124 grain -- 25 yard vs 7 yard POI?

[Sin-ster]

I thought this would be better suited here than a "gun-specific" sub forum, but... mods can move if they choose.

I noticed quite recently that I was having a heck of a time on the Upper A zone at 7 yards and in, clustering just on or below the perf. Similarly, the meat of my group on the lower A zone is always below where I know I'm holding and where I'm calling the shots.

Typically, I don't group the gun at those distances-- so I gave it a run. Sure enough, about 1 3/4" - 2" low of POA.

Backed out to 20-25 yards (eyeballed) and it's shooting spot on POA.

Then gun is a 5" M&P 9 Pro, with Warren/Sevigny sights (standard height).

My question is-- how much of this is common trajectory for a 124 grain pill (MG JHPs) @1040 FPS average, and how much is a matter of the sights being relatively high over the bore? I know the Open guys have to deal with this latter consideration, but dang-- it's a PITA on irons.

[Flatland Shooter]

As you have figured, the higher the sight above the bore the more you may need to compensate.

For my open gun, (dot is Cmore 2.165" above bore)sighted in at 17 yards.

0 yards ----- POI -2.16

5 yards ----- POI -1.47"

10 yards ---- POI -0.82"

15 yards ---- POI -0.23"

20 yards ---- POI +0.32"

25 yards ---- POI +0.81"

30 yards ---- POI +1.25"

40 yards ---- POI +1.97"

50 yard ---- POI +2.44"

In my case, it only really comes into play on those really close upper A shots. Since I know where my bullet will impact, during stage walkthrough I note where I need to aim a little high or low to make my hits. After a while it comes naturally.

Bill

[Hi-Power Jack]

I was having a heck of a time on the Upper A zone at 7 yards clustering just below the perf. Similarly, the meat of my group on the lower A zone is always below where I know I'm holding and where I'm calling the shots.

Typically, I don't group the gun at those distances-- so I gave it a run. Sure enough, about 1 3/4" - 2" low of POA.

Backed out to 20-25 yards (eyeballed) and it's shooting spot on POA.

Sin, if you've sighted your gun in at 20 - 25 yards, it shouldn't be

2" low at 7 yards. Maybe 3/4" - 1" low, but that's it, I believe.

I stand to be corrected, but your front sight is less than 1" above

the bore center, so it shouldn't drop very far from the sight at

5-7 yards.

Have you tried this from a rest?

[Sin-ster]

Sin, if you've sighted your gun in at 20 - 25 yards, it shouldn't be

2" low at 7 yards. Maybe 3/4" - 1" low, but that's it, I believe.

I stand to be corrected, but your front sight is less than 1" above

the bore center, so it shouldn't drop very far from the sight at

5-7 yards.

Have you tried this from a rest?

That's what I was thinking, too, Jack-- it seemed dramatic. And no, the sights aren't nearly as high as say a C-more would be over an open gun! I'd say 1" would be the utter max, as you suspect.

Haven't tried it off of a rest just yet, however-- I was shooting one ragged hole at 7 yards while testing, and a sub-3" cluster at 20-25 (gun is sub-2, but it's close enough)-- so it's either my eyes or something odd with the pistol! Trigger manipulation and other types of shooter error were limited, IOW.

It's possible that I am overestimating the POI shift-- I didn't take measurements on the spot (no ruler or tape), and I'm SWAGing from a clean target and my memory. I am 100% positive though that it was more than 3/4"! The upper A-box is 2", and holding at the "tip of the A" that appears there was seeing me just inside the lower perf-- right about 1.5-1.75".

There's also I chance that I was shooting at 30 yards and not 20-25. I'll have to be really precise with all of the measurements when I go out the next time.

[reptoid]

I thought this would be better suited here than a "gun-specific" sub forum, but... mods can move if they choose.

I noticed quite recently that I was having a heck of a time on the Upper A zone at 7 yards and in, clustering just on or below the perf. Similarly, the meat of my group on the lower A zone is always below where I know I'm holding and where I'm calling the shots.

Typically, I don't group the gun at those distances-- so I gave it a run. Sure enough, about 1 3/4" - 2" low of POA.

Backed out to 20-25 yards (eyeballed) and it's shooting spot on POA.

Then gun is a 5" M&P 9 Pro, with Warren/Sevigny sights (standard height).

My question is-- how much of this is common trajectory for a 124 grain pill (MG JHPs) @1040 FPS average, and how much is a matter of the sights being relatively high over the bore? I know the Open guys have to deal with this latter consideration, but dang-- it's a PITA on irons.

Here's a ballistics calculator for you to play with. You just plug in your data and hit calculate. For games with a 124 going 1040 the optimum 0 distance would be 50 yds as that gives you the least deviation from muzzle to 50. As you can see it's a pretty flat trajectory with a 9 with that load.

[Hi-Power Jack]

Sin, if you've sighted your gun in at 20 - 25 yards, it shouldn't be

2" low at 7 yards. Maybe 3/4" - 1" low, but that's it, I believe.

Haven't tried it off a rest yet, however-- I was shooting one ragged hole at 7 yards while testing, and a sub-3" cluster at 20-25 (gun is sub-2, but it's close enough)-- so it's either my eyes or something odd with the pistol!

I'll have to be really precise with all of the measurements when I go out next time.

With groups that size, you obviously don't need a rest

I bet if you measure everything more carefully, you don't really

have a problem, at all.

As someone else mentioned, if you sight it in at 50 yards, it will

probably still be pretty good.

Good luck,

[Sin-ster]

Here's a ballistics calculator for you to play with. You just plug in your data and hit calculate. For games with a 124 going 1040 the optimum 0 distance would be 50 yds as that gives you the least deviation from muzzle to 50. As you can see it's a pretty flat trajectory with a 9 with that load.

DO want-- but you didn't include a link!

[reptoid]

My bad...forgot the link

Here you go:http://www.biggameinfo.com/index.aspx?page=%2fbalcalc.ascx