QB slotted rear sight for 1740 conversion?

[aprayinbear]

  What do you think?

I'm currently building a 1740. I've just ordered a Crosman steel breech and was wondering if anyone has used a QB slotted rear sight (the extra sight that came with my QB2079.)  It's simple in design , but is fully adjustable and is all metal.  Most important ...... I like the sight picture.

Anyone tried it before?  Pics would really help!

[arkmaker †]

I think it wold work out just fine, but you may need to adjust your front site up or down a bit to match. I just looked on the Archer website and saw that they are only 10.98 plus shipping. I may grab another Tank block and a site to make the shipping costs worth wild and try it out.
Go for it!

Rich

[JEBert]

I didn't know what sight aprayingbear was asking about until he sent me an email and I researched what is a QB sight.  Here is my answer to him is case anyone else can use the info:

Hi Duffy,
Thanks,  I'm sure I will like it.
I had to look up QB rear sight to learn that the Industry Brand Field Rear Sight comes on a QB78 rifle because I didn't know which sight you were asking about.
I got mine from Archer Airguns for around $17.  It works well on my 1377 with the Crosman long steel breech, a Crosman muzzle brake #1700-023 (Crosman price $13.92), and a Crosman part# 2300-028 front sight post ($ 2.19.)  I assume that the 2300KT is the gun you are referring to.  I haven't had a chance to shoot it yet but It came with a shorter front post so I expect it to shoot high.  I'll probably have to change the the post to the same one I have on my 1377 as I have an extra of the taller one.
The pic of the 2300 shows the sight hanging off of the rear of the breech and it will go on that way with no modification as the Crosman steel breech is not rounded on top enough to prevent it from mounting.  However, with it mounted that far back, I cannot see it well enough to get a good sight picture.  When I was shooting with it on my 1377, I needed to mount it at the front of the breech to see it well enough for a decent sight picture.  With it mounted in front of the bolt and adjusted as low as it would go, the pellets were still striking the target too high.
To get it go lower, I had to sand out the bottom of the plastic part at the back of the sight to match the rest of the sight base.  I used a Dremel with a sanding drum. There is a spring inside the front of the plastic part that keeps the rear notched part spring-loaded as high as it will go.  I was not aware of how long the spring was and sanded into it.  As I was sanding, the spring popped out and produced a few sparks so I stopped, took it apart, and then finished my sanding mod.  Then I found a slightly larger in diameter spring, cut it to length, and drilled out the hole to a larger diameter taking care to not drill all the way through to the bottom so that the spring would stay in it and reassembled it.
Don't start by just sanding away like I did.  There is a small C-clip holding the windage adjustment screw in the sight.  You should start by taking the c-clip off, and unscrewing the windage adjustment screw, the plastic part with the notch in the rear of it and two springs will come out.  Pay attention to how they need to go back.
You can sand or grind the bottom off to get it to lower.  You will end up with a hole running vertically through the plastic part.  This is the hole I sanded my way into with the spring still in it.  You will need to drill this hole out larger about half of the thickness of the part and find a spring to fit in the hole, not go all of the way through, and apply upwards pressure to keep the notch in place.  Reassemble the notched peice into the base with the windage spring and windage screw.  Then put the little C-clip back on, mount it on the gun and see how it shoots.
The first attached pic shows the bottom of the plastic part roughly matching the concase base and it is adjusted as low as it will go.  You can also see the hole I sanded into where the original spring came out and if you look closely, you can see part of the new spring I fitted into it after I drilled it out a little larger from the top.  Second pic shows the tiny C-clip that you need to take off (and not loose).
Again, if you do not need to mount it closer to the front, you won't need to do any mods as it fits just fine as long as the plastic notched piece is hanging off of the back of the breech.
Good luck!
If you want any more info, please ask.
Cheers,
Jerry