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View Full Version : OS small radius FPS + 23lbs. mainspring + polished MSH = butter?


emilio
22nd September 2007, 19:38
all the parts for my RIA 5" upgrade are in, sans new grip screws (VZ "SLEX", mmm). this has included a Berryhill trigger, Wilson sear, firing pin, and mag catch, EGW disconnector, Fusion hammer, CMC grip safety, and a fun evening in a machine shop to cut the safety radius. the last things added have been an EGW FPS, ISMI 23lbs mainspring, and the stainless steel mainspring parts from a new Ed Brown rebuild kit.

http://neurostyle.net/misc/ria/take3/ria-take-3-mods-begin.jpg

still need to blend the grip safety and coat some parts with matte black Gun Kote (especially the trigger!).

i installed just the FPS one night and the main spring the next. after installing the FPS, yep, it was a little harder to rack the slide with some snap caps. no problem. when i installed the main spring, i decided to follow a tip i'd read and polish the inside of the MSH, the outside of the main spring cap, and i also did the outside of the spring a bit.

after trying to get down in there with a punch and some rolled up sandpaper or crocus cloth, i turned to ye olde Dremel. i cut down a small barrel felt tip to fit in the MSH and slowly worked it with some polishing compound on a low speed. i didn't try to get anywhere near a mirror shine, but just smoothed out the finish and some of the high spots. the crocus cloth polished the outside of the main spring cap pretty quickly, and i wrapped it around the outside of the spring to smooth it as well. i also verified that the 23lb spring was quite stiffer than the stock one in my RIA, and it all installed easily.

now it actually feels just as easy to work the slide as before the FPS and spring, and certainly smoother. like, pleasantly, butter, Michael Jordan-to-the-rim smooth. the hammer alone is much easier to cock, and that's a good thing considering the shape of the hammer. i still haven't shot it - that'll come tomorrow, and i've got the ammo to run it through its paces!

my question is: could this have defeated some of the advantages of the small-radius stop? if one of the functions of the stop is to slow unlock and change the recoil system, would it be bad to reduce the spring system's friction, or does it not really matter after the stop "breaks" over the hammer?

- emilio

pa_guns
22nd September 2007, 20:45
Hi

As far as I can see everything you have done is just fine. Some MSH's have *really* rough insides. I think that maybe they drill them with worn out drills. :D :D Smooth function is what you are after. Having the mainspring hang up is *not* a good thing.

Bob

1911Tuner
22nd September 2007, 21:30
or does it not really matter after the stop "breaks" over the hammer?


Precisely. The small radius only has an effect when the slide first starts to move. Once it gets tha hammer moving, the hammer slams backward and bounces off the grip safety. By the time that happens, the slide is on its way, and the firing pin stop's effect is over.

emilio
28th September 2007, 00:09
welp, ye olde RIA munched happily through 250 or so rounds of American Eagle 230gr FMJ with just a couple of odd feed issues (should test the extractor). this was the first time out with the small-radius stop, 23lbs main spring, and polished doohickeys.

the gun is definitely smooth! operating the slide feels much smoother than before, and recoil feels like a more even curve than a snap with follow-through. recoil also feels like more of a jump straight up than the snap up and faint rotating torque of stock.

it does not feel like much less recoil. it couldn't be less recoil, of course, but i think i was expecting a smoother termination - the spike as the slide transfers most of its remaining energy to the frame. however if it's still moving back with more or less the same amount of force, that impact couldn't possibly be reduced.

it is a much more predictable and manageable recoil, though. in the intermediate period - with beavertail etc. but no FPS+23lbs - the best i did was 10 rounds rapid fire in to something a bit narrower than a piece of paper at 7 yards. (something that i was scolded by the rangemaster for, then complimented.) i feel i could do better with this setup, or at least do it faster. can't wait to try!

- emilio