I'm going crazy trying to find it!

Thanks!!

http://www.americanhunter.org/...e.aspx?id=1427&cid=0

Looks like BC of 500

Barstooler

I did see that, but it looks like the BC is for a 30cal 180gr

If you do find the "listed" by manufacturer BC for that bullet it will probably be a G1 BC (marginally useful for modern bullets over 500yds.) and rather wishfull thinking on the part of the manufacturer. A good ballistics program will only give you the output equivilant to its input. Are you chronographing the ammo out of your rifle? The drop charts provided by Federal and others are 1) wishfull thinking 2) done with rifles with barrels longer than most casual shooters use, 7mag figures are sometimes given for 28 in barrels when your rifle may have a 24. Chambering differences may produce variations of "only" 100 to 200 fps with a given rifle. This will make the table invalid for that rifle at longer ranges.

quote:

Originally posted by Leopardtrack:
I did see that, but it looks like the BC is for a 30cal 180gr

It looks like a typical SPBT in mid-to-heavy caliber range. All such bullets are close to 500 BC + or - .15.

I agree with HunterMontana. BCs are calculated "averages" over several distances. Only way to know how a bullet/load performers in your particular rifle is to fire it over various yardages that you intend to hunt.

Barstooler

Thanks Fellas! The knowlege you guys have is very impressive.

I e-mailed Federal and they advised me that the BC is .520 so I will plug that into a program and see what I get.

I am NOT a reloader, so I use Federal Premium 160gr with the TB-Tipped bullets. They list 2950 fps with a 24" barrel...mine is 26" so hopefully my velocity is the same or real close.

I am also using turret knobs made by Kenton Industries..the are calibrated to my specific load all the way out to 1,000 yards, but I have not shot past 500 yaards. I shot a Baboon at 536 yards with it, but don't know what groups would look like on paper at specific yards. I live in New York City, and range is limited to indoor 100 yard range...you guys are so lucky!!

I really like the TB-Tipped bullet...I shot a Zebra straight on at 50 yards and the bullet was recovered from his hip bone in one piece after 4 feet of penetration. It also seems to work nice on deer, giving decent sized exit holes...unlike the TSX bullets.

I would love to hear your comments regarding my set-up, since I you guys have lots of experience, knowlege, and insight.

Thanks!!

Frank

Toss the Kenton BDC and gun an MOA scale.

Thank me later.

Busheler,

What are you saying??

Sorry, I don't get it.

Frank

A BDC denotes comeups ONLY with a given bullet,in a given atmosphere and at a given speed. When any of those things change,your predeterimined yardage mark goes out the window.

It is far easier/faster/more precise to deal in MOA,which is of course a universal unit of measure.equally adept with any/all bullets/atmospheres/velocities.

I'd liken the BDC cam to a 25' Stanley measuring tape,with but archaeic references scattered about it's length,as opposed to the actually encountered universal scale(inches) and fractions there of.

A BDC is no faster,though less precise and FAR lesser in flexibility to boot. Very easy to rerun comeups in a predetermined AO ala MOA graduated scales,that will reliably reflect the corrections mandated in say an elevation change.

That amongst a myriad of other Real World benefits. At least Leupie BDC's retain their MOA scale,which makes the specifics of the chambering/bullet/speed moot in the equation.

Savvy?

WOW, Got It! Thanks.

You make allot of sense, but it isn't practical for me unfortunetly.
Living in the city, I just don't have accesss to shoot at long range and am limited to indoor 100yard shooting...I know, it sucks!
The longest I can shoot is the occasional "upstate" shoot, which is still only 250 yards.

This is why I thought of the Kenton Knobs...set the 0 for 100 yards and then just dial the various ranges in.

Are you saying that the knob calibration is not true??

My rifle is a Hill Country customized M70 in 7mm Rem Mag with Hart barrel. I ONLY use the 160gr TB-Tipped ammo, factory made by Federal.

Busheler, With my situation in mind, do you think that the Kenton knobs are OK?? I wish that I could shoot all the way out to 1,000 yards and record the minutes, the way that you suggest (which I wish that I could do) but unfortunetly I cannot.

With all this in mind...what would you do??

I appreciate you advise very much, Thanks!

Frank

In your mind's eye,you are seeing something inherent the Kenton BDC,that isn't actually there.

For conversation,I just shot you a picture to clarify. Here's two Leupie M3 BDC cams,in seperate chambering/projectile configurations. One is 308/168 specific,the other 223/55 "tuned".




What you will note is how the yardage scale(which is what your Kenton denotes),is different in relationship to the erector. Yards are the upper scale,MOA the lower...so while the two BDC's offer differing yardage dumps atop,their MOA scale is universal. If you simply drive a straight up MOA scale ala M1 turret and it's .25MOA graduations,you can shoot/dope ANY bullet,at ANY speed,throughout the available elevation erector travel. That with an increase in Precision and the ability to fend differing atmospheres,less dicking around with faux yardage marks.

BDC's are akin to a Cough Silencer,in that they are an "answer" to a problem that doesn't exist.

Drive JBM to factor a drop chart,shoot comeups,tune MOA designations in the Real World,affix data to stock and simply Rule the World.

Nuttin' to it.

Made this clip for distant pards,to savvy.

LINK

An M1 erector,compared to an M3 scale...for more conversation.



Startin' to make sense...ain't it?!!?(grin)

You da man Busheler!

That'd be a fact.(grin)

Tutorial time...everyone go to JBM,so the whole class gets up to speed.

LINK

Plug in a .284",160,.520BC at 2950fps with a 250yd zero,wind 10mph full value,range increments in 50yds and to 1200yds,with a 1.5" sight height,standard atmosphere and 2500' elevation...for giggles.

While you girls do that,I'll shoot some pics to synch same on a .25MOA ele scale.

Busheler, you are definetly THE MAN.... but this is all way over my head!!

Short answer for my situation...Kenton knobs.....will they work as advertised for me?? Can I trust the calibrations??

I an hour or so, I am going to study your posts and video's...I promise...good stuff and I want to learn this!!

Frank

Forget the Kenton brainfart,pour a cup of coffee,close mouth,open eyes and do shit right the first time.

Thank me later.

Nowwwwww...back to bidness.

Given the above parameters and under the assumption that the speed is as advertised(in reality,simply quantify same ala chronograph),let's break some shit down and spill some blood.

We are shooting at the 250yd line and are zeroed wonderously dead nuts on. From there and irregardless of the erector scale,or head orientation,you simply loosen hex heads,so micrometer cap moves freely,less inducing actual movement of the erector spindle. You orient micrometer head to (0),which is of course now your actual 250yd zero/dead nuts on sight-in rage. It then looks like this.



Note the lineal scale beneath the now zeroed head,as a revolution reference,to come back to(I color 'em). Every complete revolution on a .25MOA or 1/4" "click" Leupold is 15MOA or 60 "clicks". I'll happily banty the nuances of MOA to inches later,for them that wish to and feel either lucky or brave.

Going to JBM,we see that a 500yd shot given the above particulars,drops 32.3 inches,which may seem daunting to some,but in actuality is nuttin'. Dividing drop in inches,by range in yards grants MOA comeups,though JBM will factor that for you. That dope is 6.20 MOA and because our erector travel scale is in .25 graduations,you can either round up or down. Personally,I'll take the 6.25MOA correction(no shit,that was a joke!). Which of course looks like this.

Press trigger,while holding crosshair intersection on where you'd like your bullet to arrive and then punch tag. Nuttin' to it...then simply go back to zero,to retain your initial 250yd sight in.



A 750yd poke,requires compensation for 111.2 inches of drop,or 14.2MOA. Dial 14 whole minutes(tallest lines on scale),add 1 "click" and you are there. Takes but a second.



Pull trigger,when you like where crosshair intersection is placed...then simply go back to (0) to recoup the 250yd initial sight-in. If/when swapping bullets,rifles,etc...simply run new dropchart on JBM,zero as per whim on paper,re-zero turret and Rock On.

Get a chuckle outta folks who think swatting flies at a distance is anything but easy,because those folks simply don't shoot and are talking out their ignorant asses.

Thank me later.

I would ask a question but I am afraid I'll get verbally bitched slapped...

Do not be shy Glasshoppa.

larrys been drinking again...

'shooter's Depends are leaking again and the itch is making her bitchy.

I suggest GoldBond in the usual locations,as well as some Cranberry Juice to quell the yeast.

Thank me later.

Busheler,
OK, I "get it" now!! I sat here for an hour and I finally understand what you're telling me. It was like trying to read chinese at first, but I understand now, and you're right, it is really pretty simple once you understand th concept.

Now you're costing me a new turret knob!!

I'm the origional poster here, so I just wanted to say "Thanks" for taking the time to anwer my question!!

Frank

Seen the "thanks" coming,which is why I mentioned it prior.

Always happy to help.

You put allot of effort to help me out and I appreciate it.

Take Care of yourself!

quote:

Originally posted by Leopardtrack:
You put allot of effort to help me out and I appreciate it.

Take Care of yourself!

Didn't want you beating your head against the wall,while pissing up a rope.

MOA is the moneyshot.

Everyone need to have this as a Favorite Place http://www.shootforum.com/forum/bulletdb.html