Marlin Firearms Forum banner

1 - 10 of 10 Posts

·
Super Moderator
Joined
·
10,910 Posts
Discussion Starter #1
Been doing my homework ad came across the term Sectional Density. http://www.chuckhawks.com/sd_beginners.htm]Found an article by Chuck Hawks.[/url]
I am not sold on his conclusions - he's said:
A SD of .180 would be acceptable for hunting varmints (Table 1). A SD of .230 would be good for hunting CXP2 game such as deer (Table 2).

Now I did the math and a 240 gr bullet in a 44 magnum sized to .432
has a SD of .183. This is at best a *varmint* round??
A 265 gr 44 magnum sized to .432 has a SD of .202 = *barely* capable of deer sized game??
Needless to say I'm not a believer unless somebody can shed some light...
 

·
Registered
Joined
·
3,466 Posts
There are a lot of these formulas floating around that don't really "model" reality or personal experience.
I think a 55 grain 223 round is plenty for white tail deer. TKO or SD be damned. My experience literaly "proves" it (to me).
They are a guide for the inexperienced and IMHO they sell gun mags but no substitute for experience.
 

·
Banned
Joined
·
16,492 Posts
There are too many other variables - monometal bullets, bullet core construction, bullet speed at impact, rotational speed, etc. I generally favor heavy-for-caliber bullets at the slightly lower velocities you get with them, but who am I to say?

I've never recovered a 250 grain 35 caliber bullet driven at 2400 fps from any elk or bear I've ever shot (SD is .279).
 

·
Super Moderator
Joined
·
10,910 Posts
Discussion Starter #4
Obviously with people taking hogs with a 240 gr 44 mag his ranges are a little skewed.
I actually got on the subject because my buddy is going to model the bullets I have in QuickLoad and I was getting the specs together. He informed me that it has a function where you specify somethign like muzzle velocity and it will give you a table of loads for a particular boolit. Nifty! I might just have to buy that stuff - I had no idea it would do that.
 

·
Premium Member
Joined
·
5,268 Posts
Like someone said on another one of these threads somewhere, "The .30-06 stomps all over the .45-70 on paper. In the field we know that isn't true."

Shot placement, shot placement, shot placement!

Jon
 
  • Like
Reactions: galaxieman

·
Registered
Joined
·
1,128 Posts
Sectional Density is the ration of bullet weight to diameter, therefore weight to frontal area: the greater the sectional density theoretically the better the penetration. Two bullets of the same weight, construction and muzzle velocity the smaller S.D. will loose velocity slower and penetrate deeper into the target. But when the bullet hits the flesh there are a lot of other factors, such as energy, mass ,the fact that a .45 bullet can't have the same construction as a .30 bullet, etc. that interfere with theory, so Sectional Density means something, as does Ballistic Coefficient, but it doesn't always mean what you think it does.
 

·
Registered
Joined
·
6,889 Posts
All of these ballistic formulas, theories, calculations, etc, taken on their merits, or at face value, do not in many cases prove "capability".....but, they are good for "comparison" value. If you compare what the 44 mag bullet at a same velocity, with a SD of .183 has done historically, then that would give you a general idea of what that bullet at that velocity is capable of. Example: We all know that the Keith 240 SWC (SD around .165 or so) at 1250 fps has "historically" taken everything in North America (and probably most everything world wide), and therefor would do the same for us. Comparing the data you have for what you shoot, against cartridges that have a proven track record (documented historical data) will put you in the ball park as to the capability of your cartridge, bullet, load, (providing all other factors are the same) so, the forumlas, etc, do have some merit in that respect, but, otherwise many are proven irrelevant if they are put into concrete categories, and in many cases do not reflect reality.

You will see in some of my postings on these forums, that when I am talking of the capabilities of my SG modifications that I am always comparing them to historically proven cartridges that have produced the approximate ballistic "numbers" of my modifications. This allows the reader to envision the power that my modifications produce. With other factors involved (such as bullet weight, shape, construction, etc), I would not say that the terminal impact results would be identical, but the formulas combined with historically documented performance of the cartridges I am "comparing" my modifications to (by using ballistic formulas) can put the ballistic scenario in the performance ball park of "proven" cartridges of like power.
 
1 - 10 of 10 Posts
Top