A little Mossberg 351 KA help

[d4dave1]

I have a Mossberg 151 KA that I purchased here quite some time ago. I have been playing with it during this isolation stuff in an attempt to make it function properly. I have stripped it right down to bits and pieces and reassembled it (more than once) but it will not cycle properly. I owned a Mossberg 151 KA as a teenager (stolen from me in the 80"s) and I know how accurate they are and how reliable they can be, so this one has me baffled. I also own another 151 KA that I purchased off here many years ago and it is in overall better condition and functions properly.

The action will fire and attempt to load another round. About half the time the round loads but the action will not be cocked and ready to fire. It is difficult to move the action back to eject the live round. The other half the time after the first round fires the next round up is caught by the action as it tries to close before the round has loaded up and into the chamber. So the live round is sort of jack knifed inside the chamber.

While I did use Ninja Midgets YouTube video as a guide to disassemble and re-assemble there are a few differences between the 151 K that he is demonstrating with the the 151 KA. The bolt assembly, firing pin and trigger group are different as well as the breech plug but the entire rifle assembles and functions as normal dry firing. The rifle had the incorrect trigger guard on it when I purchased it and the safety has been monkeyed with but I have it functional again.

Mu gut is telling me that the main spring is too strong. It is not allowing normal recoil to send the action back far enough to actually re-#### and is returning too quickly before the next live round has the chance to enter the chamber. Because this rifle had obviously been monkeyed with previously I am wondering if perhaps it may have to "mix and match" parts that are out of tolerance maybe? The rifle is spotlessly clean now and properly lubricated as well as I polished the load ramp assembly from the tube mag.
So my thinking is perhaps add a "washer" to the breech plug in order to provide a bit more distance for the spring and ease the spring pressure.
Anyone?

I do know that the exploded view that I attached is not specifically for the 151 series.

 

[Archer Sam]

This is where i would start.
Are the 4 notches in the bottom of the receiver lined up with the 4 tabs on the feed tube for the mag? Ensure trigger/sear is put together in proper manner(made that mistake once.Most likely culprit) Check to ensure the ejector is not too tight on the shells( had one like that)and is moving in the slot properly(not bent a little).I wouldn't add anything yet.
Scott...

 

[d4dave1]

This is where i would start.
Are the 4 notches in the bottom of the receiver lined up with the 4 tabs on the feed tube for the mag? Ensure trigger/sear is put together in proper manner(made that mistake once.Most likely culprit) Check to ensure the ejector is not too tight on the shells( had one like that)and is moving in the slot properly(not bent a little).I wouldn't add anything yet.
Scott...

Thanks Scott. The 4 notches are properly lined up. Unless parts are missing or have been "substituted" in the trigger assembly it is correct as well. I do need to have a closer look at the ejector.
I cannot find an actual 151 KA exploded parts view. I have found the 151 and lots of others but not the 151 KA. So every parts list is not quite proper.
Dave

 

[headhunter2]

I don't remember what the difference is from 151k to 151KA but would assume to be minor. I know one of the models had a small bolt change mid production but don't remember which model. I have tuned a few up but disregarded what model I was working on. There is an article on another forum that explains how to tune up a semi. I will try to look things up and get back here with what ever I find. If you have 2 out of 3 working you probably have tried most of what I would suggest. I tried adding a 151 parts diagram but didn't work. I will check back - Bill

 

[d4dave1]

I don't remember what the difference is from 151k to 151KA but would assume to be minor. I know one of the models had a small bolt change mid production but don't remember which model. I have tuned a few up but disregarded what model I was working on. There is an article on another forum that explains how to tune up a semi. I will try to look things up and get back here with what ever I find. If you have 2 out of 3 working you probably have tried most of what I would suggest. I tried adding a 151 parts diagram but didn't work. I will check back - Bill

Thanks Bill, much appreciated. The only obvious differences that I can find between the K and the KA are:
1. The breech plug shape. KA is plastic and sloped off. The K looks more like a breech plug.
2. The safety, or complete lack of one. KA has a conventional side safety while a lot of K's only have the slide bolt lock hole.
3. The bolt configuration.
4. The firing pin mechanism. The K firing pin slides under some detentes on the bolt while the KA is free floating and hooks into the breech plug.

*These are the differences that I see on the KA that I have compared to K's online such as in Ninja Midgets guide videos. As I mentioned before it is possible that a previous owner has played "mix and match" from a parts bin which would really leave me out in the cold on this rifle. I guess then I would just break it all down and sell if for parts.

 

[headhunter2]

Well I went to my "go to" sight and there was just too much info that "may" relate to your problem. RimfireCentral and down to the Mossberg forum. I have several 151K models and the 151M models but never had much problems that wasn't my own fault. I usually just call them an education. Have a read there and see if any of that help. - Bill

 

[Archer Sam]

Slopped and plastic breech cap sounds like a 351KA? Here is a better picture to ensure you have all the parts.
Part R479 can go in upside down to? Check your mag tube for dents also. A small dent can hinder feeding but still somewhat function.
They share a lot of similarities. Hopefully seeing the two diagrams sheds some light on if you have the proper parts or not.

351KA parts diagrahm
https://i.imgur.com/H8JJ9UT.jpg

151M( should be close to 151)
https://i.imgur.com/9nhWQ5M.jpg

Any chance you could post a couple of pictures of the action out of stock showing the trigger group?

Scott...

 

[d4dave1]

Slopped and plastic breech cap sounds like a 351KA? Here is a better picture to ensure you have all the parts.
Part R479 can go in upside down to? Check your mag tube for dents also. A small dent can hinder feeding but still somewhat function.
They share a lot of similarities. Hopefully seeing the two diagrams sheds some light on if you have the proper parts or not.

351KA parts diagrahm
https://i.imgur.com/H8JJ9UT.jpg

151M( should be close to 151)
https://i.imgur.com/9nhWQ5M.jpg

Any chance you could post a couple of pictures of the action out of stock showing the trigger group?

Scott...

Damn it getting old sucks at times! You are absolutely correct it IS a 351 KA not a 151. I went to get my cell phone to load a few pictures as you requested and there plain as day it says 351 KA on the barrel. Checked my second rifle...same thing. "Sigh" Shake my head.

Well at least I am working on the correct MODEL now.

Part number R479 can go in upside down and/or backwards....lol. Ask me how I know. No dents in the tube and the tube has been cleaned and lubricated properly. I am going to head out to my shop and disassemble the rifle again and take some more good pictures.

 

[kamlooky]

I'm surprised mikeystew hasn't chimed in yet.
I do beleaf he putter's wid deese units as well.

 

[Archer Sam]

Update. Not sure if the same but?
I have a 351C that I took out of the stock that functions 100%. R479 is pointing down at the rear away from barrel(wide section) and up towards barrel at the front(narrow section)against the sear.
I remember having an issue one time with this and took a bit to figure it out.

 

[BeansGuy]

I have a Mossberg 151k and it has similar issues to a lesser degree. I also suspect the main spring is too powerful because often the bolt catches a round going into the chamber. Sometimes it catches the empty shell casing before ejecting! Granted, mine was manufactured a long time ago (the 50's according to my grandfather) and it mostly sat in a safe collecting dust. When I got it, I did as you did and disassembled it completely and cleaned everything. Once I had done that, the malfunctions went from 1/30 to more like 1/90. Truthfully, I suspect 151k's and 151ka's are prone to the occasional FTE and FTF.

 

[headhunter2]

Good Catch Archer Sam. I was thinking the daigram didn't match the title. I was going to retrieve my 351 diagram but realized I had miss labeled a 352 diagram. If I remember right the 351 has 2 styles of firing pin with the second style used in a second style bolt. They look the same from the top but the bottoms are different. Just going by this foggy memory as I have never had a 351 but have worked on a couple over the years. Owned lots of other 350 models and many 151 models but never a 351. Hope that may be a lead. - Bill

 

[d4dave1]

Sorry for not getting back to everyone. I was informed that 4 days in a row in the gun room is too much and that I needed to deal with an electrical problem so I had to spend y-day wiring in fixtures. LOL

I would like to change the title of the Thread to correctly identify the rifle as a 351 KA but I have not been able to figure it out??

And I have about 20 pictures that I would like to load on here but I am not sure what the rules are about number of pictures? I get it, excess pictures are a burden. I was only thinking that perhaps a group of good pictures may serve a few (bunch?) of other Mossberg owners?

I will post some and see where it goes. My apologies to the Admins and/or Mod.'s if I am breaking any rules.

I am suspicious of the trigger sear in these pictures? The edge appears rounded and buffed, whether deliberate or just wear and tear?

 

[d4dave1]

My bolt assembly as it came out of the rifle today.

And here is a picture of what is happening when a jam occurs. Occasionally the action will cycle closed with the chamber empty and the trigger not cocked.

 

[d4dave1]

And the trigger - sear group as it looked today.

 

[kamlooky]

To edit the title bar, down on the bottom, hit the "Edit" button, then the "Go Advance" button.
This will allow yewse to change the title.
Buttt, yew gartzs tuh hit the "Save" button.

As far as the ammo gitt'in sqwarsh'd, did you try different ammo?

 

[TrevorJ]

That sort of jam looks like a feeding tube alignment issue. Perhaps other problems as well, but I would verify that the feeding tube is aligned with the receiver. There should be 4 tabs, and a spring. If one of them is out of sorts, can cause headaches.
It could also be the hold down screw is a bit off center.
As for the recocking, if the trigger return spring is tired, that may be contributing to not recocking as well.

 

[Archer Sam]

Your bolt assembly is same as mine. My sear is square cut with no roundness at all(edges just cleaned to not be sharp).Could be the culprit for not re cocking.

Check to make sure the shell cut off bracket(u shaped piece on the mag tube) is functioning properly or the shells will hang up(if dirty) or sometimes feed too fast( if spring is broke/weak). Try moving the action slowly while watching the face of the bolt while shells are feeding. I would bet the shells aren't getting under the extractor during loading(from the picture with the shell in it). I have had more 22's with this issue than any other over the years. Alignment(as mentioned) is also a good possibility.
Very nice pictures. They show great details!

Scott....

 

[d4dave1]

To edit the title bar, down on the bottom, hit the "Edit" button, then the "Go Advance" button.
This will allow yewse to change the title.
Buttt, yew gartzs tuh hit the "Save" button.

As far as the ammo gitt'in sqwarsh'd, did you try different ammo?

Sorry Looky, tried your directions but No Joy.
No, I have not tried different ammo yet. I am fairly certain this is a firearm problem. But then....I was also certain of the number too...!!??

 

[d4dave1]

So I re-assembled the rifle again today. I looked at almost every part under a bright light and a magnifying glass. The trigger sear still makes me wonder. But as one of you mentioned a few posts back I think the trigger group - safety might be the culprit. The safety has been wonky from the start and getting it to hold properly in position when re-assembling is a problem. Part number 1209 and 1210 the safety pin and retaining ring appear goofed.

When I re-assembled I tightened up the breech plug as normal then backed it off one full turn. Had to play with getting the safety assembly to install properly but finally succeeded. I ran 5 rounds through the rifle without a jam but the "fail to ####" issue happened twice. Knowing that the safety is kitty wonkus I carefully moved it around again until it clicked into place and then the rifle would fire and load the next round.

Here is a close up of the safety and trigger assembly. All the scratches etc that you see were there when I first opened up the rifle. The retaining ring almost looks home made?