Iron Sights

idahoguy · Jul 16, 2013

So i finally got out to shoot my Thompsen .54 New Englander and get it sighted in. The question that I have is the front sight is fixed and the rear sight adjusts side to side and up and down. I am 2 inches to the left at all ranges. I am 1 inch high at 25 yards and 5 inches low at 100 yards. Which way do I move the sights? I have been told everything from up is down to down is down. I just need a place to start because my groupings look decent. Thanks for any help you have.

Austin

FrontierGander · Jul 16, 2013

Its not a perm. fixed front sight, it has a dovetail slot. You can use a small punch and a hammer and drift it over in the opposite direction you need the POI to hit. Move the sight up to impact higher.

www.FrontierMuzzleloading.com

txhunter58 · Jul 16, 2013

LAST EDITED ON Jul-17-13 AT 05:40AM (MST)[p]For the back sight, if you move it to the left, the point of impact will move to the left, right/ right. If you move it up the POI will move up and down/down.

An easy way to remember this is by holding one of your hands out at arms length with one finger up. Hold the other hand/finger just in front of your eyes. Now move the finger closest to your eyes (the "rear sight") to the left. What do you have to do to the distant finger ("front sight") to bring it back in line? You have to move it to your left, so the POI will shift left.

So in your case, you want to move the POI to the right and up so you have to move the REAR sight to the right and up. As stated, you can move the front sight to the left to move your POI to the right if you don't have enough in your rear sight.

The opposite is true for the front sight. Moving it to the left moves your POI the opposite way (to the right).

txhunter58

venor, ergo sum (I hunt, therefore I am)

txhunter58 · Jul 16, 2013

What load are you shooting? 1 inch high at 25 and 5 low at 100 sounds unusual unless you are using low powder charges.

txhunter58

venor, ergo sum (I hunt, therefore I am)

Nim · Jul 17, 2013

The ez button: Front sight if you are hitting R chase it move to right. Rear sight hitting R move it in the direction you want to move POI left.

Nim

idahoguy · Jul 18, 2013

I am using 425 Great Plains conicals by Hornaday and 90 grains of Pyrodex. I did some shooting the last few days. I am in a 3 inch group at 25 50 75 and 100. I think I got the sights fixed. Tonight I went out and was all over the place at 100 yards. I can't seem to figure it out. Some of it could be user error. I am going to go to a range tommorow and get on a good dead rest. I have only been using a backpack because that is all I have. Any ideas would be great.

Thanks

Austin

idahoguy · Jul 19, 2013

So I am ready to throw my gun in the garbage. I went out tonight and shot off a sand bag at 100 yards. I couldn't even hit paper. It was high, low, left and right. I don't know if it is me or the gun. Any advice would be great.

Thanks

Austin

jbricejr · Mar 22, 2014

I realize this is an old thread and you may have pitched your gun in disgust, but in case you haven't there is a chance that your problem is simply a loose tang screw/s. I had this problem with my Lyman GP hunter and found that even if the screw was only slightly loose it sprayed bullets all over. The problem with my gun was that the barrel and tang were improperly inletted and thus out of alignment, and the recoil was pushing up on the tang screw. I glass bedded the tang and screw, but my stock wood was soft and it would eventually loosen. After messing around with the gun for months I finally decided to have the whole thing restocked using a rock maple blank by someone that knows what they are doing. Lyman's guns are made in italy and the QC has gotten bad. The design is also poor. Ideally the tang screw/s should pass through the stock into the trigger guard steel. Apparently that's the way most of the old ones were.

cannonball · Mar 22, 2014

Some years ago I used to purchase the Thompson Kits, finish them, shoot them, and sell them. I would then get another kit and do the same. I found some Thompson's to be dead accurate and some wouldn't hit the broad side of a barn. Some had to be shot in to be very accurate, but the most accurate guns did not. Barrel quality control was all over the board. Wished I had a solution. All you can do is check your sights for looseness, check your barrel for a bind or tightness, but mainly check your load combination. I have a Green Mountain barrel that will drill tacks with regular black powder, but has no consistency with the substitute powder, so if your using that, try Black Powder.

cannonball · Mar 22, 2014

One after thought, I had one Thompson that was skipping the riflings with the higher loads. I decreased the powder way down then it was very accurate.

cannonball · Mar 22, 2014

Sorry I mis-read your post. Apparently your grouping is OK. I have heard that if the barrel crown is off, it will throw the bullet a certain direction.