Cheely EXF Limited

[Speedemon45]

hmmm, I wonder if something like this is legal in IPSC as well, I like it better than the 5.4" sight tracker I think

I'm guessing this wouldn't fit in the IPSC box.

Sweet blaster Eric

[eric nielsen]

Mostly copied from Rules subforum (topic was thumb rest in Limited): My two cents - use the lowest thumb rest position possible, at or below the bottom of the frame/dust-cover area. Or don't use a rest at all in Limited.

Tried two different thumb-rest positions (DAA Adjustable) on my new limited STI, 3rd way was using my Production grip which is thumb curled down under the frame and alongside the trigger guard and hands torquing into the tops of both grip panels as done by Bob Vogel. Of those the Vogel grip (thumb tip not doing anything) gives me the best Limited recoil/recovery pattern, low/level thumb rest is 2nd best, high/angled thumb rest position the worst. Had to do a small Dremel job on the DAA thumb rest base to get a "level" position:

I use the high/angled in Open and it's fine for that as the recoil impulse is mostly straight back and happens in very short time frame. Not so good for Limited, the recoil impulse is much more of a 15 or 30 degree angle and the thumb rest seems to just magnify that push of the gun and by comparison to the Open gun, the impulse seems to last forever. Such an eye-opener that I've been lugging Production, Limited, and Open guns to the range every practice session every time since that first Limited shake-down. In reality the thumb-under-frame grip is best with Open gun too but results in negative (downward) recoil until 1 or 2 mags of shooting to get used to it. I keep using the Open thumb rest because it recovers the same as Production gun. Also, thumb-under grip stings on the unmodified STI frame, luckily I asked Matt to smooth that corner near the trigger on the Ltd gun.

Ranking the amount of "timing" or anticipation needed to return gun to line-of-sight:

1. Open gun, thumb-under-frame Vogel grip (zero anticipation)

2. Open gun high thumb rest, Limited gun Vogel grip, Production gun Vogel grip (all the same, small amount of anticipation)

3. Limited gun, level thumb rest (feels like 2x the anticipation of Vogel grip)

4. Limited gun, high/angled thumb rest (feels like 3x the anticipation of Vogel grip)

Sent the barrel back to Matt to do the 3rd & final version of this EXF which will be a 6" gun. As is, I found a very noticeable sight-tracker effect using grip #2 above and a very firm amount of pressure. As in, I'm closing the Captains of Crush 1.5 and using about 85% of that force to shoot the gun.

Edited June 8, 2013 by eric nielsen

[want2race]

What was the reason for modifying the sight extension. In the pic above the extension was narrowed greatly.

[eric nielsen]

Reason for narrowing is odd effects on bullet flight. Like, the sights were spec'd out to hit point of aim at 25 yards with the 9" sight radius, but instead impact was about 10" low and I ran out of "up" adjustment on the rear sight. Also after shooting many FMJ bullets w/exposed lead bases, the holes in the target went from round and grouping 7/8", to egg-shaped and grouping 2" or more at 25. Something like the wake turbulence off an airliner's wing-tips was happening, best guess.

After narrowing, both the above issues went away completely, rear sight is about a 1/2 turn from being bottomed out and bullet holes are perfect. I think the same would be true (zero problems) with a standard, Open-looking 2" cylindrical comp blank BUT unlike Open you can't get in & clean the interior or clean the muzzle crown, not without some custom Clymer reamer anyway.

Reason for going to 6" barrel assembly (8" sight radius) is presbyopia, which sucks. Still not using reading glasses but that day is not far off. Relationship of the front sight, rear sight, and target beyond (seen with right eye) is worse than years ago. When I was mid-20's and got my first Limited gun (a G20) I'd hit any & all steel with speed and very little effort, annoying the old-timers to no end. Now I'm the old-timer. I still think a very long radius - 9, 10, 11 inches - is a legit way to game Limited if you have the young eyes for it. Go with cylindrical/traditional and build some sort of cleaning tool and go at it.

Edited June 7, 2013 by eric nielsen

[wes777]

Very interesting gun.

[JaeOne3345]

Eric, I experienced very similar results to you in regards to the thumb rest on my limited gun.

I experimented with the G o G u n pedal and it sits very high and far back. On a limited gun it it was too much. I felt much better with less of an aggressive angle, like the Arredondo unit, but never experimented with it again because 2012 nationals was coming up and I knew I couldn't run it there anyway.

Is your DAA the ipsc standard legal model, or just the typical adjustable rest?

I like the idea of the thumb rest simply for consistent thumb placement. I don't even desire one for recoil control anymore. The limited gun is gonna flip. It's just a given.

Edited June 7, 2013 by JaeOne3345

[want2race]

Thanks for the honest and informative post. Pretty much verified some initial concerns with the concept. I still like the way it looks and have an idea how to minimize the ill effects.

[eric nielsen]

It's the original (too big for IPSC) DAA thumb rest. The front support post is supposed to go into one of the angled slots but I made a spot for it at the front of the horizontal (screw-in) channel. Need to dremel a distinct slot to just fit the support post, or the the whole paddle will slip and go beyond horizontal (see photo 2 above).

I went to the thumb-under frame grip when borrowing an XDm 5.25 for our factory-gun tournament. (Great production gun by the way, just SO light compared to my other guns). If you look at the pictures the CZ has by far the most comfortable shape and layout for getting your fingers under the trigger guard and the left thumb under the frame, also love the the thumb safety position and I lean on that thing a lot - it's a beautiful frame design.

FWIW my favorite thumb rest was the optional part that screwed into the bottom of the Allchin vertical mount. Something like this:

Edited June 8, 2013 by eric nielsen