Penetration: weight vs. diameter

[Roskoe]

It has long been established that, all other factors being equal, a heavier arrow is going to out penetrate a lighter arrow. But it is also widely asserted that a small diameter arrow is going to out penetrate a fatter arrow - all other factors being equal.

I'm wondering how these two factors compare when considering penetration on big game animals. On one extreme, I have some carbon express Terminators that weigh 507 grains with a 100 grain Montec. But they are kinda fat. I have some ST Axis arrows that weigh about 25% less; but are also about 16% slimmer. How much weight can you give up by going slimmer withoutlosing penetration? Is the 9.0 gpi Axis slim enough to make up for its lack of weight, in comparison to the 11.0 gpi Terminators?

[bow_hunter44]

Yikes! You pose a difficult question. I don't have a pH.D in physics, but I do have some experience in the subject. That said, I have no idea what the relationship between arrow diameter and weight realtive to penetration is. Intuatively I would say that mass is a more significant contributor to penetration than arrow diameter, but even if that is true - by how much? I dunno!!!

[Arthur P]

Probably not. But you can also add weight, like a couple strands of weedeater line, to the Axis and have the smaller diameter plus weight.

[Straightarrow]

Ashby's studies on diameter was in relation to the diameter of the broadhead ferrule. It was not small diameter vs large diameter. Penetration was very high on large diameter shafts, as long as the broadhead ferrule was even larger. He hasn't compared the two to each other, but I suspect that weight is far more important. It's easy enough to pick a broadhead with a larger ferrule, no matter what the weight.

Arthur, the nice thing about the Axis shafts is that they are fairly heavy for a carbon shaft. I just built some this past weekend. I put 220 grain tips on an Axis 300 (10.7 gr/in). I ended up at almost exactly 600 grains. FOC was about 19%. They flew just wonderfully with broadheads. Just so you know, the 300s come in a 32.5" length - almost long enough for you to shoot.

[Arthur P]

I'll have to check into that then, SA... I've got my rest set back far enough into short overdraw position so I can shoot 32" arrows.

[Kanga]

I put 220 grain tips on an Axis 300

SA

What heads are you using?

I have been testing the Muzzy Phantoms without the bleeder blades sothey come in at 200gr.

The only problem is I cant find 200gr field points[:@]

[BobCo19-65]

Try 3-rivers archery for 200 grain screw in field points. You could also get brass or steel inserts.

[Kanga]

Thanks Bob

[Straightarrow]

ORIGINAL: Ausie-guy

SA

What heads are you using?

I have been testing the Muzzy Phantoms without the bleeder blades sothey come in at 200gr.

The only problem is I cant find 200gr field points[:@]

I've managed to get quite a few quys at my local shop to use the heavy tips, so the owner stocks the 200 grain tips. Like Bob says, 3-Rivers has them.

I'm also using the Muzzy Phantoms and got them flying great with the bleeders. I'm not bothering to try matching the field tips exactly, since they fly very well at 200 grains, causing a slightly stiff arrow. With field tips, this makes no difference.

[Kanga]

I done a test yesterday at 40 yards with mine.
I have them on Beman 400's 28" with 4x2"Predator vanes, The other arrow I used as a comparison was a Easton AC Super Slim 27.5", 3x4" Dura vanes with the Muzzy 100 3 blade.

It was a brand new broad head target the Phantoms penetrated a good 8" more and to my surprise 2" higher than the lighter AC Super Slim.

The 2 arrow weights are the Beman 494gr while the AC is 410gr, both broad heads where brand new out of the packet.

The arrow flight I got the the Phantom was perfect and it did hit the target with a THUMP

The difference in FOC is Beman 24.8 and the AC 12.6