Last shot hold open

[Citoriplus]

I think the bolt hold open feature has more to do with the high spring tension of the bolt catch spring and low spring tension of the magazine.
Here's my theory.
When the bolt goes all the way back, there is a limited amount of time for the bolt catch to pop up in front of the bolt. If there is too much spring pressure for the magazine spring to overcome then it takes too long for the bolt catch action to work. When you pull the charging handle back the mechanism works, because of the huge amount of time. You can't pull the charging handle and release it as fast as a gun can.
You would think the lower powered ammo would allow more time for everything to work, as the bolt would be traveling slower. But more force back means the recoil spring has to work harder overcoming that force equaling more time.
Try the spring mod (remove 1 1/2 coils) and the cheap ammo and let us know how it works.

Something about this has been bothering me for several days until last night I was playing with one of my newly shortened mags and started fooling around with the mag and latch until I figured it out.
Lower powered ammo may not be letting bolt latch hold the bolt open not because it doesn't push the bolt back far enough, because it obviously does.
Otherwise the rifle couldn't eject fired cases or feed new rounds properly.

I believe the bolt latch isn't operating properly with lower powered ammo because its not slamming the bolt back violently enough.

Firing higher speed/power ammo slams the bolt back hard enough to jar the entire mechanism and so helps the mag follower overcome both the metal/plastic friction of the latch in its slot and its spring.

I figured it out when I was checking my newly shortened mags and found that they were not operating the bolt latch correctly when the bolt was manually operated with the charging handle until I put a small drop of oil on the sides of the latch.
Then it started working about half the time.
So I pulled the spring out and cut one coil out of it and it now works 100% of the time no matter how slowly or quickly I operated it.

I think with time and use any latches that are iffy today will eventually wear or break in until they work all the time.

But in the mean time, putting a drop of oil on the side of the latch inside the receiver and cutting a coil or a coil and a half out off the end of the spring will be a good way out of the problem.

 

[fastsw]

Just found this thread. I had one mag that randomly did not hold open. I rotated the mag spring and it has been perfect since. Will only work if you can isolate the problem to one mag.

 

[FullMonte]

Hmmm. I think I'm the only one having the opposite bolt problem. My bolt will sometimes jam open after the last round. The catch will not move to release the bolt. Separating the upper is the only way to fix it.

P.S. My rifle is a snob and demands mini mags exclusively.

 

[bulldozerd8t]

Hmmm. I think I'm the only one having the opposite bolt problem. My bolt will sometimes jam open after the last round. The catch will not move to release the bolt. Separating the upper is the only way to fix it.

P.S. My rifle is a snob and demands mini mags exclusively.

My rifle will eat any 22lr you feed it. Does your rifle have the upgraded blue springs?

 

[FullMonte]

My rifle will eat any 22lr you feed it. Does your rifle have the upgraded blue springs?

Yes, but it's this dang iphone spell correction got me. I meant to say that I am a snob, and demand mini mags exclusively.

 

[bulldozerd8t]

Yes, but it's this dang iphone spell correction got me. I meant to say that I am a snob, and demand mini mags exclusively.

Aah I like mini-mags too but I save mine for hunting. I'm a (tightwad) I'm glad you leave the cheap ammo for me, He He

 

[Roman51]

Thanks Tacticool22!! Just cut about 2 coils off of my spring. Works great.Locks back at the end of every empty mag now.

 

[Wyo15-22]

Mine locks back about 25% of the time using Remington Golden ammo. Just got some CCI Mini Mags to try so we'll see if this solves the problem.

 

[Smiling Bob Masterson]

Tacticool22,

Many thanks for your input on this mod, compadre.

Cut two coils (.050 inch) off the bolt lock spring, 100 percent bolt hold open function with blazer ammo even with rearward pressure against mag.

Mag wobble was really bugging me, sos I made an experimental tape shim (9 layers blue painters tape .035" thick) and placed it on the inside front of the mag well near the bottom, problem cured. Mag no longer drops free of the rifle when mag release button pressed, not a problem in my opinion as I would rather remove and retain the mag with my off hand instead of letting it hit the ground. Will make a more permanent shim out of aluminum tape or perhaps epoxy putty.

Smiling Bob

 

[tacticool22]

Hmmm. I think I'm the only one having the opposite bolt problem. My bolt will sometimes jam open after the last round. The catch will not move to release the bolt. Separating the upper is the only way to fix it.

P.S. My rifle is a snob and demands mini mags exclusively.

There have been some bolt catches that were molded (yes molded) incorrectly. These and the breech block are metal injection molded.
Contact S&W Customer Service and see if they will send you a new one. There is a thread about your very problem.

My theory about the lower power ammo not working is there is not enough force to push the bolt back for a long enough amount of time for the magazine spring to overpower the bolt release spring.
With a minimum amount of recoil the recoil spring can act immediately. With a bigger recoil the energy of the bolt flying back keeps it back until the recoil spring overcomes the recoil energy and can push the bolt forward.
Just a theory and basic physics.
You could trim the recoil spring, but the bolt catch spring is an off the shelf item.
My rifle loads, shoots, ejects and locks back on anything now.

 

[stimr2]

I just wanted to thank tacticool22 for the quick easy fix with the bolt catch spring. I just recently purchased my 15-22 and after 50 rds of CCI Tactical the bolt wouldn't hold back on the last round. After I cut one coil of the spring it works now.

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