FOC Field Application?

Roskoe · 06-24-2007, 10:49 AM

After talking to quite a few archers and archery shop employees, it seems like the majority of the compound shooters use arrows that weigh around 400 to 430 grains total weight - and most use 100 gr. heads. (Guess this would be a good poll question)

I'm wondering why more shooters don't use 125 gr. heads for hunting. An arrow that weighs 9.4 gpi with a 100 grain broadhead will have a total weight of about the same as an arrow that weighs 8.5 gpi with a 125 grain broadhead. If the arrow diameter is the same, the lighter arrow with the heavier head should have better broadhead flight and better penetration - based on FOC principles - right?

Only downside I could see to all this would be that the 125 grain point might require the next stiffer spine rating, and subsquently move you into an arrow shaft that is heavier and/or fatter. My 61 lb. bow, for instance,can use the3-39 series arrows with 100 grain points; but actually needs the 3-49's for 125 grain heads.

But otherwise, why don't more folks use 125 grain heads?

Arthur P · 06-24-2007, 12:11 PM

'Cuz 125 grain heads have got cooties.[8D]

Quote:

Only downside I could see to all this would be that the 125 grain point might require the next stiffer spine rating, and subsquently move you into an arrow shaft that is heavier and/or fatter. My 61 lb. bow, for instance,can use the3-39 series arrows with 100 grain points; but actually needs the 3-49's for 125 grain heads.

Being right on the top edge of a shaft's spine rating and not wanting to buy more arrows is a good reason to go with 100's over 125's. Or maybe a preferred broadhead only comes in 100 grains and not in 125's. Other than that, I doubt anyone could give you a semi-coherent reason.

Straightarrow · 06-24-2007, 12:30 PM

The 'need for speed' all but requires the use of light broadheads. Far too many people are looking for this over all else. For guys like myself, speed never enters the equation, but we are far and few between. Manufacturers cater to the masses.

Paul L Mohr · 06-24-2007, 03:47 PM

I usually don't use a 125 grn fixed blade because most of them have a larger cutting diameter. I have a fairly light set up so I try to go with a better penitrating smaller diameter head most of the time. It also makes them easier to tune and a tadd more forgiving in the wind.

If I want to add weight to my arrow I do it inside the arrow most of the time.

Paul

davepjr71 · 06-24-2007, 04:18 PM

Roskoe,

I've been wondering that since I got back into shooting and it seems to baffle me.Arrow manufacturers even offer add on 25 gr weights. Why not just get the 125 gr tip. Which it seems are harder and harder to find in the newer designs.

I like the additional weight up front to help with penetration and right now my 421 gr arrow isabout 293 fps which his fast enough for me and I have an FOC over 12%. I gain about 1 fps for every 5 gr I remove from my arrows. With the 100 gr tips I'd be at 299 with the FOC dropping by 2%.

Roskoe · 06-24-2007, 05:13 PM

I'm wondering how much 2% increase in FOC would stack up against 6 fps in terms of real world penetration? Everyone talks about FOC . . . . but if it was that big of a deal, I would think we would all be shooting very lightshafts with fairly hefty broadheads.

I was doing a little broadhead testing this afternoon - upped the pull weight 6 lbs.on my Hoyt a couple of weeks ago, and wanted to see what effect it had on the point of impact of various heads. I was somewhat surprised to find that the 125 gr. Muzzy and the 145 gr. Bear Razorheads both hit the same point of impact (20 yards) as the various 100 grain broadheads/field points - even though the spine charts show I should be going to the next stiffer shaft with heads this heavy. I could nock one of these without changing much of anything - at least out to 40 yards or so. The 75 gr. broadheads, however,all hit several inches high at 20 yards.

Elkcrazy8 · 06-24-2007, 05:27 PM

Roskoe, on the 75 grain head that hit high, if you were to move your gang adjustment to compensate, I would be willing to bet that your pin gap wouldn't change very much at normal hunting distances..

Roskoe · 06-24-2007, 05:48 PM

Probably not. Awhile back, I was playing with some lighter 3-D type carbon arrows. They had 75 gr. field tips, and weighed only 320 grains total. My regular arrows weigh almost400 grains total. There wasn't much difference in point of impact, even with this light of an arrow, until you got past 50 yards. At 60 yards, the light arrow was about 6" high.

brucelanthier · 06-24-2007, 06:38 PM

One of my arrows has a Muzzy Phantom 220 grain tip (242 w/insert). I practice with a 200 grain field tip. There is a 17% FOC on my 534 grain arrow. Now, this is totally UNscientific, but when I switched to these 534 grain, 17% FOC arrows they penetrated very differently than the lighter arrows I was using with a 125 grain tip (about 140 w/insert) with a 11.5%FOC. The 17% FOC arrows routinely come 6+inches out the back of the bag targets and also penetrate the rinehart deeper. Like I said totally unscientific but from what I have seen with the heavy arrows with a larger FOC % I am sold. The other day I was measuring the speed and the numbers went like this:
[ol][*]0 yds - 234FPS[*]20 yds - 228FPS[*]30 yds - 225FPS[*]40 yds - 222FPS[*]50 yds - 219FPS[/ol]
I like these arrows and I am sold on a heavy arrow with a high FOC.

davepjr71 · 06-24-2007, 06:55 PM

Quote:

ORIGINAL: Roskoe

I'm wondering how much 2% increase in FOC would stack up against 6 fps in terms of real world penetration? Everyone talks about FOC . . . . but if it was that big of a deal, I would think we would all be shooting very lightshafts with fairly hefty broadheads.

I was doing a little broadhead testing this afternoon - upped the pull weight 6 lbs.on my Hoyt a couple of weeks ago, and wanted to see what effect it had on the point of impact of various heads. I was somewhat surprised to find that the 125 gr. Muzzy and the 145 gr. Bear Razorheads both hit the same point of impact (20 yards) as the various 100 grain broadheads/field points - even though the spine charts show I should be going to the next stiffer shaft with heads this heavy. I could nock one of these without changing much of anything - at least out to 40 yards or so. The 75 gr. broadheads, however,all hit several inches high at 20 yards.

I'm not sure myself to be honest what the difference will make. I've just always shot 125 grains and have no problem with how they perform. Though it limits my broadhead choice unless I use the 25 gr inserts.

By going lighterthespine would be stiffer which would aid in penetration and offset the weight penetration. I'd probably have to go up 50 grains or more to see a diference. I can shoot my 3D Select 300's at 73#'s and they shoot fine even though the arrow is way underspined.

I switched to the GT 7595's though to stiffen the spine.