Page 1 of 1
Sub six hold and POI shift
Posted: Mon Aug 07, 2006 7:44 am
by ChrisL
We have a very interesting discussion going in Belgium.
I shoot AP (IZH46M), .22 (new Haemmerli 208s) and 9mm (SIG P210-6S). Sighted sub six at 10m (AP) and 25 m (others).
I usually shoot a couple at 12m, to calm down, group and whatnot, and then move on to 25 m.
At the shorter distance, I'm low (but don't care), at 25m I'm about right (that is, pilot error excluded), at 50 m I'm high.
For me, all this is to be expected.
Now there's a guy (pretending to have an extreme sub six hold: halfway between bottom black and edge of target), and he says with his Free Pistol or with anything else he does not need to compensate for 25m or 50m.
I have difficulty to believe his - doesn't sound logical to me, unless he involontarily compensates his hold...
What are your experiences?
Thx,
Chris.
Posted: Mon Aug 07, 2006 8:16 am
by Ed Hall
This fits in with some of my own experiences. With my Service Pistol - open sighted 1911, in .45 caliber - I have little or no change from 50 yards to 25 yards, when I use a sub six hold. Additionally, my 208s has very little change when using a one inch red dot scope.
The reason for the limited need to change has several factors. One is the target size for my 1911 being different. Another is the sight line above the bore for my 208s. And, in both cases, the ammo velocity is an important factor. If all the parameters are right, you can have a crossover of the round raising through the target at the closer distance and falling through the target at the further distance. For my 208s with standard velocity ammo, for a coincidence at center of the two distances, the scope is mounted somewhere around an inch above the bore line. Obviously, an inch is far too high for the open sights on my 1911 (also the velocity is quite different), so that's why the need to use a sub six hold. It allows for the trajectory of the slower bullet to be more pronounced and meet both crossovers at the two different distances.
Take Care,
Ed Hall
http://www.airforceshooting.org/
http://www.starreloaders.com/edhall/
Posted: Mon Aug 07, 2006 9:32 am
by Richard H
Fits with my experiences aswell. Between 25 and 50m with my GSP I rarely have to change sight settings (when I do it is usually less than 5 clicks).
There is more than just bullet trajectory going on, things such as eyesight and lighting will have an effect on sight settings from one individual to another. Have you ever shot someone elses pistol that is sight for sub-six or center hold and its not even close for you.
In the big picture who cares what someone elses if doing to their sights, if you have to adjust then adjust, if he doesn't, he doesn't. It doesn't make him a liar as you are aluding to ("pretending to have a sub-six hold").
Posted: Mon Aug 07, 2006 11:30 am
by ChrisL
Richard H wrote:It doesn't make him a liar as you are aluding to ("pretending to have a sub-six hold").
Whoa, easy. I'm not calling anyone a liar. The guy pretends to have an extremely deep sub six hold, that's all I said, and I'm not aluding anything, I just try to understand.
But genuine thanks for your reactions,
Chris.
Posted: Mon Aug 07, 2006 1:08 pm
by Steve Swartz
Sub six hold.
Free Pistol: No change 50 feet to 50 meters. Maybe a click or two to make me feel better.
Standard Pistol: No change 50 feet to 25 meters. Maybe a click or two to make me feel better.
Rationale:
- 50 feet - 25 meters .22LR pretty much travels in a straight line. I'm probably sighted a little low at 50 feet with my SP and probably a little high at 25 meters; all inside the ten ring certainly. Sight in perfect at 25 meters and you should be well within distance from muzzle to top of front sight.
- 50 feet - 50 meters the .22 LR is rising into the 25m ten ring and falling through the 50m ten ring.
Plug some numbers into a ballistic calculator. If you are making radical (more than 3 clicks?) adjustments, something other than ballistics of the .22LR must be going on?
Steve Swartz
Posted: Mon Aug 07, 2006 1:45 pm
by Richard H
ChrisL wrote:Richard H wrote:It doesn't make him a liar as you are aluding to ("pretending to have a sub-six hold").
Whoa, easy. I'm not calling anyone a liar. The guy pretends to have an extremely deep sub six hold, that's all I said, and I'm not aluding anything, I just try to understand.
But genuine thanks for your reactions,
Chris.
No problem I probably just read it wrong.
Posted: Tue Aug 08, 2006 3:06 am
by ChrisL
Steve Swartz wrote:
Plug some numbers into a ballistic calculator. If you are making radical (more than 3 clicks?) adjustments, something other than ballistics of the .22LR must be going on?
Steve Swartz
I'll try to run the numbers.
Actually, I don't click (most of the time), I stick to the 25 m distance settings. I have figured out&written down how much to click to move from 12 to 25 m, but I dont use it'often: I take a couple of shots at 12m to ease my mind and move on to 25 m (a good grouping at the start builds my confidence).
Oh, don't forget - I'm an absolute amateur!
At 12 m (about 36 ft), I know I have to aim at the 8 ring instead of top of 5 ring to compensate.
If the 25-50 transition w/o clicks works because of the .22 ballistics, I'd expect a different result with the 9mm. But then again, me shooting 50 m with a 9mm handgun may not be accurate enough to draw conclusions in the first place...
I'll try the different distances (12-25-50), including clicks, and I'll report later this week, or early next week...
Posted: Tue Aug 08, 2006 8:28 am
by Richard H
ChrisL wrote:Steve Swartz wrote:
Plug some numbers into a ballistic calculator. If you are making radical (more than 3 clicks?) adjustments, something other than ballistics of the .22LR must be going on?
Steve Swartz
I'll try to run the numbers.
Actually, I don't click (most of the time), I stick to the 25 m distance settings. I have figured out&written down how much to click to move from 12 to 25 m, but I dont use it'often: I take a couple of shots at 12m to ease my mind and move on to 25 m (a good grouping at the start builds my confidence).
Oh, don't forget - I'm an absolute amateur!
At 12 m (about 36 ft), I know I have to aim at the 8 ring instead of top of 5 ring to compensate.
If the 25-50 transition w/o clicks works because of the .22 ballistics, I'd expect a different result with the 9mm. But then again, me shooting 50 m with a 9mm handgun may not be accurate enough to draw conclusions in the first place...
I'll try the different distances (12-25-50), including clicks, and I'll report later this week, or early next week...
Due to the phase of trajectory that the bullet is in there probably is a bigger difference between 12 m and 25 m than 25m and 50 m.