Fixing a cantilever base on a Mossberg rifled barrel for 870

[Tokarev]

I bought this barrel long time ago and did not use for several years. Recently I pulled it from the box and installed the scope only to realize that it ran out of windage. But of course, the base was soldered out of alignment with the barrel. The red lines show the axis of the base and blue line shows the axis of the barrel.
Is this something that can be fixed easily by heating to about 340 and re-aligning the base with the barrel? Are these bases soft-soldered or TIG welded?

[tomme boy]

Send it back to Mossberg to have them fix it. It is silver soldered so it will not be an easy fix.

[Tokarev]

Silver soldered like in plumbing, or silver brazed?

[tomme boy]

Brazed. A regular propane torch will not work. You will need a oxy acetylene setup. And it is going to mess up the finish completely on the barrel. You will have a real chance of warping the barrel.

[Tokarev]

Anyway, I finally got some response from the local service centre after unsuccessfully emailing Mossberg a few times. They want me to ship barrel to them for replacement, so all is well.

[Tokarev]

Got a replacement. Base is now visibly straight.
However there is a small black mark in one of the riflings just ahead of chamber.
Using a piano string I picked the dot and the string got stuck. So that's a cavity.
If this was near the muzzle, I would not be worried, but so close to the chamber is an area with still lots of pressure.
Would you shoot a brand new barrel with a pit in rifling? Anyway I've asked them for another replacement. Where is this world going?

[Tokarev]

Another replacement received and we have a winner.
Base is straight (checked with a 3' ruler) and bore is spotless.

I want to put a red dot on this gun. After internet window shopping I came across this Ebay ad which should be a knock off of some brand name product:

http://www.ebay.com/itm/120775085973

This looks compact, slick and does not have too many turrets and knobs sticking out.
Does anybody know what is this a knock off of?

[tomme boy]

Better make sure they will ship to Canada. Most optics are forbidden to be shipped out of the USA.

[Tokarev]

This particular seller is in China, but anyway I am not looking to buy his knock off.
Instead I am researching whose product they copied to buy the original.
I like more robust lens housing this one has, even that they still have a large knob on the other side that can get caught in the branches or clothes, it's still the sleekest red dot with rail mount.

[Tokarev]

I am starting to have doubts regarding the red dot scopes in general.
Looking at the reflex red dot site picture and moving the eye around I can clearly see how the reticle or dot is moving versus the target.
This can't be accurate unless the head is always in the exact same position every shot. In other words this kind of sights has too much parallax.
Anybody has any input regarding red dot sights?

[Tokarev]

I am starting to have doubts regarding the red dot scopes in general.
Looking at the reflex red dot site picture and moving the eye around I can clearly see how the reticle or dot is moving versus the target.
This can't be accurate unless the head is always in the exact same position every shot. In other words this kind of sights has too much parallax.
Anybody has any input regarding red dot sights?

[I'll Make Mine]

I'm surprised to hear that, Tokarev -- I have a red dot (BSA) that doesn't do that, and an optically similar device for my telescope that's also immune to parallax; from what I understood, the optics in those projects the dot to optical infinity (by placing the light emitter precisely at the focus of a concave partially reflective mirror surface), so it stays in the same position relative to the bore regardless of eye position. Did you test with the rifle (or sight) clamped, or is there a possibility your hold wandered as you moved your head?

[tomme boy]

Some red dots do have a parallax. It is usually the cheap ones that are like that.

[Tokarev]

Only had a chance to fondle some cheap Nc Star red dots while mounted on a rail.
At what price do the red dot sights become decent and have no parallax? I mean, very compact red dots that can mount low close to the rail?

[I'll Make Mine]

Only had a chance to fondle some cheap Nc Star red dots while mounted on a rail.
At what price do the red dot sights become decent and have no parallax? I mean, very compact red dots that can mount low close to the rail?

As with many things in life that vary with price, there's probably not a clear dividing line. The ones made and sold for BB guns are likely to be on the bad side, the ones that sell for $150 are probably on the good side, but there's a lot of gray area in between. The only way to be sure is to test it -- mount the sight on a rail, barrel or receiver, clamp the mount (or just directly clamp the sight), and check if the red dot moves against the background (at least 25 yards away, preferably 50) when you move your eye.

Do note that the red dot, projected at infinity, will exhibit "reverse parallax" when viewing against a nearby target (say, the rack in the gun store, ten feet from the sight) -- just like a distant mountain top seems to "follow" you if you look out the car window past the "moving" nearby scenery, the dot will seem to move the same direction as your eye movement. The only way you'll get "direct parallax", where the dot moves opposite your eye movement, is if the dot is optically projected to a shorter distance than the target distance -- which might happen with air gun sights, designed for use inside 25 yards (projected close to prevent reverse parallax), but shouldn't happen with anything built for a powder burning rifle or handgun.