Same Zero for 25 and 50

I mount my scopes so that they are 2" above bore on the .22 and near mid range trajectory on what ever I've loaded in .45. Doing that I eliminate the need for sight adjustment between 25 and 50 yards.
 I don't think I ever gone to a match that someone hasn't complained about forgetting to make a sight adjustment. Being the 2" is mid range for standard velocity .22 I have no adjustment
 I one time was talking with Fred Kart at Perry and he told me that the additional black 8 ring on the 50 yard target was to compensate for the trajectory using a 6 o clock sight hold. At the time he was selling 1X scopes so we determined if mounted with the center 2" above the bore no sight change will be needed. I did and tested it, found it worked as thought.

Finding zero is always a issue for most shooters, this topic is about mounting a rail and the dot but I think we can continue down the zero trail for sure if there is a way to mount your dot to help get a sustained zero or reduce adjustments from 25-50



Frank, You say mounted 2'' above bore is that 2'' from center of bore to center of dot? Also on your loads, do you shoot the same load, and bullet at 25 and 50?
I find a 22 shoots flat and mine require no adjustments from 25-50 using SV ammo.  My 45 dot sits 1''+5/8'' from center bore to center dot, and requires about 4 clicks from 25 -50 when using same load for long and short line. Is there a brand of ring you use or do you just build the rail taller?

.

The listed Mid range trajectory for the .22 is 2 " The same for .45 ACP factory but I don't shoot factory loads in the 45. Benching my gun I get center X at 25 and 50 yards. No bullet shoots flat, every bullet begins to drop as soon as it leaves the barrel. Therefore the barrel must be elevated so that the bullet drops to the target. If sighted in at a particular range an arc defines the bullet path. Most manuals will have the trajectory shown as a mid range.That is the height of the bullet 1/2 the distance to the sighted target. Therefor if a 22 is sighted in at 50 yards it will be 2" high at 25 yards as given as the mid range of the .22 std velocity. Putting the center of the scope 2" above the bore will have the bullet cross the line of sight as seen thru the scope at 25 yards and 50 yards if sighted in at 50 yards.
 Same for the 45 but with factory loads. So with re-loads the mid range has to be determined.
 Yes once I develop a load I don't change it, shoot the same 25 and 50 yards. One less thing I have to remember to do at the range. What is interesting is that the load I was using had the same trajectory as the loads for the AMU 50 yard ammo. Adam gave me a box and I tested it. I just got 2000 rounds of 185 JHP Zero bullets I have to develop a load for.
 Weaver has rings of different height but if I use those that come with like the Ultradot I make the base to give me the height I need.. If you  go to the photo of the Homemade gun it has the center of the scope 2" above the bore. I'll try to post a Photo of the 45 I built for Adam, It too has the scope about 2" but adjusted to the loads he was using when he was home. You have to understand that if I were to make the scope center only 1 3/4" above bore it will shoot about 1/4" high at 25 yards if sighted for 50 yards. That's not bad! Heck then let it shoot 1/8" low at 50 and it will shoot 1/8" high at 25! The same will be true for the height needed for the 45
 Keep mind the bullet is rising to the line of sight and dropping back to the line of sight at the sighted in distance.

 Here is a photo of the slide on Adams 45, I'm getting it ready to take to Perry as a back up. Got my dirty fingerprints on the scope base. Plain Glass bead finish. Base taper matches the Barrel exactly. Vee on both sides cut after the base was mounted and barrel indicated . Millet scope still works good!

The scope in that pic looks much lower than 2'', the age old theory has been, closer to the bore the sight is the more accurately a shooter can shoot it., your theory might change that if we can nail down exactly how we can do that.

Did you fit the lower lug and link..????
What apparatus/fixture do you use to determine lock up angle??

Here's a few more photos, the gun has a 6" barrel. It's been a long time since I made the base, it may be a little less than 2 " but it was made to the mid range of the loads used. might be 1 3/4"

Yes I fit the lower lug, first 5"barrel  lug was used so much it was wearing out so having  Eutetic Spray Welding torches both Hot and Cold. I spray welded carbide on the 6" lower lug. . Hasn't worn in years! I also use a very small radius on the front of the lower lug so I have absolutely no bump when it closes. I chose the 6" barrel because I noticed the gun not shooting as well as it was supposed to but Perry was a short time away so I used a 6" I had. I might add this is the gun that the AMU tested and it shot 50X!
 I have rods ground to various diameters and choose the one that will slide in with no movement. However if I don't like how the rod fits I take a larger one and grind it to fit or completely make another. I have a spring I put under the slide to keep the barrel locked up while indicating the rod both for center and angle. All are done on the mount except the Vee that fits the scope rings. The mount is finished to the rod I indicated in the bore of the barrel. The exact angle I don't know, never needed a reason to measure it but it is exactly the same as the bore of the barrel.
 Therefore the scope as best that can be established by the rings is exactly in the center of the bore and exactly at the same angle. Most of the time when mounting a new scope it will shoot 10 ring or better at 25 yards.
 I mentioned it someplace but a friend of mine seeing my .22 decided to mount his Ultradot 2" above bore using a mount that Fit the Walter GSP and high scope rings. He too is now shooting 25 and 50 yards with no sight adjustment. Shot 872 last Wednesday with no sight adjustment.

A simple sine plate dedicated to barrel lock up angle makes it possible to mathematically determine the exact angle. This angle is then transferred to the angle within the bushing.  I do not mount my optics high.. Most of mine are approx. one inch  Bore C/L to  Optic C/L

I have a few sine bars even a 10" one a sine plate and a magnetic chuck with a double sine base. The magnetic chuck probably has an inch of dust one it since I used it last! I simply use a vise that will tilt in the long direction and adjust it to whatever the rod indicates in at. Since I don't work on many guns it's just as easy to use the vise.
 I'm working on one now that I hard chromed the rails. Did one a while ago that worked great so time to do another. A friend of mine is bringing a piece of new rail track, the heavy duty type used on curves. I have a new precision rail with 2 precision ball bearing slides I plan to mount on it and make a barrel testing fixture. I could have sold that slide on ebay for about a $1000 but heck make a precision tester!
 I did check the red dots I have and found that parallax lessens as the scope gets closer to the eye. Probably why rifle shooters don't complain. Field of view increases too so the dot is a lot easier to find.

Jerry Keefer wrote:A simple sine plate dedicated to barrel lock up angle makes it possible to mathematically determine the exact angle. This angle is then transferred to the angle within the bushing.  I do not mount my optics high.. Most of mine are approx. one inch  Bore C/L to  Optic C/L

jerry since this topic is about zeros with various setups, with your closer to the bore mounting what kind of difference do you see in zero from 25-50?

The Marvel on SA lower is 1.4" ctr. to ctr. shooting CCI SV or Center X or Eley red box.
I do not adjust the dot between 50 and 25.
Now shooting indoor 50 feet, maybe a clickish.

The Clark Sr. long slide is 1.5" ctr. to ctr. shooting 4.6gr of BE under Nosler 185gr JHP competitions.
I do not adjust the dot between 50 and 25.

The S&W M52-1 is 1.7" ctr. to ctr. shooting 2.8gr of BE under Remington 148gr HBWC's.
This is where the M52 is kind of odd in my hands...
If I have a good hold and solid fundamentals on a given day there will be no adjustment on the dot between 50 and 25.
Other days for some reason will be about 4 clickish between 50 and 25.
Don't ask me why, don't know
Still my favorite pistol.

Clarence

[quote="DavidR"]

Jerry Keefer wrote:

jerry since this topic is about zeros with various setups, with your closer to the bore mounting what kind of difference do you see in zero from 25-50?

Dave
No adjustments on the Pardini which is slightly less than an inch C/L to C/L and shooting different ammo at each distance.
The 52 requires adjustment between lines as does the .45.. Both of those dots are right at approx one inch C/Ls. I have never felt changing settings to be a big deal.. She marks her zeros on the tube with a pencil.. Settings change thru out the match, as conditions, lighting, the body, stance, eyes, fatigue, & whatever. The match never ends on the start zero..
I am rather certain, that the average shooter will score better with the lowest optic. Sustained fire recovery is better. Longline benefits from less brain/eye perceived lateral motion of the dot..

I have always had to make adjustments from 25 to 50, and from one range to another, I also mark my dot then record changes in a notebook for each range. That's why a 25-50 no change idea is so interesting.

pencil marks, I need to try that. It's bound to be better than keeping it in my head.

I use the small tip sharpie, red 25 blue 50 then if I need to change it later for different load, alcohol on a qtip wipes right off

From a physics-based perspective the higher the scope the more felt recoil. Why? Slide travels in linear motion along frame rails. For the most part regardless of scope location (front middle rear) it will be the same along that path of slide motion. The higher the scope the higher the center of gravity for the scope/slide combo. The moment (torque) will be greater the higher the scope is mounted. I can feel a difference when I shoot a extremely low mounted scope vs. typical slide mount with higher rings (like Ultradot rings). I would rather change elevation between 50 &25 than have a high mounted scope to avoid turning a screw driver. 
Jon

I just used "Handloads.com" ballistic calculator and figured out this was never going to work for me or anyone using weenie loads in a .45. I used 700 fps, a 200gr SWC and a BC. of .123. I would have to have the center line of the scope 4.5" above the barrel to yield a POI .16" low at 50yds with a 25yd zero.

Len

Measuring with a tape measure (all I have at the house) the center of the barrel bore to top of the side is dam near 1/2" Plus half the 1" scope is 1/2" add that to the distance from the bottom of the scope to the center of the vee 5/16 that becomes 1  5/16" Add 1/4" for the base (I've seen higher) that's 1 9/16 (1.562) Looking up the load information of a similar load we were using and it's 1.7" So to have 0 sight change from 25 to 50 yards the scope has to be mounted 3/16" (.187) higher. Measuring the scope in the photos it's almost 1 3/4" (1.750). Adam never adjusted the sights between 25 and 50 yards! I doubt that 3/16' increase in torque was even felt plus at the time he was 10 years old and was beating most of the line! I used the same height, same loads and never made a sight change! Adam went on to set a Junior Record with that gun. (Look it up)
 Now I just measured Primary Arms micro. It's dam near if not actually 13/16" (.812) to the center of the Weaver mount Vee. That will make it the same as the 1" Ultradot. If a 30mm tube was used it would be higher! I doubt very much that a scope can be mounted 1" above bore without special machining! I'm willing to bet most scopes mounted on the 45 of those here is greater than 1 7/16"
 Bottom line if sight adjustment don't bother you and you like the low mount do it! If your like me and don't want more things to remember to do then get you scope height to near Mid range. Being that the average red dot is only a short distance from the mid range height adjust the scope so it shoots 1/8" high at 25, it will shoot 1/8" low at 50 yards (actually little less)

Soooo, returning to the op, when using irons, old school, what is the preferred hold point at 25 and 50 to minimize sight adjustment?

With Iron the Bullseye was set-up to shoot both 25 and 50 yards with the .22 because of the black 8 ring at 50 yards with 6 o'clock hold. When I and Fred Kart were talking about this issue we looked up factory specs for both .22 and 45. Been loooong time ago and I don't remember what 45 load we looked at and it may have been ball. However both had a mid range of 2" However that may have been a miscalculation on our part. I have found bullet drop information for the 45 ACP that give the ballistic trajectory in bullet drop, at 25 yards it drops 1.6" at 50 yards it drops 3.6" we may have concluded the mid range to be 2" That will be a slight error! Fred said that the target was set up so as to be able to use the 6 o'clock hold for both guns. I had read someplace (can't remember where) that is was the Army that did it for the 45 so I'm thinking it was ball but what ever they were loading at the time. Getting more info I've read that the Military Ball has a 1.6" mid range and it may be that the target is designed around a 1.6" midrange. I seem to have some recollection of that being discussed at one of the DCM schools and anyone using the center hold would have to make sight changes. The 38 Special also has a mid range of 2" With that information you can see that the difference is very minor, if the sights were adjusted to give perfect impact .20' below center at 50yards it will be above center .20" and much smaller than the best of guns can produce.
 The actual exact impact will change due to the height of the sights over bore but that minor change will result in small fractions of an inch on the targets and much smaller than anyone can hold.
 Bench testing my some what complete AW with the Precision Arms red dot exactly 2" above the bore. Being that the Vertical spread I'm getting at 50 yards is about .50" to center of bullet hole I'm getting near perfect center impact at both 25 and 50 yards. Last Wednesday I shot a 858-59X and being it was getting late we opted to shoot a 20 round timed and rapid fire. Not shooting for 5 years I could feel the strain on my arm shooting four 5 shot strings without a break but happy with the results I got. The scope seem a bit high in looks, I may decide to lower it 1/4" then sight it to split the difference between 50 and 25 yards.

I have found the opposite of what Frank has found. I have found that a center hold with iron sights works best for not having to adjust the sights. The ballistics of a .45 hardball round would seem to bear this out. With a 50 yd zero the point of impact at 25 yds is only 1" high. The actual high point of the trajectory coming at 30 yds. Those that shoot 6:00 often have to raise their sights when moving from 50 to 25. That is what I have found. YMMV

Len

I think we are saying the same thing Len. But how is it that if the bullet hits 1" high the sights don't have to be adjusted? Plus the iron sights used will make a difference too. But lets assume a low mount Bo-Mar was used and it's 5/8" above the bore. And the mid range is 1.6 as I've found it to be posted for ball.  Sighting in at 50 yards will have the bullet hit the 25 yard target 1.6" high if the gun were held in a good rest and the target placed in the exact same place as the 50 only at 25 yards. The bullet will be crossing the line of sight much before the 25 yards but about 5/8" (.625) above center at 25 yards. Lowering the gun 5/8" so the sights align with the center of the 25 yard target the bullet will strike the target .975" above center. Hence the same conclusion.
 The point is this, If the two targets were put exactly in the same location with respect to each other and a shot fired that was not distorted by the target out of a great rest that did not move, or two shots fired out of that super rest but the targets replaced to avoid any bullet path distortion. If I had a red dot scope with a magnetic bottom that put the sight 1.6" above the bore and looked at the 25 yard target it would be the same height as the bullet, removing the 25 yarder and looking at the 50 yard target I would see the same. Removing the Magnetic mounted Red Dot and looking thru the iron it would be the same height at 50 but 1" lower than the bullet at 25 yards. The only change will be to lower the rear sight to align with the bullet hole. However when done the trajectory will change slightly because the gun to hit in the 25 yard center will be lowered but it will not be much! The High point will move back, remember that the trajectory is an arc and therefore the amount of elevation change near the High point vs the distance traveled is very slight.
 As per what has been told to me by Fred Kart is that if I were to take that same target and same rest and move the rear sight up so that the sights aligned with the bottom of the 8 ring and looked at the 25 yard target is that the sights will align 1" above the 9 ring so that when the gun is moved down to have the sights at the bottom of the 9 ring the bullet impact will be in the center and why the only ring on the Bullseye target is exactly 8.00 inches while all the others some odd number.
 Mid range information is given for 1/2 the distance to the sighted target. Though the peak of the arc maybe be at another distance the data given is at 1/2 the sighted distance. So the bullet may have a peak of 2" but not at the target and where I mentioned Kart and I may have wrong selecting 2" as a mid range and why I have Adams gun 1 3/4" above bore.
 Dave; While at the AW topic I notice your AW has the scope mounted at least 1 1/2" above the bore. The center of the barrel bore on an AW is at the same height as the top of the slide, 1/2 the extractor can be seen. I'm assuming you have a 1" Ultradot so that 1/2" the distance from the bottom of the scope to the slide seems to be slightly larger than the scope diameter so tha't at least 1 1/2". As the height aproaches the mid range height the amount of impact difference gets smaller. If your scope were 1 1/2" high then the difference in impact between 25 and 50 yards will only be 1/2" and less if the scope were more than 1 1/2" above bore.

Simple Frank, I zero it at the bottom of the x at 50 and it strikes the middle of the x at 25. I tried to type that with a straight face and failed. What I am saying is during a match 1" difference twixt 50 and 25 is something very few people on this planet can tell with a hardball gun in their hand. In conclusion it prob doesn't make a bit of difference to the normal hardball shooter which sight picture he/she goes with. Both could have zero zero by adjusting their load.

Not sure where you getting your data from Len: Most places on the web list the midrange for 230 hardball as 1.6" for 50 yards. That means it will strike 1.6" high at 25 yards when sighted at 50. It would make no difference if sighted center hold or 6 o'clock.  If I was to put a super good barrel in a rest so that it shot a great group so as to confirm the ballistics and adjusted the rest so that it shot center X at 50 yards I would have to hold the gun in the same exact angle to place that shot in the X shooting it with my hand. The sights are so that I can reference the target to adjust the gun as it was tested in the rest. As the gun is lowered in elevation the drop increases at the shorter distance simply because the bullet is fighting gravity. If I were to shoot a bullet with no elevation it will fall to the earth and hit the ground at exactly the same time as if a bullet were dropped straight down. So if I were able to attach a bullet to a string so that it was cut by the bullet leaving the barrel that was adjusted to have 0 elevation both bullets will drop the same distance in the same amount of time.
 So no matter what the gun has to be placed it the exact same position every time to have the bullet hit the center of the intended target. The sights are nothing more than a reference. The sights are line of sight and always a straight line and the bullet arc will cross the line of sight in 2 places. So if adjusted to 50 yards the bullet will strike the target 1.6" high at 25. As you have stated it will strike the target at 25 yards 1" high using center hold. The gun is still in the exact same place. So if a line were drawn from the sights to the 50 yard center it will be about 1" below the bullet hole. By using the difference in size see that the difference between the 9 ring at 50 yards and the 8 ring at 50 is 1.23" (4.00 - 2.77) and your information about center hold is 1" so there is a mere .23" difference and can be attributed to the difference in ballistics being there will be a greater drop as the gun is leveled.
 I agree that a good shooter can judge a 1" difference at 25 yards but when trying to shoot a shot every 2 seconds rapid fire I would rather use the 6 o'clock hold. Ever since Fred Kart told me that I have been using 6 o'clock hold With no sight change and doing well with ball when I was shooting, my personnel High at Perry was 284.

I just ran some numbers on a rifle ballistic spreadsheet I made some years ago.  It's made for CF rifle velocities, so 22 and pistol bullets may not work in it.  But it does indicate that for a consistent BC and velocity in pistol parameters, there is a certain height of sight that will have the trajectory arc pass the line of sight at 25 (on the way up) and again at 50 (on the way down).  The midrange trajectory (arc's peak) will be about 38 yards.  The sight height above bore for these data is about 2.8"

Again the formulae are for rifle velocities, and not claimed to be accurate for slower pistol loads.  When using rifle data, this spreadsheet agrees very very well with the tables in the Hornady book and other sources.