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What effect does the poundage of the recoil spring have on the rate at which the action cycles? What difference should I expect to see between a 16lb and a 24lb spring?


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Assuming using the same bullets and same gun, the heavier recoil spring should increase the amount of cycle time because it will take that much more energy to push the slide back for its cycle. Assuming that the recoil was equal to the spring weight and parts friction, you would get no movement. Excess energy above the spring and friction drive the slide rearward. More excess energy means the slide will be driven back even faster. So, the slide should move faster with a 16# spring than a 24# spring since there will be more energy available after overcoming the spring and friction.

Here is where the timing becomes important. If the slide moves too fast, it is possible to have too little time to get the spent case out and the new round in the chamber and so there can be malfunctions. Also, when a slide is too fast, that means the extra energy eventually is dumped into the frame when the slide reaches the end of the stroke. You don't want to have the gun pounded like that since it can eventually damage the gun.

If the slide moves too slow, it is quite likely that it won't complete a full cycle and as a result, will not move far enough back to pick up a new round.

What the shooter wants is a balance between ammo, gun, and spring. Shorter guns like commanders and officer model using high # springs to slow the cycle as much as possible, in part compensating for the reduced mass of the shortened slides.

Browning designed the gun to shoot 230 gr unjacketed lead ball ammo given the type of powder used at the time that produced a certain pressure that fired the bullet at 850 fps and cycled the gun. The 16# spring was optimal. Nowadays, we have a variety of attributes to take into account such as lighter bullets (e.g. 200 gr, 185 gr., 165 gr)and varied amounts and types of pressures. There is faster burning powder and slower burning powder. Some rounds are loaded hotter than others. The trick is to match the spring weight to the ammo and gun so that the gun cycles reliably, but is not getting battered. If everything is in balance, a gun with a 16# spring and specific ammo should handle very similarly to when the gun is fitted with a 24# spring that balances for much hotter ammo.

For example, I shoot Blazer 230 gr FMJ ball for practice. It has been my observation that the felt recoil on this ammo is similar to the recoil I experience shooting 230 gr Hydrashok. Both have a greater felt recoil than what I feel with Fiocchi 230 gr ball that I used to shoot more. I like to shoot the Blazer because it is cheap, but also because it behaves very similarly to the Hydrashok that I can't afford to practice with. Being as the felt recoil is higher for these two rounds, I went with a 22# recoil spring instead of the 18.5 that came with the gun. The gun cycles extremely reliably with the 22# spring and those two ammos.

As an added benefit of the higher poundage spring, there is more force to pick up the next round from the magazine and drive it up the ramp and into battery. One of the common problems that happens sometimes is that rounds fail to feed and are hung up on the ramp. The extra strength helps keep this from happening.

Remember, it is all about balance.
 

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So DNS. I reckon with the stock 18.5 pound spring you're shooting a Commander. I too like to practice with Blazer and was considering moving to a stronger spring as many seem to favor doing so with full power ammo. I've heard 20# alot but if you're getting good results with a 22# spring I think I'll try that out too. Figure I'll pick up a fresh 18.5#, a 20#, and a 22# to play with. Thanks!
BTW, I assume a stronger spring will help the issue of throwing the spent brass really far which I seem to have a problem with. That and the mouth of the case gets a ding in it even though the ejection port is flared/lowered. I don't reload so it's not that big of a deal and I haven't had any related stoppages as far as I can tell, just doesn't seem right.
 

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If you use a heavier-than-normal spring, the total cycle time might be the same as with the spec spring, but the timing will be completely different. With a heavy spring, the slide will move rearward more slowly, and move forward more quickly - just the opposite of what I'd want. I want the gun to stay locked in battery as long as possible, then move rearward smartly, to ensure reliable extraction and ejection. Then, I'd want the slide to come forward slowly enough to pick up the next cartridge without pushing it ahead of the extractor or pounding the bullet nose against the frame or barrel throat. Obviously, a 1911 can reliably feed with a 8#-10# spring, so you don't need any extra spring to handle the feed side of the cycle, and if you use a heavy spring you might find that rubbing your thumb or cover/barricade against the slide will rob it of enough energy to cause an ejection failure. I think people are way too concerned about the "battering" that takes place in the normal cycle (the slide IS supposed to come back and sandwich the spring guide against the frame, after all), and not concerned enough about the battering of the bullet and the lugs/slide stop on the on the return, that is caused by using a too-heavy spring. I read an article about Dick Casull's work on adapting the 1911 design to his .38 Casull cartridge, and he did a lot of fiddling with spring rates, trying to keep the gun locked-up during firing, and getting reliable cycling, and he concluded that it is the weight of the barrel and slide that really determine the speed or rate of unlocking, and that you can't do much with spring rates to affect it. I've always thought that if you want to slow unlocking by increasing your spring rates, it should be the MAINspring, and not the recoil spring that should be made heavier. The heavy recoil spring can introduce negatives to the equation, while increasng the rate of the mainspring can slow unlocking while remaining otherwise fairly benign.
 

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I agree with RickB, and Casull's findings.
For a theoretical explanation please go to my "spring rates" and "1911 dynamics" posts in the gunsmithing section.
It is mainly the mass of the slide and barrel and the goemetry of the locking system that keep the slide locked initially, recoil spring has little to do. Of course, for a given power factor and slide/barrel weight there are reasonable margins for the spring rates.
After that, spring weight does affect many things, please also check: http://www.1911forum.com/ubb/Forum1/HTML/003953.html
 
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