short barreled fixed sights

[dragonmouse]

Not sure if this is the right spot for my question but if not mods please move. Gun is a uberti 45 colt with a 3.5 in barrel and birds head grip.
At the range today 7yd, and 10yd I finally found that a fine bead,(top of front blade maybe 1/8" above the rear sight groove) gave me
stellar poa/poi. All in the 8/9/10 ring on a 8in circle. One ragged hole more or less assuming I get enough finger on the trigger. The small grip
has me pulling low/left every time using the pad. More finger (to the crease) 9/10 ring dead on. After about 100rds I moved back for 10 rounds 5 and 5 at 25yds just to see if I could even get
on the paper. First shot was .5 in off the paper low, next round touching paper low. I threw the third shot called left about 2in or so. 4 and 5 were in the
5 ring low. Second five were a vertical string starting 1 in the 7 ring 2 in the 8 (one left of other 1in) 4th shot was dead on bullseye in the 10 and the last shot was a
9 ring straight on low.
I was truly impressed with this little cannon, but here is the question. During the second string I was simply getting more and more front sight to get to the bull ending with about 2/3s of the front blade in the groove.
While this was all freehand and the adjustment is subjective, I don't really understand the ballistics here. I would have thought that in 45 colt 7yards or 25 shouldn't cause me to have to get that much more front sight for correct impact. My sig p220 45acp with a 4.25 barrel is simply line the dots and squeeze the trigger at either distance. I guess I'm trying to figure out if its the way I am sighting the fixed sights on the sixgun, or is it simply a matter of physics with the 3.5 in barrel in that large of a bullet. All were with handloads 8.5 grains unique under a 255gr keith lswc. This is mild to medium recoil and seems to be what this gun really likes. I'm sorry for the description but I cannot upload a picture on this computer. Any thoughts?

[okie john]

Take a break and try it again in a few days. 100 rounds of 45 Colt in a light revolver all in one sitting can affect your trigger squeeze.


Okie John

[dragonmouse]

While I absolutely agree with the idea of fatigue, I will point out that at that distance in the second group of five I was able to walk the last five
rounds into the bull. My question is whether there is a real chance that the 3.5 in barrel could have ~8in of drop in 25yds out of the uberti. Otherwise
changing the sight picture(getting more front sight) doesn't really seem to agree with what I thought I knew about ballistics. I was hoping the
shooters here could tell me something that my sight picture on the fixed sights was causing that kind of difference between, 7/10 yards and 25. It may be that
short barrel actually loses enough velocity at that distance to account for the drop but I don't know. That's why I asked.

[okie john]

It's probably not your sight picture. There could easily be that much drop between 7 yards and 25 yards based on your zero. Have you chronographed that load? Cylinder gap and other internal dimensions can have as much effect on velocity as changes in barrel length.


Okue John

[dragonmouse]

Thanks John, and no unfortunately my chrono went fubar, when I got it out to check for the weekend trip. It's an old pact but
worked really well. I have to call their customer service rep tomorrow after an email exchange to see what I have to do to either
fix or replace it. Their customer service has been great up to this point. But thank you I think that was the answer I was looking for.
Simply knowing that it was possible that kind of drop was within the realms of normal just means I have to have more info. More range
time! I can live with that. Truthfully I'm just tickled the little gun did that well. While my sig isn't going anywhere, I live really rural so
there are times that it gets to go for snake killin and such.