jsha22lr
Member
Has anybody else encountered any light primerstrikes with after market triggers? I have a jard 3# trigger and i have at least 2-5 light primer strikes every mag. Am I the only one with this problem?
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light primer strikes with lighter triggers?
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CPTBeaker
Member
In my 15-22, I'm using a 3.5# CMC drop-in and have not experienced any light strikes in around 1000-1500rds.
I have experienced a couple light strikes with my Timney 3# in my Stag AR, using 5.56, not .223
I have experienced a couple light strikes with my Timney 3# in my Stag AR, using 5.56, not .223
CPTBeaker
Member
In my 15-22, I'm using a 3.5# CMC drop-in and have not experienced any light strikes in around 1000-1500rds.
I have experienced a couple light strikes with my Timney 3# in my Stag AR, using 5.56, not .223
I have experienced a couple light strikes with my Timney 3# in my Stag AR, using 5.56, not .223
Majorlk
Member
The problem is not the weight of the trigger pull but the power of the hammer spring and hammer combination. Make sure you use the Jard spring and the Jard hammer.
FWIW, I have the Single-stage adjustable with the 1.5 lb spring in mine with no problems.
Lock&Load53
Member
I had the same problem with my Timney 3 lb. triger. I went to Fastenal supply and was able to order the same size/ tension spring that came on the factory firing pin, just a little to long. I used a Dremel tool and cut the new one about 3 coils shorter than the factory spring, to let off some tension so the firing pin would strike harder.
I also ploished the firing pin shaft with 1000 grit sand paper to decrease friction. Polish the shaft where the spring rides and works, not the ends.
It takes very little polishing on the shaft. That took care of my ligth strikes.
The springs cost me $9.00 for a pack of 3 springs, there label on the package reads. FNL.SPR.CMP.M.P. / 120087821 / I think there stock is # 110166661 ( it's on top of package label above the bar code ). You can also go to Fastenal on line and order, I'm sure.
Good Luck
I also ploished the firing pin shaft with 1000 grit sand paper to decrease friction. Polish the shaft where the spring rides and works, not the ends.
It takes very little polishing on the shaft. That took care of my ligth strikes.
The springs cost me $9.00 for a pack of 3 springs, there label on the package reads. FNL.SPR.CMP.M.P. / 120087821 / I think there stock is # 110166661 ( it's on top of package label above the bar code ). You can also go to Fastenal on line and order, I'm sure.
Good Luck
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photoracer
Member
Well it might have fixed your problem but cutting coils off a spring has the effect of increasing the rate of the spring not decreasing it. The formula for coil spring tension has the number of coils and the diameter of the coil on the bottom of the equation so that decreasing the number of coils will have the effect of increasing the spring rate.
In your case cutting the coils reduces the spring bind height allowing the FP a little more forward travel.
In my case I use the Geissele Super 3-Gun trigger, which has a 2 stage combined pull of 2.5# on an RCBS trigger gauge and no light strikes. Even with JP "yellow" springs on it and the pull reduced to 1.25# I experienced no light strikes.
In your case cutting the coils reduces the spring bind height allowing the FP a little more forward travel.
In my case I use the Geissele Super 3-Gun trigger, which has a 2 stage combined pull of 2.5# on an RCBS trigger gauge and no light strikes. Even with JP "yellow" springs on it and the pull reduced to 1.25# I experienced no light strikes.
Lock&Load53
Member
photoracer
I'm not real sure what you are refering to. I took the firing spring out of the bolt and was surprised how much tension there was holding the firing pin rearward. I can't control how much forward thrust the triger has when striking the firing pin with brand of triger I have, but I can control how much resistance the hammer has to overcome to strike the rim of the case.
The springs I orderd and trimed was mic with digital calipers, for coil diameter, inside and out, plus coil wire thickness to achieve the same tension as a factory spring. Reducing the amount of coils, changes the amount of force needed to strike the cases harder.
I'm not real sure what you are refering to. I took the firing spring out of the bolt and was surprised how much tension there was holding the firing pin rearward. I can't control how much forward thrust the triger has when striking the firing pin with brand of triger I have, but I can control how much resistance the hammer has to overcome to strike the rim of the case.
The springs I orderd and trimed was mic with digital calipers, for coil diameter, inside and out, plus coil wire thickness to achieve the same tension as a factory spring. Reducing the amount of coils, changes the amount of force needed to strike the cases harder.
Lock & Load53 is absolutely correct in that clipping the FP spring will increase the thrust of the Hammer allowing a harder strike on the rim, for any given hammer spring tension. Clipping the spring does not allow the FPin to move any further forward. The FPin forward travel is limited by a pin stop, the same one you remove to take the FPin out. Travel distance has nothing to do with the length of the spring, except that a lighter shorter spring allows a stronger hit on the rim....this is common with any rebounding FPin/ hammer combination....,and it has nothing to do with any spring tension formula in real life application..............best regards Plum
Allen 1
Member
Just for the record.
Cutting the coils off of the spring will NEVER change its rate. It's called "spring constant". Cutting coils only changes its compression length or "set".
A 10# spring will always remain a 10# spring regardless of its coil count. That's why there are 10# springs in 1" or 2" or whatever.
Cutting the coils off of the spring will NEVER change its rate. It's called "spring constant". Cutting coils only changes its compression length or "set".
A 10# spring will always remain a 10# spring regardless of its coil count. That's why there are 10# springs in 1" or 2" or whatever.
photoracer
Member
What I am saying is that cutting any coil from a coil spring increases the spring rate, it does not decrease it. So when the hammer hits the spring the spring will resist even more than it did when stock. Cutting a spring will reduce the preload but when in deflection it will resist compression even more than before it was cut. But if the only thing stopping the spring's forward motion is spring bind then cutting coils will let the firing pin go farther forward.
If 2 coils springs have the same diameter dimensions inside and out and wire thickness then the spring's actual rate is determined by the number of active coils. The one with more coils will have a lighter rate. Reducing the number of coils has the effect of increasing the stiffness (the rate) of the spring.
That means that cutting coils will have the effect of increasing the resistance of the spring to compression.
if the spring is installed compressed then the preload comes into play. If the spring has a rate of 10 lbsf/inch and it is compressed 3 inches the preload will be 30 lbsf/inch. it will still only increase pressure by 10 lbsf/inch for every aditional inch it is compressed when working. If you cut three coils off out of say 15 the spring rate will go up to around 13 lbsf/inch. And lets say that the amount of preload length (or compression) is now about 2.75 inches because we shortened the spring. 13 x 2.75 = 35.75 lbsf/inch of preload. So now we have shortened the spring and now the preload rate has gone up to 35.75 lbsf/inch. Plus for every inch we now compress the spring the rate goes up 13 lbsf/inch for every inch.
So basically I am saying that when you cut the spring the hammer is now working to compress an even stiffer spring against the FP.
However if the spring goes to coil bind when hit by the hammer then cutting coils has the effect of letting the firing pin go farther forward, i. e. allowing it to drive farther into the rim of the case to eliminate light strikes. What you did to the spring was actually counterproductive to what you wanted to accomplish except for that.
The main cause of light strikes is powder residue building up on the breech face, pushing the bolt farther back from the breech when closed. Blowback designs usually have this covered by having the action go into battery slightly before it contacts the breech so the gun will still fire. Too much can lead to OOBs (like early AR15-22s had) so the spring rate of the bolt has to be carefully done to prevent this.
My main open rimfire pistol I use for Steel Challenge is an older Browning Buckmark, heavily customized. It had an occasional light strike issue. The FP has a coil spring but the FP is held to a limited travel by a roll pin an a slot in the FP. Rather than fooling with the spring which would have no real effect I instead increased the slot in the rear of the FP retaining pin slot a few thousands to enable the FP to travel a little farther forward. This eliminated the problem entirely. I think currently it has gone something like 47 straight matches over 3 years without any ejection or feeding issues and no light strikes. You get the occasional dud .22 round now and then but using better ammo can minimize that.
photoracer
Member
Incorrect I am afraid. The number of coils directly effects the spring rate. See the formula for coil spring rate. The number of coils is on the bottom of the equation so reducing the number of coils has the effect of increasing the rate. Any good engineer or coil spring maker can confirm that. If you have 10 active coils in the spring cutting one off will increase the rate by about 10%. Cutting the coils affects preload if it is installed compressed, so even though the preload may remain fairly similar depending on the spring properties, the rate will always increase if you reduce the number of coils. The length of the spring has no part of the equation as it is irrelavent. What matters is the dimensions and the number of coils.
The only constant in the equation is a value based on the material used called the "shear modulus". Steel has a fixed value.
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photoracer
Member
I'm sorry but doing that to the spring will increase the rate of the spring not lessen it. See the formula for coil spring rate if you don't believe me. This is something automotive people seem to know but most don't have a real clue. And it does not matter what the coil spring is on, whether a gun, car, or ballpoint pen. The formula itself is just an explanation of what you get with a coil spring tester.
If the FP has a retaining pin then what I said does not apply. The force of the spring has little or no effect on light strikes if the FP has a travel limit. It can't do anymore regardless of the spring. The only way to cure light strikes is to increase the length of the FP travel and the only way to do that is to increase the length of the FP retaining pin slot by a few thousands in the rear. However you have to limit corrections so that the FP can't go forward enough to peen the breech of the gun or it will be damaged by dryfiring.
If the FP has enough travel then to reduce the spring tension you must come up with a spring with the same dimensions but MORE coils not less in the same free length so as to keep the preload the same if it is compressed.
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TAMARISK
Member
Do I understand you to say then that the firing pin in our rifles, if left stock, will not contact the breech face during dry firing if the slot is not lengthened? Therefore no harm in dry firing?
Steve
Steve: Yes, what you are saying is correct, however S&W does not recommend dry fireing. The FP spring has nothing to do with the maximum foreward travel of the fireing pin in the 15-22 with exceptions. Maximum forward FP travel is determined by the FP slot and stop pin, period..... 1) The first exception being that the Hammer spring is too weak (light) and it can not overcome the FP spring tension to drive the rebound fireing pin far enough forward into the shell and hit with impact hard enough to fire the shell.....Exception 2) the length of the FP spring is too long and was put in at S&W factory by mistake....(you won't find this), but an overly long FP spring could cause the FP to be restricted in full travel length...... This max forward FP travel is determined by the FP stop pin and slot. If it was assembled at the Factory correctly, the FP at full extension will just clear the breech face of the barrel, and leave no marking....at least this is the way it is on my 15-22, and I suspect it is purposely manufactured this way...Do Not increase the slot length on the FP. It is not needed, and has plenty of full travel to detenate the shell.....Take a look at it yourself, simply push the FP in as far as it will go and look at the FP protursion, it should be just shy of the face of the bolt, and I mean just a few thousands....Look at it under some magnification and you will see this....best regards Plum
TAMARISK
Member
Thanks! I'll get a look at it tonight! I don't dry fire any of my firearms anyway, was always taught it would damage the pin.
Steve
Allen 1
Member
Photoracer.
You are correct my friend! I admit, I was wrong.
I contacted a friend of mine who works in this field and he informed me that indeed, removing coils from a set rate spring will change its rate.
I was amazed at some of the facts he taught me. Just goes to show, we can all learn new things if we are open minded and willing to learn.
So, I apologize.
stavman11
Member
Soooooooo
should i try cutting a FEW coils off and see if the LIGHT STRIKES go away....
And we are talking Firing Pin... NOT Blue BCG Spring Right???
Never taken Firing pin out Yet.... may be time ta try
Thanks all
Stav
should i try cutting a FEW coils off and see if the LIGHT STRIKES go away....
And we are talking Firing Pin... NOT Blue BCG Spring Right???
Never taken Firing pin out Yet.... may be time ta try
Thanks all
Stav
rraisley
Member
While I haven't been following ALL of this, I think you're missing something. Yes, cutting a spring down increases its spring rate. In a car, that works out great, because you get increased spring rate AND a lower ride height. But most springs used in firearms don't work that way. We can't change the "ride height".
Using your example above, of a spring with 10 #/" spring rate compressed 3", and cutting 20% (3 of the 15 coils) off, I don't think you will see an increased in installed force, either before it is compressed or after. Let's say the free length of that spring is 4", and it's compressed 3" in normal use. So, it's total length goes from 4" (free) to 1" (compressed). We'll assume here it doesn't go solid.
Now, if you cut off 3 coils, or 20%, ignoring end treatment, you will be shortening the spring by 20%. It will now be 3.2" long, free length. It's spring constant, as you say, will be 12.5 #/". BUT - it will no longer be compressed 3". If it's placed in the same mounting as the previous spring, it will be compressed until it is the same compressed length as before: 1". Which means it's now being compressed only 2.2", not 3". And the total force to compress it will be 2.2 x 12.5 = 27.5#, not 30#. Partial compression, say where it was 1.5" compressed before, will be even worse: whereas the 4" spring was compressed to 2.5" under those conditions, the cut spring will also be 2.5" long, being compressed only 0.7". So at a 2.5" length, the uncut spring had a force on it of 1.5 x 10 = 15#, while the cut spring has a force of 0.7 x 12.5 = 8.75#.
A simple way of looking at it is if the 4", 10#/" spring was cut to be only 1" long, it would not be compressed at all to fit in the 1" area, and while its spring constant would indeed by 40 #/1", it would provide no force at all in this example.
Am I missing something?
photoracer
Member
You were not paying attention to what I was using as an example. With the original example I was showing a captured length that was 3 inches less than the free length. After cutting the spring the free length is less so the amount of compression preload will be a shorter multiple and my example was based on a theoretical spring so when I cut 3 coils off and remounted it the compression preload of a shortened spring would be a lower multiple than the original 3 inches. I was using 2.75" as the amount of compression length to fit in the same captured space. Of course that varies by the dimensions of the parts and the space.
The example was based on showing that regardless of the amount of cutting (as long as the spring still needs to be compressed to fit) while the preload may be lower, once the spring is compressed in action the spring rate will go up past the original as some point in it travel.
I'm pointing out that if you want the spring to hit harder you have 2 choices. Increase the rate of the hammer spring so it hits the FP harder or lessen the rate of the FP spring. And to do that correctly you need to choose a new spring with the same free length but a smaller diameter wire, to lessen the spring rate. And that was so you keep the springs rate of change the same. Anything else is hit or miss. Basic rule is if you cut off 10% of the active coils you will get a change in rate of around 10% (slightly higher actually but not significant). Cutting 20% actually changes the rate by around 21%. This is why when you want to correctly change the recoil spring in your pistol you get a new spring with a different rate, you don't cut the old one, because you need to keep the free length the same. In a car the issue is that cutting the springs will lower the spring bind point to below the bump stop height. So you need a lower, stiffer bump stop in that case.
This is one reason JP sells a spring kit that has the Yellow trigger spring but the Red hammer spring. If I was having light strike issues I would have left the factory hammer spring in and just put in the JP yellow trigger spring. I have considered that for my S3G trigger since it appeared to work fine with both yellow springs in ,but I went back to the Geissele springs to get the pull back up into the 2.5# range. Maybe later this year I will try it with the yellow trigger spring in and see what the trigger characteristics are.
Light hammer springs go hand-in-hand with light trigger pulls, assuming the parts have appropriate geometry. Reliable ignition is dependant on hammer SPEED. As such, reduced hammer weight (bobbed stocker or JP Speed Hammer), as well as proper spring rate will give the desired reliability.
Keep in mind, my experience is modifying stock AR triggers or using the original JP parts, not the current drop in replacement triggers. The physics shouldn't change but the options for actually getting reliable rimfire ignition may.
Keep in mind, my experience is modifying stock AR triggers or using the original JP parts, not the current drop in replacement triggers. The physics shouldn't change but the options for actually getting reliable rimfire ignition may.
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