So I got inventive again.
I was looking at the CAA RONI and the B&T pistol chassis available but they are all for striker fired polymer guns.
I wanted something for all my metal framed hammer fire handguns so I started with my SP-01 which is usually chambered in 357 SIG, but I swapped in the 40 S&W barrel to make test shooting easier. I wanted a folding brace for it so I had to buy a SB Tactical folding brace for the SIG MPX.
With the necessary restrictions to avoid ATF involvement I had to remove 2" from it.
I brief explanation...
A few years ago the ATF went after a guy for putting a brace on a handgun. They claimed it was beyond the length-of-pull limit for a braced handgun.
The problem with that statement is that until then the ATF had never officially published that length-of-pull dimension.
The ATF stated that the length of pull limit is 13.25" from trigger face to butt.
They claimed the gun in question measured 13.5 inches, but the problem was they measured it at a diagonal, when their own specifications stated it must be measured in-line with the bore. When measured correctly it came to only 13.125" so it was legal and the ATF had to drop the charges.
Anyway I had to shorten the brace with some steel side plates. The brace is mounted to a short section of vertical Pic rail on the end of an adjustable arm.
The entire thing is made of steel so I had the challenge of finding some sort of available item made of steel that can grab a pic rail on the gun.
The only items I could find are Weaver scope rings. I ended up chopping 3 of them.
Another interesting thing I discovered is that CZ gave as an actuall section of Pic rail on the SP-01, but most gun companies don't.
They give you a section of rail with maybe 1 slot, but if they give you 2 slots they are not usually spaced correctly per Pic rail specs.
I initially made it using just 2 of the ring bases, but realized if I added a 3rd behind the first 2 and removed the cross bar inside I could use this chassis on almost every railed gun I own. I had some sections of steel pic rail from past experiments. I used a steel 1/2" shaft coupler to provide the arm adjustment and bought a cheap green dot sight off amazon.
Jigging this up was tricky, but eventually I figure out a jigging bar that allows all the components to be aligned.
The first time I shot it the optic rail was too far forward and deflected debris from the muzzle brake ports back at my face.
I believe I fixed that problem.
I had no trouble putting 10 shots in a 2 inch circle at 20 yards so I would call it a success.
The forward grip is angled because it is illegal to have a vertical forward grip on a handgun.
I'll shoot it this week with a few different handguns.
I would probably not make more of these.
It is a tricky legal situation because you could easily screw up and attach the firearm while the rear arm was adjusted out too far and accidentally create an SBR.
I think that is the main reason nobody has tried to sell an adjustable pistol chassis that fits many guns.
It is much safer with the ATF to simply make it fit 1 gun legally.
I have no intent on selling these so it isn't an issue for me.
I also don't think any of this is patentable as it is all derived from "prior art".
https://live.staticflickr.com/65535/49637423286_3ce3e4a20f_h.jpghttps://live.staticflickr.com/65535/49636899823_657e227609_h.jpghttps://live.staticflickr.com/65535/49637422536_35be8106e8_b.jpghttps://live.staticflickr.com/65535/49637696172_92d8c8bba7_b.jpghttps://live.staticflickr.com/65535/49636899043_998150218d_b.jpghttps://live.staticflickr.com/65535/49637421676_75b051f7f5_b.jpghttps://live.staticflickr.com/65535/49637695317_7e5a40e63b_b.jpghttps://live.staticflickr.com/65535/49637694992_1f31e89294_b.jpghttps://live.staticflickr.com/65535/49636897363_f56429cfa9_b.jpg
