SmallCaliberCentral

In case you guys haven't been the the JBM ballistics calculators site lately. They've been making improvements.

Remember that batch of 1000 rounds I loaded up? That's a 34gr Dogtown bullet with a 3900fps muzzle velocity (chrono at 10ft). I hadn't shot it at more than 200 yards with no wind. I'm actually going out today to set up and zero at 200 with that bullet, and verify this drop data anyway. I'm guessing my clicks chart is going to change after verifying the load at longer range, but I wanted to see if I'm converting the data from the ballistics chart to my scope cap chart.

Does this look about right to you?


If I want a scope cap chart according to the data in the chart above, is this correct? (My scope is 8 clicks per MOA)

I hope it's not too windy. The scope doesn't give me 142 clicks for windage. That's a lot of clicking!

It looked like this bullet is pretty much dead past 400 yards with only 200ft-lbs energy left. Will that even penetrate a prairie dog's skin? What range can I expect explosive acrobatics out to?

Baba, you'd be better off making your chart in MOA "come-up's" from my experience. Trying to count clicks, remember how many clicks are already in the turret, subtracting clicks, .......it gets pretty frustrating in the field. If you make the chart in MOA, all you have to do is look at your turret, and it'll tell you exactly where you are in regard to elevation or windage or where you need to be according to your chart. It's worked that way for me very well for quite a long time. Just a suggestion.

I noticed I read from the wrong column in that first scope chart too.

So just take the numbers straight from the JBM chart eh? Like this?


That should be much quicker than counting so many clicks. Thanks

BabaOriley wrote:
It looked like this bullet is pretty much dead past 400 yards with only 200ft-lbs energy left. Will that even penetrate a prairie dog's skin? What range can I expect explosive acrobatics out to?

I would say out 700 and maybe a bit beyond.

Not sure about your program though. Even Hornady 32 gr factory ammo has 256 ft/lbs at 500 yds.

Here's a reference to possibly compare ME to something we are all familiar with... .22 LR. Offered as input to the ME question posed. Interesting also that the BC for one of the rounds shown is the same as the advertised BC for the Dogtown bullet.

http://www.gunsmoke.com/guns/1022/22ballistics.html

I read a great article in The Varmint Hunter a few years ago, if I can find the article, I will get it to you. I normally just "held over", I am now going to dial my elevation in on my targets this year. If I remember correctly the easiest way was to zero at 100 and then if the drop at 550 yards was 24 inches....divide the drop by the yardage (5.50) equals 4.3636" inches. If your scope has resetable turrets and you set at zero at 100 yards, just turn it to 4.25 or 4.5 or 4.375 with 8th" adjustments. Write the yardages and the number you need to turn your elevation to on the cap sticker. Is this done correctly guys??? If you don't have resettable turrets, get a scope that does, if you have a Leupold w/0 resettables, the Stoney Creek knob will work...or just hold over the amount of drop.

remy: Try this instead: If you're using a Leupold or similar scope with turret values in .25 MOA, make up your chart in MOA instead of inches, then no math required at all (all ballistic programs will read out in MOA or inches). Range to the target, read the range 'come-up' on your chart, dial exact number, hold dead-on for elevation, hold off for wind if needed and shoot.

This is what mine looks like on one of my 204's:



Either way will work, but this way eliminates all the math and greatly increases your first shot hit probability at any range the caliber is good for. HTH

Do you guys notice anything weird about that chart from the JBM page I posted?

I expected the 34gr dogtown, with a BC of .149, to run out of gas out past about 400, but something on that chart I posted above doesn't make sense. At 600, it says the 34gr bullet will still be going 1066fps. That's the velocity of many 22LR cartridges at the muzzle, and with a 40gr bullet, they carry 300ft-lbs + of plenty deadly energy. I don't care whether it's at the muzzle, or out at 600 yards, 34gr's of lead going 1066fps should carry more than 86ft-lbs, right? The JBM page says to contact them if anyone sees an error, so what do you think?

Here's the formula to calculate muzzle energy.... E=MV2/450400 or E=bullet mass(in grains) times muzzle velocity squared divided by 450400. For a 40 gr bullet at 1066 that equals 101 ft. lbs rounded to nearest whole number. With that in mind the 86 ft. lbs for the 34 gr is right on.

Off Topic:
Larry! Great avatar photos, buddy! I'm still chuckling.

6.5swede wrote:Here's the formula to calculate muzzle energy.... E=MV2/450400 or E=bullet mass(in grains) times muzzle velocity squared divided by 450400. For a 40 gr bullet at 1066 that equals 101 ft. lbs rounded to nearest whole number. With that in mind the 86 ft. lbs for the 34 gr is right on.

Thanks for the verification Larry.

I got out to do some shooting with this load tonight, and it was very enlightening. My main goal was to zero at 200 yards. There was a 5-7 intermittent breeze from my 3:00 when I started. It was moving my bullet 3-5 inches left of my previous zero. At 200, I think it was 3 or 4 clicks took care of that.

After resetting my turrets to my new 200 yard zero, I meant to move my plywood target to 400 yards, as the sun was getting low. I figured I had maybe a half hour of good light left. Somehow I got the target set up and got back to my shooting position and found it actually lasered 502 yards. I figured "oh well" and checked the chart for 500 yards. 8.8 MOA. Cool. So I turn my elevation turret and it tops out at 5 MOA. Great. I go back out and move the target to 400 yards, then proceeded to turn up 4.6 MOA on my scope. My shots registered 3+ feet low. About 6" from the dirt. ??? Didn't figure I'd need a 20 MOA base for 400 yards, let alone 500. I'm using an Armalite 1pc scope mount. I knew my scope was kind of a POS, but only 40 clicks? (5x8)

Always feel like I'm missing something. Nothing ever just works the first time.

Going to have to check my scope out. It stopped at 40 clicks, but I wonder if anything is really moving when I adjust the turret.

Best laid plans and all that.... Hope you get it figured out without having to jump thru too many hoops!!

I was TRYING to do what Rick just showed.....There's a great reason to purchase flip-up scope caps!!! Nice!!!! Now if I can just get this figured out....RIO, you might be getting a PM if I can't get this worked out this weekend!!! I might be a special ed student dealing with this stuff. I hope Baba is taking notes, this is good stuff.

While cleaning last night, I found that I did have more than 40 clicks adjustment on the elevation turret. It was just sticky, and you're not supposed to force it at the extreme ends of adjustment. I took it apart last night and put some CLP on it. Can get +23 MOA now. This still doesn't explain setting 4.6 MOA and being 3 feet low at 400 yards. I'll have to get out and shoot it again tonight to see if it's actually adjusting anything or not. Scope might be broke. Or, it just needed some time to let the CLP soak in. We'll see. I AM taking notes.

The dogtown bullets have a pretty large HP on them. They simply cannot be as effecient as those sharply pointed bullets with tiny HP's. In my opinion, they will lose more velocity that better shaped bullets. On 6MM benchrest site, there was an article of using a die to point up those bullets with a large HP, thus making them more efficient.

Was out sunday with a friend and a 257 weatherby. He added two inches to the ballistic table recommendations and was right on with elevation at 400-500 yards. He is shooting a swaroski(SP) scope with the dials that can be set for a given distance.