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Discussion Starter · #1 ·
Have just finished pulling my mini gas block apart (screws were loose!), out of curiosity I snugged up the halves (without the little port thingy fitted) in the same position marked with the port fitted and closed the action. It seems to move the block about a half mm further down the barrel. Is it supposed to hit it or have I missed a memo? surley this would stop the action closing completely and add extra vibration/damage?
 

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doonnzl, I wouldn't shoot the mini with out all the parts in or you could damage the mini or your self. The gas bushing indexes the gas block to the barrel. So with the 4 screws snugged down (use loctite blue on the threads), and the halves evenly gaped, the slide rod will contact the gas block, the gas piston will be housed inside the hole in the end of the slide rod.
I once put a rubber shock buffer in there to lessen the main springs shock, (slide rod end to gas block). It worked great for about 500 rds. then the rubber cracked from the heat. Mike Knifong is working on a more durrable solution.
It is normal for the slide rod end to strike the gas block. It shouldn't strike the gas piston. I hope this helps.
 

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Discussion Starter · #3 ·
As per normal you've answered my question plus the next couple....
Wasnt planning on shooting it without the port in place but was curious to know if it would improve the performance with a little head space between the slider end and the gas block lower half, ie less shock would take away the need for a buffer at the front or less shock sent thru the barrel.
With the gas block off altogether the slider seems to stop once it closes the action. Just a thought, wondered if anyone has shaved a bit off the slider to find out...
Have since reassembled the block as per the instruction found here while I make up a barrel shroud/brace. Will post range results when its finished, but if no one has any experience (or warnings) with shortening the slider I ll give it a whirl too and let ya know....
 

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doonnzl---I've done what you're refering to. I read an article by a man called CE Harris who worked in R&D for Ruger. If you'll look at the design you'll see that with the operating rod hitting the lower gas block it is in effect stopping the bolt from going into full battery. This accounts for the slack in the bolt when the action is closed. On my Mini-14 I found that I had to take off quite abit from the gas piston as well as the operating rod. I didn't have access to a lathe so I was forced to use a bench gringer. It ain't pretty but it got the job done. I finally ended up with clearence between the operating rod & the gas block & between the gas piston & the bottom of the bore in the end of the operating rod. Once you get this the bolt is driven into battery by the force of the recoil spring & there is no slop in the bolt at all. I can't help but believe that this would be of benefit to those people who have trouble firing the hard primers found on military surplus ammo. I've only had the rifle to the range once since then & the wind was blowing so bad that I couldn't tell if the modification helped at all with the accuracy. I can say it didn't hurt the function any. If you decide to try this remember to keep taking a little off then check your fit. Once you get clearence between the oprod & the gas block check to see if the gas piston is bottoming in the oprod bore, if so correct that. I've heard people voice concerns about the ability of the bolt to take the force of the spring slamming it into battery. I can't see this because in my opinion the reverse force of the oprod camming the bolt open & forcing it back to recock the hammer has to be just as great. I looked at the action & how it was designed for a longtime before I ever did any grinding, you do the same. Sorry for being so windy.

Good shooting
Bushwack
 

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Hey bushwack, just how much DID you take off the op-rod? Did you place a buffer at the gas tube so when the bolt was in battery the op-rod was resting against the buffer? Was thinking about doing the same.
The only other thing I cant figure is if I replaced the gas bushing with a reduced NWS and the shallowed depth of the slider block; How much pressure will I lose? Hopefully have enough to cycle the bolt. Guessestmits anyone?

rollingstone
 

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rstone---Sorry I can't really say how much I removed from the end of the oprod. This was all kitchen table gunsmithing you understand. I kept on removing metal from the end of the oprod until I had clearence between it & the gasblock. This was when I found out that the gas piston was bottomed out in the bore if the oprod. I remove a good 1/8" from the gas piston. You can tell when the gas piston bottoms out because you'll have clearence between the oprod & the gasblock but the bolt will still be loose. Just keep removing small amounts from both the end of the oprod & the end of the gas piston until the bolt goes into battery tightly & you have about .010" clearence between the end of the oprod & the gasblock. I haven't tried any kind of buffer yet & with clearence between the oprod & the gasblock there is no need for one there. Where you need the buffer is between the back of the oprod & the receiver, that's where all the punishment takes place. I will probably try the buffer when I send off my trigger assm. to Mike. I want to try his gas bushings too. Ruger has what they call a buffer in the frame but to me it's more of a replacable wearing surface. All the force of the oprod slamming into it is transmitted to a small steel pin that's only 1/4" in diameter.

Good luck
Bushwack
 

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Discussion Starter · #7 ·
Have just finished filing my slider, only needed about a mm taken off, the piston hole inside the slider WAS 27mm deep and the piston 24mm long so had lots to play with.
Theres one less clunk when the action closes now.

couple of observations......
When closed I have about half a mm gap at the block but the bolt is still moveable (so I stopped filing). There is still about 1.5 to 2 mm difference in length between the piston and hole in the slider.

The slider is now using a little knob on the inside by the cocking handle as the stop.

It was friggin hard to get the end of the slider perfectly square at the kitchen table!

Am still waiting for my shroud to be finished B4 I go to the range to have a play.....
 

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doonzl---There is square then there is Square. I used a combination square & figured that was close enough. While your measurements sound good I can't understand why you're still able to move your bolt. On my Ranch the bolt locks up so tightly you can't move it at all. I'm looking forward to hearing if this mod helps your accuracy. I haven't been able to get back to the range yet to try mine again. Like yours the "Knob" on the side of the bolt halts forward movement of my oprod as well.

Good shooting
Bushwack
 

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Should the op rod hit the gas block? Yes, no doubt that's the way the shootin' machine was made. I think we should step back and ask, Why is that so? Of course, I'm no gunsmith, but I am learning a lot from this forum.

I was informed some months back that the firing pin is free floating. I've since verified that there is no spring inside the bolt to keep the firing pin from advancing.

I'm guessing that if the weight of the op rod forces the bolt to close and lock, that there might be the chance of a slam fire.

Any experience on this from others?

KC

:usa:
 

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KC---I've fired one hundred rounds thru mine after this mod & didn't have any malfunctions outside of some failure to feeds from crappy mags.

Just my 2¢
Bushwack
 

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I was thinking about a second buffer; One to handle the recoil at the rear hitting the reciver and a second one to lock up the op-rod along with the bolt so nothing moves until its time. A double lock up system. The op-rod assembly is suspend by tenson of the recoil spring and the fore end buffer, not resting atop the the gas port. With the current design, there is no way of centering the slider hole and the gas port. If the gas port had a ever so slight taper to it, when locked up it would have minimual contact with the op-rod and a better seal with the slider hole............
I think I just gave myself a project when I get back from vacay.

rollingstone
 

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I can't say for sure if the firing pin on the Mini is truly free floating or not as I've never disassembled the bolt. I do know there is some tension against the firing pin. If you will remove the action & place the barrel down you can press against the rear of the firing pin & watch it rebound. It's not much but it may be enough. As to rollingstones idea of tighening up the fit of the oprod I think this get's away from the idea of reliability through loose tolorances. Also the idea of a better seal between the gas piston & the oprod bore will just launch your brass further & batter your receiver harder. The volume of gas reaching the oprod is more than enough as is demonstrated by Mikes gas bushings. I also think that proper fitting of the oprod to give clearence between it & the gasblock negates any need for a buffer in that area. If you have no contact there's no shock to buffer. These are just my thoughts so don't let me deter you from trying out any ideas you may have. If I knew what I was talking about I'd be building my own little rifle & you all would be telling me what was wrong with it.

Good luck
Bushwack
 

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Well, Bushwack,
There seem to be at least 3 safety features built into the bolt.

1) One bolt lock, which is disengaged when the op-rod moves rearward. By the way, the bolt lug follows a not-so-precise path, in fact it looks pretty sloppy to me.

2) I think the op-rod stopping on the gas block might be a safety feature to help prevent slam-fires, though this is only a guess on my part. So it's only the inertia of the bolt assembly that seats the round.

3) The firing pin and hammer seem to be matched so that only if the bolt is properly seated will the hammer send the firing pin home.

I put an o-ring around the gas "piston" in an attempt to absorb some shock when the op-rod slams into the gas block. I get a very nice plunk once in a while, when the op-rod just happens to seat without hitting the gas "piston". Now if I could think of a way to get the op-rod and gas "piston" to seat perfectly every time!

KC

:cool:
 

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I had a similar idea about the impact of the slider rod on the gas block, so I trimed a 1/8" piece of neopreme rubber to fit around the gas piston, to absorbe the slide rod impact. It worked GREAT! , and really quited the mini's metal to metal noise. It worked great for 500 rds, then I checked the buffer, and it had gotten a crack in it so I took the buffer out. I talked with Mike of Org. He thougt the idea was worth working on. The last time I talked with him he was working on a more heat resistant solution.
The mini's bolt/firing pin system seem to work on inertia the last 1/8" , so forcing the bolt home with the inertia taken out of the equation for the bolt, may create a new wear area i.e. the bolt roll lug. Since the mini's bolt dosen't have a bearing in there, it may be tough enough to hold up. Time will tell.
As far as ram fire, the mod seems to work ok, but it could be a 1 mini in a hundred will not work with out a ram fire. No one knows for shure, so guys just be careful, and good luck. I am searching for a more heat resistant rubber to make a buffer.
 
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