Last shot hold open

[bulldozerd8t]

I sent my M&P 15-22 back to S&W for firing 2 to 3 shells with one trigger pull. It's been a while back. S&W installed updated springs on the bolt and trigger (blue springs).Since the fix my hold open on last rd works with certain ammo. 510 feds, cci mini mags no problems but blazers and a few more brands, I don't remember the brands does not hold bolt open. The new spring must be stronger. Any fix to this problem other than not to shoot this ammo. I don't like dry-firing or counting rds.

 

[tylerrybkowski]

Hope mine comes with a fire burst setting i would have kept it lol

 

[VooDuuChild]

Hope mine comes with a fire burst setting i would have kept it lol

Until the wrong person hears and you get a vacation at "don't drop the soap hotel".

 

[monk]

I have been having the same problem as of late. Not all the time but often enough to get my attention. I have been shooting only CCI Blazers. I think it might be the mags, need to start taking note of wich mag's it is happening on.

 

[chuck s]

Dirty bolt catch will prevent the magazine follower from pushing it high enough to catch the bolt. Blow back operation puts a lot of crud in that area. Loose magazine can also do this. Check the magazine catch tension.

-- Chuck

 

[bulldozerd8t]

I have been having the same problem as of late. Not all the time but often enough to get my attention. I have been shooting only CCI Blazers. I think it might be the mags, need to start taking note of wich mag's it is happening on.

If you change ammo from the blazers you will not have this problem. 510 feds ,cci mini-mag,Gb's,PMC zapper's holds the bolt open. I quit shooting the bulk feds so I don't remember if they will hold bolt open. But blazers sometimes will hold bolt open maybe 25% of the time, I like the blazers been finding deals on them $15 a box of 525( no duds) I like the 510's also but they do not come in a bulk box. I don't think its a mag problem I was sent the new mags and I still have a 1st generation mag all 3 mags do it.

 

[bulldozerd8t]

Until the wrong person hears and you get a vacation at "don't drop the soap hotel".

That's why I sent mine back. I don't think I would like that hotel your talking about.

 

[bulldozerd8t]

Went out and shot 300 rds of federal 510's today the bolt stayed open every time after I emptied the mag. I don't think it is a dirty gun problem. When I first bought this gun I cleaned it so much because of jamming problem. Then I found out to bend the ejector rod. Then the gun stared doubling so i clean very much again, Sented it back now the only problem is mainly shooting blazers . I haven't clean the gun for about 1500 rds now. I guess its time to clean it now. Since I bought a new barrel nut wrench going to take barrel off and clean thoroughly.

 

[ChattanoogaPhil]

Since I had new springs put in.... the bolt hold open works about 50%. It used to work just fine with the old springs. I really don't care one way or the other. I have learned to accept my 15-22 as an enigma.

 

[tacticool22]

I trimmed about .050 inch or almost 1mm off the bolt catch spring. Or 1 and 1/2 turns.
It dropped the preload to nearly nothing, so the magazine spring does not have to work as hard. 100% so far.
Don't trim too much off or the catch will rattle. Put the trimmed end in first so the factory end is against the shoulder of the bolt catch plunger.

 

[bulldozerd8t]

I'm glad to know mine isn't the only one out their with this problem. My only concern is dry firing it. It eats any ammo i feed it since the springs upgrade and no feeding problems. It will even shoot GB's now.I will quit complaining now thought there might be a fix.

 

[tacticool22]

So after the mod, the bolt hold open was 100%. Then I let a friend shoot the rifle.
The bolt would not stay open after the last round on a lot of the mags. Then we only used the last mag that didn't work. Same thing, sometimes the hold open would work, then it wouldn't.
Then I noticed where they were gripping the rifle. On the mag well, mindful of not touching the mag.
The heel of their hand was riding on the bolt release catch sometimes. So the bolt catch didn't have a chance to work because their hand was pressing on the lever.
They changed thier grip to the handguard and the bolt always held open.
Simple mod to the spring and a simple fix to the shooter.

 

[mrasgt]

Maybe too sensative to ask, but....

In the 15-22, what makes it go multiple shots on one trigger pull? Sorry for the stupid question, I know what you have to change in an AR.

 

[Citoriplus]

In the 15-22, what makes it go multiple shots on one trigger pull? Sorry for the stupid question, I know what you have to change in an AR.

If it isn't a faulty trigger assemble letting the hammer go on its own it can be caused by whats known as a slam fire.
It happens when the bolt closing generates enough speed for the firing pin to overcome its spring letting it 'slam' forward into the shell primer.
Oddly enough its how a lot of full autos like the good old grease gun and the Sten gun work.
Except in guns like them they don't bother with an separate firing pin or spring.
They just use a machined bump on the bolt face and fire from an open bolt.

 

[bulldozerd8t]

So after the mod, the bolt hold open was 100%. Then I let a friend shoot the rifle.
The bolt would not stay open after the last round on a lot of the mags. Then we only used the last mag that didn't work. Same thing, sometimes the hold open would work, then it wouldn't.
Then I noticed where they were gripping the rifle. On the mag well, mindful of not touching the mag.
The heel of their hand was riding on the bolt release catch sometimes. So the bolt catch didn't have a chance to work because their hand was pressing on the lever.
They changed thier grip to the handguard and the bolt always held open.
Simple mod to the spring and a simple fix to the shooter.

I installed a fore grip on my rail so I never hold back by the mag. Mine only has problem with certain ammo and one of my favorite cheap ammo it shoots it fine but 75% of the time the bolt does not hold open, blazers. My thought that the ammo does not create enough energy to hold the bolt open. I shot some sv and the bolt does not stay open. Now cci mini mags, federal 510's, GB's hold the bolt open.

 

[tacticool22]

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.

 

[bulldozerd8t]

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.

Never thought of it that way. I thought the bolt was not going back far enough because of low powered ammo. When you say spring mod can you elaborate on this modification?

 

[Citoriplus]

Never thought of it that way. I thought the bolt was not going back far enough because of low powered ammo. When you say spring mod can you elaborate on this modification?

Check post # 10 in this thread.

 

[bulldozerd8t]

Check post # 10 in this thread.

Thanks for the info, post 10 sorta blowed over my head,didn't quite understand it.

 

[bulldozerd8t]

I trimmed about .050 inch or almost 1mm off the bolt catch spring. Or 1 and 1/2 turns.
It dropped the preload to nearly nothing, so the magazine spring does not have to work as hard. 100% so far.
Don't trim too much off or the catch will rattle. Put the trimmed end in first so the factory end is against the shoulder of the bolt catch plunger.

The bolt release latch on the left side .You drive that pin out to get to the spring?