# Ballistics question on M77 MII Compact .243



## DelSnavely (Oct 17, 2007)

I have a Ruger M77 MII Compact .243 that only has a 16" barrel. All of the ballistics I can find are for 24" barrels and doesn't do me any good. I know it's dead on at 100 yards, but what happens after that and at what rate, that I don't know.

Can anyone explain to me how this is calculated, or give me some idea how to figure out my own ballistics? I would greatly appreciate it.

Thanks.
Del


----------



## southdakbearfan (Oct 11, 2004)

The difference in ballistics in barrel length is due to a decrease in velocity in shorter barrels. This decrease is dependant on the caliber and the burn rate of the powder used in the cartridge. The slower the powder, the more pronounced the decrease will be as not all the powder will burn in the barrel. I would expect about a 50 fps loss for every 2" as a rule of thumb, but like I said, there are many different variables.

Here is one article with some numbers.

http://www.loadammo.com/Topics/October05.htm


----------



## NDTerminator (Aug 20, 2003)

You need to chronograph it to learn the amount of velocity loss, but I think it's safe to say you will not be happy with the numbers. The 20" barrel of my wife's Remington Model 7 loses a good 100-150FPS depending on the load, compared to the 22" barrel of my Tikka T3, which I use for coyotes.

Frankly, really short barrels on rifles of calibers that rely on velocity (like the 243 which IMO is a marginal deer round under all but perfect conditions to start) puzzles me no end....


----------



## DelSnavely (Oct 17, 2007)

Well this .243 has to have "some" punch. I took a doe this year at about 250 yards with a perfect heart shot. I also took my first big buck with it in 2000, the year I bought it. He was a 4x6 muley and I dropped him at about 200 yards.

I bought the standard model M77 MII in .243 first. Once I got it home and started thinking about my daughter (who loved to hunt and was only 11) wanting to hunt deer, I decided on the compact and they exchanged it for me the same day.

My problem is, now I want to use it for varmints like coyotes. and I want to know how much the bullet will drop at 350 - 500 yards. I didn't know it was going to be so much work...lol

I used to take ballistics from the Shooter's Bible, write them down and tape them to the butt of my gun (on other rifles I had) and it worked great. Find your ammo and write down the ballistics. That was easy...lol Now I'm going to have to buy a chronograph and figure it all out myself. I read the page that "southdakotabearfan" posted. I'm no math whiz...lol That page confused me to no end.

I hate to sell this gun, but my daughter quit hunting and I want something that will really "reach out" and touch them at long range. Wish I had taken this into consideration at the time, but then my little girl hunting deer with dad was most important. 

I guess I'll have to sell or trade it for something else. I'm not going into physics class again. I barely passed the first time in HS...lol

Thanks guys!
Del


----------



## beartooth (Feb 18, 2007)

Your 243 with a 16" barrel will still do with a 75gr bullet over 3200fps and that means if you sight in 2 1/2" high at 100 your zero will be around 250yds and your point blank (-5" below line of sight) 325yds

Now a 22-250 pushing a 55gr bullet out of a 24" inch barrel will give you 3850fps and if you sight in 2 1/2" at 100yds your zero will be 300yds and your point blank will be around 375yds

You can still kill coyotes just fine with your compact if you practice to see just how far you are able to hit but a 22-250 would give you a good advantage in not missing the 5" kill area on a coyote.

Now that said, a few years ago me and a game warden were shooting coyotes to get rid of some and I killed in a year and a half 52 coyote with my average shot for the 52 was 290yds and my shortest was 125yds and longest 426yds.

Now I did all of this with my 30-06 and my 165gr deer load. You can kill coyote all day long if you know what your bullet is doing but ballistic charts will not tell it to you, you have to set up targets at different ranges and see what your load is doing at those distances out of your rifle.


----------



## Plainsman (Jul 30, 2003)

DelSnavely, sight in your favorite load at 100 yards, then shoot at 300 yards and measure your drop. If you put that information on here I can run a program and keep changing the velocity until it matches. Then I think I can get you within inches out to 500 yards.

If you reload you can get the most out of that short barrel. Fast powders will get the most velocity for you. Normally you use fast powders with light bullets and slow powder with heavy bullets, but in a short barrel your best combination will be fast powders with slow bullets.

If your shooting factory something in the mid-range like 80 gr may work best.

If I forget about this thread and don't get back to it PM me.


----------

