Sight Adjustment

[joe sebia]

Ok, Purchased my first custom rifle and am pleased to death (.36 Cal PA Schimmell). After shooting about 100 rounds though the rifle I believe I have settled on a charge. 20 grains FFFg yields beautiful 5 shot 3/8 inch groups from bench at 25 yards with 0.350 RBs and 0.15 Wonderlube patches.. (look out squirrels).

The groups are about 2 inches low and about 1 1/2 inch to right. I used a drift to move the rear sight so that the windage is now correct.

Question #1 Is it prudent to use Loctite or similar on rear sight to keep it from moving or it this really not an issue. (I am not at all concerned if it is HC/PC)my goal here is shooting squirrels not impressing HC/PC Police.

Question #2. A internet search produced the following equation to determine amt to file off brass front sight to bring elevation in line.

Sight radius inches x correction inches / distance inches = Amt to remove

In my case 30.5" x 2.0"/900" (25 yds x 3ft/yd x 12"/ft)= 0.067 inches

My plan is to place a mark ~0.07 inches down from tip of front blade . Take a few passes with file and fire 3 shots. Continuing this until shots fall at proper elevation.

I AM PETRIFIED to put a file to this (although the builder is only about 45 minutes from me and I could easily get another front sight)

I also want to maintain the shape of the blade, sort of D shaped. I noticed that the back of the sight (part that faces the shooter) has a bevel near the top. I think it rather neat in that it reflects light back to the shooter and maintaining a proper sight picture is easy. Filing the blade down will remove this bevel.

The bevel is square to the shooter and if not kept square i can see that the reflect back to the shooter would/could cause sighting errors.

How does one mainting the file square when doing this work at the range with no vise available.

Appreciate your assistance and guidance before i under take this.

thanks in advance.

 

[Flint311]

The formula should work. I used something similar for mine.

To "help" keep the sight square, try a little marker swipe on the part to be filed. If you're not filing the entire width of the marker off with a file pass, it's not square on the sight. Use a very fine file to not take off much and file front-to-back or back-to-front, not sideways.

Go slow and you should be fine. Squirrels won't notice a slight flaw :rotf:

 

[jackpine54]

That formula sounds right.
You've got a good plan. Take some off and put 3 shots on paper, repeat as needed until you're there.
That's how I've always done it and my freezer's got meat in it.

 

[S.Kenton]

Ive never done it with formulas.. just shot and adjusted in small increments to get it in the bulls eye.

 

[jamesthomas]

For the rear sight I would just take a punch and use it to tap the dove tail down on the sight so it doesn't move.

 

[S.Kenton]

For the rear sight I would just take a punch and use it to tap the dove tail down on the sight so it doesn't move.

Spot on!... :thumbsup:

 

[sean30ber]

Just a word of caution and advise. Take a piece of scrap leather @ 3x3 or larger and cut a slit in it that is just long enough to fit over the front sight and cover the barrel. It never fails, no matter how careful you are you'll hit the barrel with the file and mark it. The leather will protect it. Formula sound right but I mark mine just short of the formula and then do 3 easy swipes and shoot 3, over and over until im there. should only take a few passes and gives you more trigger time. Enjoy. Sean

 

[necchi]

Sound advice Sean,
I wish you would have told me that years ago !

 

[joe sebia]

thank you all. weather permitting i will shoot the rifle this weekend and report back the results. great advice. i knew you guys would come through :bow: :hatsoff:

 

[bpd303]

I use duct tape to protect the barrel when filing the sight.

 

[joe sebia]

Worked out pretty well. No marred barrel and the gun is right on. Thank you for the tips about covering the barrel before using the file.

However i find that my sight picture is now very poor. It seems the flat top to the sight causes alot of light distortion, and the front blade is tough to see.

Originally this sight was kind of rounded on top. I think what this was to reflect most light away from the shooter and just enough back to the shooter's eye to have the tip of the sight "glow", Making shooting accurately much easier

I did not file to the original contour. Just flat accross the top I am thinking I can contour the blade as close to original as possible being careful not to change the height. Basically round it off. Hopefully regaining that crisp sight picture with "glowing " tip of front blade.

 

[Birddog6]

You didn't post a photo...... but it sounds to me like you may have the sight mounted backwards. Normally, that dished out part on the sight goes towards the Front sight & the flat part goes to the rear. (if these are primitive sights) When sighting it, all you should see is the notch & flat rear face of it...... not the sides of the notch, which is why it is dished out on the front part, & that part you cannot see if mounted correctly. :wink:

Also, on the flat top, slightly angle it so the edge facing you so almost sharp & the flat top slopes Away from you towards the muzzle, then blacken it & that will remove the glare off the top of it.

Initially, when finding rear sight placement for Your Eye to see it clearly, best to pout a refrigerator magnet on the barrel, rear sight on that, shoulder the rifle & hold muzzle towards a light & slide magnet/sight towards the muzzle til you have a Clear sight picture. Once obtaining that, slide the sight 1" further towards the muzzle & set it there.

I always Epoxy the sights on the rifle first when setting sights til I am SURE that is where I want it. Then tap & it is off & cut the dovetail & mount it.

Keith Lisle

 

[joe sebia]

I will try to get pics though i am challenged in this 'puter stuff.

The gun was built by a local smith that came highly recommended by Chuck Dixon himself. I will err on the side the sight was installed correctly as prior to my shaving off a few thousanths the sight picture was perfect. In fact much much better than I could have imagined.

Looking at the rifle from the side,muzzle to the right, best i could descibe the sight would be D shaped layed on its side (1/4 rotation left). The front of the blade (facing left toward the shooter) is perpendicular to the barrel. Near the upper most point there was a bevel cut at approx 20 degrees from the front of the blade to the apex of the arch.

From the arch toward the muzzle,it was tapered again away from the shooter about 45 degrees from the apex down to the barrel.

As i see this, the design deflects most light away from the shooter but that little 20 degree bevel reflects some back to the shooter creating the illusion that the tip of the sight "glows". The sight is brass. It is very ez to place that little glowing spot in the notch and utilize a 6 o'clock hold.

I guess at this point I am not so much asking for guidance as much as confirmation of my understanding the physics of the design.

This in no way is to detract or show ingratitude for the the help everyone has given ,as I am a ML noobie and alot of this stuff fascinates me. I really am indebt to a lot of folks here not only for this little task but a few others.

The wealth of knowledge here is priceless.

I just looked and there are 27088 registered members. If each just had 1 year experience imagine the depth. Iam confident it is much greater than that.

Thank you all for listening.

 

[Birddog6]

Sorry..... :idunno: but that is clear as mud to me.

Here are some sights with this dished out place on them.



If your sight is similar, they are to be mounted as indicated. Regardless of who built the rifle, he may have accidentally installed it backwards & didn't even realize it. :wink:

Somewhere it says on this Forum it tells how to post a photo. I suggest ya start a PhotoBucket account & learn how to upload photos & post the photos on here. I think
they will come in quite handy on here & possibly other times as well.

Keith Lisle

 

[jamesthomas]

Yep, I had to turn mine around.

 

[joe sebia]

This picture shows the blade with ~60 thousandth file away. Note the flat area at the tip of the pencil.

Just to the left of the tip you can see the slight bevel at the rear (breech) side of the sight.

What I think need to do is re shape the blade to remove the flat on top by tapering the front (muzzle)side so that any light striking down reflects forward ( toward the muzzle). instead of up interfering with sight picture, being careful not to change the height of the sight

 

[joe sebia]

RATS. Lemme see WTH I did wrong :surrender: :cursing:

 

[necchi]

 

[flattail]

John,
That sight is in correctly. Now all you need to do is take the front radius of the sight down so the profile matches the original shape. You are correct that the flat area left from your "sight in" filing will cause reflection. Just angle it down to the front, without changing the height of the rear of the sight. You're doing fine! :thumbsup:
Ed

 

[flattail]

Whoops! :redface:
That last post should have been directed to squirrel duster! :slap:
Ed