Thompson Center questions.

Discussion in 'Percussion Rifles' started by mjpchief, Jun 13, 2019.

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  1. Jun 13, 2019 #1

    mjpchief

    mjpchief

    mjpchief

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    So I finally caught a day when it wasn't raining and the range wasn't flooded and took out my T/C .54 cal. Put up a target at 50 yds and couldn't hit it. Put paper all around it to see where ball was hitting and found it to be hitting about a foot high. I went to adjust the rear sight down and found it to be all the way down on the barrel. I started with 60 gr of Pyrodex weighed. Started dropping powder amount until I was down below about 45 gr. Made no difference. Still hitting high and began to produce a really bad group. The front sight is already about a 1/2" high and anything higher would look crazy.

    Any suggestions as to how bring this group down and if I need a new set of sights what would you suggest?
     
  2. Jun 13, 2019 #2

    SDSmlf

    SDSmlf

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    If you are a foot high at 50 yards, simple math says you need to raise the front sight or lower the rear sight about .140”, assuming your sights are 21” apart (I believe that is the distance between sights on a TC Hawken, you will have to check).

    What is the measurement from the barrel flat to the top of your front sight?
     
  3. Jun 13, 2019 #3

    mjpchief

    mjpchief

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    Front sight is about 1/2". Rear sight is already setting on barrel. Won't go any lower.
     
  4. Jun 13, 2019 #4

    SDSmlf

    SDSmlf

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    Most TC front sights that I have seen are around .375” above the barrel flat. How are you measuring it?
    upload_2019-6-13_15-6-17.jpeg
     
  5. Jun 13, 2019 #5

    Elkeater

    Elkeater

    Elkeater

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    Something is not allowing your rear sight from lowering further
     
  6. Jun 13, 2019 #6

    mjpchief

    mjpchief

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    You're right. It's 3/8". Like everything else, trying to stretch it.
     
  7. Jun 13, 2019 #7

    bubba.50

    bubba.50

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    Are you shooting from a rest? If so, try shooting offhand.
     
  8. Jun 13, 2019 #8

    mjpchief

    mjpchief

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    Yeah. It's setting down on the barrel. Will not go any lower.
     
  9. Jun 13, 2019 #9

    SDSmlf

    SDSmlf

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    Just gathering some info here.
    • Are you shooting at a measured 50 yards?
    • What kind of target (size of the black) are you using?
    • Are you using a six o’clock hold?
    • Could you post a photograph of your rear sight?
    • Have you tried shooting offhand as Bubba suggested? Or are you shooting off hand already? If so, try from the bench.
    • A foot high, with a ‘factory’ TC rear sight all way down, at 50 yards is quite a bit. Is this the first time shooting this gun?
     
  10. Jun 13, 2019 #10

    mjpchief

    mjpchief

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    measured 50 yds.
    1" diamond in center of target.
    6 o'clock hold
    Sight is setting as low as it will go. Setting down on barrel. Standard sight issued with rifle.
    Shooting from bench. Sighting rifle in.
    Have shot rifle years ago but never got serious with it until now.
     
  11. Jun 13, 2019 #11

    Dwight Rutherford

    Dwight Rutherford

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    Could the fact the OP is weighing Pyrodex instead of measuring by volume have an effect?
     
  12. Jun 13, 2019 #12

    SDSmlf

    SDSmlf

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    Wouldn’t think so in this case. I believe the lighter Pyrodox gives about 30% more volume equivalent by weight. In other words, a 60 grain weighed charge of Pyrodox would be the equivalent to about 78 grains of BP, if the 30% value is correct. Not a heavy charge in a 54.

    But going from volume to weighed charges with subs can be confusing and potentially dangerous.
     
  13. Jun 13, 2019 #13

    ppg1949

    ppg1949

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    This may sound ridiculous, but is the barrel properly seated in the stock?
     
  14. Jun 13, 2019 #14

    Billy Boy

    Billy Boy

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    60 gr by weight is about 80 gr volume? I might increase the powder charge to 100 - 110 gr VOLUME and see if it prints lower- quite a bit shorter barrel time usually works at average ranges for me to bring POI down
     
  15. Jun 13, 2019 #15

    SDSmlf

    SDSmlf

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    If for the moment we assume that everything is ok except for the vertical alignment of the sights to the bore , how about a simple test to confirm how much sight adjustment is needed to bring the point of impact down to where you want it?

    Take something like a small piece of wood or metal and glue (maybe hot glue) it to the top of the sight. If you raise the front sight 3/16” you should go low and be able to raise the rear sight a bit to get things where you want them. Just something to try.

    Also, could you post photographs of the front and especially the rear sight? A picture is worth a 1000 words. Maybe someone will notice something you are not seeing.
     
  16. Jun 13, 2019 #16

    SDSmlf

    SDSmlf

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    You really see that vertical POI change with pistols going from standard to magnum velocity, but not so much with a rifle. But a foot high at 50 yards??? Don’t think so. I have quite a few TCs, and only one required a bit higher front sight to give full range of adjustment. It’s the T/C style front sight from TOW, #FS-D37-1, but I believe it only .035 higher (maybe .410 from barrel flat). Based on OP’s numbers he would still be 9” high with that front sight’s height.
     
  17. Jun 13, 2019 #17

    Grimord

    Grimord

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    I would also check the crown of the muzzle to see if there is evidence of bunged up rifling.
     
  18. Jun 14, 2019 #18

    Kansas Jake

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    would a bent barrel cause this? If you have a longer straight edge, you could use that to check. Another thought is to remove the barrel and sight along the flats and you rotate it to see if there appears to be an issue. I'm guessing it is something else, but this is worth a quick check.
     
  19. Jun 14, 2019 #19

    waarp8nt

    waarp8nt

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    I couple of things I have noticed while purchasing used T/C muzzleloaders is there are three different rear sight heights. I have seen three Patridge rear sight heights and two v notch sight heights. With many of the T/C products being put together from random T/C parts, especially since T/C stopped making traditional style muzzleloaders, you may have a sight intended to be on another Thompson Center product as the inserts will interchange with the removal of a roll pin.

    Also, I have seen an aftermarket screw that fits the rear sight base to barrel well, but is simply too tall when compared to the factory screw and will not allow the rear sight to be lowered all the way. The rear sight will instead bottom out on the screw head and will not allow the sight to go as low as the factory screws. I replaced the aftermarket rear sight screws that mount the base to barrel and my rifle was cured of a similar sighting in problem.

    Below is a picture of the sight height difference. I didn't have all the patridge adjustable sights off my rifles, but you will get the idea when compared with the v notch sight. Sorry, but no pictures of the factory and aftermarket screw head height difference.

    TC sights.jpg
     
    Bon Sauvage likes this.
  20. Jun 14, 2019 #20

    mjpchief

    mjpchief

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    Will get some pictures of the sights when I get back home. Neither of those sights pictured are like mine. My rear sight will not go any lower. It is setting on the barrel now.
     

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