bullet drop, 38 special

B

Bezoar

Moderator
Just got my new revolver out for her first range visit. didnt shoot much. to much bugs and humidity. However noted a few things that have me perplexed.


6 inch barrel. adjustable sights. .357 magnum. finally found the caliber engraved UNDER the barrel rib in 1/16 inch lettering. after shooting.

110 grain remington sjhp at 25 yards hits 8 inches LOW.
130 grain winchester fmj hit 2.5-3 inches low 25 yards
158 grain lrn federal champion hits 4 inches low at 25 yards
158 grain jsp 357 federal champion 1250 fps on the box hits 3-4 inches low


birchwood casey sight in target. plain paper. using the lolipon hold, sights lined up on bottom of bullseye. the 110 grain sjho and the first round of 357 had the most recoil.
didnt shoot much, but it was FUN.
 
What's got you perplexed? That 158gr .38spl and .357mag shoot to the same point? At handgun distances, it's bullet weight, not velocity, that changes POI, with a heavier bullet hitting higher than a lighter one. You'll notice the 158s hit higher than the 110s.

Does sound like all rounds hit surprisingly low for a gun with (presumably) sights set at the factory. Did you buy it new? Does it have the original front sight on it?
 
MrBorland said:
Does sound like all rounds hit surprisingly low for a gun with (presumably) sights set at the factory.
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Some older revolvers have sights regulated for PPC shooting competitions, which involve shooting at B-27 and B-27E silhouette targets at 25-50yds. At ranges this long, many shooters prefer using a neck hold, since the neck is the narrowest and most readily visible part of the target. However, in order to hit the 9-ring or 10-ring with a neck hold, the sights must be regulated to hit ~12" low. Even with the rear sight cranked all the way up, these types of sights will still hit 4"-8" low.

The solution is a lower front or higher rear sight- possibly both.
 
MrBorland said:
What's got you perplexed? That 158gr .38spl and .357mag shoot to the same point? At handgun distances, it's bullet weight, not velocity, that changes POI, with a heavier bullet hitting higher than a lighter one. You'll notice the 158s hit higher than the 110s.
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Sorry, but I'll disagree with you there. The lighter bullets hit lower because they get out of the barrel quicker, before the gun has risen as much in recoil.

Bob Wright
 
what has me perplexed is that the 110 grain sjhp has been recorded at actual velocities of 930-980 fps in SIMILAR BAREL LENGTHS be hitting so low?


why i am perplexed is that in 22 lr the slower bullets hit lower then the faster ones of same weight.

the wierd thing is that the 110 grainers hit soft dirt and put some half inch deep gouges in the ground.
 
I don't think so, Bob. I'm too tired to re-type right now, so I'm pasting what I wrote on the topic below. Physics says the POI shift is mass-, not velocity-dependent.
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hmmmm If I am understanding this, the poster is saying that a 158 grain bullet at 700 fps will hit the same point as a 158 grain bullet at 1400 fps. That is not what I experience.
 
Hook686 said:
hmmmm If I am understanding this, the poster is saying that a 158 grain bullet at 700 fps will hit the same point as a 158 grain bullet at 1400 fps. That is not what I experience.
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That may sound good but it doesn't jive with my experiences either. For example, take my Ruger Blackhawk in 45 colt. I have benched certain loads. With the exact same 255gr LSWC one load is made with 16gr of 2400 the other is made with 20gr of 2400(both over standard load data, load at your own risk). The lighter load always has a higher POI on the target than the faster load. Same bullet weight.
 
IMHO the best way to summarize the Weight vs. Velocity argument is that the POI depends on both weight AND velocity, but it's typically MORE dependent on weight.

Case in point...
Bezoar said:
130 grain winchester fmj hit 2.5-3 inches low 25 yards
158 grain lrn federal champion hits 4 inches low at 25 yards
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The 130gr RemChester "Air Force" FMJ loads are low-pressure and notoriously slow. (They were originally designed to help the USAF's old alloy-frame Aircrewman revolvers hold together better.) The long dwell time in the barrel explains why they print higher on the target than a relatively hot 158gr load, despite the lighter weight.
 
I had this experience, using a Ruger Bisley, 7 1/2" barrel, in .45 Colt:

I had loaded a hundred rounds of .45 Colt, using a 250 grain Round Nosed Flat Point (RNFP) bullet and 38 grs. of Fffg DuPont black powder. (Obviously, this was some time ago.) I was shooting at twenty five yards, outdoor range. My gun was sighted in, using a six o'clock hold, to hit dead center of the six inch (or so) bullseye. As I shot, my groups began to climb, until after about thirty shots or so, I was nearly off the top of the target paper.

I switched ammunition, going to one with my pet load of Winchester 231 using the same bullets. I think I shot a few JHPs just to ream out the fouling. As I continued to shoot the smokeless loads, my groups began to drop back down until I was once again center in the bull.

What happened? The black powder fouling slowed the velocity of those loads so the bullet was spending more time traveling down that bore, leaving the muzzle slightly later than previous shots. Thus, the gun continued in its upward arc so that it was directed slighter higher towards the target.

My revolvers don't move directly rearward in recoil very much, restrained by my rather rigid arm. But they do scribe a considerable arc.

So, I'll cling to the theory that the faster the bullet gets out of the barrel, the lower it will impact, sights and hold remaining the same.

Bob Wright
 
So to test for what sight picture you have got, first try a 6 o clock hold, if that is off target, try a POI hold.
I shoot mainly 158gr lead bullets at about 750-775 fps.
I have to try this test and see where this HB Model 10-6 shoots. It was formerlly a gun on loan to the Brits for arming their Bobbys.
ZVP
 
ZVP said:
So to test for what sight picture you have got, first try a 6 o clock hold, if that is off target, try a POI hold.
I shoot mainly 158gr lead bullets at about 750-775 fps.
I have to try this test and see where this HB Model 10-6 shoots. It was formerlly a gun on loan to the Brits for arming their Bobbys.
ZVP
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You should never have to adjust your sight picture to correct. Make you gun shoot to your sight picture.

Bob Wright
 
I'll cling to the theory that the faster the bullet gets out of the barrel, the lower it will impact, sights and hold remaining the same.
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My experience too (bullet of the same weight of course).
 
well the thing is i dont know how the heck they have the gun set up at the factory so i just tried the traditional 6 oclock. but i still shouldnt have had such a wierd drop to the second fastest bullets i shot.
 
Bezoar said:
well the thing is i dont know how the heck they have the gun set up at the factory so i just tried the traditional 6 oclock. but i still shouldnt have had such a wierd drop to the second fastest bullets i shot.
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First of all, you are not experiencing "bullet drop" but rather a difference in points of impact.

Consider this: When your sights are lined up on the target, the line of the bore is pointed well below the aiming point. As the gun is fired, it scribes an arc in recoil, so that the bullet exits the muzzle at the exact moment to hit the aiming point. As the velocity of your load is increased, the bullet exits sooner, thus hitting lower. If the velocity is slowed, then the angle of departure is above the line of sight, so the bullet strikes higher.

Handguns have very little rearward movement in recoil. The wrist, and grip, form a pivot point so recoil is in an upward arc. To minimize this arc, the line of the bore has been made as close to the line of resistance (the shooter's arm/grip). Many years ago the Russian Olympic team fielded the "Upside down pistol", looking much like a hacksaw frame. The sights were on a frame while the barrel and slide assembly were below the heel of the hand. Visualize a hacksaw, with the slide and barrel in place of the blade, the sights on the top of the frame.

Try firing your gun upside down ~ you'll see you end up using a twelve o'clock hold to hit center. Same if you turn the gun to the three o'clock or nine o'clock holds.


Bob Wright
 
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