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Is it true that you should cut your recoil springs down to the point that they may fully compress inside the plug or reverse plug. I was instructed to do this by a G.M. IPSC shooter. His reasoning sounded good but I would like a few "smiths" opinions. His reasoning was that if the spring fully compresses but doesnt fit, it wil batter the gun. Thanks in advance for your help.
 

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Hi Shane
You may have misinterpreted what he said or he was speaking in general terms. The recoil spring must not compress to coil bind before the slide hits the shok buff or spring guide. If you take your slide ,bushing and spring plug. And assemble them, Measure from the back of the slide to the bottom of the spring plug. (Gov't mdl. usully about 1.6"-1.7")this would be the max compressed length.If you shorten it to compress into the spring plug (usually about 1.375"inside)You will be cutting off a lot of spring for no reason. I trim my springs to 1.6" compressed.Keep in mind that a reverse plug is a whole different animal. It is flush with the back of the slide. And therfore it must compress fully into the reverse plug.The bottom line is that you do not want the spring to get to coil bind before the slide is fully retracted.
Hope that helped

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Scott D. Mulkerin

www.sdmfabricating.com
 

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I am not a smith, but you are kidding, right?

When do you know when you have cut enough off? If you cut down the spring, it won't have as much force to keep battering from occurring or will won't have it for long.

The IPSC shooter might have a good reason for doing so. IPSC shooters use powered down loads and hence can use powered down springs. Why he wouldn't simply choose a lessor weight spring is beyond me, however.
 

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You are absolutley right,there is no reason to cut down a spring. Unless it is too long.Which I have seen many times.This holds true to what ever weight spring you are using . If you use a quality spring from a reputable supplier 99 out of 100 times every thing will be fine.When I say I trim them to 1.6" That is only about 2 coils from coil bind.Most springs are shorter than that, about 1.5". But If it is too long, the spring becomes solid and trys to push the spring plug out the front of the gun.This breaks bushings and batters the frame and ruins the spring. It is not comman but it happens. It is just one of those things I check.I am not saying you should cut your springs.(unless they are too long)

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Scott D. Mulkerin

www.sdmfabricating.com
 

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If you will measure the total available length for the spring at full recoil like Scott said, and then measure the wire diameter of the spring and multiply this by the number of coils, and compare the two numbers, you are there. Measuring the spring this way gets you its fully compressed length-- otherwise you're going to need 4 big hands, Z-rated safety glasses, and a steam-powered dial caliper! As long as the spring is not coil bound in full recoil you're OK. If you had to nip a coil or two to prevent it, I don't see a prob.

I do sometimes cut recoil springs for some special applications like for shooting 130 power factor loads out of a compensated .45.

Scott, somebody mentioned a recoil spring tester and you in the same sentence. Is this a product you make? Is it the rod-and-weights thing I saw a few years ago for testing a spring's rating? I suppose with such a took you could easily close the spring and measure it's coil-bound length.... info please, and a pic if you have it.
 

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Ned, the SDM spring tester that Brownells sells is the one created by Scott (part # 864-100-000) and I'll verify that it works. I use Wolff springs and have found a few that were slightly out of spec (a 20# that measured 16#).
 

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Well, I expect to re-acquaint with Scott at a pinshoot here in MI next month. That means he'll have a vehicle backed in and wide open and unattended while he's on the line shooting, a shoplifter's dream come true.....
 

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ISMI recoil springs come over-long, and they (might) need to be trimmed for the specific gun. I assembled my gun without the spring, pulled the slide back, and made a reference mark. Then I installed the spring, and checked the slide travel again. I needed to take off 1.5 coils to get full slide travel. That's different than "tuning" your spring rate by trimming coils. If you want a spring of reduced rate, get a full-length spring of the proper rate.
 

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Please note this is the "other" Shane, and I completely agree with the advice above. Never any reason to trim a recoil spring. Get one of the correct weight to start with.
 

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Here's my easy way to check for coil bind no calculations needed. Put a small piece of masking tape on the side of the slide and another on the side of the frame. With a known good spring or even without a spring just the guide rod pull the slide back all the way to the rear and make a mark from one piece of tape to the other. In other words the mark on the slide and frame line up exactly with the slide completely to the rear. Reassemble with your new spring and if you pull the slide back and the marks line up your ok, if not you know you need to trim the spring until they do. You really should do this everytime you change springs or guide rods. try it it's easier than it sounds.

JJ
 

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Discussion Starter #13
Guys, great advice, thank you very much. As most of you interprted, I was speeking more of tuning to avoid bind than blindly hacking off coils heheh. I in fact have been experiencing shock buff damage and I have a pretty heavy spring in there, jeese its been a while but I think it was an 18 pounder. Now that I have a more detailed method to check, I will let you all know the outcome. Thanks again to all of you.

To Double Naught Spy, you might have wanted to read a little before speaking. As you can see by my original post , we are talking about IPSC. As for IPSC using powered down loads, I really don't think you know what you speak of. I realise they have lowered the power floor for open. However my load works to good to fiddle with. My shooting partner feels the same way. I shoot a .45 to a power factor in the mid 180s.I shoot a 155 grainer at about 1200 fps. He shoots a 9X25 Dillan to about 185. I don't really think these are wimpy loads.

Damn Spelling errors

[This message has been edited by shane45 (edited 06-18-2001).]
 

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JJ's method is what I tell all my customer's to do every time they change a recoil spring. I've had several customer's over the years with broken barrel bushing flanges from too long recoil springs (the majority Kimbers).

I have put Scott's spring tester to good use and would put up a heck of a wrestling match to keep it, but most of my customers haven't ponied up the coin for their own.
Now if I can figure out a rate schedule for helping folks sort through bags of "take-out" recoil springs & identifying the current weight, I would be all set!

John
 
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