FWB 600 shooting high

[Adam77K]

Hi, I've just picked up a Feinwerkbau 600, SSP match rifle.
It's shooting about 1" high at 10m with the rear diopter sight elevation adjustment bottomed out. There are no riser rails installed and the sights look OEM. The rifle also seems to function fine otherwise and there is no obvious mechanical issue like a bent barrel.

A small raiser for the foresight would presumably solve the issue but I wanted to check if anything is up first. As this rifle is designed for 10m, this does not seem right.

[PL_at_WRC]

Hi LN2 (@ 77K :^)

First, make sure you are turning the knob the correct direction. If it's the German sight we'd expect on an FWB, then H is hoch/high and T is tief/low. Important point: if " bei " is printed between the H and the T, that means " with ", so with high shots, you'd turn in the direction of the H.
Aside from that, are the front & rear sights matched? Same brand/style. Are they FWB? Our experience with used guns is that sometimes you get unmatched bits n pieces. And of course make sure it's correctly on the dovetail. (Umm, been there, done that too ...)

Coach P (4.5k He, sometimes)

[Adam77K]

Thanks for the reply. The sights don't seem to carry any branding but from what I can see on google images they do seem to closely resemble those on some 600s. So I'm assuming they are OEM but if not then it's going to be hard to tell if they are matched.

With open sights I generally take no notice of the printed adjustment direction, as sometimes it refers to the direction to turn to correct for high/low shots, and sometimes it refers to the direction turning the knob will move the point of impact. I just turn it and see which way the carriage moves.

So in this case, the carriage that holds the aperture is bottomed out, i.e. is as far down as it will travel, therefore the POI is as low as the sights will go but is still too high.

[Bob Foth]

Photos might help us, but most likely a mismatched sight set. You are right that adding a riser to the front will move your shots in the correct direction. About 2mm would barely get you to shoot 10s then a few more mm to get you in the center of your rear sight adjustment range.

[Adam77K]

Photos of the sights here

The foresight has a perspex insert with numbers 3 above 8 (I guess refers to 3.8mm aperture)

[ChickenChowda]

Its probably designed to have a short riser in the front, I find that the sight globes often come much shorter and require a riser even if none is used in the rear, if the rifle is functioning correctly and grouping properly, I would say you're probably okay. One thing i've done and helps, is to adjust my rear to the middle of its travel, then place the rear and the front on a flat surface and compare their heights. I find that if I even them out usually this will net a slightly low POI that can be adjusted for with further riser fine tuning or just clicks if you're lazy like me. I've never personally tested to see if any of my rifles are accurate without risers as I pretty much require them to be able to look through the sights so YMMV.

[Tim S]

I'm not a FWB expert, but those look like FWB sights of roughly the right vintage. What size is the tunnel? Early FWBs took 16mm inserts, then 18mm, and up to 22mm 20-25 years ago. If someone replaced a 22mm tunnel with an 18mm, that would lower the tunnel, possibly enough that the rearsight can't cope.

Apologies if you have done this already, but do check the muzzle weight is mounted properly and not bent. Are you sure the tunnel is mounted securely; it's probably nothing, but the back of the tunnel looks like it's catching on the muzzle weight. Ditto, check the insert/element is central in the tunnel, not biased to 6 o'clock.

The 3.8mm on the foresight insert is indeed the diameter of the aperture. It wouldn't hurt to try a larger aperture for standing.

[Lukas90]

The front and rear sight are correct OEM sights for your rifle.
The tunnel ist mounted backwards, the insert screw should point towards the shooter, but that shouldn't be the problem.
If any magnifying lens is mounted in the tunnel, try to remove it. These could eventually be the reason for your problem.

[Adam77K]

Thanks for your replies.

Answers to some questions raised. The tunnel is 16mm internally (a bit more as the insert measures 16.1) and there is no magnifying lens in it. The sight was this way round when I bought it but I have tried it both ways round. It has made no difference to the POI however I wouldn’t expect it to. The sight is not contacting the muzzle weight.

What is the purpose of the screw the other side of the insert screw?

[Tim S]

Adam,

I wonder if a previous owner swapped the foresight tunnel for an older pattern.

As suggested above a slim (say 4mm) raiser block under the foresight should raise it enough that you can zero the rearsight comfortably. Alternatively buy a new foresight tunnel, either 18mm or 22mm; this needn't be an FWB product, both Gehmann and Centra make tunnels compatible with FWB rifles. 18mm and 22mm foresight inserts are much easier to find than 16mm.

The screw at the other end of the tunnel would be for a spirit level, lens, or anti-glare tube/sunshade. These aren't allowed under ISSF 10m rules, but FWB fitted the same tunnel to their smallbore rifles.

[spektr]

Ot really looks to me that somebody has the action out of the stock and didn't get it put back in correctly..... The rear metal is sticking up above the wood a small bit, and it should be a bit below the stock...... Perhaps loosening the screws and moving the action around will resettle the action. I believe it is being held up too high

[marky-d]

That would not change the alignment of the sights.

[spektr]

That would not change the alignment of the sights.

Respectfully, it does or I wouldn't have posted it. If the rear of the action is held "proud" of the stock,
the effect will be for the front sight to move down, the rear sight to move up relative to the cheek piece.
The hold change required would naturally cause you to center the front sight to the target and that would force
a move of the rear sight down to realign things from where it was if the action was in the correct place.
One could very well end up where this guy is....... Thanks for prompting me to explain it better........

[Tim S]

Um, if the foresight moves down surely the rifle will shoot low not high? If you change your hold so the sights are aligned, the sights are aligned, no need to run out of clicks. Your position only would change.

[bandur60]

Only if the rear sight was mounted on the stock (instead of on the action/receiver) and the rear of the action was raised (proud) of the stock could the result be low shots --- highly unlikely situation ...???? Not that this applies here, show me wrong.

[marky-d]

Respectfully, you are talking about a change in hold -- the sights remain aligned as others explained, unless the rear sight was mounted to the stock, which is not.

Thanks for prompting others to explain it better.

[sandy22]

The front and rear sight are correct OEM sights for your rifle.

I'm not so sure. I think the rearsight is for a 601, and that the 600 & 601 rearsights are not necessarily 100% interchangeable.

[GoodEnuf]

I have had a FWB 602 since it was new (bought it sight unseen from defunct Beeman) but was never really happy with its 'fit' until I recently worked with it as a package deal, not just cranking this adjustment, or that one. Since you report an unworkable sight situation, you might benefit from my experience...

What I did with good results for me:

Get the stock and action to fit you first, without concern for the sight alignment problems. You might even remove the sights so they don't unconsciously influence your adjustment choices. Get the pull right to suit your arm/hand length, and shooting coat (if you use one) by adjusting the butt plate in or out while in shooting position. Coarsely adjust the trigger location on the bar; fine tune it later.

Get the forearm support properly situated to minimize muscle participation and maximize bone support, i.e. forearm as vertical as possible and close to your trunk. Your 600 is similar to my 602 - they are heavy, so this is very important. I require a fore end riser because I have very short arms, and the FWB SSP rifles were designed and sold before integral risers were commonplace. Without it, the rifle is too low relative to my eye and shoulder height and I had to use muscle strength to get it up to a good height. I use the TEC-HRO.

Locate the butt in a comfortable position on your shoulder/chest and use the adjustments to lower/raise the barrel so it is nearly parallel to the ground plane, while supporting it with the previously adjusted fore end.

Before I went through all this, the 602 sight design and low fore end height required me to scrunch down to look through the stock positioned rear sight. This, even with a padded shooting glove and hand hold that maximized height. Now, equipment available allows you to keep your head up, even with the older rifles, and with a hand hold to suit you, not to make up height. With the sights still off, raise the cheek piece to a position that allows your head to be as upright as you need to be comfortable.

Now, address your original problem with an adjustable sight riser system. I use a TEC-HRO product here as well. Without changing any of the previous adjustments as described above, use the riser adjustments on the rear sight that allow your sighting eye to see through the center of the sight with it also centered in its adjustment range. To finish, choose the front sight riser height to group on target center and fine tune with the rear sight knobs.

If you are happy with the fit of the "stock" stock, just acquiring the adjustable risers will solve your mismatched sight problem. More expensive that a simple one size riser pair, they are very flexible and allow you the freedom to experiment to see what works for you. (~$100 vs ~$40, but you will be confident you will solve your problem.) A side benefit is many of the adjustable sight systems allow you to offset the sights to achieve a more vertical head position minimizing the need for rifle cant. Whatever you do, be sure that the accessories are sized as FWB compatible.

This worked for me, but each shooter may approach the adjustment process differently to suit his/her perspective and budget.

JE

[Adam77K]

Thanks for all the inputs. I've sorted the issue with a single 4mm Centra foresight riser. I verified by shooting from a rest that it was shooting high initially and is now "on". This 4mm riser has put the rifle dead on at 10m and almost in the middle of the vertical adjustment which is perfect. As there is no obvious misalignment in the barrel my conclusion is mismatched sights.

If anybody has a FWB6xx it would be really appreciated if they could set the rearsight elevation in the middle and accurately measure (with calipers if possible) the offset of the apertures from the dovetails. This would help confirm or rule out the theory.

[GoodEnuf]

Adam:

You should be able to precisely locate center, both vertically and laterally, without need to measure -
- crank the adjustment to one end or the other, being gentle and slow so as not to damage the sight
- go the other end of the adjustment range, counting the clicks to get there
- divide by two, and that is the number of clicks to get to center from one end; click that number from where you are now (at the end of the range)
and you will be at the physical center of the adjustment range

If you want to return to where you are at the beginning of the exercise and where you are getting the shooting results you want, be sure to count the clicks from the start. If you do it as I will describe you will go up and down the range only once:

Count the clicks to the first endpoint; record that number; count the clicks from the one endpoint to the other (divide by two to get the center as per above); take the undivided total number of clicks and subtract from it the number of clicks it took to get to the first endpoint; you now have the number of clicks needed to get to exactly where you started from where you are now.

Example: Say 30 clicks to get to the first endpoint from where you start; say 50 clicks to get to the other endpoint; then 50-30=20 clicks needed from where you are now to where you started.

The whole saga works both vertically, and laterally. Be careful to not force the adjustment beyond normal endpoints.

JE