Understanding Recoil Spring Weight and Effect

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Understanding Recoil Spring Weight and Effect

Post by chiltech500 on 3/29/2015, 5:25 am

Hello,

I have restructured a wad gun which had an aluminum frame mount and used an ultra light Burris reflex sight - switched to a full length rib and an Ultradot. The rib and Ultradot on the slide make for a pretty heavy slide - the rib weighed more than I expected because it's made of steel vs aluminum.

Naturally I'm shooting lighter loads; to give an idea with a 200gr LSWC: VV310 4.0 gr. was my favorite for 1911's.

But need to figure out a 1911 load for WST  - was using 4.0-4.2g  WST based on work ups on two 45acp revolvers.  Have not accuracy tested those loads on my Baer wad gun yet, because I just started shooting it again -  have WST 4.2 and 4.5 to try out for starters.

Using current loads as listed above can folks give me ideas of what they would use for a recoil spring weight. My current spring is 16 lbs but it's worn down.

Thanks

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Re: Understanding Recoil Spring Weight and Effect

Post by kc.crawford.7 on 3/29/2015, 5:38 am

I would start at around 11 pound and see how the function goes.  What weight main spring do you have in the gun?
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Re: Understanding Recoil Spring Weight and Effect

Post by chiltech500 on 3/30/2015, 4:09 pm

I believe a 16, and have the Wolf spring kit. The slide feels so heavy because of the steel rib and Ultradot 1" that the round can barely move it back. That said have not had any feed issues and I belive the slide only failed to lock once in 20 plus magazines.

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Re: Understanding Recoil Spring Weight and Effect

Post by DavidR on 3/30/2015, 4:48 pm

10 lb
with bullseye or v310, 11 with wst,should do it wst  has a higher pressure per grain than be powder.
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Re: Understanding Recoil Spring Weight and Effect

Post by farmboy on 3/30/2015, 9:35 pm

I use 4.3 wst  under 200 or 185 lead SWC's and 10lb spring  - very accurate
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Re: Understanding Recoil Spring Weight and Effect

Post by Froneck on 3/31/2015, 10:00 am

My preference is not to lighten the spring. Doing so has caused closing problems. I prefer to shorten the link to get the gun to function flawlessly. The most important thing in an accurate 1911 is to have it fully closed and tight against the slide stop pin.

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Re: Understanding Recoil Spring Weight and Effect

Post by Jon Eulette on 3/31/2015, 10:21 am

Froneck,
How does shortening the link effect this? As I'm sure you know the slidestop rides the link until the slidestop meets the bearing surface of the bottom lugs and unlocks barrel from the slide lugs during recoil as slide travels to the rear. Short link only begins pulling barrel out of slide lugs minutely sooner (0.005-0.010"). Short links have a tendency to allow slidestop to batter the radius at leading edge of the bottom barrel lugs. Battering causes vertical stringing at 50 yards. If you relieve the battering then you have less lockup/bearing surface for keeping pistol in battery; result is loss of accuracy and increased recoil.

Link length is determined by barrel lug to slidestop pin fit. Will vary from pistol to pistol. Link length is determined from this! I'm of the opinion that you cannot indescriminately decide what your link length will be. It's dependent on upper barrel to slide lug fit and the dimensions of slide to frame fit (slide lug distance to slidestop pin hole in frame). 99% of the pistols I work on have the link incorrectly fit.

Too light of recoil spring also can cause larger groups at 50 because the barrel comes out of battery sooner. From a Ransom Rest not always the case, but from hand I guarantee it!

Jon
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Re: Understanding Recoil Spring Weight and Effect

Post by Bullshooter on 3/31/2015, 11:48 am

I agree that a light recoil spring negatively affects lockup and accuracy and prefer not to go lighter than a 13 lb spring with a slide mounted scope. Using lighter aluminum split rings, this is usually achievable. My standard indoor and short line load is an H&G 68BB bullet behind 3.6 grains of Bullseye. It's a very accurate load and functions fine on my gun along with a 14 lb Wolff variable power recoil spring. 

I'm in the minority here I know, but I use the standard low Ultradot split rings, and I never remove them. This saves several ounces over the popular Weaver or Burris steel rings. Since I never take the aluminum rings off, I'm not concerned with repeating the zero replacement.

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Re: Understanding Recoil Spring Weight and Effect

Post by Froneck on 3/31/2015, 1:11 pm

Short links are made in thousandths of an inch. One can easily modify the short link to make it slightly longer if necessary. The link is the device that pulls the barrel out of the upper lugs. Basically the 1911 is delayed blow back. Recoil unlocks the lugs and the blow back completes the operation. Unlocking the lugs at a slightly earlier moment measured in thousandths will give blow back a greater force and over come a heavy spring! If the lower lug is not done correctly it will cause many problems, most make the radius too large, I use a very small radius! Furthermore that larger radius will cause upper lug rounding because the barrel comes down at a radius and then push up with too much force causing drag but as the lugs near alignment the area decreases creating an ever increasing pressure in pound/square inch rounding the upper lugs coming out and going in!
 A light spring will cause it to come out of battery sooner simply because it will take slightly less recoil and why it works with lighter loads, lighter spring has about the same effect of making the link shorter. But the lighter spring will cause closing problems. Hammer spring is also included during opening  Being that the lower lug clearance is needed for a shorter link and the link lengths are in thousandths, it is a simple task to move the front face of the lower lug back a few thousandths! The link is the device that pulls the barrel out of battery but it can't until the slide stop pin allows it! Again another reason I do not use a large radius on the lower lug.
 I don't think the larger groups are because it comes out of battery sooner, recoil starts after the bullet as left the barrel. But lighter spring will cause larger groups because the gun did not lock up tight the same way every time, the main reason I do not use light springs! Plus forward travel closing is not aided by hammer spring. Light recoil spring and over rounded lower lugs are a prime cause of failure to completely close causing alibi's and bigger groups. Probably why as you said it will shoot bad by hand and not seen in fixed rest being that the body absorbs some of the energy.
 For example I built a 1911 wad gun for my son Adam, He shot usually every day after school (about 150 rounds) we shot every match we could get to every weekend for 2 years! The lugs in the gun looks just about as good as the day I built the gun and there is NO rounding. At 18 years old he won our club match with a 2629! He also still has the Junior Record. He shot the entire season without 1 alibi!  After 2 years of shooting he took the gun to the AMU, they tested it and it shot 50 rounds in the "X" ring and the gun has a 20 pound spring and Ultra Dot slide mount! Or my other son purchased a Kimber from a guy at the club. I told him not to but he did anyway. Another butcher job, someone cut large radius in the lower lug and had an 8 pound spring that required Factory ball to cycle the gun. I spray welded the lower lug, re-cut the angle and installed a shorter link. My son said that will never work! Put the gun together, used 18 pound spring and it cycled wad easily, redid the bushing, it shot just under 2" at 50 yards! That was 10 years ago, he don't shoot a lot but it's still shooting great!
 I had the great fortune to become friends with a guy that graduated from Colorado School for Gunsmiths. We spent a lot of time discussing the function of the 1911. (yes he knew about other types but I was interested in only the 1911) Plus George Madore and Floyd Aikman added quite a bit too as far as getting accuracy from the 1911. Combined with their teaching I was able to build some outstanding 1911's And of course my son Adam that was twice the NTI winner at Perry, 2650 shooter with both right and left hand and now coach of the AMU and gives me information that the AMU is using! I was his teacher, now he is mine!!

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Re: Understanding Recoil Spring Weight and Effect

Post by DavidR on 3/31/2015, 2:34 pm

All this is very interesting as I have been experimenting with different recoil springs, so what is the softest spring that will fully lock the gun up. Right now it has a 10lb in it and running 3.8 be with a 200 hg68 lswc. Would it be better to bump the load up and go to say a 12 or 13?
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Re: Understanding Recoil Spring Weight and Effect

Post by Froneck on 3/31/2015, 3:20 pm

Actually it will depend on the gun. I usually test it the other way, increase spring weight shooting one round loaded in the mag. When the spring weight it too much it will not lock back. I also shoot a few strings of slow fire and check to see that the slide is completely closed every time I shot. I look for a reference point or make one so I can see a very small change. Another thing I look for is that "bump before it closes. The slide should go to battery with a smooooth forward motion. If you have the "bump" either the link is pushing the barrel up or the radius on the lower lug is too large. A very large radius or a too long a link that is usually modified will cause the link to push-up the barrel.
 I set my guns up the other way. I use a 18 pound spring and adjust the link length to make it work. Then test it again as mentioned above an increase the spring weight to 20 pounds if I have to!

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Re: Understanding Recoil Spring Weight and Effect

Post by Bullshooter on 3/31/2015, 3:33 pm

 >>> I don't think the larger groups are because it comes out of battery sooner, recoil starts after the bullet as left the barrel.


Gotta disagree with you there, according to Newton's third law of motion, for every action, there is an equal and opposite reaction, meaning recoil begins the moment that bullet starts moving forward.


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Re: Understanding Recoil Spring Weight and Effect

Post by C.Perkins on 3/31/2015, 3:47 pm

I have always used a recoil spring that is just heavy enough that once in a while after the last round fires, it will lock back and the empty casing is still sitting on top of the empty magazine or on top of my hand.

I quit reloading lead and now only load jacketed ammo since I do not shoot as much anymore.
With the Clark Sr. long slide, aluminum slide mount, 1" Utradot, Leupold PRW rings and using a 16# recoil spring does what I stated in the first paragraph.

The load is 4.6gr of BE under either a Nosler 185gr custom competition for the long line or Hornady 185gr button nosed for the short line.

Pistol is accurate and reliable with no alibies to date.

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Re: Understanding Recoil Spring Weight and Effect

Post by DavidR on 3/31/2015, 4:24 pm

Does anyone recommend tuning a recoil spring by cutting coils?
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Re: Understanding Recoil Spring Weight and Effect

Post by Bullshooter on 3/31/2015, 4:30 pm

IMHO, that is never a good idea. Using a lighter variable power recoil spring is the way to go. I also try to get to the point where the last case in the magazine barely clears the slide.

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Re: Understanding Recoil Spring Weight and Effect

Post by r_zerr on 3/31/2015, 5:38 pm

Cutting coils does not seem to me to be the thing to do since this changes both the preload, (closed/locked-up force) and full compressed force (slide all the way back).

I have not checked my springs, but based on the different lengths, # of coils, wire size and etc., I am guessing that this is to try to "ideally" make the pre-load forces as similar as possible between them, along with the other factors.  Which, as I sit here typing this makes me wonder a lot more.  I always figured like Walt on sizing the spring:minimize velocity, yet full function for the load used.  I am still seeking enlightenment.

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Re: Understanding Recoil Spring Weight and Effect

Post by marlin1881 on 3/31/2015, 8:39 pm

re: WST load for bullseye...  With the 200 SWC bullet, I would suggest 4.2gr.  Any lighter than that, and you'll get some unburnt granules hanging around in the action/slide and it can cause problems.  This WST load will also run a 185gr bullet, but I prefer to bump it up to 4.5gr as it runs cleaner there.

WST makes an accurate bullseye load.  Run it to where it just burns clean for you.  It cycles the slide with an UltraDot on top, using a 10-12lb spring (at least, that's what I do).

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Re: Understanding Recoil Spring Weight and Effect

Post by Froneck on 3/31/2015, 9:21 pm

Cutting the coils is not good! As previously mentioned by r_zerr it will change the preload. The most important situation of the 1911 is the closed action ready to fire! There is where all the accuracy happens! If it don't close the same way every time accuracy will suffer. Most of the time failure to completely close will cause vertical stringing.
 I'm also not fond of the ransome rest, yes it can hold the gun better than I can but when using it to test accuracy I also use the sights. With every shot made out of the rest I adjust it so that the red dot is in the exact center of the target.

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Re: Understanding Recoil Spring Weight and Effect

Post by chiltech500 on 4/2/2015, 5:24 pm

Gentleman you are quite advanced in your knowledge.

Does the lighter recoil spring result in a more forceful contact of the slide at the end of its' travel? Is the function of the lighter recoil spring to allow a lighter load to work the slide? I'm picturing that a heavier recoil spring requires more powder but slows down the slide on its' movement backwards. Is that correct?

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Re: Understanding Recoil Spring Weight and Effect

Post by chiltech500 on 4/2/2015, 5:29 pm

I have now tried WST 4.3 and 4.5 pushing the lswc 200g and will retest again this weekend. Seems that the 4.3 is adequate and don't know if the 4.5 presents any advantage.

My setup it turns out is heavy because instead of checking here for advice, I bought a steel rail - chose the one I did because it has adjustable iron sights to use as an option and didn't realize it was steel. But then I didn't ask, shame on me.

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Re: Understanding Recoil Spring Weight and Effect

Post by Jon Eulette on 4/2/2015, 6:13 pm

You can have the rail machined on the bottom to lighten it. You won't be able to tell visually it's been lightened when mounted.
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Re: Understanding Recoil Spring Weight and Effect

Post by Froneck on 4/2/2015, 8:25 pm

Chiltech the spring has a rate either in compression or extension. Think of a fish scale 1 pound moves the scale to the 1, 2 pounds to the 2 and so on. As the recoil spring compresses it requires more weight. The hammer spring is also involved but as the slide moves back the spring pressure decreases because of the location of the strut on the hammer and the angle of engagement between the hammer and the slide. Yes if your spring it too light the slide will travel to the end of it's travel as stop abruptly. Something you want to avoid especially if you have a slide mount scope.
 Yes a heavier spring will require more powder if nothing else is changed.
 Also remember that spring is also required to close the slide and over come weight of the slide,the friction of the round entering the barrel, the slide ways, the bushing, eventually the round in the clip rubbing the bottom of the slide and the slide stop pin pushing up on the barrel. All without the help of the hammer spring.

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Re: Understanding Recoil Spring Weight and Effect

Post by chiltech500 on 4/4/2015, 6:00 am

Thanks so much Froneck for the great explanation. Reportedly the slide striking the frame too firmly also causes more stress to the connective tissue in the elbow, which a gent with bad tendonitis told me. I have a tennis elbow going on.

Sounds like I seek a spring that has adequate resistance to being compressed without overpowering the bullet charge and enough strength to close the slide properly.

Does the use of a slide heavier than most guys' here- but with a similar light powder charge - suggest a spring weight as low as 12 lbs? As a caveat, I have no knowledge base other than knowing stock was around 16 to 16.5 lbs. I did buy a Wolf spring kit with varied weights to try.

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Re: Understanding Recoil Spring Weight and Effect

Post by Froneck on 4/4/2015, 8:57 am

I would assume your correct, though I am not a doctor. Making the slide heavier will work and using a slide mount scope does change the recoil. The reload in slide mount after the gun fires is more like a slow constant push whereas the frame mount feels like a quick snap. Back when scopes started showing up on Bullseye guns a grip mount was available. Was an aluminum casting that fit on the left side in place of the wood grip panel. It extended up and over the slide and accepted Weaver type mounts. Fit tight on the grip screw bushings. I could not keep if from eventually getting loose. It was suggested roll pins be inserted in various locations but the recoil egged the holes and it came loose even though the contact area was loctited to the frame. Later some were milling a recess and tightly fitting a steel insert that also fitted tight in the opening in the frame under the grip panel, worked for a while but eventually recoil loosened it to. Changing to slide mount ended my problems. Over the years various other frame mount were developed but all that used Aluminum failed. Yet the slide mount Aluminum weaver type mount is used quite a bit these days and has no problems. Frame mounts also have been developed but I know of none that are Aluminum. Steel is used with quite a few screws to firmly attach it to the frame so you can see the stress difference between a weighted slide slow movement and the fast snap from the standard slide. Another point is my son Adam went to the Army AMU right after High School and Basic training, they had frame mounted red dots. He told me he did not like it because of the quick snap. They did change to slide mount but decided to go back to frame mount again. Because of the amount of shooting he did and the shock from the frame mounted gun his wrist began giving him pain. He had a slide mount installed and started shooting left handed to give his right a rest. (got quite good left handed broke 2650 and is only one of the very few that have done it with both right and left hands) He's back shooting right handed but will only shoot slide mount.
 So those long a boring stories to suggest you look into slide mount red dot or ribbed iron sights. However you have to be careful when using light springs, as I mentioned before the most important condition the gun be in for a target shooter is when the slide it tightly closed the same way every time.. Keep in mind the barrel is locked up at an angle and is not parallel the the top or bottom of the slide. That angle is formed between the contact with the bushing and slide stop pin about a distance of 4". therefore .001 change will cause ,450 at 50 yards. Also because the slide is not fully forward alignment in the bushing is not at opium increasing error at 50 yards.
 Again more long and boring information to tell you that using light springs becomes a slippery slope leading to bigger groups and failure to load creating alibis.

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Re: Understanding Recoil Spring Weight and Effect

Post by Jerry Keefer on 4/4/2015, 5:12 pm

Heavy slides, greatly limit the ability to tune the gun.. It will require a specific amount of energy to function. The military teams use contract ammo often from Altanta Arms or other vendors..It is what it is... No tuning.. The shooters are young strong, and practice constantly.. Repetitive stress injuries from recoil, are not uncommon.  Why, subject one self to that..??Recoil equals lost points..  Why shoot hard recoiling jacketed ammmo when lead will shoot as well, with much less recoil and wear and tear on the gun and shooter.?? I have posted numerous photos of a frame mounts based on Dave Sams design, developed when he was in the AMU..It is not bolted to the frame, it is silver soldered to the frame. I know of no failure, ever.  There is nothing yet, better available. Today was our first local match of the season... My shooter is making a slow recovery from the flu, and struggled, but with cast lead, and frame  mounted optics, bested the 45 NMC with a 295-11. A very accomplished Air Force shooter who has recently switched to lead, dropped 2 points over the entire shortline. Don't follow the crowd..


Last edited by Jerry Keefer on 4/4/2015, 5:16 pm; edited 1 time in total (Reason for editing : spell check)
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