Sub-compact 5.7x28mm pistol (Split from Ruger LCP thread)

[f3rr37]

Now, if there were a ~3" barrel ~10 round sub-compact 5.7x28mm that would be a nice little back-up gun!

Would buy one in a heart beat.

[ArtosDracon]

I suppose it wouldn't be THAT hard to build one, especially if one were to use an existing design that used a similar caliber to the case and just changed everything from the breech face forward and had ample room in the handle for the length of the round. It seems to me that a revolver would be quite easy to build and should be able to handle 7 rounds in a pretty compact package, like the J frame that's so popular. If one were to use just the smaller and lighter bullets like found in S4's and SS197s a 2" barrel should suffice for stabilizing it. A semi-auto would be much tougher. I'd immagine you'd want to start with a very compact .22LR design and work your way up from there. Unless FN were to just take the FsN, thin it out for a single stack, shorten the grip .5-.75" and use a 2.5-3" barrel, because the round is so thin, with a single stack magazine and proper work it shouldn't be that tough to get it as thin as the LCP or the P3AT, it will have to be a bit longer though, because of the length of the round.

[mickey223]

Actually, there was a long discussion on a compact 5.7 on the old forum. I believe that the final word from FN, was that it would require a complete redesign, but can't remember why.

[f3rr37]

I believe FN has stated that they do not intend to produce a compact version of the 5.7

[ArtosDracon]

Maybe we'll just have to make one then :evil;

I'm sure we could do a revolver to get things started off with a DA/SA compact to follow. I'll have to let it stew to see if I can come up with anything. It would definately not be easy, I'll say that for darn sure.

[Esteves]

I've thought for a while that the NAA mini-master or Black Widow ( http://www.naaminis.com/bwmm.html" onclick="window.open(this.href);return false; ) would be a great starting point. The chamber dimensions would need to be about 1.1 times bigger in each direction than the existing .22WMR version, although the cylinder would probably need to be beefed up.

I can live with SA, 5 shots that are a drag to reload, and a marginal trigger if it stays small and light.

I'd lean toward the 4" barrel length since the round really does benefit from velocity, but others will want maximum concealability and a shorter barrel.

[ArtosDracon]

Oh, I hadn't thought along the lines of a deringer like revolver. The cylinder would definately need to be beefed up.

[f3rr37]

Any idea what kind of pressures the revolver cylinders are rated for?

[Esteves]

http://www.handloads.com/misc/saami.htm" onclick="window.open(this.href);return false;
http://www.lasc.us/SAAMIMaxPressure.htm" onclick="window.open(this.href);return false;
http://www.naaminis.com/hpwhite.pdf" onclick="window.open(this.href);return false;
The 5.7x28mm is definitely on the higher end of the scale.

[f3rr37]

Then again, would the pressures be different (lower) because of the cylinder gap?

[ArtosDracon]

It would depend on the size of the gap, a lot of higher end revolvers have a shroud to cover the gap now a days, that black widow and mini master have a seemingly tiny gap but, it will lower pressure, it's just a matter of how much.

[Grantness]

Remember that keltec survey that was probing interest in a compact 5.7x28 pistol / PDW?

[ArtosDracon]

The only unfortunate thing about that is the broad spectrum of weapons systems that are considered compact. The 1911 officers model is considered compact and it's pretty huge. The P90 is a compact weapons system comparatively. I'm honestly thinking more along the lines of a sub-compact. I really like the size of my Sig P230 but, it's the largest thing I would think of carrying as a back-up, and it's simlar in size to a large portion of peoples primary CCW.

[SOFMatchstaff]

anyone heard of the .224 Harvey K-Chuk, Ive been shooting one for 20 yrs, Its pretty much what you been yakin about. I get a nice sedate 1850 fps out of an old 5 screw K22 SW with a 33 to 40gr pill. It is just a bit sharper than the auto noise wise, but accuacy is superb, Its a hornet case blown and shortened, like the "K" version. No extraction problems like the old Jet, and no set back that tended to lock the cylinder. If you need a real close comparison to what you are proposing, try a 4" SW M-51 in 22mag, Nasty noise, vel about 1300 or so. I would bet that the 5.7 case in a revolver would be very prone to case set back, to much built in slop in the cyl gap/headspace values, and the extractor would be a ruger wirespring type mess. The 5.7 case coating would probably be the make or break factor in a revolver adaptation.
A K frame size cyl is about as small as I would trust, cant think of small frame that meets the need. the taurus 22H might be a candidate, the std Hornet chamber would be small enough to poke out, but ejector is useless, besides its a bit large. AMT made a 22mag SA, another decibel bomb, and the extractor hitting the rim on the feed cycle always puckered me. they worked though.
I need to feel a little better armed that anything proposed in this discussion, but folks have defended themslves with less. With the improvement of ammo for the existing calibers things are getting better, slowly. Cant see the need or logic in reducing the performance of the 5.7 just to get a smaller less effective package that already exists in several systems today.

[Esteves]

I think the intent here is for a backup gun or a more concealable gun, that minimally has ammo compatibility with a platform that the majority of board members here already use. It should be smaller in at least one dimension and/or lighter weight than the Five-seveN, especially if capacity is reduced.

The "least engineering approach" would be a FsN with a full length slide, but a shorter grip and reduced-capacity magazine (with the ability to use standard magazines.) A 14-round version could be about an inch shorter in the grip. Got dremel?

[ArtosDracon]

I've been stewing on this for a few hours whilst asleep today and I'm pretty convinced that most of us will be pretty disappointed with any revolver we could possibly bake up. I'm convinced the only feasible alternative would be to start from scratch, using the FsN as a reference and build a semi-auto around a single stack magazine and a 3.5" barrel. Width would be determined by the chamber, which would have to be similar to the FsN but, slide design could be updated pretty dramatically to ride closer to the chamber/barrel to thin it down. The enclosed hammer is ideal so that should remain. the grip length and the area behind the barrel would have to be pretty similar in length to accommodate the length of case cause let's face it, this is a LONG round for a compact pistol. The angle of the handle could be increased to keep total height to a minimum without loosing too much capacity. A double stack would be feasible with the small diameter of the round but, in a thinner double stack than the existing magazines, again to keep the width down. I suppose we could take the Glock approach. Take the FsN, cut it off about half way down the light rail, gut the grip in half and take an inch and a half out of the middle of the magazine and call it a sub-compact.

[f3rr37]

I've been stewing on this for a few hours whilst asleep today and I'm pretty convinced that most of us will be pretty disappointed with any revolver we could possibly bake up. I'm convinced the only feasible alternative would be to start from scratch, using the FsN as a reference and build a semi-auto around a single stack magazine and a 3.5" barrel. Width would be determined by the chamber, which would have to be similar to the FsN but, slide design could be updated pretty dramatically to ride closer to the chamber/barrel to thin it down. The enclosed hammer is ideal so that should remain. the grip length and the area behind the barrel would have to be pretty similar in length to accommodate the length of case cause let's face it, this is a LONG round for a compact pistol. The angle of the handle could be increased to keep total height to a minimum without loosing too much capacity. A double stack would be feasible with the small diameter of the round but, in a thinner double stack than the existing magazines, again to keep the width down. I suppose we could take the Glock approach. Take the FsN, cut it off about half way down the light rail, gut the grip in half and take an inch and a half out of the middle of the magazine and call it a sub-compact.

Would work for me.

I'd also like to see something similar except with an alloy frame.

[ArtosDracon]

I've had a friend who does custom gunsmithing, the guy who helped me build the mini-14, and he said no way. He'll CNC mill out a 1911 or a glock lower, he even does custom P92/96 lowers but, he wouldn't touch the FsN. Could be ignorance for the design but, seems as though it would be tough, he tends to liken to a challenge.