Sighting a Lyman GPR

[BrownBear]

...standard sight is screw adjustable....

In my experience you have to really watch it with that sight. It's spring loaded with a very weak spring, and the slightest downward pressure lowers it. Might seem alright because it pops right back up when the pressure is relieved.

But the problem is, that adjustment screw is free and easy to move while the sight is depressed. REALLY easy to dingle that sight out of adjustment as a result.

I considered replacing the spring with a heavier one. But being a leather guy I found an easier solution. I just drove a little wedge of leather in between the sight and the base.

Ultimately I replaced the sight with a non-adjustable primitive. Speaking of which, unless something has changed, the primitive supplied with the rifle is too small for the slot and simply slips through.

My solution was to buy the sight I wanted, which happened to have a US-standard 3/8" base, and is too large for the metric slot on the Lyman. Not a problem. Five minutes with a file brought it down to a perfect fit.

 

[PowderMonkey]

Interesting, I may look for options to that rear sight.

 

[larry wv]

Now trying to be rude. But calling the rear sight the front sight isn't helping your explanation very much. Every time I get started on reading your post you call the rear sight the front. :v

Larry

 

[PowderMonkey]

Now trying to be rude. But calling the rear sight the front sight isn't helping your explanation very much. Every time I get started on reading your post you call the rear sight the front. :v

Larry

You are right Larry, I caught myself doing it a few times when I was searching for a pic, don't know why I kept doing that, sorry to cause confusion. I do mean the rear sight.

 

[Maven]

"In my experience you have to really watch it with that sight. It's spring loaded with a very weak spring, and the slightest downward pressure lowers it. Might seem alright because it pops right back up when the pressure is relieved. But the problem is, that adjustment screw is free and easy to move while the sight is depressed. REALLY easy to dingle that sight out of adjustment as a result." ...brown bear

Powder Monkey, Brown Bear is correct about that sight and spring. Mine wouldn't remain zeroed for both windage & elevation either. The solution was to replace it with the [supplied] primitive sight and file (and reblue) the actual front one.

 

[longcruise]

In my experience you have to really watch it with that sight. It's spring loaded with a very weak spring, and the slightest downward pressure lowers it. Might seem alright because it pops right back up when the pressure is relieved.

But the problem is, that adjustment screw is free and easy to move while the sight is depressed. REALLY easy to dingle that sight out of adjustment as a result.

Yes, that is exactly what I was refereing to when labeling it "crude". That's the reason I have three of them around here somewhere with no use for them in sight.

Also agree on the lyman fixed rear. That's why I went to one like that pictured in my previous post. I also had to file it to fit the dovetail, but purposely made it a slip fit and then drilled and tapped for a set screw throught the top making it easily adjustable for windage and easy to remove if desired.

 

[PowderMonkey]

In my experience you have to really watch it with that sight. It's spring loaded with a very weak spring, and the slightest downward pressure lowers it. Might seem alright because it pops right back up when the pressure is relieved.

But the problem is, that adjustment screw is free and easy to move while the sight is depressed. REALLY easy to dingle that sight out of adjustment as a result.

Yes, that is exactly what I was refereing to when labeling it "crude". That's the reason I have three of them around here somewhere with no use for them in sight.

Also agree on the lyman fixed rear. That's why I went to one like that pictured in my previous post. I also had to file it to fit the dovetail, but purposely made it a slip fit and then drilled and tapped for a set screw throught the top making it easily adjustable for windage and easy to remove if desired.

Thanks for the info. I have the fixed rear sight that came with it. Will give that a try.

 

[Zonie]

Going with the primitive, fixed rear sight is the best way.

Not only is there little chance of it changing after the gun is sighted in but on the off chance you might see a muzzleloading rifle competition in your neighborhood and decide to try it out just for fun your rear sight won't stop you.

That happened to me once. There was a turkey shoot where the prize was a frozen turkey and I thought it might be fun to go and shoot a few shots.

Surprise, surprise! The rules said "fixed sights" and my rear sight was adjustable. That ruled my favorite gun illegal right off the bat. Because I didn't know that this rule is pretty common, I wasted the gas to drive out to the shoot.

I admit I didn't read all the answers but you do know that the front sight is intentionally left high so all new GPR's shoot low at first?

Take a flat metal cutting file with you when you start to get serious about sighting in your GPR.

Do your first shots at 25 yards. When you get it shooting to the point of aim at 25 yards, move the target out to 50 yards.
After getting it zeroed at 50 yards, move the target to 75 or 80 yards if you want to use the gun for hunting.

If your only going to target shoot, sight it in for your favorite distance and use "estimated windage" for the other distances.

 

[longcruise]

I agree with Zonie. If you are going to abandon adjustable sights, the Lyman primitive is as good a choice as any. Twere me, I would thin that front sight but leave the height as is till you settle on a load.

 

[PowderMonkey]

Going with the primitive, fixed rear sight is the best way.

Not only is there little chance of it changing after the gun is sighted in but on the off chance you might see a muzzleloading rifle competition in your neighborhood and decide to try it out just for fun your rear sight won't stop you.

That happened to me once. There was a turkey shoot where the prize was a frozen turkey and I thought it might be fun to go and shoot a few shots.

Surprise, surprise! The rules said "fixed sights" and my rear sight was adjustable. That ruled my favorite gun illegal right off the bat. Because I didn't know that this rule is pretty common, I wasted the gas to drive out to the shoot.

I admit I didn't read all the answers but you do know that the front sight is intentionally left high so all new GPR's shoot low at first?

Take a flat metal cutting file with you when you start to get serious about sighting in your GPR.

Do your first shots at 25 yards. When you get it shooting to the point of aim at 25 yards, move the target out to 50 yards.
After getting it zeroed at 50 yards, move the target to 75 or 80 yards if you want to use the gun for hunting.

If your only going to target shoot, sight it in for your favorite distance and use "estimated windage" for the other distances.

Thanks Zonie, i have never attended a shoot like that but i think it would be fun. Switching to a fixed back sight is what i will do. Yes the Lyman manual states they made the front sight taller for that reason, so it can be filed down.

I have never done it before but it looks interesting. Heck if i screw it up i will just get new sights and start over so no worries.

Thank you for the info on the procedure to sight in with primitive sights, i was wondering about how you progress to the distance you want.

I have been going every Thursday to the range to get used to the rifle and work up a load. This past week was an improvement. I started to use pillow ticking for patches and cutting it at the muzzle, it actually improved my groups and it was way more fun then store bought patches.

I would also like to thank everyone that chipped in with their replies. I'm a newbie at this and it really helps to have you guys guide me through the process. I have along way to go to get this rifle to where i want it but i'm getting there, slowly but surely.

 

[PowderMonkey]

...standard sight is screw adjustable....

In my experience you have to really watch it with that sight. It's spring loaded with a very weak spring, and the slightest downward pressure lowers it. Might seem alright because it pops right back up when the pressure is relieved.

But the problem is, that adjustment screw is free and easy to move while the sight is depressed. REALLY easy to dingle that sight out of adjustment as a result.

I considered replacing the spring with a heavier one. But being a leather guy I found an easier solution. I just drove a little wedge of leather in between the sight and the base.

Ultimately I replaced the sight with a non-adjustable primitive. Speaking of which, unless something has changed, the primitive supplied with the rifle is too small for the slot and simply slips through.

My solution was to buy the sight I wanted, which happened to have a US-standard 3/8" base, and is too large for the metric slot on the Lyman. Not a problem. Five minutes with a file brought it down to a perfect fit.

Ughhh, you were right. I just tried replacing the rear fixed sight that comes with the rifle and it's too small, slips right in and also out. Man, what a pain. I was going to go shooting tomorrow now i have to find a sight. Any recommendations for a rear fixed sight for this rifle?

 

[longcruise]

You could drill and tap for a small set screw and have a readily adjustable rear sight. Or, center it and stake it in place with a few light raps on a punch. Stake it in such a way as to be squeezing the top edge of the dovetail down onto the sight.

 

[BrownBear]

Ughhh, you were right. I just tried replacing the rear fixed sight that comes with the rifle and it's too small, slips right in and also out. Man, what a pain. I was going to go shooting tomorrow now i have to find a sight. Any recommendations for a rear fixed sight for this rifle?

A good short term quick-fix is to flip the factory sight upside down and put it in a vise. Use a good punch to raise several deep dimples in the bottom of the base, then drive it into the slot of the rifle. The cratering around the dimples should raise the metal enough for engagement. I know guys who have done this and nothing more.

I settled on this sight because I like the style. In addition to fitting the base (easy), I used a needle file to open the sight notch a little. Another easy job. Pretty cheap fix.

 

[PowderMonkey]

Ughhh, you were right. I just tried replacing the rear fixed sight that comes with the rifle and it's too small, slips right in and also out. Man, what a pain. I was going to go shooting tomorrow now i have to find a sight. Any recommendations for a rear fixed sight for this rifle?

A good short term quick-fix is to flip the factory sight upside down and put it in a vise. Use a good punch to raise several deep dimples in the bottom of the base, then drive it into the slot of the rifle. The cratering around the dimples should raise the metal enough for engagement. I know guys who have done this and nothing more.

I settled on this sight because I like the style. In addition to fitting the base (easy), I used a needle file to open the sight notch a little. Another easy job. Pretty cheap fix.

Thanks for the tip, i will try that with the sight i have and see how it works out. If not then i will the new sight.

 

[Pete G]

Solder a brass shim to the bottom of the sight dovetail. Shim stock can be had at most hardware and auto parts stores.

 

[Billnpatti]

Yes, you need to sight your rifle for a specific distance. Since a muzzleloader shoould be limited by its owner to shots not to exceed 100 yards for hunting since the ball looses a lot of energy by the time it reaches 100 yards and besides you will be sighting it with an open sight, not a scope. You want to make clean ethical kills. With that in mind, most folks like to sight in for dead on at 75 yards. At lesser ranges, you will be only a very few inches high and at 100 yards, you will be just a few inches low. At any rate, all shots within the 100 yard range will be well within an acceptable group to kill a deer. The following assumes a blade front sight and not one with a bead on it. To set your sights, start with your rear sight set all the way down. It should be settingflad down against the top of the barrel. Now, turn the adjusting screw and use a feeler gauge under the sight to raise it about 10 thousandths of an inch. This will give you a bit of up and down adjusting room for the final adjustment of your sights once you get the front sight filed. Place your target first at 25 yards to be sure that you are on the paper. Don't worry about exacty where, just so long as you are on the paper so you can see where your shots are going. If you are on the papere, then move back to 50 yards and once again, make sure that you are somewhere on the paper. At this point, it doesn't really matter where, just on the paper. Lastly set your target at 75 yards and fire three shots from a bench reast with sand bags. Note where the center of your group is relative to the center of the bulls eye. Hopefully, you will be low and filing your front sight will bring your group up to just below level with the bulls eye. Now is when you will start to use your file on your front sight. You will need a micrometer to measure the highth of your front sight before you begin filing and to keep track of your progress as you file. Once you have the highth of your front sight you need to do a bit of simple math. Calculate the number of inches from the muzzle of your rifle to the target. If you are at 75 yards that number will be 36 inches per yard times 75 yards which is 2,700 inches. Then you need to measure from your front sight to your rear sight. Let's just suppose it is 29 inches. Let's also suppose that your group at 75 yards is 5 inches LOW . You simply divide 29 by 2,700 to get 0.01074. Then you multiply 0.01074 by how low your group is (in this example it is 5 inches) 5 X 0.01074= 0.0537. Rounding that number off to three decimels, we find that we need to remove 0.054 inches or 54 thousandths of an inch off your front sight. Use your micromenter and a fine cut file and file a couple strokes and measure the front sight highth. Keep doing this until you have removed close to 54 thousandths. Stop before reaching the 54 thousandths. Stop at about 40 thousandths and check your group to see where you have moved it. Ease it up to within about an inch below the bulls eye. Do not overshoot the center of the bulls eye. Leave it just a bit shy (maybe an inch low) of reaching the bulls eye. Final adjustments can be made with your rear sight by simply raising it to bring your group up to the final setting to put your shots in the bulls eye at 75 yards. If you make a minor boo boo and take jut a tiny bit too much off your front sight, that is why before you started adjusting your sights, I had you set your rear sight 10 thousandths high. Just back it down to bring your group down as much as about an inch at 75 yards if you need to.

If you work carefully and not use a coarse file or be too vigorous with your filing, adjusting your sights is a simple and easy job.

Let's assume that you do not have a micrometer or you don't know how to use one. Here's a little trick to make a gauge for filing your front sight. YOu will need a small machine screw that is an inch or so longer than the front sight is high. Place two nuts on it. One nut will act as a jam nut to hold the other nut in place. You will need a feeler gauge. If you don't have one, they are available from many auto parts stores and aren't that expensive. Set your feeler gauge to just a few thousandths more than you want to remove from your front sight. Lay teh feeler gauge on the top of your barrel at teh base of the front sight and then set the end of the machine screw on top of the feeler gauge. Carefully run the nut down until it just touches the top of your front sight. Without moving it, bring teh jam nut down against the first nut and tighten it without moving the first not in the least. Once they are tightened, re-check to be sure that the screw is setting on top of the feeler gauge and the nut is just touching the top of your front sight. Now when you remove the feeler gauge, yuo can use the machine screw as a gauge to see when you have removed the desired amount of metal off the front sight. Just take a few strokes with your file and use your machine screw gauge to see how close you are to reaching your goal. Just be sure to stop about 10 thousandths before removing all of the metal from your front sight. Those last few thousandths will be carefully removed by referring to the groups that you will be shooting to check your progress. "Tain't hard, just takes care and patience. Anybody with a modicum of moxy and patience can easily do a fine job. :thumbsup:

 

[PowderMonkey]

Thank you billnpatti, that is quite interestin method, wiil give it a try when the time comes.

 

[Gonetocamp]

I removed the rear sight spring. Then I shimmed the back end of the rear sight to the right to stop lateral movement and tightened the screw until it bottomed out. Lastly, I filed the notch wider to get sight alignment and to gain daylight around the front sight. With the screw bottomed out, my point of aim is 50 yards. The Lyman GPR adjustable rear sight, at least mine, is not a finished product. However, the Lyman GPR is one fine shooting firearm.

 

[Twisted_1in66]

Hey Powder Monkey,

I would NOT recommend sighting your muzzleloader in to be dead on at 75 yards. I sight my rifles in to be "point blank" (point of impact [POI] is the same as the point of aim [POA]) or "dead-on" at 100 yards. I did that on the first production flintlock I had (Traditions Pennsylvania Rifle) and also with my current Early Lancaster Rifle made by tg here on the forum.

I looked into it a lot and decided to make the Point of Aim (POA) and point of Impact (POI) to be the same at 100-yards because anywhere I shot within 115-yards, my POI would be within 2" of my POA. Sighted in to be point blank at 100 yards will put you 2" high at 50 yards, dead on at 100 yards, and 2" low at 115-yards. Presuming I do my part, that pretty much guarantees a killing shot anywhere within 115-yds. There was a post on here years ago that outlined all the ballistics info on that and, it worked for me. I had actually saved it for future reference, but that was at least 2 hard drives ago.

When sighting in with point blank at 50-yards the POI was about 2-feet lower than the POA at a 100 yard target. Sighting in at 75-yards had the drop from POA at about a foot if I recall correctly. This is all based on using a .490 patched round ball and achieving 1800 fps at the muzzle. With my rifle an 80 grain load of 3f does that just fine.

Anyhow, that's another option for you that I've found to work very well with both my .50 cal flintlocks.

Twisted_1in66 :thumbsup:

 

[BrownBear]

I don't understand.