As I have with other posts, I'd like to share some of my experiences and analysis... this time regarding a 188-series Mini-14 ranch rifle in stainless steel.
Personally, I prefer the M14/M1A platform over just about any other semi-auto. That's just me. Take it for what it's worth. Unfortunately, some among us (e.g. my wife) can't handle the size of the M14. So I've been exploring the Mini-14 option. The majority of the controls, etc. are the same as the M14, just 2/3 the size.
However, one of the widespread complaints about the Mini is its accuracy:
(The A-Team theme is playing as I write this. Go figure.)
Some of the possible contributors to Mini-14 inaccuracy are:
- Poor/Crunchy Trigger
- Barrel Whip (especially with the older, thinner barrels)
- Barrel deformantion with heat (shots string vertically as temperature increases)
- Ammunition Quality
- Sights
I never expected the Mini to be a tack driver. Rather, I was simply interested in determining its baseline capability and seeing if a few quick/relatively inexpensive fixes would improve the accuracy somewhat. It's good to know what options are out there, how much they cost, and what they actually change. This stuff fascinates me, and I'd rather share what I've learned than keep it to myself. Maybe it will save someone else some time or money.
Some of the elements investigated:
- Muzzle Brake (Choate M16 A2 style "bird cage"-type, later changed to the "Mo-Reaper" brake) (I needed something with an integral front sight.)
- Barrel Strut (Accu-Strut)
- Scout Scope Mount (Amega Mount)
- Ammunition (all kinds, primarily 55gr FMJ)
All testing was done at 100 yards. I mounted a 12x Leupold scope to the receiver so that I would have a consistent sighting system throughout the duration of the test. (The Leupold to be replaced with something more practical after testing.) All groups were 5 shots or greater, with the exception of a few groups where I was down to the last four rounds in the box.
A Note on Metrics:
I found it very difficult to get a good metric for this analysis. "Group size" -- the greatest distance between centers of any two shots in the group -- didn't accurately reflect what was changing. What I found was that some things reduced horizontal dispersion whereas other things reduced vertical dispersion. You could also think of it as, "Some things reduce cold bore group size, other things reduce vertical stringing." Until the vertical stringing is dealt with, it will always dominate the traditional "group size" metric. But looking at horizontal dispersion can give an idea of what the group size would be without the vertical dispersion.
You'll notice that I often use Winchester white box for the comparisons. This is because it started out grouping the worst, so any effect is magnified. With the good ammo that already groups around 2" (cold bore), it's more difficult to see a statistical change.
Trigger
The Ruger came with a very heavy, very crunchy trigger. I prefer a 2-stage military trigger for rifle, but this one had some easy take-up followed by about 3 stages of gritty creep before the final break. I followed the video found at greatwestgunsmithing.com and was able to make a crisp 5-pound break with virtually no creep through a little bit of Dremel grinding and some patient stone work. I watched the video twice and had the trigger done after about 30 minutes. Your mileage may vary. There's some concern about breaking through the hardened surface when doing a trigger job. After 400 rounds, there was no visible change in the sear surfaces, so I think I'm still ok.
Muzzle Brake
I had high hopes for the Choate flash suppressor/muzzle brake. Unfortunately, it was bored off-center. I returned it to Choate for replacement, only to find that they had none in stock that weren't bored off-center. (They were very friendly about it, but I have now lost about $20 in shipping costs going back and forth trying to get this sorted out.) When I did test with their flash hider/brake, the bullets did not contact the flash hider, but it was such that the front sight wasn't perpendicular to the bore axis. I was able to do a little bit of testing with it (to see the effect of the extra mass on the muzzle). From a cold bore, all else being equal, neither vertical nor horizontal dispersion changed with the addition of the Choate flash hider (measured difference in either direction was 0.25" with S&B ammo). I have since purchased an installed a Mo-Reaper muzzle brake. I'm not a big fan of the name, but it did install without a hitch and the front sight is very nice. (See picture of it and the Accu-Strut below.)
Amega Scope Mount
There's some talk that adding an Amega (or Ultimak) scout scope mount will improve group size. The idea is that the clamping action of the mount prevents barrel whip (and barrel warping as the barrel heats up). All else being equal, the horizontal change was negligible (e.g. 0.25") in my testing. With Winchester white box ammo, the vertical stringing actually increased with the addition of the rail (5.5" to 7.5"). (Keep in mind that the 12x Leupold was used for the tests, not a scout scope.) My guess is that the barrel is already clamped pretty well between the receiver and the gas block, so the addition of the Amega rail didn't do a whole lot. At least, it didn't do a whole lot for me.
Accu-Strut
The Accu-Strut is aimed at preventing barrel whip forward of the gas block. It had one of the larger effects on horizontal dispersion (5" to 2.75", or 45% improvement with Winchester white box). It also decreased vertical dispersion somewhat (6.25" to 5.5")
Now, so far I've been writing about each component one at a time, but interactions between the various parts should be expected.
So I did a design of experiments (DOE) to better capture the interactions. It wasn't a full-factorial DOE, as I had too many types of ammo, and I didn't consistently cool the barrel between strings.
Key learnings so far:
- The largest factor in group size is ammo quality. Winchester white box 55gr grouped greater than 5", regardless of configuration or temperature. S&B 55gr grouped less than 4" regardless of configuration or temperature. Lapua 55gr grouped consistently around or under 2" regardless of configuration or temperature. The Mini didn't like heavier bullets (such as 62gr) at all.
- The Accu-Strut helps horizontal dispersion, regardless of ammo, barrel temperature, or whatever else is bolted on. But it doesn't do a whole lot for vertical stringing.
- Even with the Accu-Strut (and everything else), group size opens up by vertical stringing as the barrel heats up.
- At cool barrel temperatures, with reasonably good ammo, the rifle shoots 2 MOA. As temperature increases, the group size would expand to 3 MOA with good ammo. But with Winchester white box, the groups would be ~3" wide and 9" tall.
My gut feeling is that the Accu-Strut goes a long way to eliminating the muzzle whip of a thin barrel. However, when the groups open up, it looks to be because the barrel is warping (due to heat).
One other option that may help reduce stringing is cryogenic treatment. It's a relatively quick and inexpensive process. People seem to either love it or hate it. Two cryo companies close to Indiana are 300 Below in Illinois and CryoPlus in Ohio. I went with CryoPlus in Ohio. They were extremely friendly and professional. I shipped the barrel to them on Tuesday and got it back the following Wednesday. (They treat over the weekends.)
After cryo treatment, I assembled the rifle with the strut, rail, and muzzle brake.
Again, all groups are at least 4 shots (usually 5) at 100 yards.
Using S&B 55gr ammo, cryo reduced group size from 2.25" wide x 2" tall (before cryo, hot barrel) to 1.38" wide x 0.5" tall (after cryo, hot barrel).
Using Lapua 55gr ammo, cryo reduced group size from 1.5" wide x 2" tall (before cryo, cool barrel) to 0.75" wide x 1.25" tall (after cryo, hot barrel).
Using Winchester white box 55gr ammo, cryo reduced group size from 3" wide x 8.75" tall (before cryo, hot barrel) to 3.25" wide x 3" tall (after cryo, hot barrel).
Looking at all of the different variations I tried and the group geometries, it appears that the Accu-strut reduces overall group size (by reducing barrel whip), while the cryo treatment reduces vertical stringing (caused by stress as the barrel heats up).
From a "most bang for your buck" perspective on improving Mini-14 (old style with the straight barrel) accuracy:
- Use good ammo. I can't emphasize this enough. Test out several brands before you buy a crate of anything!
- Get a trigger job (DIY or about $100 from a gunsmith)
- Cryo the barrel (so group sizes are consistent as barrel heats up) ( < $100, including shipping)
- Add an Accu-Strut (to reduce baseline group size) (~$100 depending on the brand)
If you've already got an old Mini that you stuck in the corner because it wasn't accurate, it might be worthwhile to spend ~$200 to make it acceptable. (At least it's cheaper than buying a new rifle.)
After removing the 12x Leupold, I was getting 3-4" groups with iron sights and Winchester white box. I then put a 5 MOA red dot and was able to hit 6" gongs with no problem (two magazines of 20, just to make sure the barrel was hot). Shots grouped similarly at 3-4".
So was all this just "throwing good money after bad"? That's up for each individual to decide. It was certainly a fun and educational project for me.
As I said in the beginning, I prefer the M14-style action over the AR-style. You'll have to determine for yourself how important ergonomics, magazine price, accuracy, spare parts, reliability, appearance, etc. are to your own needs. A Mini-14 with a wood stock looks rather "friendly" when compared to an AR or AK, IMO.
Personally, I prefer the M14/M1A platform over just about any other semi-auto. That's just me. Take it for what it's worth. Unfortunately, some among us (e.g. my wife) can't handle the size of the M14. So I've been exploring the Mini-14 option. The majority of the controls, etc. are the same as the M14, just 2/3 the size.
However, one of the widespread complaints about the Mini is its accuracy:
(The A-Team theme is playing as I write this. Go figure.)
Some of the possible contributors to Mini-14 inaccuracy are:
- Poor/Crunchy Trigger
- Barrel Whip (especially with the older, thinner barrels)
- Barrel deformantion with heat (shots string vertically as temperature increases)
- Ammunition Quality
- Sights
I never expected the Mini to be a tack driver. Rather, I was simply interested in determining its baseline capability and seeing if a few quick/relatively inexpensive fixes would improve the accuracy somewhat. It's good to know what options are out there, how much they cost, and what they actually change. This stuff fascinates me, and I'd rather share what I've learned than keep it to myself. Maybe it will save someone else some time or money.
Some of the elements investigated:
- Muzzle Brake (Choate M16 A2 style "bird cage"-type, later changed to the "Mo-Reaper" brake) (I needed something with an integral front sight.)
- Barrel Strut (Accu-Strut)
- Scout Scope Mount (Amega Mount)
- Ammunition (all kinds, primarily 55gr FMJ)
All testing was done at 100 yards. I mounted a 12x Leupold scope to the receiver so that I would have a consistent sighting system throughout the duration of the test. (The Leupold to be replaced with something more practical after testing.) All groups were 5 shots or greater, with the exception of a few groups where I was down to the last four rounds in the box.
A Note on Metrics:
I found it very difficult to get a good metric for this analysis. "Group size" -- the greatest distance between centers of any two shots in the group -- didn't accurately reflect what was changing. What I found was that some things reduced horizontal dispersion whereas other things reduced vertical dispersion. You could also think of it as, "Some things reduce cold bore group size, other things reduce vertical stringing." Until the vertical stringing is dealt with, it will always dominate the traditional "group size" metric. But looking at horizontal dispersion can give an idea of what the group size would be without the vertical dispersion.
You'll notice that I often use Winchester white box for the comparisons. This is because it started out grouping the worst, so any effect is magnified. With the good ammo that already groups around 2" (cold bore), it's more difficult to see a statistical change.
Trigger
The Ruger came with a very heavy, very crunchy trigger. I prefer a 2-stage military trigger for rifle, but this one had some easy take-up followed by about 3 stages of gritty creep before the final break. I followed the video found at greatwestgunsmithing.com and was able to make a crisp 5-pound break with virtually no creep through a little bit of Dremel grinding and some patient stone work. I watched the video twice and had the trigger done after about 30 minutes. Your mileage may vary. There's some concern about breaking through the hardened surface when doing a trigger job. After 400 rounds, there was no visible change in the sear surfaces, so I think I'm still ok.
Muzzle Brake
I had high hopes for the Choate flash suppressor/muzzle brake. Unfortunately, it was bored off-center. I returned it to Choate for replacement, only to find that they had none in stock that weren't bored off-center. (They were very friendly about it, but I have now lost about $20 in shipping costs going back and forth trying to get this sorted out.) When I did test with their flash hider/brake, the bullets did not contact the flash hider, but it was such that the front sight wasn't perpendicular to the bore axis. I was able to do a little bit of testing with it (to see the effect of the extra mass on the muzzle). From a cold bore, all else being equal, neither vertical nor horizontal dispersion changed with the addition of the Choate flash hider (measured difference in either direction was 0.25" with S&B ammo). I have since purchased an installed a Mo-Reaper muzzle brake. I'm not a big fan of the name, but it did install without a hitch and the front sight is very nice. (See picture of it and the Accu-Strut below.)
Amega Scope Mount
There's some talk that adding an Amega (or Ultimak) scout scope mount will improve group size. The idea is that the clamping action of the mount prevents barrel whip (and barrel warping as the barrel heats up). All else being equal, the horizontal change was negligible (e.g. 0.25") in my testing. With Winchester white box ammo, the vertical stringing actually increased with the addition of the rail (5.5" to 7.5"). (Keep in mind that the 12x Leupold was used for the tests, not a scout scope.) My guess is that the barrel is already clamped pretty well between the receiver and the gas block, so the addition of the Amega rail didn't do a whole lot. At least, it didn't do a whole lot for me.
Accu-Strut
The Accu-Strut is aimed at preventing barrel whip forward of the gas block. It had one of the larger effects on horizontal dispersion (5" to 2.75", or 45% improvement with Winchester white box). It also decreased vertical dispersion somewhat (6.25" to 5.5")
Now, so far I've been writing about each component one at a time, but interactions between the various parts should be expected.
So I did a design of experiments (DOE) to better capture the interactions. It wasn't a full-factorial DOE, as I had too many types of ammo, and I didn't consistently cool the barrel between strings.
Key learnings so far:
- The largest factor in group size is ammo quality. Winchester white box 55gr grouped greater than 5", regardless of configuration or temperature. S&B 55gr grouped less than 4" regardless of configuration or temperature. Lapua 55gr grouped consistently around or under 2" regardless of configuration or temperature. The Mini didn't like heavier bullets (such as 62gr) at all.
- The Accu-Strut helps horizontal dispersion, regardless of ammo, barrel temperature, or whatever else is bolted on. But it doesn't do a whole lot for vertical stringing.
- Even with the Accu-Strut (and everything else), group size opens up by vertical stringing as the barrel heats up.
- At cool barrel temperatures, with reasonably good ammo, the rifle shoots 2 MOA. As temperature increases, the group size would expand to 3 MOA with good ammo. But with Winchester white box, the groups would be ~3" wide and 9" tall.
My gut feeling is that the Accu-Strut goes a long way to eliminating the muzzle whip of a thin barrel. However, when the groups open up, it looks to be because the barrel is warping (due to heat).
One other option that may help reduce stringing is cryogenic treatment. It's a relatively quick and inexpensive process. People seem to either love it or hate it. Two cryo companies close to Indiana are 300 Below in Illinois and CryoPlus in Ohio. I went with CryoPlus in Ohio. They were extremely friendly and professional. I shipped the barrel to them on Tuesday and got it back the following Wednesday. (They treat over the weekends.)
After cryo treatment, I assembled the rifle with the strut, rail, and muzzle brake.
Again, all groups are at least 4 shots (usually 5) at 100 yards.
Using S&B 55gr ammo, cryo reduced group size from 2.25" wide x 2" tall (before cryo, hot barrel) to 1.38" wide x 0.5" tall (after cryo, hot barrel).
Using Lapua 55gr ammo, cryo reduced group size from 1.5" wide x 2" tall (before cryo, cool barrel) to 0.75" wide x 1.25" tall (after cryo, hot barrel).
Using Winchester white box 55gr ammo, cryo reduced group size from 3" wide x 8.75" tall (before cryo, hot barrel) to 3.25" wide x 3" tall (after cryo, hot barrel).
Looking at all of the different variations I tried and the group geometries, it appears that the Accu-strut reduces overall group size (by reducing barrel whip), while the cryo treatment reduces vertical stringing (caused by stress as the barrel heats up).
From a "most bang for your buck" perspective on improving Mini-14 (old style with the straight barrel) accuracy:
- Use good ammo. I can't emphasize this enough. Test out several brands before you buy a crate of anything!
- Get a trigger job (DIY or about $100 from a gunsmith)
- Cryo the barrel (so group sizes are consistent as barrel heats up) ( < $100, including shipping)
- Add an Accu-Strut (to reduce baseline group size) (~$100 depending on the brand)
If you've already got an old Mini that you stuck in the corner because it wasn't accurate, it might be worthwhile to spend ~$200 to make it acceptable. (At least it's cheaper than buying a new rifle.)
After removing the 12x Leupold, I was getting 3-4" groups with iron sights and Winchester white box. I then put a 5 MOA red dot and was able to hit 6" gongs with no problem (two magazines of 20, just to make sure the barrel was hot). Shots grouped similarly at 3-4".
So was all this just "throwing good money after bad"? That's up for each individual to decide. It was certainly a fun and educational project for me.
As I said in the beginning, I prefer the M14-style action over the AR-style. You'll have to determine for yourself how important ergonomics, magazine price, accuracy, spare parts, reliability, appearance, etc. are to your own needs. A Mini-14 with a wood stock looks rather "friendly" when compared to an AR or AK, IMO.
I am going to pass all of this along to a buddy with a Mini-14 because he is getting very frustrated with his and is wanting to do something about his trigger to start.
