caguns.net

Due to growing usage, our Advanced Search is now for registered members.
However, You can still browse for free!
Listing an item is easy and easy for people to find.

Register a free account today to become a member! Once signed in, you'll be able to participate and use features that aren't available to guests!

Mini 14 Heavy Barrel Build

classicist

New member
Messages
10
New here. I was a longtime member of CalGuns, but seldom contributed there. I thought I’d share one my most recent rifles.

I’m not a huge fan of the AR aesthetic. So, I’ve had a Mini 14 for a number of years now. Because it flung brass right into the scope turrets, I previously mounted a scout scope on an aluminum integrated rail/handguard. One unique modification I did was to drill into the bolt stop/ejector, and modify it into a left hand bolt release. It’s a 580-series, but at 3 MOA or so it was never a target rifle, and I’ve been looking for better accuracy for some time.

Well, finally, I pulled the trigger on swapping in a full-length heavy barrel, and building the Mini into something of a target rifle.

Parts consisted of a $70 Green Mountain .223 8 twist 1.05” unturned blank, and an ASI .750” adjustable gas block, which was around $200. For tooling, I bought a .750” round nose end mill (which proved unnecessary, as described later) and a .910” bushing for my barrel vise (which I had to make). Nobody makes action wrenches, at least as far as I could find, for a Mini; however, the owner of ASI recommended using a large crescent wrench on the forward lower part of the receiver, where the recoil spring sits. Obviously, a reamer and gauges were necessary.

Getting the stock barrel off turned out to be trivial. Soaking the threads in penetrating oil was probably unnecessary, as the old barrel popped right off with just a small application of hand force to the 15” crescent wrench. I measured the thread pitch and turned to the barrel blank.

Once I turned down the barrel blank to .910” at the breech end, stepped down to .750” through the gas block and to the muzzle, crowned the muzzle, and cut the tenon, I set up my lathe for 20 TPI and threaded the tenon to match the receiver. Cutting the recessed breech face was a bit of trial and error, but I got it close enough. I went with a standard .223/5.56 chamber. Finished length came in at 21”.

IMG_5545.jpeg

The final two machining steps were to drill the gas port and recess the top of the operating rod to match the .750” barrel profile. The latter I did with hand files and a lot of patience; however, I had purchased the ball nose end mill for this purpose. The gas port I drilled with a drill press and cleaned up with a small end mill chucked in my drill press. I was successful in avoiding the trip to the Bay Area, where I have access to a Bridgeport mill.

The rifle went right back together and test functioned smoothly. Because the Mini now had an adjustable gas block, I felt it was safe to mount an optic over the receiver, where it belongs. I already had the illuminated 1-6 Vortex Strike Eagle, and found some rings that worked. I glass bedded the stock, and mounted a permanent cheek riser.

IMG_5627.jpeg

The thing shoots pretty well. I’ve got some minor reliability issues to work out, common whenever you start custom gunsmithing. But, so far, with good quality factory ammo, I get around 1.5” 5-round groups at 100 yards. It takes quite a bit of sustained shooting for the groups to start opening. I’m going to work up a load for it at some point, but doing so is pretty far down my list. (6.5x55AI is my first priority, then 8x57 I for a Commission Rifle.) Once I do get around to loading some .223 for this rifle, I sincerely hope that I have a 1 MOA Mini.

IMG_5584.jpeg

Some time down the road, I’m going to take this thing back out of the stock and refinish it. I’m not too happy with the way the stock came out.

This was not a terribly difficult job, simpler than rebarreling a Garand or M1A in my opinion. It’s a shame you don’t see more accurized Minis. They really are well made, simple, and dead reliable. Anybody got questions?
 
When I started working on Mini 14's, I built myself an action wrench head that works with the Brownells handle.
It's a pair of steel blocks milled to fit around the receiver at the front ring where the breech threads are.
That way, you don't twist the receiver.
I have removed and installed lots of Mini14 barrels since then for various shorten/thread jobs as well as installing different barrels.
A mini14 barrel is easier to make than a garand or M14 barrel due to the mini14 using simple V threads instead of square threads as well as the simpler external contour.
 
AR15barrels,

When I first started looking into the project, I was afraid I’d have to make an action wrench my thought was to mill an insert out of brass to fit the right side of the receiver since the left side was already flat. But, I thought I’d try the crescent wrench suggestion first. Given how little torque it required, I think there’s no risk that I damaged the receiver. But if it put up a fight, I’d have changed tactics.

Since you’ve done some Minis, I was wondering if you had any practical advice for machining the breech face. When I did mine, I started by boring down to the same depth as with the stock barrel, then opened it up until the bolt went into battery. I did not mill an extractor cut; instead, I opened the entire circumference. Although there are no signs that the case bases are not adequately supported, I’m concerned that the asymmetrical bolt seating in the symmetrical breech face may be impairing the accuracy. What what was your practice? Thanks in advance.
 
AR15barrels,

When I first started looking into the project, I was afraid I’d have to make an action wrench my thought was to mill an insert out of brass to fit the right side of the receiver since the left side was already flat. But, I thought I’d try the crescent wrench suggestion first. Given how little torque it required, I think there’s no risk that I damaged the receiver. But if it put up a fight, I’d have changed tactics.

Since you’ve done some Minis, I was wondering if you had any practical advice for machining the breech face. When I did mine, I started by boring down to the same depth as with the stock barrel, then opened it up until the bolt went into battery. I did not mill an extractor cut; instead, I opened the entire circumference. Although there are no signs that the case bases are not adequately supported, I’m concerned that the asymmetrical bolt seating in the symmetrical breech face may be impairing the accuracy. What what was your practice? Thanks in advance.
Do you have an earlier or later mini?
I think the earlier ones are the ones with timed extractor cuts while the later ones went to a symetrical counterbore on the back of the barrel (likely to simplify machining).
I would time the extractor cut if that's how the original barrel was.
 
Someone made a heavy sleeve in the 80s to control barrel whip.

It was a name manufacturer.

Clamping pressure btw trigger group and action was a thing with the M14. Iirc anyone playing with mini 14 accurizing would apply the same forearm stiffening and back of the receiver bedding.

Those pads are a pain to balance out in relation to gas system downward force.

Once you get that return harmonized, they shoot.
 
Great job!

I was thinking of getting a Mini 14 for my son to shoot 2 or 3 gun.
 
Someone made a heavy sleeve in the 80s to control barrel whip.

It was a name manufacturer.

Clamping pressure btw trigger group and action was a thing with the M14. Iirc anyone playing with mini 14 accurizing would apply the same forearm stiffening and back of the receiver bedding.

Those pads are a pain to balance out in relation to gas system downward force.

Once you get that return harmonized, they shoot.
I was able to accomplish barrel stiffening with a larger diameter barrel. Any larger behind the gas block would require modification to the gas system. And I did glass bed the action. But I’m still having trouble getting 1” groups.

I’m interested in exploring how clamping force and balance can be tuned. Do you happen to know of a reference or guide explaining the process? I did a little google search and came up empty handed.
 
I was able to accomplish barrel stiffening with a larger diameter barrel. Any larger behind the gas block would require modification to the gas system. And I did glass bed the action. But I’m still having trouble getting 1” groups.

I’m interested in exploring how clamping force and balance can be tuned. Do you happen to know of a reference or guide explaining the process? I did a little google search and came up empty handed.
It's something I noticed bedding M14 actions. You start asking about fitting precision stocks to the heel of an action and you get dead air from that community.

They're solely concerned with unitizing gas system parts for the purpose of the system returning to about the same place shot to shot.

You build up the cap at the end of the stock for more tension on the barrel band.
How much tension is desirable from a NM band I never got a satisfactory answer.

There are double lugged M14 receivers. What I gathered over time was that gluing in an action + reinforcing my forearm weren't enough control over the levering action for people chasing accuracy.

This was notable when I used a Sage ebr chassis and had to mill out the chassis to get my usgi parts to clamp down. Once the rear of the action was basically fixtures in place, you remove the barrel band from your gas system. You have to tune the gas systems return with a limiting screw on top of the barrel. Ideally rocket the screw and maintain your chassis top section torque bc any shifts or changes makes a ~1moa action spray 10mins when locating parts loosen up.
 
Great looking work! I just recently tried a Mini 14 for the 1st time. The stock barrel is a bit fugly - yours looks much nicer.
 
Putting aside the "I wanted the fun of doing it myself", why didn't you just get a Mini 14 Target model?
 
Putting aside the "I wanted the fun of doing it myself", why didn't you just get a Mini 14 Target model?
It wasn’t on my radar when I originally bought the rifle. By the time I was ready to start accurizing it, I already had a rifle, already had a plan, and already had the tools. In the end, I got a rifle that was much closer to what I wanted.
 
My California spec Target was the worst shooting Mini I've ever had till I sent it to GunDoc to get cut down. I am not 💩ting here, you could get a nickle on each side of the receiver in that Hogue. I hear the thumbholes shot better.
 

Attachments

  • IMG_20210918_140430.jpg
    IMG_20210918_140430.jpg
    54.6 KB · Views: 1
There’s a few minis at the pawn shop by my house. 2 first years if you can believe it and a mini 30. Unfortunately ykid have to pay up for the low serial number but otherwise I’d love a new mini project. Anyone remember the perfect union forum? I guess it’s still around.
 
There’s a few minis at the pawn shop by my house. 2 first years if you can believe it and a mini 30. Unfortunately ykid have to pay up for the low serial number but otherwise I’d love a new mini project. Anyone remember the perfect union forum? I guess it’s still around.
Is it busy? I'm not even sure I remember my credentials at this point.
 
Back
Top Bottom