50 yards w/C-MORE

[Chris iliff]

Recently blew a 50 yard classifier, didn't learn my lesson and blew another one on Sunday. Figured it was time to learn something so I set-up a 50 yard target. I had been aiming right at shoulder height above the "A" zone. Maybe if I was lucky I'd get 3 or 4 out of 6 on the target. I discovered that if I aimed almost dead center at the bottom of the target I could get all the hits on the target. My open gun is sighted in at 10yards. 124 grain cmj MG bullet. Major power factor. I shot groups of 6 and planted 36 straight shots into the target once I figured out where to hold the dot.

OK......Why do I have to aim low? Is this a ballistic trajectory thing, is it a Cmore above the bore thing, is it a 10 yard dead on thing? I would like someone to explain this to me. HELP ME UNDERSTAND!

[open17]

Your line of sight and bullet path intersect at 10 yds. The bullet is ABOVE line of sight for

quite a while after that---I'm sure someone with a ballistic calculator will chime in with the yardage

at which the bullet drops back through line of sight and mid-range height.

Sight in at 50 yards. Then from zero to 50 the bullet will impact low---but it won't be further

off that the vertical distance from the c-more to the bore. Or sight in at 25---then you will only

be high a couple of inches at 50, and you can impress people by rolling pop cans at 100.

[blkbrd]

Sight in using 5 inch paper plates at 50 yards, or whatever is the longest shot you will take.

[AikiDale]

Here is the data for your bullet at 1400 fps assuming your sight is 1.5 inches above the bore:

Range Velocity Impact Drop ToF Energy Drift

0 1400 -1.5 0 0 540 0

10 1356 0 0.14 0.02 506 0.49

20 1319 1.31 0.46 0.05 479 0.66

30 1283 2.43 0.98 0.07 453 0.94

40 1249 3.33 1.72 0.09 430 1.33

50 1217 4.01 2.68 0.12 408 1.82

60 1187 4.45 3.87 0.14 388 2.42

70 1160 4.65 5.31 0.17 371 3.12

80 1134 4.59 7.01 0.19 354 3.93

90 1111 4.25 8.98 0.22 340 4.83

100 1089 3.63 11.24 0.25 327 5.83

As you can see, with a 10 yard zero you will be 4.01 inches high at 50 yards.

You can play with your data here: ballistic calculator

[Jeff686]

My guess is that 1.5" dot to barrel is a little short. I didn't get mine out out to measure, but...

Cmore is 2" max height. Since the lens is offset, I think the dot is probably 1.5" from the base. Now, add the extra clearance, slide, and 1/2 barrel. I'm guessing the total is over 2 inches from center of barrel to dot, maybe even 2.5 inches

With the sight 2 inches above the barrel, the ballistic calculator says a 10 yard zero would impact 6 inches high at 50 yards.

With the sight 2.5 inches high, a 10 yard zero would impact 8 inches high at 50!!!

See how much your sight height impacts things with a 10 yard zero.

[AikiDale]

I was just playing with this and it looks like 17 yards is the sweet zero, if the sight is 1.5 above the bore. If it is higher or lower put it in the chart and figure it out for your pistol. With a 17 yard zero you are within an inch from 5 to 35 yards, an inch and a quarter high at 50 and less than 2 inches low at 100. Zero at 17 and just shoot the darn thing!

Did Brian already mention this before we went to the new board?

[XD Niner]

I had read somewhere on this forum that 17 yards was the sweet spot as AikiDale says above. I find that it works very well for my Brazos Open SX and SC at anything less than 35 yards. Truthfully, after that my groups spread out considerably anyway.

About the only time you really need to remember that it shoots low at very short ranges is a short head shot. Then I just aim for the top center of the target.

[Flatland Shooter]

You can play with your data here: ballistic calculator

Thanks for the posting of the ballistic calculator.

On my open gun, the C-more is 2.165" above the bore. I always zero'd at 17 yards. After review of the calculator results, I will be sighting in at 25 yards in the future.

Bill

[Chris iliff]

My guess is that 1.5" dot to barrel is a little short. I didn't get mine out out to measure, but...

Cmore is 2" max height. Since the lens is offset, I think the dot is probably 1.5" from the base. Now, add the extra clearance, slide, and 1/2 barrel. I'm guessing the total is over 2 inches from center of barrel to dot, maybe even 2.5 inches

With the sight 2 inches above the barrel, the ballistic calculator says a 10 yard zero would impact 6 inches high at 50 yards.

With the sight 2.5 inches high, a 10 yard zero would impact 8 inches high at 50!!!

See how much your sight height impacts things with a 10 yard zero.

you are right, I am 2" and thanks for all the input. I can't believe I have been shooting over a fifty yard target.

[Chris iliff]

Thanks for all the input. Seems so obvious now,.... almost duh. The ballistic table helped me a lot. Now to decide on my zero....any recommendations for a 2" sight height? I'm thinking 18-20 yards?

[-XX-]

Anyone know the ballistic coefficient to use for a 115 MG jhp in the calculator above.

Edited November 29, 2010 by -XX-

[G-ManBart]

Anyone know the ballistic coefficient to use for a 115 MG jhp in the calculator above.

I'd use data from a Hornady 115gr XTP, which is .129. That should get you close. Hornady also has most of these same calculators on their website. R,

[outerlimits]

Shouldn't ypu be taking into consuderation tge 1degree barrel offset somewhere? A 1911 design ain't a rifle.

[G-ManBart]

I measured the height on my C-more on a Brazos mount, and it was more like 2" from the bore to the center of the glass. R,

[-XX-]

Shouldn't ypu be taking into consuderation tge 1degree barrel offset somewhere? A 1911 design ain't a rifle.

I do not think the 1 degree barrel offset would effect the trajectory calculation. The barrel and sight plane are never going to be perfectly parallel (rifle or pistol), they only intersect at two points. But then I could be wrong.

[big50]

i sighted my race gun in at 50 yrd's using a 115gr zero bullet .it shoot's dead on at 25yrds and at 10yrd's ihave to hold it about 1" high . and thats easy to do at ten yrds .

hope that will help ,

[Jan R.]

i sighted my race gun in at 50 yrd's using a 115gr zero bullet .it shoot's dead on at 25yrds and at 10yrd's ihave to hold it about 1" high . and thats easy to do at ten yrds .

hope that will help ,

Do you guys sight in from a sand bag rest or a vise type like a ransom?

Thanks

Jan

[Alaskapopo]

Your line of sight and bullet path intersect at 10 yds. The bullet is ABOVE line of sight for

quite a while after that---I'm sure someone with a ballistic calculator will chime in with the yardage

at which the bullet drops back through line of sight and mid-range height.

Sight in at 50 yards. Then from zero to 50 the bullet will impact low---but it won't be further

off that the vertical distance from the c-more to the bore. Or sight in at 25---then you will only

be high a couple of inches at 50, and you can impress people by rolling pop cans at 100.

New to open but I have always sighted my pistols in at 25 yards for the reason you said above. You can easily hit out to 50 by aiming normal.

Pat

[boz1911]

How often do we shoot at 50 yards? Most of my shooting is at 12 yards or less. I sight in much closer and just hold at the bottom of the A zone at 50. Seems easier than holding a inch high all the rest of the time.

[Alaskapopo]

How often do we shoot at 50 yards? Most of my shooting is at 12 yards or less. I sight in much closer and just hold at the bottom of the A zone at 50. Seems easier than holding a inch high all the rest of the time.

At least one stage at every out door match I attend up here has 50 yard targets. At the indoor matches we shoot at least 1 stage at 20 yards. Shooting inside 12 yards all the time is boring.

Pat

[DyNo!]

And in multigun, they love to push pistol targets out - I'll be rolling with a long zero for that game.

A 10 yard zero is good to go for USPSA though.

[XD Niner]

i sighted my race gun in at 50 yrd's using a 115gr zero bullet .it shoot's dead on at 25yrds and at 10yrd's ihave to hold it about 1" high . and thats easy to do at ten yrds .

hope that will help ,

Do you guys sight in from a sand bag rest or a vise type like a ransom?

Thanks

Jan

I sight in at 17 yards offhand. The gun will move differently in my hand than from a sandbag rest and definitely differently than from a Ransom Rest. I want the zero to correspond to my normal two handed grip.

[boz1911]

How often do we shoot at 50 yards? Most of my shooting is at 12 yards or less. I sight in much closer and just hold at the bottom of the A zone at 50. Seems easier than holding a inch high all the rest of the time.

At least one stage at every out door match I attend up here has 50 yard targets. At the indoor matches we shoot at least 1 stage at 20 yards. Shooting inside 12 yards all the time is boring.

Pat

I wish we would use more long range stuff, but that's only because I shoot open.

[Alaskapopo]

How often do we shoot at 50 yards? Most of my shooting is at 12 yards or less. I sight in much closer and just hold at the bottom of the A zone at 50. Seems easier than holding a inch high all the rest of the time.

At least one stage at every out door match I attend up here has 50 yard targets. At the indoor matches we shoot at least 1 stage at 20 yards. Shooting inside 12 yards all the time is boring.

Pat

I wish we would use more long range stuff, but that's only because I shoot open.

I like long stages because I have a good long game. I need to work on my speed on the short stages though. Here is a stage I shot in limited. at 50 yards. I got 1st on this stage even beating the open shooters there.

Now that I am shooting open I want to do long stuff even more.

I watched your videos on your youtube channel your fast! Good shooting.

Edited December 6, 2010 by Alaskapopo

[joecichlid]

How often do we shoot at 50 yards? Most of my shooting is at 12 yards or less. I sight in much closer and just hold at the bottom of the A zone at 50. Seems easier than holding a inch high all the rest of the time.

I know what you mean. We sure as heck didn't see anything over 25 yards at the Nats this year. When I shot the KS Sectional this year we had a standard with two rounds in four seconds on a 75 yard target. Four rounds in four seconds on a 50 yard target. Six rounds in four seconds on a 25 yard target. For the most part I am shooting targets inside of 20 yards at the local indoor range.

Joe W.