I shoot the old 4 blades Choppers.

I don't think so either. Just think about it, a field point is less likely to veer off in flight because there are obviously no blades to catch wind and steer it. A fixed broadhead has 2-4 steering "fins" on it. Then, all broadheads are different sizes and tolerances that will make them different in flight compared to eachother and especially to a field point.

The following is a link to a broadhead poi test conducted out of a shooting machine. The bow was tuned and all variables were eliminated or at least minimized. Test results were that different broadheads have different poi's, sometimes as much as 3 or more inchesofffrom a field point's poi. How do you explain this besides that broadheads do not hit exactly where field points do.

http://www.prorelease.com/xring.aspx?action=1

For me, my bow this year was not tuned that great, so I basically shot my practice broadheads all the time so I wouldnt have to readjust...I have had bows that have shot field points and broadheads almost identical without any tweaking at all on the sight...was nice.

ABSOLUTELY!
I'm no expert, but I've absorbed a lot since I started shooting back in March last year... both from experience and the gurus on here.

When I got my Drenalin in March, my shop owner set me up with GT 5575s (.400" deflection) for a 70#, 29" draw with 100 grain points. It shot great, and I got pretty decent with the fieldpoints. When I finally tried broadheads (G5 Montecs)around July, it was like a bad dream. Always low left, sometimes more than othersand sometimes missing the block target altogether at 30 yards. I bought an arrow spinner and aligned the broadheads perfectly with no significant improvement. Finally, with the help of TFOX and the Goldtip selection chart, I found out that the 5575's were underspined. I bought a dozen 7595s in(.300" deflection) and that fixed everything. FPs and Montecs fly the same PROVIDED my form is good and consistent.

Not saying that's your problem, but it sounds like it. If you're shooting vanes and you had a contact issue, I think you'd already know it, especiallyshooting broadheads.

My Jennings Buckmaster 2000 shooting 2117s/100gr wasps was underspined, and I never was able to get consistant groups with BHs and field points (I shot with this setup for a few years when I was just starting all the way up to two years ago). Thankfully I found this site, and was told about my spine issue, and was able to correct it (ordered a new set of gamegetters set to the correct spine, and voila!, my BH and field points were hitting VERY close (not perfect, but close).

Fast forward to this past winter. I ordered my CR334, knew I wanted to shoot Slicktricks (100gr), and with my DL and draw weight, I was a little in between the 3-39 and 3-49 range (I went with 3-49s), and my BH's hit very close as well. Neither bow was professionally tuned (my CR334 still isn't and I need Rob to walk me through some of that once I get new strings). So from what little experience I have with the issue, I believe it to be much more related to spine that broadheads (although I do agree different broadhead designs will exhibit various characteristics in flight).

when i shot fixed blades they shot completely different. the rages really do fly just like my field points though

BH will test the setup and tuning of both the arrow AND bow. As Paul said, if you are underspined, you don't stand a chance. If you are spined right to a touch on the stiff side, there is a good chance.

BH will change the FOC a little bit, but the thing that gets most BH off line are either the insert/bh are not alighned right, or the arrow is leaving the bow at an angle. With FP the fletching can make up for either, that's its job. With a fixed blade BH on the front, now you have the wings of the BH trying to keep the front of the arrow going in the direction its going. When its not straight you get air flow actually pushing on the blade to push the arrow further off line.

You say 4 inches or so at 20 yards? That's a lot and indicates a tuning issue of some sort, bow, arrow or both. You can "tweak" the rest SLIGHTLY towards the FP grouping, slightly as in 1/32 inch at a time. This fixes any leaving the bow straight issues.

Fletching also makes a HUGE difference with BH. Try a more offset fletch, or a different kind. I've found feathers to be alot better than vanes.

Good advice Bob, Im going to the archery shop sat. we have a lot to do and discuss.

VA, if you want to get away with shooting broadheads from an untuned bow you will need to use a low profile head like a Slick Trick or the newer Muzzy MX series. This is why mechanicals are so popular. Ifthe bow is not tuned properly the arrow comes out ofthe bow crooked and that is when the blades catch most of the air and it planes. If you tune the bow and get it shooting straight right from the beginning you will reduce the variation you are seeing between the field points and the broad head.

No difference here

Dan