How to weaken a coil spring?

[Potashminer]

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Potash , I'm not familiar with the workings of a Rem 783 but if it is a "positive angle" sear latch-up system similar to what Savage uses in their inexpensive Axis, removing spring tension from the firing pin spring will also reduce trigger weight. By Positive angle latch-up I am meaning that the trigger sear actually catches the hook on the firing pin to hold it back and any reduction in firing spring tension also reduces hook engagement tension so for a young lads rifle , I would pay close attention to this.

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Good points! However, I think the result of using the Rem 700 springs, even with a couple coils removed, is intended to result in a greater spring force, than what the original factory 783 spring is delivering. So increased bolt lift is likely a result - to cam that cocking piece up that ramp, and the trigger pull thing is for sure something to be looked at, when the time comes. From discussion above, I am now thinking a thorough cleaning, scraping and polish is likely the first step, before I start swapping parts. Will really suck if a deer finally shows itself to grandson, and "Grandpa's" gun went click - at that point, reasons "why" will not really matter...

The hand loads he was using had 55 grain V-Max bullets - intention was to blaze away at gophers and coyotes in his other Grandpa's pastures - get used to safe carrying, manipulating the detachable magazine, picking his "safe" shots - passing up shots when prudent, etc., long before loading up with "deer bullets".

 

[Leeper]

Can I disagree about cutting a 28lb spring just makes it a shorter 28lb. Spring rate is actually force / distance so I’m guessing the spring is lbs / in. Cutting the spring shorter would result in the spring rate increasing as you have fewer coils to compress it takes more force to compress the same distance. That said by cutting the spring you would also be decreasing the amount of compression likely resulting and overall decrease in total force. As a side note cutting a spring results in an end that’s no longer flat and can affect function in somethings. I do completely agree that changing wire diameter or spring pitch are the ideal way to adjust spring rate. Depending on how much spring travel you need you can also try shimming your existing spring increasing “preload” vehicles do it all the time.

Yes. Shortening a spring makes a stiffer spring while, at the same time, reducing preload. If you heat the final coils to collapse them rather than cutting the spring, you will effectively stiffen the spring while leaving the end intact. Put the collapsed coils on the cocking piece end.

 

[porpoise]

If you reduce preload by cutting coils you have effectively made a weaker spring as long as it operates over the same distance as it did before you cut it.

 

[Leeper]

You have not made a weaker spring. you have made a stiffer spring but reduced pre-load. replacing the removed coils with a spacer which restores the total amount of compression, will restore preload and increase the compressed load. Now, one must also recognize, compressing a shorter spring the same distance will stress the spring to a greater extent which will reduce spring life.

 

[porpoise]

OK but did you ever cut a spring to get the effect I stated. Also it's not a stiffer spring it's the same one. To compress fully the longer and shorter springs would take the same weight the short one would just stack up quicker

 

[Potashminer]

For better or worse, job is done. three pictures below -

Top spring is original from the 783 - lower spring is the Wolff replacement 28 pound spring for a Remington 700 Short action



This is the spring with about 1/2" cut off with dremel disc, then threaded through that plate that is held in the vice - I was able to use a fine tip torch and turn the last full coil to red - without the rest of the spring seeing torch heat. I let it air cool - that last coil then squeezed closed nicely with a pair of needle nose pliers.



End result - two coil springs about the same length. I installed the heavier one with a bit of fussing to collapse it - required rigging a clamp - not enough strength in my fingers.



To be seen whether that improved anything. He had two "duds" - primer did not fire - my son said they were re-chambered and attempted 3 times - out of 33 shots - the rest before and after fired fine. He now has another 100 rounds from exact same components. To be seen what happens as those get fired off. His two "duds" fired off fine in my Ruger 77.