What Recoil Spring for slide mounted red dot on Mil Spec?

First topic message reminder :

A number of years ago I had a gunsmith put a rail on top of my 1911 Mil Spec so I could mount a red dot.   He told me I might have to cut a few coils off the factory spring.  

I have never gotten to feed reliably.  At FTF jam or two every 100 rounds. Usually the last round in the mag.  I am now down to using a 9lb spring and I put in a buffer.  

It happens with pretty much any load/bullet, but I am currently using 4.8gr 700x and a 185 or 200gr bullet. 




I do see an 8lb spring on Midway and also a variable power recoil spring.

I did a search and found nothing.

Any advice would be appreciated.

I haven't seen this mentioned exactly, but I have a couple of questions:

1) Was this gun ever reliable? That is, did you encounter this issue before the rail was mounted to the slide?

2) Have you removed the rail to see if the issue goes away (and everything put back to "stock")?

3) Have you switched magazines to test and see if the issue is duplicated across multiple brands/types?

4) When you changed the mainspring, did you try both the 18 and 19 pound springs? If so, did both of them increase the trigger weight?

These seem like cheap/easy changes that may provide additional insight on what to check next.

Best,
Chase

Are any of the rail screws protruding past flush with the inside of the slide?

Let's try this again...

Define FTF!!

Does the slide cycle, and the empty case remain in the chamber?

Does the fired round eject and the new round not get picked up by the slide?

Does the new round jam against the frame feed ramp?

Does the new round jam against the barrel feed ramp?

Does the new round partially enter the chamber but remain at an angle to the chamber?

Does the round jam on the barrel hood?

Does the round enter the chamber and the slide only partially close?

Does it enter the chamber and stop just short of battery?

And last but not least, was the pistol properly lubed after the rail was installed?

Wow!  I appreciate how succinct these questions are.  I will need some time to try some of these things.  But I can answer many of those questions now.  

- The gun was always reliable before the red dot sight was installed.

- I have not tried it with the red dot removed because there is no longer an iron sight on it, and I might have to shoot a hundred rounds or more to get a jam.  Given that it was reliable before, that seemed to be both expensive and unnecessary.

- I have tried various magazines, but they were all Springfields,

- I have cleaned and lubed the gun many times since I put on the scope.

- The spent round ejects and the slide picks up the next round, the round then jams as the nose has enters the chamber well past the hood, preventing the slide from closing.  If I pull back the slide slightly and release it, the round will usually chamber the rest of the way.

-  I will take a picture the next time it jams. Should have done this before.  But when I am concentrating on shooting, I tend to have tunnel vision for anything else except safety.

-   I don't think it's the crimp.  My crimp a the mouth is 0.469" which I thought was correct, and my stock Trophy Match east anything I feed it.

-  I am still not sure if everyone thinks the main spring may be a factor.  

-  However, any further experiments will have to wait.  As I was swapping out the main springs for about the 5th time, the takedown pin slipped out, boing, and I could not find the spring or the cap.  So, I will have to order new ones. 

- I want to clarify my goal here.  I am not looking to turn this into a "bullseye" gun shooting 2 inch groups.  I don't have the skills and I've been told gunsmiths like to work on new guns for this purpose.  I just need it to be reliable.  I have four .22s, including a S&W 41 that I spend most of the time improving my technique with.  I just want to try a few matches.  I shot a few 15 years ago, but never had enough time to put in what it would take to shoot what I considered a respectable score.  If I really decide to get into it more seriously, I will look at buying something like a Les Baer or Rock River gun with an accuracy guarantee. 

I am in the Sacramento area.  There are some Bullseye clubs in the area, and I will reach out to them.  But if any of you know a good 1911/bullseye gunsmith around here I would love to get the contact info.

And again, thank you all for your help.  One of the things I have found is that shooters are the most helpful people in the world.

Thanks again for all your help.

Bluesguy wrote:

- The spent round ejects and the slide picks up the next round, the round then jams as the nose has enters the chamber well past the hood, preventing the slide from closing.  If I pull back the slide slightly and release it, the round will usually chamber the rest of the way.

-  I will take a picture the next time it jams. Should have done this before.  But when I am concentrating on shooting, I tend to have tunnel vision for anything else except safety.

-   I don't think it's the crimp.  My crimp a the mouth is 0.469" which I thought was correct, and my stock Trophy Match east anything I feed it.

You might try shortening the cartridge OAL about .010" or .015" and see what happens. It may be that the slide is loosing energy as the round transitions from an angle to being parallel to the chamber bore. The slide velocity was probably higher before the additional weight of the rail and optic.

I don't think the main spring has anything to do with the problem! You seem to have a lighter than 23lb main spring. The main spring will increase opening pressure being it is combined with the recoil spring for a short time. The main spring via the hammer will exert most of the pressure on the slide just after the slide starts to return, due to the increasing advantage the engagement between the hammer and slide pressure decreases as hammer is moved back. In addition the strut due to rotation of the hammer on the hammer pin apples less pressure on the hammer though as compressed the main spring pressure increases, if allowed to rotate enough the hammer will eventually reverse direction. That impact mark of the barrel on the frame indicated the barrel is hammering back indicating spring pressure is too low on the slide. I should have asked the questions SA/DA did but I did assume correctly the FTF problem you are having. Shortening the round will help as SA/DA suggested, a shorter OAL of the round will allow the round to be released by the magazine sooner. It will reduce the angle the bullet has as entering the chamber therefore lowering the friction created pushing the barrel forward that is amplified by the action of either the link or slide stop pin hitting the lower lug. Do the test, allow the slide to close slowly by hand to see if you feel the bump, it must be done while cambering a round. In addition check by increasing recoil spring weight to find what weight stops the slide from being locked back.
When does the FTF happen? never, always or sometimes when the first round of 5 chambered? 2nd round? 3rd and so on until last round?

I am no expert in 1911's, so my question may not apply.  But after reading everything above, did you change the main spring parts from the Springfield ILS parts to standard Colt type parts?  If not, that may explain why your 19# spring results in increased trigger pull.  It is my understanding that ILS springs are different from standard Colt mainsprings.

I didn't see any reference t0 a ILS so I looked back and all I found is Mil Spec Springfield 1911 that's about 10 years old. I also noticed I misread your text as to what springs you ordered, I was thinking 18 and 19lb recoil spring not main spring! I did explain why I didn't thimk you had issue with main spring in previous reply. If you did cut the recoil spring as suggested by that gun smith that knows in my opinion very little about the 1911 function, you possibly made the problem worse. You have a closing issue! Lowering the main spring will allow you to increase recoil spring weight. But as I mentioned many times main spring weight has little effect on closing the slide.
 One question I didn't think I asked, why if you did cut the recoil spring as per your gunsmiths suggestion after mounting a red dot sight? One thing most don't realize is the added weight of the scope and mount is that the weight does slow rear travel of the slide due to inertia but helps close the slide with inertia that slowed rear travel. In addition the inertia that slowed rear travel limits the recoil spring in stopping slide rear travel.

Are any of the rail screws protruding past flush with the inside of the slide?

No.

One question I didn't think I asked, why if you did cut the recoil spring as per your gunsmiths suggestion after mounting a red dot sight?


I understood it to be a closing issue all the time.  I only cut a few coils off the original recoil spring. After that I bought lighter springs.  As you know, when you cut a spring, you change the k factor in Hooks law (F=-kx), so you don't really know what you are working with at that point.  It seemed obvious to me why he said cut off a few coils or maybe use lighter springs.  F=ma and if you add mass you slow acceleration.

trying to talk about forces, especially dynamic ones, without diagrams or at least pictures is hard. Let me get my gun back together and I will take a picture of the jam.  I tried to recreate it by removing the springs and using a dummy round, but I really couldn't do that.

And again, thanks for all the help you guys have given me. It seems like it has become a group project.

Your gun locks-back, it loaded rounds from the magazine so your spring was not too heavy. You gun is failing to close. That could indicated the recoil spring is too light! In addition the rear of the frame is being hammered by the barrel again indicating the recoil spring is too light. Though that may have been done prior to mounting the scope and mount. You also have to check for the bump! Order a recoil spring kit from Wolff or other of your choosing. Good to have as you change loads. Shorten the OAL of the reload as suggested! I just did a re-barreling for a friend of mine, I thought he gave me a box of his reloads, I had a box of semi-wad cutters. Later he brought over his reloads that were 185JHP loaded the same as Atlanta Arms. They would not work because they were longer so I had to alter the barrel lower lug. So length does make a difference!

Froneck, that makes a lot of sense. Intuitively a lighter recoil spring makes sense to me, but dynamics are not always intuitive.  I have tried many COLs, but can do so again more methodically.

You probably saw where rbruk indicated the ILS may be an issue.  I contacted Springfield, and VERY long story short, it can be.  You can't talk to a tech directly and even the Customer Service rep had different part numbers for ILS vs. non-ILS equipped guns. I did receive this response from a tech when I asked about ILS and the mainspring.
 


All of the Mil-Spec 1911 pistols made in 2012 would have come with the ILS system. You would need the internals designed for that ILS system unless you replace the whole Mainspring Housing inside and out.


I also found in other forums that ILS was an issue for some, and swapping out the whole housing solved the issues.  Just for fun, I asked Bing AI and it indicated the ILS mainsprings were actually shorter.  Spring weight is defined by the force needed to compress the spring by 1 in. So, a longer spring might result in a heavier trigger pull even if it had a lower nominal weight.

So here is my plan:

1. I will replace the factory "humped" housing with a flat Nighthawk housing.  I prefer that over the humped housing anyway.
2. I will install the Wilson Combat Mainspring with non-ILS retainer and cap.
3. I will reinstall the original recoil spring.
4. I will order recoil spring kit.
5. Start from there.

I will then try different recoil springs, new magazine springs, and shorter COLs one at a time.

If nothing else, I have learned a lot about 1911s, and how much more there is to learn.  Thanks so much to everyone for their help.

I seen the reference to Mil Spec. so assumed you had standard 1911. I don't like or work on any ILS equipped guns or any other similar devices. Any of that added is useless to target shooting. Possibly acceptable for carry gun but in most cases not! Nothing more than some politician, ATF or anti gun organization attempt at adding cost to firearms.  Simply put anything involved with trigger release will add to keeping the trigger pull movement as simple as possible. My 1911's don't have a grip safety! But simply defeating those items in some cases can't be done on pistols intended for NRA competition. For example a series 80 Colt 1911 can't have the firing pin block disabled. I'm not sure what would happen if a .22 conversion was installed on a series 80 frame.

Yep, to the plated bullets.  If you have a micrometer measure the bullet diameter, I think you will find a large variance in the plated bullets.  My experience has shown as much as 0.004. Which is unacceptable for producing accurate loads.  IMO. Try some Zero or Nosler 185 jacketed and see if your results produce better accuracy.  In my Rock River 1911's and Colt 1911's I run a 11-pound recoil spring and a 19-pound mainspring on a slide mounted Ultra Dot with steel rings have no feeding or extraction problems.  I also use Wilson Combat magazines with rounded followers.  Go slow and change only one thing at a time until you find what works for you.  Every firearm is different, it just takes experimentation to find the right combination.

Froneck and Allen,

As I said I am still an infant at this, so the accuracy is secondary to reliability, and I have a lot of plated bullets to burn. But I won't use them if I compete.  

But I do have a question.  I thought most Bullseye shooter's used LSWCs.  The high-end vendors even refer to their Bullseye models as "wad guns".   Is that not true?

And yes.  The ILS is a pain, causes a lot of confusion and I never once used it. That's what gun safes are for. I am done with it. Hopefully.

As per the quote above all the MilSpecs manufactured that year had the ILS.  Today, I think it is only for those for sale in California. Another weird thing was that CS rep said my serial number indicated it wasn't a California gun, but I bought it here in the Sacramento area. So, the standard-length mainsprings CS sent me probably won't work. 

 I wish I had not lost the spring and cap so I could compare them with the non-ILS parts I ordered.  But I still have the retainer and can see if it is different.

Nothing more than some politician, ATF or anti gun organization attempt at adding cost to firearms

That's exactly right.  There are tons of useless laws here in California that contribute nothing to gun safety but make it more difficult to buy and use firearms.  Ruger no longer markets semi-autos here because of the microstamping requirement.  Any new gun must employ that "technology" and any change to any existing gun model, no matter how minor, also triggers the microstamp requirement.  With the manufacturers selling as many guns as they are there is no reason for them to deal with it even in what is the largest US market.

The next one coming is an 11% tax on all ammo sales.  So now my CCI Target, which is already about $6 a box.  Is gonna go to almost $7. 

Thanks again,

LSWC bullets were quite popular, LSWC could be cast at home or purchased because of the lower cost than JSWC. Wad-guns usually indicate they are not intended to be used with 230gr ball ammo which are known as ball-guns. I haven't shot lead for years, purchased bulk quantity of JSWC. That was until the 185gr JHP was determined to be more accurate. Now I use only 185gr JHP bullets. Some shooters to lower bullet cost will shoot 185JHP at 50yards and LSWC at 25 yards.

Keep in mind equipment accuracy is important to all shooters including new shooters. Your target is nothing more than test results of your skill. Having to learn on equipment that does not record your actual application will result in never learning the skill needed. Like taking a math test with a calculator that don't work. You enter 2+2 and it posts 5 do it again and 3 is posted, again and 6 is posted. After a while you will give up thinking you will never learn to use a calculator! You did what was needed but you will never got the correct answer simply because the calculator was broken!  X ring is 1.695" and 10 ring 3.36", you can see why equipment that will produce 2" or better group is desired. The results posted (target score) is what your did!
 185gr JHP is made by Zero is what I use. Magnus sells them too but are actually made by Zero. Atlanta Arms was selling 45ACP rounds with Zero Bullets but I'm told their latest rounds had bullets that didn't look like Zero brand. I had 2 Kart 45 barrel tested at 50yards by very reputable tester (not willing to say who) Atlanta Arms 185gr rounds tested far better than Federal Gold Match 185gr.

I certainly understand the value of an accurate 45.  But the gun in question is never going to be one that shoots 2 in groups at 50 yards.  I am not prepared to pay $4k for a Rock River until I take part in a few matches.  Same with the bullets I use.  We cannot order ammo over the internet here in California unless we go through a FFL. I am limited to those bullets I can buy as components. I checked Aero's website and they are $80/500.  Not too bad.

I generally shoot at the B-2 50 ft. target. I shot a few Matches with a Master shooter at a 20 yard gallery match and he told me his worst scores were at indoor gallery matches.  I have shot at 50 yards occasionally and intend to do it more often before I enter a match.

I shoot my .22s the most and I am confident of their accuracy. I have a S&W 41, two Buckmarks and a Ruger Mark II.

It's interesting that these bullets test better than Gold Match because that is the round Rock River says their gun is guaranteed to shoot 1.5 in. groups with.

Most .22LR pistols will shoot good at 50yards. Simply because the barrel is attached to the frame and the scope mount attached to the barrel.
 You can shoot matches with an inaccurate gun so as to get match experience. Practice with the 1911 45acp at 25yard reduced SF targets or 50' reduced targets. Most 1911s and 45acp ammo will do well at short range.
 Atlanta Arms loaded 45acp with 185gr JHP ammo shot better than Gold Match in a barrel testing machine so barrel was fixed and couldn't move. I can send photo of test target if desired. I do find the Zero 185gr JHP work well in my reloads but haven't compared my reloads to Gold Match.