RaylanGivens Posted January 19, 2016 Share Posted January 19, 2016 I have an STI Edge Limited gun running .40 major... I've always rounded off the radius of the edge of the firing pin stop that contacts the hammer. My reasoning was that this would smooth out the action of the slide and get the gun to shoot faster... Lately, I've been reading that my extra radiusing of the firing pin stop allows the slide to contain more energy, which causes more muzzle flip - a bad thing. I'm curious about the general consensus regarding the firing pin stop radius on Edge limited guns... I'm currently using the standard STI Edge firing pin stop (radiused), but would be open to another brand if better. Link to comment Share on other sites More sharing options...
Quack Posted January 19, 2016 Share Posted January 19, 2016 EGW flat bottom and use a slight radius (break the corner). Link to comment Share on other sites More sharing options...
MikeRush Posted January 19, 2016 Share Posted January 19, 2016 I've been reading that my extra radiusing of the firing pin stop allows the slide to contain more energy, which causes more muzzle flip - a bad thing. There are a whole lot of variables in play here. A heavier mainspring and more squared stop might indeed reduce the secondary recoil impulse but the energy isn't disappearing. You are just experiencing it sooner. I experimented with an EGW square stop, beveled as described above. I ended up rounding it. Somewhat recently I tried a beveled stop again... still nope. Since it is less than $20 get one and try it out. EGW and Wilson both make them. Run some bill drills, check your splits, see how the sights track. It is a cheap experiment. There is plenty to read on it, but most of the square stop hype seems to revolve around "that was JMB's original design, so it is better" or "dude, the spring absorbs the energy". I currently have my stop cut to raise the contact point between hammer and FPS, and increase slide speed. Stroking, square stops, and other modifications that spread the recoil event over a longer period of time may very well shoot "flatter" in terms of perceived and/or absolute lift as you have more time to counteract the recoil impulse. Whether or not that results in a faster return to an acceptable sight picture depends on grip, vision, other design attributes of gun... it is preference. Buy one, fit it, try it, time it... Link to comment Share on other sites More sharing options...
Aircooled6racer Posted January 19, 2016 Share Posted January 19, 2016 Hello: Think of the leverage action on the hammer by the firing pin stop. If it hits the hammer further up it will take less force to overcome the mainspring so the slide will rack easier. I made a fixture so I can angle the firing pin stop in my Bridgeport. I have tried square, radius and the angled and the angled works better for me. The radius works very well but you have to get the radius correct to optimize it. Thanks, Eric Link to comment Share on other sites More sharing options...
jcc7x7 Posted January 20, 2016 Share Posted January 20, 2016 Above +1 Cheap investment to buy the EGW and break the edge and then run a series of drills with both FP stops. I like to quantify my drills by only counting the Alpha hits, that makes "ME" use my sights and not just blast and say I'm going faster with it etc. When I've done both I've not seen a difference on the timer. BUT I've read like you that other guys says it works great for them. Whether its perceived or real if they think it works it will probably help them in the confidence realm of their shooting. Again for me on the timer with good hits on all the drills I did it made no noticeable difference. Give it a try and then you'll know how it works for you Link to comment Share on other sites More sharing options...
Scott Steele Posted January 20, 2016 Share Posted January 20, 2016 I tend to like to break the edge and move the radius up just a little. Works for me but not for everyone. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
ParaGunner Posted January 23, 2016 Share Posted January 23, 2016 (edited) I tried a square bottom fps and didn't like it. Went back to a radius fps. Edited January 23, 2016 by ParaGunner Link to comment Share on other sites More sharing options...
teros135 Posted January 23, 2016 Share Posted January 23, 2016 Another approach to slowing the slide's momentum at the beginning of its movement (and reducing the dot's movement in recoil because the slide is hitting the frame more softly) is to alter the mainspring tension by changing springs. I originally had a 19# with 2 coils removed and recently put in a stock 17#, which is somewhat stiffer. The slide is noticeably more resistant at start of its movement backward when racking. More importantly, the dot seems to move less and my splits on 7- and 15-yard Bills were lower. And the trigger feels more crisp. To see if this was just because I was having a good day, I'm going to test this more "scientifically" by bringing mainspring housings with both springs and see if I (and the timer) can tell a difference. It'll be interesting. Link to comment Share on other sites More sharing options...
singlestackman Posted January 23, 2016 Share Posted January 23, 2016 Hello: Think of the leverage action on the hammer by the firing pin stop. If it hits the hammer further up it will take less force to overcome the mainspring so the slide will rack easier. I made a fixture so I can angle the firing pin stop in my Bridgeport. I have tried square, radius and the angled and the angled works better for me. The radius works very well but you have to get the radius correct to optimize it. Thanks, Eric Eric What angle do you use? 45* Clint Link to comment Share on other sites More sharing options...
RaylanGivens Posted January 29, 2016 Author Share Posted January 29, 2016 EGW flat bottom and use a slight radius (break the corner). I've been reading that my extra radiusing of the firing pin stop allows the slide to contain more energy, which causes more muzzle flip - a bad thing. There are a whole lot of variables in play here. A heavier mainspring and more squared stop might indeed reduce the secondary recoil impulse but the energy isn't disappearing. You are just experiencing it sooner. I experimented with an EGW square stop, beveled as described above. I ended up rounding it. Somewhat recently I tried a beveled stop again... still nope. Since it is less than $20 get one and try it out. EGW and Wilson both make them. Run some bill drills, check your splits, see how the sights track. It is a cheap experiment. There is plenty to read on it, but most of the square stop hype seems to revolve around "that was JMB's original design, so it is better" or "dude, the spring absorbs the energy". I currently have my stop cut to raise the contact point between hammer and FPS, and increase slide speed. Stroking, square stops, and other modifications that spread the recoil event over a longer period of time may very well shoot "flatter" in terms of perceived and/or absolute lift as you have more time to counteract the recoil impulse. Whether or not that results in a faster return to an acceptable sight picture depends on grip, vision, other design attributes of gun... it is preference. Buy one, fit it, try it, time it... I like EGW parts... They make an over-sized firing pin stop for a model 70... Is that the correct firing pin stop for an STI Edge? I'm currently running a 17 pound main spring in both my Edges... Link to comment Share on other sites More sharing options...
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