SwampCollie

So whats the deal with this: I've been shooting Easton FMJ 400s, cut at 29 3/4" with 100 gr heads off my HCA Iron Mace for the better part of the year. No issues with flight or anything. I shot a bear shaft last week and noticed I was getting a bad wobble with the arrow sticking in the target with the nock to the left of the point of impact. This would indicate a weak spine. Correct? I tried both 85 and 75gr points. I was shooting 64#s, but have backed it off to 60#s. I am also trying some ACC 3-49s, same length. I am noticing some odd if not erradic flight. I am assuming that the spine is just too weak. The bow is tuned, and though I'm not perfect, my shooting is solid enough to rule it out, and I have a few other semi-professional opinions on that. Is my problem my arrow spine? The charts say I should be right on or even a little bit too stiff... I don't really want to throw out $300 worth of FMJs and ACCs. What can I do?

davepjr71

Swamp,

Did you run your set-up through OT2 or another program? If you'd like post or send me your set-up specs and I'll run it. The Iron Mace is a very fast bow and I'd bet that due to the speed and energy produced by it the arrows are underspined. You need to add weight to the rear to increase spine or shorten the arrows or do both. I had to do that with the GT 7595's fpr my Allegiance.

MeanV2

Go to a stiffer arrow and keep your FOC up to at least 12% you will get noticeably better arrow flight and groups. I shoot 400's at 60# cut to 27" with great results out of my Allegiance

Dan

SwampCollie

I cannot cut the arrows any shorter than they are already. 29 3/4" is just enough for the broadheads to clear the shelf before the shaffer lifts the arrow up at full draw. My draw length is 29.5".

I have dipped and crested my FMJs, and fletched them with blazers. What I don't get is why they "seemed" to be flying great before, but now are noticably jacked up. Everything is tight, and everything is the same except I've turned the # down, which should have helped if anything.

How can I add more weight to the back of my arrows. I don't exactly have $300 sitting around to buy two dozen new arrows this time of year. Lumenocks are non-compatable with ACCs, as they don't make a G nock. Might work in the FMJs.



Dave; I don't have any sort of program like that. What exact number do you need? I'll throw a few at you and hopefully it will help. My bow is set now at 60#, 29.5"... has a 7 3/8" brace (which is spec), my arrows are Easton ACCs 3-49 cut at 29.75" with a 100gr tip. Blazer vanes, no crests or wraps. The Mace has Trinary cams, which are the same deal as the Bowtech's Binary's. I'd say its a bit more aggressive though perhaps, as the BTs, even with speed mods don't seem to load up quite as much. Shooting it on 60#s is kind of nice though. Those ACCs are weighin in at 404gr, and speed with the radar chrono is right at 278fps. Plenty fast enough for me. Thats the arrow that shot the best last night of the two I have... so I'm going to run with it. Let me know what the computer spits out at you. Thanks in advance.

davepjr71

That should be enough info. Thank you. I'll run it tonight. Longer draw lengths have problems with being underspined with a high performance bow.

Have you checked out your rest at all? My arrows started doing a little tail wobble and it turned out that my rest had moved a very, very small amount. Less than 1/32"

MeanV2

On another note I did shoot 400's out of my 70# Allegiance with good results, but they were cut off to 27" and that's a lot of different than 29.5"

Dan

Kanga

The draw force curve of the Iron Mace is close to the BT Pro 40 Dually draw force curve.

That with your 29" draw and 29.75" arrow your current arrows are under spined you really should be shooting the 340's or ACC 3-60's with a 100gr head.

Adding a wrap to the back of the arrow is not going to do a thing for your current arrows.

Roskoe

Although the Iron Mace has a pretty radical draw curve, I'm shooting 29" Easton Axis 400 arrows out of two different 61 lb. bows and the spine is perfect with 100 grain heads. The fact that you said things were good at first, and now have gone down hill, makes me wonder if you suddenly don't have some sort of clearance issue. What sort of rest are you using?

bigcountry

On my Ontarget using aussie's suggestion about the bowtech Dually 40, I show you are weak, even at 60lbs. I agree with ausie, that a 340 might be in order. A 340 shows a tad stiff at 60lbs, but you can always raise it to 65#.

davepjr71

For the OT2 guys. The Iron Mace is listed in the selection guide under "Newburry Iron Mace", not under HCA. You don't have to use the BT Pro 40 Dually. Not sure why they do not have it under HCA. I didn't find this out until this morning so my output was based on the Dually.

Also, if you haven't done so make sure to derate the IBO to match the speed for the arrow and DW that Swamp listed. WhenI ran the derated set-upthe arrowwas spined propery for 'Target' and 'Both' catagories and low for 'Hunting'.If that is the case I would think that for tuning purposes the arrow should fly properly? I'm going to run using the Newburry model tonight and see if there is any difference.