

    In a traditional recoil operated action, the barrel is mechanically locked to the slide, and unlocked after imparting enough momentum to cycle the action... where in this case the slide is not locked to the barrel, and thus moves backwards under blowback.
  14. Pete D.

    Pete D. Well-Known Member

    Delayed blowback

    About the delayed blowback system and the polymer coating on the cases..it took a few days and some time at the FiveSeven Forum. But I ended up with this info...
    So...friction created by the polymer coating creates a drag that affects and effects the timing of the delay.
    The gun is not a straight blowback. Not at operating pressures in the 50K psi range.
    Last edited: Jan 7, 2013
  15. LightningMan

    LightningMan Well-Known Member

    From the limited reloading I have done for my FiveseveN pistol, I don't worry about the case coating too much, just don't tumble them. The reason is at the operating pressure of the 5.7x28mm, I usually wear out the cartridge case before the varnish is gone. If you reload this cartridge to its potentual, unlike the watered down SS197 rounds, you will be lucky to get 3 reloadings out of a once fired factory round, and 2 times is more like it. I know that Elite Ammunition advises NOT to reload their fired cases, as they really load this round HOT! So much so, I have found that some of the cases will not fit into my shell holder and many times the primer will not stay in place either. As you can see I tried. LM
  16. barnbwt

    barnbwt Well-Known Member

    I could have sworn the coating was Teflon-based. It actually increases friction? Interesting. I wonder why they didn't just do a crappy job reaming out the chamber ("micro-flutes" ;)) to accomplish this.

    My Five-seveN also appears to have a true chamber-locking mechanism (though I may be interpreting its function incorrectly) instead of merely delayed blowback. A lever/cam in front of the trigger (below the barrel) links the frame and barrel together when both are forward in battery. For 1/4" or so (maybe longer) the two are tied as they recoil, until the lever rotates enough to free the slide from the barrel, and it continues back (I presume) under its own momentum (with little to no case pressure). Classic recoil action, except the barrel doesn't tilt to disengage, that little lever does (kinda similar to the CZ52 in that respect).

    (Strangely, neither Wikipeida nor WorldGuns have a description of the mechanism, and merely refer to it as "delayed blowback," so I cannot guarantee this description's accuracy)


    ^^^No kidding on the hot loads and (presumably, since I don't reload) short brass life. Remember, that thing is operatinig at 454 Casull pressures, but with zero margin for error as far as case volume. I'm suprised the primer pockets are loosened up after a single shot. Even "watered down" SS197 in my pistol has nearly consistent cratered primers that I've never gotten on any other firearm. It's so consistent, however, that I don't really worry about it. I guess you wouldn't want to use thin/wimpy Winchester primers on these, huh?;)
  17. Pete D.

    Pete D. Well-Known Member


    Very true about cratered primers in factory loads. A hot round. Another reason for care in reloading is that the amount of shoulder movement is substantial and the amount of reset work hardens the neck very quickly.
    One will also notice that case head expansion is apt to exceed 0.0005".
  18. mes228

    mes228 Well-Known Member


    My friend had the rifle & pistol by FN in 5.7 caliber. The rifle was quite accurate, the pistol was VERY inaccurate at normal pistol range. Not so lousy as to be useless. But bad enough to kinda sour someone that can shoot. May have been that particular pistol as it's the only one I've shot. Also the rifle had the scope on it with the "green" reticule. I could not even see the aiming point against a white target at 25 yards. I absolutely hated the scope. But loved the rifle.
  19. Orion8472

    Orion8472 Well-Known Member

    mes, . . . when I got mine, I patterned all over the place. Later, I discovered that it was ME causing it, not the gun. It takes a bit to learn it. Mine is very accurate for me now.
  20. nwilliams

    nwilliams Well-Known Member

    I had a FiveSeven for a while and then sold it. I really regret selling it now they are fun as hell to shoot and mine was a tack driver! A friend of mine has three of them and said he'd sell me one for $1,100 so I'll probably have another soon. I still have my PS90 and I love it, probably because I'm such a huge Stargate fan:D

    Prices on FiveSeven's and PS90's have skyrocketed on Gunbroker. FiveSevens are seling for up to $2k and PS90's up to $3k! 5.7x28 ammo is selling for over a $1 per round on Gunbroker as well.

    Sadly I didn't stock up on 5.7 ammo and nobody has it in stock anywhere, so I'm gonna sit on the couple hundred rounds of 5.7 I do have and wait impatiently for it to come back in stock. I'd reload it but I've heard too many experienced reloaders advise against reloading the 5.7 round.

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