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Discussion Starter · #1 ·
I've read in several places that the metal to metal banging of the oprod against the gas block affects accuracy. But, I don't understand how....
Trigger gets pulled, powder explodes, bullet shoots out, gas goes through piston and forces oprod back/ compressing recoil spring, recoil spring slams oprod forward, a new round is loaded, and the oprod slams home against the gas block long after the bullet leaves.
How does this process affect accuracy.... how could that projectile be affected by the slamming op-rod after its passed the muzzle?

(Also, my piston has a minute bit of play in it.. could this affect accuracy? Is the slamming op-rod changing the position of the gas port bushing?)

Let's keep these factors constant: good ammo, stock magazines,.050 gas port bushing, accustrut Harmonic barrel stabilizer, Solid bench rest, upgraded trigger job, great scope and seekins rings.... clean gun/ barrel and lightly lubed parts, 30 inch lbs and evenly torqued gas block screws, glass bedded stock.... and let's assume I'm a decent shooter ( I consistently get sub MOA on my Ruger American Hunter).

Please help me understand how the metal to metal slamming of the op-rod against the gas block affects accuracy?
I'm just trying to understand why the Mini-14 isn't consistently more accurate... I'm ok with it, I just want to know why.
 

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· Formerly "raf"
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My understanding is that there can be issues caused by the Op-rod contacting (hitting) the surface of the gas block in an uneven pattern. Ideally the Op-rod should contact the surface of the gas block squarely, and make 100% contact; not off to one side or the other and making partial contact. If you carefully examine the finish wear on your Op-rod and the place where the Op-rod contacts the gas block, the wear pattern should indicate if there are any problems.

The solution is to gently sand the contact point (high point) on the gas block, coat with Prussian blue or a colored sharpie, and then rack the Op-rod many times allowing it to slam home. Re-examine wear pattern and continue as needed.

It may be that installing a forward buffer can mask this condition to some degree.
 

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Solid: first of all, welcome to the forum!

The metal-metal hammering of the gas block produces some harmonic effects, although with your set-up (tapered barrel and strut), those effects are dampened considerably.

I prefer using at least a front 1911 buffer to eliminate the metal-metal contact for four main reasons:
1) they work well - particularly in my skinny-barreled 181 (without a strut) and is an easy non-permanent mod.
2) they reduce/eliminate the forward shock of the op-rod slamming into the gas block. It is tough on many optics not designed for that direction of shock. Mini-14s - for years - were known as "scope killers" because of this. Newer scopes generally address this, and air-gun scopes are designed to handle this "forward shock".
3) for the newer generation Mini-14s (Ranch Rifles), front buffers tend to get chewed up because of the face of the op-rod, which has a lip that acts like a RONCO slicer/dicer. Some buffers do better than others. FYI, I ground off the lip on a 583 with no ill effects but understand I will always need a buffer at least as thick as the lip's length was. But they pretty much last forever that way. This, though, is a non-reversible mod. I did it because my 181 (without a lip) has done me well for 42 years. No problems without the lip as long as I have a front buffer in place.
4) the shooting experience is - IMHO - far nicer with the 1911 buffers (both fore and aft), but each Mini is different.

I also run a rear buffer with no ill-effects. The key is that some thicker buffers may affect cycling: check the distance the op-rod travels before it engages the bolt. Mine generally have about a 1/8 - 1/4 travel before that, but - again - each Mini is different. Give the op-rod some travel before engaging to allow for some rearward momentum. Generally, a typical 1911 buffer is fine. As with a front buffer, it makes for a greater shooting experience.

I have "rolled my own" buffers and found vinyl baseboard works and survives well, using a 9mm casing for the holes. I had the material around which was the only reason I tried it. For most, though, 1911 buffers work well and ther is no "manufacturing" to make a buffer. They are inexpensive and hold up well (although now as well as the vinyl baseboard). I have both. I have also tried out other materials that I had around the farm but for the cost and time, 1911 buffers is now my go-to solution. The 583s' lip at the front-end of the op-rod is the demon in terms of survival/life expectancy. During a typical clean up after firing, just include inspecting the front buffer and replace as needed. My "flat-faced" 181 op-rod has lasted for ten years of use because there was no RONCO lip. After about 100 rds through my modified 583 (ground-off lip) there have no problems and no wear of the front buffer.

Lots of things to consider and my personal "solutions" may not work for you as "each Mini is different"!!!
 

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Discussion Starter · #6 ·
My understanding is that there can be issues caused by the Op-rod contacting (hitting) the surface of the gas block in an uneven pattern. Ideally the Op-rod should contact the surface of the gas block squarely, and make 100% contact; not off to one side or the other and making partial contact. If you carefully examine the finish wear on your Op-rod and the place where the Op-rod contacts the gas block, the wear pattern should indicate if there are any problems.

The solution is to gently sand the contact point (high point) on the gas block, coat with Prussian blue or a colored sharpie, and then rack the Op-rod many times allowing it to slam home. Re-examine wear pattern and continue as needed.

It may be that installing a forward buffer can mask this condition to some degree.
Thanks for the reply....

If the bullet passes the muzzle before the oprod slams, how does uneven contact impact accuracy?
 

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Discussion Starter · #7 ·
Solid: first of all, welcome to the forum!

The metal-metal hammering of the gas block produces some harmonic effects, although with your set-up (tapered barrel and strut), those effects are dampened considerably.

I prefer using at least a front 1911 buffer to eliminate the metal-metal contact for four main reasons:
1) they work well - particularly in my skinny-barreled 181 (without a strut) and is an easy non-permanent mod.
2) they reduce/eliminate the forward shock of the op-rod slamming into the gas block. It is tough on many optics not designed for that direction of shock. Mini-14s - for years - were known as "scope killers" because of this. Newer scopes generally address this, and air-gun scopes are designed to handle this "forward shock".
3) for the newer generation Mini-14s (Ranch Rifles), front buffers tend to get chewed up because of the face of the op-rod, which has a lip that acts like a RONCO slicer/dicer. Some buffers do better than others. FYI, I ground off the lip on a 583 with no ill effects but understand I will always need a buffer at least as thick as the lip's length was. But they pretty much last forever that way. This, though, is a non-reversible mod. I did it because my 181 (without a lip) has done me well for 42 years. No problems without the lip as long as I have a front buffer in place.
4) the shooting experience is - IMHO - far nicer with the 1911 buffers (both fore and aft), but each Mini is different.

I also run a rear buffer with no ill-effects. The key is that some thicker buffers may affect cycling: check the distance the op-rod travels before it engages the bolt. Mine generally have about a 1/8 - 1/4 travel before that, but - again - each Mini is different. Give the op-rod some travel before engaging to allow for some rearward momentum. Generally, a typical 1911 buffer is fine. As with a front buffer, it makes for a greater shooting experience.

I have "rolled my own" buffers and found vinyl baseboard works and survives well, using a 9mm casing for the holes. I had the material around which was the only reason I tried it. For most, though, 1911 buffers work well and ther is no "manufacturing" to make a buffer. They are inexpensive and hold up well (although now as well as the vinyl baseboard). I have both. I have also tried out other materials that I had around the farm but for the cost and time, 1911 buffers is now my go-to solution. The 583s' lip at the front-end of the op-rod is the demon in terms of survival/life expectancy. During a typical clean up after firing, just include inspecting the front buffer and replace as needed. My "flat-faced" 181 op-rod has lasted for ten years of use because there was no RONCO lip. After about 100 rds through my modified 583 (ground-off lip) there have no problems and no wear of the front buffer.

Lots of things to consider and my personal "solutions" may not work for you as "each Mini is different"!!!
Thanks for the reply...

I have the rear buffer installed- but, for the front buffer, do you just slide it over the piston?

Is the piston supposed to be rigid, or is a little movement ok?

I wonder why ruger designed the oprod face to have the little lip? It appears that lip allows the oprod to make contact with the gas block at the block's most solid area....
 

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If the bullet passes the muzzle before the oprod slams, how does uneven contact impact accuracy?
By the time the Op rod hits the back-end, the bullet is long gone out of the barrel. By the time the Op rod comes home at the gas block, asumming that the rod and block are contacting properly/evenly, any residual harmonic should have already dissipated by the time you can pull the trigger again. As Bob mentioned, uneven impact of the Op rod on the gas block will likely cause an issue, as its likely to introduce a new resonance along the barrel, and gawd knows what else.

Link posted by another Member recently, a good read:

G
 

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Ruger ranch model 5802; Norma 5.56 62 grain penetrator 👍
Nice looking rifle.

I have the 5855 and it took a lot of trial and error to match the right ammo for it. Your mileage may vary, but I have the best results with .223 at 69gr to 73gr, and it's sub-MOA (my best ammos have a minimum ballistic coefficient of 0.3xx). I also put some shims in at the receiver (a poor man's bedding) which not only tightened the groups, but reduced the number of flyers.

The purported twist rate by Ruger for my 5855 should have worked with 55gr, but I was all over the map. So you might consider trying different ammos, lower and high grains, to find what works with your particular rifle. I'd be interested in seeing the results.

.02
 

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Discussion Starter · #10 ·
Nice looking rifle.

I have the 5855 and it took a lot of trial and error to match the right ammo for it. Your mileage may vary, but I have the best results with .223 at 69gr to 73gr, and it's sub-MOA (my best ammos have a minimum ballistic coefficient of 0.3xx). I also put some shims in at the receiver (a poor man's bedding) which not only tightened the groups, but reduced the number of flyers.

The purported twist rate by Ruger for my 5855 should have worked with 55gr, but I was all over the map. So you might consider trying different ammos, lower and high grains, to find what works with your particular rifle. I'd be interested in seeing the results.

.02
Hi,
If I try higher grain ammo, I'll have to go back to the factory gas port bushing.
I tried some 69gr Federal match premium, and my .050 bushing wouldn't cycle it.
Are you running a factory gas port bushing with your heavier/ hotter loads?
 

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From what I've read and seen, the accuracy problems are not caused by the op rod cylinder slamming into the gasblock per se. It's caused by inconsistent seating of the op rod when it's in the forward position. Sometimes it seats a little to one side, then on a subsequent shot it seats to the other side.

So when the op rod and gasblock separate on firing, the reactive forces are aligned just differently enough to affect the rifle's harmonics, and therefore accuracy.

I generally see a bimodal spread with respect to the op rod seating, i.e. either canted to the left, or to the right. However, one orientation seems to be favored more, typically about a 1:4 ratio of one side vs. the other. So for every 5 shots, 4 go to the left, and 1 goes to the right, or vice versa. This would explain why minis tend to throw off a flyer every 5 shots or so.

As mentioned above, there is a procedure called the Harris modification, by one of Ruger's engineers. He called for milling down the face of the op rod until it no longer contacted the gasblock at all. I haven't actually tried this, so can't vouch for how well it works.
 

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Discussion Starter · #12 ·
From what I've read and seen, the accuracy problems are not caused by the op rod cylinder slamming into the gasblock per se. It's caused by inconsistent seating of the op rod when it's in the forward position. Sometimes it seats a little to one side, then on a subsequent shot it seats to the other side.

So when the op rod and gasblock separate on firing, the reactive forces are aligned just differently enough to affect the rifle's harmonics, and therefore accuracy.

I generally see a bimodal spread with respect to the op rod seating, i.e. either canted to the left, or to the right. However, one orientation seems to be favored more, typically about a 1:4 ratio of one side vs. the other. So for every 5 shots, 4 go to the left, and 1 goes to the right, or vice versa. This would explain why minis tend to throw off a flyer every 5 shots or so.

As mentioned above, there is a procedure called the Harris modification, by one of Ruger's engineers. He called for milling down the face of the op rod until it no longer contacted the gasblock at all. I haven't actually tried this, so can't vouch for how well it works.
Wow... makes sense. I knew something was going on, and there does seem to be a pattern with the fliers.
I may buy an extra oprod online and give it a trim... and then put a 1911 buffer around the piston so that it'll buffer the oprod/ gas block slamming , and, hopefully give the oprod an even "landing ". I just hope this doesn't cause undo stress somewhere else like on the bolt or something.... Ruger came so close to making the ultimate rifle... why not fix this issue?
 

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Two questions on this "modification." #1, will Ruger sell a new op rod to a customer?, and #2, will Ruger cancel any future warranty work on the firearm if they see it's been tampered with?

One more question. Ever since I've had my mini, I've had a 1911 buffer on the rear end of the op rod spring, with good results, and at 1st, also had one on the gas block end too but eventually removed it because I wasn't sure that it wouldn't cause future problems. Why wouldn't just having the forward buffer in place accomplish what the Ed Harris mod would do?
 

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From what I've read and seen, the accuracy problems are not caused by the op rod cylinder slamming into the gasblock per se. It's caused by inconsistent seating of the op rod when it's in the forward position. Sometimes it seats a little to one side, then on a subsequent shot it seats to the other side.

So when the op rod and gasblock separate on firing, the reactive forces are aligned just differently enough to affect the rifle's harmonics, and therefore accuracy.

I generally see a bimodal spread with respect to the op rod seating, i.e. either canted to the left, or to the right. However, one orientation seems to be favored more, typically about a 1:4 ratio of one side vs. the other. So for every 5 shots, 4 go to the left, and 1 goes to the right, or vice versa. This would explain why minis tend to throw off a flyer every 5 shots or so.

As mentioned above, there is a procedure called the Harris modification, by one of Ruger's engineers. He called for milling down the face of the op rod until it no longer contacted the gasblock at all. I haven't actually tried this, so can't vouch for how well it works.
I recall reading years ago that Mini accuracy was improved some by squeezing the forearm liner sides inward just enough to take most sideways play of the op rod out. IIRC, the writer determined that only the front few inches needed the squeeze where the front block of the op rod began to settle in to it's rest against the gas block.

In theory, this makes sense. Taking most of the side-to-side play of the op rod where it interfaces with the gas block makes everything more consistent. While it may not shrink groups big time, I'm sure it would reduce those flyers that bite our a$$.

I did this procedure to one of my minis many yrs ago. I'm not sure I even still have that one and I didn't do any before/ after testing to investigate possible improvements. Coulda, shoulda....
 

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From what I've read and seen, the accuracy problems are not caused by the op rod cylinder slamming into the gasblock per se. It's caused by inconsistent seating of the op rod when it's in the forward position. Sometimes it seats a little to one side, then on a subsequent shot it seats to the other side. So when the op rod and gasblock separate on firing, the reactive forces are aligned just differently enough to affect the rifle's harmonics, and therefore accuracy.
A very valid point, that would certainly have an effect. After thinking on this, my described scenario would only apply for quick follow up shots. The scenario you describe would affect any shot at any interval.
 

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Discussion Starter · #17 ·
Two questions on this "modification." #1, will Ruger sell a new op rod to a customer?, and #2, will Ruger cancel any future warranty work on the firearm if they see it's been tampered with?

One more question. Ever since I've had my mini, I've had a 1911 buffer on the rear end of the op rod spring, with good results, and at 1st, also had one on the gas block end too but eventually removed it because I wasn't sure that it wouldn't cause future problems. Why wouldn't just having the forward buffer in place accomplish what the Ed Harris mod would do?
When I had a buffer in the front, the little lip at the bottom of the slide assembly / oprod tore it up unevenly, shredded it.. does anyone have a picture they can post of a Forward mounted buffer after it's been through more than 50 rounds?
 

· Formerly "raf"
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Lots of interesting ideas being proposed.

Let's begin from initial design goals: Ruger wanted a firearm that would shoot most any ammo reliably and with "acceptable" accuracy. IMHO, they suceeded in the first part, and not so much on the second part, at least with the early "Pencil" bareled rifles. I think that's a reasonable statement.

As we all know, the OEM Ruger gas block "Piston" has some amount of "wobble" built-in. Presumably this is to ensure a correct initial alignment between the Piston and with the Cylinder for the Piston in the Op-rod, and to accomodate any likely mis-alignment between gas block Piston and the Op-rod Cylinder when the Op-rod is moving forward towards engagement with the Piston and its' Cylinder in the Op-rod. The "Cylinder" in the Op-rod has a chamfer at the beginning of its' bore to help engagement with the tapered end of the Piston.

Forgive me for stating the obvious, but sometimes it is useful to do so, especially as far as definition of terms/ nomenclature goes. Helps if we all use the proper terms.

My new Adjustable Gas block from ASI has a Piston which is firmly anchored in place, and without typical OEM Ruger "wobble". I've not installed it yet. but I will try to take some shots before-and-after to see whether this "Piston-wobble" makes any difference. My 186 Mini is pretty accurate with good handlloads, so a significant difference between the "fixed" ASI gas block Piston and the OEM Gas block with "wobbling" gas Piston might show up. IDK. Please don't wait for my results; I'm no scientist, and I have lot of other "irons in the fire", so to speak.

I have a "suspicion" that a fixed gas piston, along with a somewhat wider and deepened chamfer on the Op-rod "Chamber" might be part of the the ultimate solution. That's a guess.

As always, Correct initial assembly of the gas block on the barrel, and CORRECTLY aligning the gas block and Piston with the Op-rod is essential. Not so sure this "Correct assembly" was always done by Ruger, and some valued posters (sandog) have suggested gas block screw values of 25 Inch-Lbs are more likely to be "accuracy-inducing" than the much greater gas block torque values that Ruger specifies. Strongly suggest always replacing previously torqued fasteners with NEW ones

Allow me to return to a feature Ruger "designed-in" to the Mini: RELIABILITY. It may be that Ruger figured that the gas Piston having a tapered forward edge along eith some "wobble", as well as the Chamber in the Op-rod having a chamfer on forward edge were conducive to Reliability, as opposed to conducive to Accuracy.

As we all know, "tightening" some tolerances makes firearms more subject to dirt/crud caused failures. My ancient NM 1911 runs brilliantly as long as I clean it often. My Norinco-based 1911, using excellent components, but with somewhat looser tolerances/fit in selected points runs far longer with minimal cleaning.

"Tightening" some tolerances/components on the Mini might have some beneficial accuracy enhancements, but perhaps at the cost of Reliability. I think we can all agree that the larer "heavy' barrels are an accuracy enhancement with no reliability drawbacks. Other mods may have positives and possibly drawbacks.

Case-by-case risk analysis. of accuracy vs. reliability, IMHO.

I hope the above blather is useful to most folks; I DO tend to be "windy" but I hope my comments might still be useful.
 

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Why wouldn't just having the forward buffer in place accomplish what the Ed Harris mod would do?
I believe that it does. Due to its malleability, the buffer will develop a nice consistent landing zone after so many rounds. I think all the anecdotal accounts of a front-end buffer improving accuracy is due to this phenomenon, vs. cushioning of the cylinder/gasblock impact which most people assume is the cause.
 

· Formerly "raf"
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I believe that it does. Due to its malleability, the buffer will develop a nice consistent landing zone after so many rounds. I think all the anecdotal accounts of a front-end buffer improving accuracy is due to this phenomenon, vs. cushioning of the cylinder/gasblock impact which most people assume is the cause.
I'm no expert, and the Op-rod interface with my particular OEM gas block seems to show full, side-to-side contact.

Forward-mounted buffer may serve to mask any original mis-match between contacting surfaces of Op-rod and the mating surface on the gas block.. Admitedly a pure guess on my part.
 
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