Nolan Posted December 14, 2003 Share Posted December 14, 2003 (edited) Well, I've broken another grip frame. This one is an SV grip and it's broken in the same place as the other three. I just put this grip on 2 days before the Nationals and it's never been off the gun. The previous thread was Broken STI grip frame Here's a picture of 3 of them (I was too lazy to dig out the 4th one). They are from left to right SV, STI, STI. All of them are breaking in the top of the mag catch area. It actually looks like the material is getting pushed OUT. Anybody else having this problem or have any ideas? Edited January 17, 2006 by Nolan Link to comment Share on other sites More sharing options...
EricW Posted December 14, 2003 Share Posted December 14, 2003 What looks like a crack in the plastic is really a weld line. That material was never really joined together to begin with. The phenomenon occurs due to the fact that the plastic had to flow around a piece of metal in order to form the hole for the mag catch. Weld lines are always weaker than the surrounding plastic because the flow fronts of the plastic are always colder when they rejoin one another. As long as the crack doesn't propagate or cause any other malfunctions it's probably OK. Stop drilling the crack may be a viable solution to prevent propagation. I think if you stop drill your current frame that it will be OK. Virtually nothing will bond chemically with nylon, so don't try glue as a fix. On the manufacturing end the only 100% solution is for S_I to remove the core (a piece of the mold) that forms the mag catch hole and machine the hole in a secondary operation. (Not cheap.) Another cause could be that some floor monkey was messing the press settings and molded a number of bad frames - which you happen to be getting repetitively. Process parameters can have a substantial effect on weld-line strength. The middle frame has the weld line in a different location, which would indicate the someone did indeed alter the processing parameters - substantially. Link to comment Share on other sites More sharing options...
Larry White Posted December 14, 2003 Share Posted December 14, 2003 I've got 100k plus rds thur 3 pistols and have never had a grip failure( well one, self induced with a grinder) What malfuction are these cracks causing? Have you tried changing mag release? Do you use a extended oversized button, really hi spring pressure ect? BE was talking once about useing a pin inside a mag release to limit overtravel. Strange deal. I just pulled out all three pistols and two spare used grips and checked them and all I can see is that I have some really dirty guns. Has to be something diffrent about your set up. Larry Link to comment Share on other sites More sharing options...
shred Posted December 15, 2003 Share Posted December 15, 2003 I think STI/SV do drill the mag catch hole as a secondary operation. I've got some with drill swarf remaining in there. Link to comment Share on other sites More sharing options...
EricW Posted December 15, 2003 Share Posted December 15, 2003 Nolan, Could there be something funny about the way your mag catch fits? Any sharp corners that dig into the frame and make a cut? Or maybe your catch has too much material and is getting bashed into the plastic when you seat a magazine. Why I ask is that plastic is really tough, right up to the instant a sharp cut is made into it. After that, It'll snap easier than a frozen Butterfinger. Even a very shallow scratch or cut can literally remove all the strength. It's a very dramatic effect. FWIW.... Link to comment Share on other sites More sharing options...
Nolan Posted December 15, 2003 Author Share Posted December 15, 2003 (edited) The set of grips in photo #2 are the set I modified by expoxying on a set of Navidrex grip panels to increase the grip diameter. All of the grips are broken at the rear of the mag catch hole. There is a 'shelf' inside that forms the bottom of the trigger bow slot in the grip. When the grip breaks the 'shelf' drags on the bottom of the trigger bow causing a very inconsistant trigger pull. The mag catch can slightly rotate up and down causing feed problems. That's not a mold line, it's the edge of the crack and this has happened on both my Limited gun and my Open gun. Both guns have un-modified SVI mag catches. I guess I'll replace both the grip and the mag catch and see what happens. Here's a shot of the trigger bow slot. Edited January 17, 2006 by Nolan Link to comment Share on other sites More sharing options...
sfinney Posted December 15, 2003 Share Posted December 15, 2003 Only thing I can think of is..... just how hard do you seat our mags in your gun ? Maybe a combo of brake cleaner or solvent on the plastic making it brittle, and a an overzealous mag change? I've never had any of my 4 or 5 grips break there... I have seen some crack due to over relieving though. But I agree its something unique to you or your gun setup to have that many break the same way. Link to comment Share on other sites More sharing options...
diehli Posted December 15, 2003 Share Posted December 15, 2003 You and Erik, man... sheesh! Hope you get it worked out. I'd put money on a he-man grip/mag catch combo causing the problem. Exuberant mag changes might exacerbate it. Link to comment Share on other sites More sharing options...
EricW Posted December 15, 2003 Share Posted December 15, 2003 Here's an idea out of left field: Have you thought about lowering the mag catch notch in your mags so that when you seat them, there's no force pushing *up* on the mag catch? One of BE's "edge safe swiss miss" files ought to do the trick. It won't affect the height or retention of the mag. Link to comment Share on other sites More sharing options...
Paul B Posted December 15, 2003 Share Posted December 15, 2003 I'm not a gunsmith, nor do I play one on TV, but all the grip frames look like there's some torque going on at the rear of the mag catch. The frame is actually gouged out at that point. Someone suggested too heavy mag changes and that may be it. One other thing you might try is to polish and maybe relieve the bottom of the mag catch lug (the thingy that actually goes in the slot of the mag). The underside of this is ramped and you could take a little off and polish without compromising the "shelf" that locks into the mag. Maybe more at the rear as this looks like the area that is getting the stress. Good luck. Link to comment Share on other sites More sharing options...
old shooter Posted December 15, 2003 Share Posted December 15, 2003 Just out of curiosity, are the grip frames truly nylon? I don't know if nylon can be welded, but I have welded polypropylene, polyethylene, pvc, polycarbinate, and teflon. Eric, can it be welded? Mike Link to comment Share on other sites More sharing options...
Flexmoney Posted December 15, 2003 Share Posted December 15, 2003 Just for clarity...what EricW was talking about earlier isn't a "mold line" like most of us would think of it. Eric is talking about a flow line...from the plastic, in a liquid form, flowing around a solid object. I think of it like air getting split by the leading edge of a wing...then the two "flows" of air meeting on the back side of the wing. In plastic, I wouldn't think the line would be clean and straight. Nolan...something is putting pressure on the frame (likely in this area). And it is cracking at the weak point. It is most likely you, your mags, or your mag catch. (pretty simple, huh? ) Link to comment Share on other sites More sharing options...
EricW Posted December 15, 2003 Share Posted December 15, 2003 Just out of curiosity, are the grip frames truly nylon? I don't know if nylon can be welded, but I have welded polypropylene, polyethylene, pvc, polycarbinate, and teflon. Eric, can it be welded? Mike I'm 75% certain that the grip is nylon or a nylon blend - probably with some glass filler. Nylon is generally used for guns just because of the chemical resistance. Glass fiber is generally added to improve strength and rigidity. Unfortunately, I have no clue about plastic welding. That's totally out of my expertise. The nylon probably isn't a problem, but the glass filler would be a bugaboo. If it was possible, by the time you welded it up and re-machined everything, you might as well have bought a new grip. The grip has a total value of maybe 1 or 2 bucks. It's the secondary operations and the tooling that make it cost $90. Link to comment Share on other sites More sharing options...
shred Posted December 15, 2003 Share Posted December 15, 2003 Glass-filled nylon is what I think I've heard them referred to as.. anyway, another random thought.. could extra force pushing forwards on the trigger bow cause this? Nolan, does your grip safety move? Link to comment Share on other sites More sharing options...
Julien Boit Posted December 15, 2003 Share Posted December 15, 2003 I experienced something like this in the past. I had a SPS grip mounted on my training pistols and it broke at the same spot as you Nolan. I found that the front hole on the grip A was not perfectly corresponding with the frame hole. I also noticed that the area B was a little too wide and needed some trimming to perfectly fit the frame corresponding area. Before I noticed it all, what resulted is a crack on both side of mag catch housing C like you experience on your grips. I believe that the fact that the front hole A and the B area being way too tight made a crack after firing some rounds caused by too much tension in the mag catch area. Maybe you might look around here. If that's not that, well i'm .......................... Link to comment Share on other sites More sharing options...
Nolan Posted December 16, 2003 Author Share Posted December 16, 2003 Thanks Julien. I checked the grip fit and the front screw just slips right in. So that probably isn't my problem. On second inspection the mag catches are both STI, not SVI as I originally thought. As per the STI advertising they are "Non-beveled for no over-insertions" The bottom edge of the mag catch is very square. I noticed that one mag catch is actually slightly peened where the bottom edge of the mag body cut is hitting. I think it's time to break out the Dremel tool and make the bottom of the mag catch look like the one on the SVI website or just do the right thing and buy a new SVI mag catch to go with the new grip. Link to comment Share on other sites More sharing options...
dvc40jim Posted December 18, 2003 Share Posted December 18, 2003 For some strange reason, some grips break and others don't. The spot where yours keep breaking is a common occurance. Of course I am only working on about 20 grips a week. If you want, I can actually repair the broken grips, give you plenty of spares. The "Plastic" can be welded and the problem will go away, the area will actually be stronger than when you first got the grip. If you haven't noticed before, one brand grip is better material than the other, and less prone to break, offline I will tell you which one and why if that matters. Online I can say that alot of people work on thier own grips, undercuts, textures, reductions and such, and alot of people send them my way to fix what went wrong with the homesmithing. Especially if we paint a grip, its pretty hard to tell where the repair was and it won't break there again, just like welding metals, the weld is the strong spot at that point. Link to comment Share on other sites More sharing options...
ErikW Posted December 18, 2003 Share Posted December 18, 2003 one brand grip is better material than the other, and less prone to break Well now that's very interesting, because I was told both STI and SV get the same grips from the same mold and that SV removes the molded STI logo and inserts their own SV emblem. Link to comment Share on other sites More sharing options...
shred Posted December 18, 2003 Share Posted December 18, 2003 one brand grip is better material than the other, and less prone to break Well now that's very interesting, because I was told both STI and SV get the same grips from the same mold and that SV removes the molded STI logo and inserts their own SV emblem. That was absolutely true as of several years ago (I have a sack of grips in various stages of the 'conversion'). It may not be anymore. Link to comment Share on other sites More sharing options...
joshua Posted December 19, 2003 Share Posted December 19, 2003 Nolan, the way you're breaking grips and Erik Warren breaking sights on limited guns it's my conclusion that the air in the bay area is causing all these breakage Link to comment Share on other sites More sharing options...
Nolan Posted December 20, 2003 Author Share Posted December 20, 2003 Yeah I think it's all the MTBE pollution in the air! Link to comment Share on other sites More sharing options...
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