Ruger Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
I have a Mini 14 5831 tactical, i think it is referred to as the tactical scout. Anyway, it is the model with the factory picatinny forearm rail that the factory gas block lower, screws to. When I received the rifle, the fitment between the rail and the gas block lower was poorly aligned and was tighter at the rear than it was at the front, actually contacting on the rear (toward action, away from muzzle). I have since purchased an aftermarket gas block lower which introduces a stabilizer bar. I know the bar doesn't do much for the tapered barrel, regardless it was I purchase I wanted, and the bar isn't relevant to my question. With the new gas block lower, with it being slightly taller up the sides of the barrel, it makes full contact with the OEM scout rail prior to tightening. This left me with the option of either having the end of the OEM scout rail milled down (which is beyond the capability of the glorified gun cleaners in my area), or to shim against either the top or bottom of the barrel at the gas block. the internal cutaway of the OEM scout rail is 5 sided (imagine a stop sign shaped half of a "hole") against the top of the barrel. the bottom of the barrel fits the scoop of the gas block lower and of course encapsulates the gas bushing between the barrel and gas block. other than the gas block, the OEM rail is only held to the barrel by a bolt on clip closer to the action. effectively the rail/gas-block assembly is held captive by the forearm end and the barrel detent. If I were to shim under the barrel, the shim would have to be drilled out to have the gas bushing pass through it. the barrel topside only contacts the 45 degree sides of the rail cutout. I opted to shim the top of the barrel from the rail, so to keep a square and true mating of the gas block lower to the underside of the barrel, and oddly enough the gap between the gas block lower and the rail is now square to each other, no more pinching at the rear. I made the shim from brass, a spent .270 shell casing, with short ears turned up (and one in the center folded back) to be held captive by the half-octagonal shape of the rail and held captive between the barrel detent and the rail end. My questions are: will brass sustain the temperature load from the barrel? do you see any potential faults with my prescribed solution? should i have shimmed under the barrel instead? thanks in advance for any insight.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #2 ·
the best info i can find on above barrel shim temps is as follows "an AR 15 barrel temp can frequently reach above 300 degrees fahrenheit in heavy fire situations" "the melting point of brass is 1710 degrees fahrenheit". so if such is not disproved, the questions of the pros/cons of shimming above or below the barrel remain.
 

·
Exalted One
Joined
·
1,881 Posts
John, it is not unusual for the gap between the upper and lower halves of a newer Mini-14 to have a gap. The important part is that the gap is even fore-and-aft and port-and-starboard, with about 25-30 INCH-pounds of torque for the screws, cross tightened. Most Mini-14 these days have a gap which is normal...just make sure the gap is even and the screws properly tightened. No need for shims.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #4 ·
@RJF thanks for the spec info. what was stated was that there was not a gap as it should have been. shims were to create the gap. the question was would shimming over or under be better?
 

·
Registered
Joined
·
2,384 Posts
A Tactical that comes from the factory with a handguard rail must be a new offering. Is it an Ultimak or Amega brand ?
Curious as to why you went with a new gas block lower to get your strut, as opposed to adding a strut like the Accustrut, to your existing lower gas block ? It might have prevented the gap problem you are having.

And John, please break up a long post into several paragraphs, it makes it much easier on our eyes when trying to take it all in.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #6 ·
@sandog i will do better about paragraphs. the 5831 series with the factory pic rail is fairly new from what i can tell, it is poorly documented.

the pic rail is ruger branded, if it is some re-badge - i do not know. again, the fitment was poor even with the OEM gas block. the issue is not gas blocks, but a lax tolerance OEM pic rail which also exists as the gas block's upper.

aftermarket milling is a trade not found in my area. i have to shim against the barrel to make either gas block fit correctly. is it better to shim under around the bushing, or to shim over? my reasoning on shimming over, was to let the barrel, bushing, and gas block lower fully mate, introducing no weak points to that area of gas flow.

but gas actuated guns are new to me, therefore i am after experienced opinions on which shim placement is better, not to debate the gas block (yet again, even the OEM fitment was poor).
 

·
Registered
Joined
·
4,231 Posts
If the rail is touching the gas block either something is out of spec or it's been over torqued. The rail is aluminum the gas block is steel and I suspect the rail is pulled to the gas block. I would replace the rail before the gas block. jmho
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #9 ·
@RJF thanks! @Sr40ken the fit was poor out of the box, i just didnt realize it until much later. it's hard to portray on camera, but the naked eye can see definite imperfections in the ruger badged rail. the mating surface of the ruger rail for the gas block is not even cut squarely, with a slope rearward on one side.

until i can find a skilled aftermarket miller and someone to anodize the milled surface, i am relegated to shims.

i was able to puts ears on the shim to capture between the forward face of the rail and the flare on the barrel, additionally folding back a piece to set in the half octagonal slot in the rail for the barrel, which additionally captures it the shim from rotating around the barrel.
 

·
Exalted One
Joined
·
1,881 Posts
John, if the rail is Ruger badged and came from the factory that way, a call to Ruger CS should get them going on a replacement. Beware, though, if you send it in with the aftermarket (strut) gas block bottom, what you'll likely get in return is a standard Ruger gas block bottom. I doubt they'll just sent you another rail - they'll say replacing it requires "fitment"...
 
1 - 13 of 13 Posts
Top