How much to file the front sight

[flatcreek]

I want to raise the poi 10" at 50 yards. How much do I need to file off the front sight. 50 cal Rice A weight swamped barrel, the sights are 28" apart and front and back sight are both about 3/10 of a inch high. I'm using a .490 ball, .015 patch and 50gr of 2f Goex. From my calculations I may not have much of a front sight left when I'm done. I've read of others having this same problem with a swamped barrels and have to use a higher rear sight, which I don't want to do. So want to get some imputt and have my thinking double checked before I move forward.
Thank in advance Phil

 

[SDSmlf]

I want to raise the poi 10" at 50 yards. How much do I need to file off the front sight. 50 cal Rice A weight swamped barrel, the sights are 28" apart and front and back sight are both about 3/10 of a inch high. I'm using a .490 ball, .015 patch and 50gr of 2f Goex. From my calculations I may not have much of a front sight left when I'm done. I've read of others having this same problem with a swamped barrels and have to use a higher rear sight, which I don't want to do. So want to get some imputt and have my thinking double checked before I move forward.
Thank in advance Phil

Assuming all your measurements are correct, to raise the POI 10” at 50 yards with the sights 28” apart, a quick calculation says you will need to alter your sights about .156”. Doesn’t matter if you lower the front or raise rear, the change between both sights will need to be .156” or so, again assuming measurements are correct.

 

[Caterpillar Hunter]

According to my math, raising the point of impact by 10" at a range of 50 yards (1800") would be proportional to filing the front sight down by 0.156" with a 28" distance between sights. That is,
X = 10”
28” 1800”

1800 (X) =280

X = 280
1800
X = 0.156”

You beat me to it, SDSmlf

 

[Phil Coffins]

As often as that bit of math is needed shouldn’t it be pinned to the top?

 

[flatcreek]

I used basically the same math, but this math is for straight lines. The bullet travels in and ark so how does the effect it or doesn't it? Probably will be using more powder in the future maybe 65 or 70 gr and how will that play into it. This is a brand new gun and these were the first shots through it, doesn't even have finish on it yet, I just couldn't wait.

 

[SDSmlf]

I used basically the same math, but this math is for straight lines. The bullet travels in and ark so how does the effect it or doesn't it?

Your line of sight is a straight line by definition. The bullet will travel above or below that line as it goes down range.

 

[tenngun]

Math is great, but our ancestors didn’t carry michs around and most never knew the formula.
Take file to range, shoot a group, hit the sight with three strokes shoot another group, if you only raised a smidgen( old measurement equal to three hairs then you can try five strokes, or ten if you feel froggy
But I go three at a time on German silver or brass repeat till satisfied

 

[flatcreek]

Your line of sight is a straight line by definition. The bullet will travel above or below that line as it goes down range.

Now I understand, I need to look at it as I'm moving the POA to the POI and then I am moving a straight line. Been thinking about tweaking the barrel a bite so I don't run out of front sight. I really like the rear sight and can't get a higher one unless I make it. at these calculations my front sight will be around 1/8 inch and I don't think I'll be happy with that. As @tenngun advises, I guess I'll get the file out and have at it, front sights are cheap.

 

[LME]

Some people draw a fine bead, some people use a full bead and some people level the post with the rear sight. I have noticed some guns in museums that hardly had a bead which indicates the user used a fine bead. Doesn't this make the measurement vary depending on what method is being used? I am sure some one other than me gets confused now and then? LOL!

 

[oldwood]

Oh my , so much mathematics. First , for the barrel you have , the sweet spot load is 80 gr. FFFg. I'de sight in for that which will raise the poi , then file the front sight off at the covered range , or on a cloudy day to prevent front sight glare. Dose of cold blue will make the sights non-glare as well. Put 4" square target up at 50 yds. using a backer behind the 4" square , and use the file , and shoot method to zero your group. Use a coarse file to make the group move up quickly. If your hitting 10 " low , 8 to 10 shots should bring the poi to where you desire. I used the same barrel....Colerain , 1 turn in 60" , and if 80 gr. FFFg used dead on to one inch high at 50 , should give you 1" low ...75 yds. to 100 yds.. LOL to ya.

 

[bpd303]

the sweet spot load is 80 gr. FFFg.

That is the first step I would do before filing the front sight increase the powder, with FFG 80gr would not be too heavy. Increase in 5/10 gr increments.

 

[TDM]

File the front sight down a few passes at a time until it hits where you want it too. Just take your time.

 

[Rich44]

I make it. at these calculations my front sight will be around 1/8 inch and I don't think I'll be happy with that. As @tenngun advises, I guess I'll get the file out and have at it, front sights are cheap.

More like .146 high.
I would really try the suggested heaver loads first to see what happens with the group position and size first. You need to enjoy the trouble shooting and slow down. A combination higher rear sight and lower front sight might be what is really needed. You can think this one out if you give it some thought time.

 

[flconch53]

With that much to come off I think I would get a new rear sight and start over.

 

[flatcreek]

With that much to come off I think I would get a new rear sight and start over.

Like the rear sight, I use it on all my muzzleloaders and a taller one is not available. Was thinkinking of bending the barrel a few maybe .030 lower in the middle, that should be equivalent to about .060 off the front sight.

 

[flconch53]

Can you bend a Rice barrel. I have only ever done it on smoothbores

 

[Grenadier1758]

I can't speculate on Rice barrels as I think they are made fron a steel more suited to rifle barrels than the old standby of 12L14. When shooting chunk gun matches with a 12L14 barrel, barrels resting at the muzzle shoot higher than when the barrel is rested at the entry thimble.

 

[Rob M.]

Keep filing the front sight till it hits at the height you want on paper ...

 

[SDSmlf]

Like the rear sight, I use it on all my muzzleloaders and a taller one is not available. Was thinkinking of bending the barrel a few maybe .030 lower in the middle, that should be equivalent to about .060 off the front sight.

Must be a unique rear sight. Could you post a photograph of it?

As to the thought of bending the barrel, you stated you have a 50 caliber ‘A’ profile barrel. That’s quite a light barrel for a 50. I don’t believe I’ve seen an ‘A’ profile with a bore any larger than 40 caliber in it, with ‘B’ profiles most common for 50 caliber, though obviously there is a lot out there I have not seen. Still, with an ‘A’ profile 50 caliber barrel I would approach bending it with caution, and only after being 100% settled on a load and having exhausted all the other options.

50 cal Rice A weight swamped barrel

 

[flatcreek]

The barrel is A weight Southern Classic 50 cal. So I bent it, took almost an inch of belly to get .040. Here is the rear sight, the bending set up and the target from 10 minutes ago. Filed the sight down to .150 and the highest shot that says file is the best I could do and I may have pulled that as I wasn't getting much change with 10 strokes of heavy filing. I filed between almost every shot and the shots only went up 2.5 inches except for that one. I filed almost .100 off before the first shot. It appeared as I got .040 of bend in the barrel and it moved it up to where I'm happy to go ahead and finish the gun. I'm also very pleased with the group, all are about 1.5 inches wide and the last 3 I didn't file and that's about a 1 inch group. I did raise the powder to 65 gr, .022 patch and .490 ball for all shots. The shots to the right were from the other day when I was trying to get it on paper, I was aiming at the top of the target board for the few you see. POI should of been POA on the target and the target is 40 yds. Thanks to all, Phil