Ballistics Info on boxes of .22's?


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zero_chances
December 24, 2006, 02:09 PM
I just picked up a box of Federal 22LRs and a box of Remington Subsonics to see what they are like. I was bored and read the ballistic info on the back of the boxes and became confused. The Federals shoot a lighter bullet(36 gr vs. 38) at a higher velocity (1280 vs 1050) and they still have more drop at 100 yards than the subsonics. The Subs drop 2.6" at 100 yards and the federals drop 3.4" at 100.

This makes no sense to me at all. I am thinking one of the boxes info is wrong. Anyone have any input on this?

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History Nut
December 24, 2006, 02:35 PM
My 'guess' is that the lighter bullet doesn't retain the velocity compared to the heavier bullet. Heavier bullets are preferred for match shooting as they retain velocity better among other reasons. Reaching WAY back into my high school Physics class, it is a matter of inertia. The greater mass retains inertia better than the lesser mass. OW! Now my brain hurts!:evil:

I am sure someone with real knowledge will chime in soon.

CypherNinja
December 24, 2006, 04:29 PM
Yeah, its because the lighter bullets will lose velocity quicker.

RecoilRob
December 24, 2006, 06:33 PM
I agree, that doesn't make any sense. Maybe they used different sighting in distances? The higher velocity round should drop less....all other factors being equal.

History Nut
December 24, 2006, 07:50 PM
Gravity is a constant. Everything drops at the same rate. Given the same barrel angle and target distance, a "faster" projectile will hit 'higher' on the target. What happens in the real world is air friction slowing the projectile. The lighter projectile has less 'mass' so retains velocity less well than a heavier bullet. Over a given distance it will slow down to average a lesser speed. The heavier bullet will lose less speed so its average velocity will be closer to its muzzle velocity. If the distance was halved, the lighter bullet would impact higher than the heaver one. Once you go past a certain point though, the heavier bullet will impact 'higher'. Actually because its average speed over the distance is greater than the lighter one, it doesn't have time to drop as far as the lighter bullet.

Now, if your brain is aching like mine right now, take a break. Later read up on bullet drop and trajectory and it should make sense. It is just Physics.
:evil:

redbone
December 24, 2006, 07:51 PM
ballistic coefficient?

griz
December 24, 2006, 08:08 PM
I'm not going to bet any money on this because I still can't grasp the physics, but I have been told that the amount of time a bullet spends very near the Speed of Sound has a greater effect on it's drag than time spent below the SoS. So a high velocity 22, which starts out just supersonic, spends most of it's first 100 yards fighting that handicap. Hopefully someone who understands it better will come along and explain it more fully.

Twycross
December 24, 2006, 09:40 PM
I realize that heavier bullets retain velocity better than light bullets, but in the given example, would 2 grains really make that much of a difference?

Fly320s
December 24, 2006, 10:09 PM
What about bullet shape? One is probably higher drag than the other.

rangerruck
December 24, 2006, 10:26 PM
yes, I will say it is a mistake. just go out and shoot em'; that'll tell you. A lot of rimfire info is wrong, especially in the guns and ammo and peterson's annual. you have to check them closely, but the mistakes will pop out at you.

zero_chances
December 25, 2006, 10:28 AM
The bullets look about the same shape, but it just confused me when i saw that the cartridge with no powder had a flatter trajectory than one with powder. Oh well.

bhk
December 25, 2006, 10:58 AM
No Powder!!?? Where did you get that idea?

Anyway, if we use Remington ballistics published iin their catalogue, we know we are comparing cartidge types using the same techniques. They have the subsonics dropping 2.6 inches at 100 yards using a 50 yard zero. With their regular high velocity 36 grain hollow point (same published velocity and bullet weight at the Federals), they show a 1.8 inch drop at 100 yards with a 50 yard zero. This makes more sense. My guess is that one company or the other goofed on the box data, or that they were using different zeros to calculate the 100 yard drop.

zero_chances
December 25, 2006, 02:07 PM
I thought thats how the subsonics worked, with no/ very little powder. I cant hear any when i shake them. I can hear powder when i shake the federals. Anyway, your info makes more sense.

VARifleman
December 25, 2006, 02:52 PM
No that's Colibri by Aguila that has no powder, and it uses a 20 gr bullet. It will drop a lot before it reaches 100 yds.

Couple things...

for a given profile, a projectile with more mass will retain it's velocity better than one that is less massive because with the same profile you get the same air resistance, which is force, and since F=ma, as mass goes up for a given force acceleration lessens.

Someone mentioned the how supersonic speeds effect drag. They do, but it's trans and supersonic. Transonic effects start at around .8 Mach which is around 900 ft/sec. Both of them are affected by this.

rangerruck
December 25, 2006, 03:45 PM
also bullets typed as 'cb''s , have little or no powder, with usually a 20 or 29 grain bullet. subsonics have powder. the biggest subsonic, with the smallest amount of powder, is the monster 60 grainer, in a short case, called the sniper sss subsonic, by Aguila.

230RN
December 26, 2006, 04:42 AM
BHK says,

My guess is that one company or the other goofed on the box data, or that they were using different zeros to calculate the 100 yard drop.

Possibly true.

But there are a lot of unstated variables in these ballistic tables. One of the more important ones is line-of-sight to axis-of-bore distance.

In general, a higher line of sight will give the impression of a flatter trajectory if two rifles are sighted in for the same intermediate range. This is because the angle of departure is greater with the higher line of sight. *

This line-of-sight to axis-of-bore distance is rarely stated, but can be quite different for an iron sighted .22 versus a scope sighted one.

I don't know offhand if SAAMI has any standards for this.

In any case, all you can do is take the ballistics quoted by the manufacturer as a guideline to get you on the paper, and then determine the trajectory for your firearm empirically.

I once taped a range table for Remington .22LR High Velocity HPs to the side of my favorite scoped bolt .22 rifle. I took the numbers right off the manufacturer's data sheet and zeroed the rifle at 25 yards, which was what the table said.

I soon found that at 100 yards my shots were about an inch higher than the table would have me believe. Now with a .22, with an effective humane hunting range of (at the most) 75 yards, it wasn't all that critical, so I just remembered that the table was off and compensated with "Kentucky Elevation." This method was used for hunting dangerous game like pop bottle caps at random ranges.

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* To visualize this, imagine some extreme cases: two rifles zeroed at, let's say 50 yards, but one with close-to-the-bore-axis iron sights, the other with a telescopic sight mounted 1.5 inches, then 5 inches, and then 10 inches above the bore line.

You'll notice that with the scope mounted at the (ridiculous) height of 10 inches above the bore, the angle of departure must be greater for the bullet to strike the zero point at the stated fifty yards.

dfaugh
December 26, 2006, 09:28 AM
but in the given example, would 2 grains really make that much of a difference?

Well, it's more than a 5% difference which I would say is significant.

Also, the hi-velocity rounds PROBABLY are dropping to sub-sonic speed by the time they reach 100 yards, which may mean they are not losing velocity linearly.

Tested alot of .22 ammo in several different guns, and they were all most accurate with 40 grn (and almost as good w/ some 38 grn.) loads. WHile I have no way of testing it, I attribute that to the fact that they retain velocity better, and aren't transonic.

kb2iaw
December 26, 2006, 09:28 AM
you can leaern an awful lot reading these threads .................:)

zero_chances
December 26, 2006, 05:51 PM
dfaugh-Are there any factory loads that come with the 40 grain bullet?

Although it will be a while before im buying more 22 ammo. 1100 of the Federals may take a while to use up. Hopefully not too long though:evil:

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