Question about sight risers?

[RED RAIDER]

I have a shooter who just joined our club. She come from another club with some very capable coaches. She shoots a FWB P70 JR.

I am trying to figure out why the rifle is set up with risers only on the rear sight but none on the front sight. The shooter is shooting pretty good, but I noticed that the rear sight is almost clicked all the way to the bottom. Is there any logic to why the rifle is set up this way?

[marky-d]

Is she using a 22mm front aperture instead of 18mm?

Just a guess.

marky-d

[RED RAIDER]

The front sight is 22mm. But I believe that is what the rifle came with new. There is no riser on the front sight.

[Trooperjake]

There should be matching risers, front and rear.
That is why the sight is bottomed out.

The reason risers are used is to get your head straight up.
Then the cheekpiece is raised to get proper sight alignment.

[gspell68]

Is she using a 22mm front aperture instead of 18mm?

Just a guess.

marky-d

Does the aperture of a 18mm front sight sit 2mm lower than that of an 22mm one???
I would've assumed that the apertures would be at the same line-of-sight height from the barrel.

I put risers on my son's Walther LG-400 with sport sights (22mm on the front, I think) and the elevation pegs out just below the centerline of the target.
I was considering cutting a couple of mm's off the front height adapters (like in the right foreground of the photo) on the lathe to raise the front of the rifle.

Wonder if all I need to do is swap out the front sight?

[Trooperjake]

Sorry I can’t answer this.

There are more expert people, than me.

Give the gunsmith at Champions Choice a call.

Marty G

[40xguy]

why not call the coaches (that she worked with) at the other club and ask them why ?? But, then again, as the old saying goes: "Whatever works."

[pfiori]

Yes, the center height of a 22mm front sight will be 2mm higher than an 18mm sight. Another thing to keep in mind is that the center height of every manufacturer's 18 or 22mm front sight is not the same. There are 2 and 4mm riser spacers available for these situations.

[gspell68]

Yes, the center height of a 22mm front sight will be 2mm higher than an 18mm sight. Another thing to keep in mind is that the center height of every manufacturer's 18 or 22mm front sight is not the same. There are 2 and 4mm riser spacers available for these situations.

You'd think they'd give you little warning about potential situations that could crop up.
I hate having to learn things the hard way and/or re-invent the wheel.

I work on small meticulous stuff like this everyday.
I feel sorry for the folks that may not have that kind of experience.
Even some of the manufacturers' literature is pretty lame in the air rifle shooting realm.
It reminds me of the pre-internet days when you'd buy something like a 25-piece automotive carb rebuild kit and get no instructions, whatsoever...

[RED RAIDER]

Is she using a 22mm front aperture instead of 18mm?

Just a guess.

marky-d

Does the aperture of a 18mm front sight sit 2mm lower than that of an 22mm one???
I would've assumed that the apertures would be at the same line-of-sight height from the barrel.

I put risers on my son's Walther LG-400 with sport sights (22mm on the front, I think) and the elevation pegs out just below the centerline of the target.
I was considering cutting a couple of mm's off the front height adapters (like in the right foreground of the photo) on the lathe to raise the front of the rifle.

Wonder if all I need to do is swap out the front sight?

The rifle has the same rear riser with the towers as shown in your picture. However the front sight is mounted direct to the rail on the rifle (No Riser).

[Pat McCoy]

The shooter is shooting pretty good, but I noticed that the rear sight is almost clicked all the way to the bottom. Is there any logic to why the rifle is set up this way?

Just a guess, but her old coach may have added the rear riser to get a better head/neck position for her, and since when still had adjustment left in the rear sight they didn't bother with a front riser (or they didn't have one available). They may also have tried a front riser and found it caused a slight change in her position that she disliked. Have you asked her if they'd tried a riser in the front? Have you asked the old coach?

It appears that it is bothering you a lot more than her (if she is shooting well).

[RED RAIDER]

I first noticed this because the shooters eye & cheek position looked off. It looked as if the shooter was looking down through the rear sight. The shooter said that the gun was already set up like that when they got it from the previous coach.
The thing that caused the most concern to me was that the rear sight was almost bottomed out on adjustment.

I added a riser of my own to the front of the rifle, and all is good now. The head/cheek position is improved. The read sight is now in the center of adjustment. The shooters scores have not changed much, but things look more like they are supposed to. Hopefully with a few practices we will see some gain.

Thanks for all the advise.

[gspell68]

Well, I finally got around to tweaking my son's rifle.
The front and rear risers had to be set up exactly like in the photos above to mechanically center the rear aperture...