help gettin' crossbow sighted in
 

i'm shooting a 20" bolt with 125 grain 3 blade broadhead . when i shoot with a 125 grain field point it's dead on everytime... with a broadhead it's shootin' to the left about 10-12". i really don't want to spend $40 on expandables any ideas?

RE: help gettin' crossbow sighted in
 

Just make some adjustments when shooting your broadheads. Then again they should not be off that far .. are you sure the blades are straight?

RE: help gettin' crossbow sighted in
 

Shoot each arrow 3 times with a different vane down each time, mark the vane that shoots best. Worked for my cb. Also spin test them first.

Good luck, Stan

RE: help gettin' crossbow sighted in
 

Imho, you got real problems. I set up a Horton RT HD 175 for a friend last fall, had great groups w/ field tips at 20 and 30, but my beloved Slicks were 10" low right at 30. Obviously, something wrong w/ bow, but Horton told me to "just go w/ mechanicals" even though this was a package bow w/ Horton low profile bheads included. We didn't try them, as the friend had already decided to off the Horton for a different name bow. It's still a puzzle to me, if you figure yours out, please post the answer.......

RE: help gettin' crossbow sighted in
 

I'm having a similar problem. Dead on with 125gr field points out to 40 yards. Decided to go with G5 Montec 125gr 3 blade BH's so I bought the practice BH's made by Montec for that BH. Well, now my grouping seems eratic (not usually a problem for me). How important is it that the blades of the BH align with the bolt's vanes? Could this be my problem?

RE: help gettin' crossbow sighted in
 

2 things to consider. What is the diameter of the broadhead? What is your FOC? IMO, both will help you get the stability you are looking for. Too large a diameter seems to make a broadhead spin drift, IME. Also, more FOC helps your vanes point the arrow better. Moving the balance point forward gives them a longer axis to work with. In the end, I don't really know exactly what helped, but switching to ABC Bolt Sonics and Blazer 2" Vanes has me running in top form at 467 gr.

RE: help gettin' crossbow sighted in
 

Good advice, added FOC has cured alot of bhead ailments. I wished I'd of been able to try that w/ the Horton I mentioned in previous post on this thread.

Trying to align 3 blade bheads w/ vanes on carbons is a good way to get in trouble, imho. I'm a bigger believer in added FOC and spin testing than I am that method.

RE: help gettin' crossbow sighted in
 

My cutting diameter is 1 1/8" Please pardon my ignorance but I don't know what FOC is. Please let me know because it sounds like a solution!!

RE: help gettin' crossbow sighted in
 

i had the exact same problem u are having a couple years ago.....iswitched tomechanical broadheads and that fixed it......again this year a cousin of mine bought hell razors for his xbow and called and said his field tips were dead on but when he put a hellrazor on that it shot to the left about a foote...i suggested mechanicals so the next day he tried mechanicals and it fixed his problem also............hope this helped

RE: help gettin' crossbow sighted in
 

Well, I'm not thrilled about buying a new set of BH's but it's looking like that is the easiest solution. Thanks!

RE: help gettin' crossbow sighted in
 

chesty: check pm's

RE: help gettin' crossbow sighted in
 

FOC is Front of Center. Like a dart, crossbow arrows fly best if their balance point is in front of the center point. Usually this is measured in % FOC. For example, if an arrow is 21" tip to tail, the center point is 10.5". If the arrow's balance point with broadhead is 3" in front of that, it is said to be 3/10.5 or 29% FOC. This is the point the centering force from the vanes is working against. The shorter the vane and the longer the distance from the vane, the more this force centers the arrow for stable flight.

There is also an effect caused by arrow spin. It is said, but I have no test data to prove it, that the faster an arrow spins, the less likely out of eccentric forces are to pull it off line. I think this is basically the principal which which a childs top works with. When you spin them fast enough, they spin in place. As they slow down, they move around. I use a Blazer vane with right helical. I'm not sure if left or right helical is the trick, but I do see helical deflects more air and thus should give more spin. Does it work better than offset or straight, I don't know. Offset or straight might be mandated if the barrel is narrow on your crossbow and your vanes are long. That might cause a touch condition which surely would be bad.

So first, I spin test arrows to get the best spin balance and also to check straightness. I make them straight by putting inserts in the shafts and then puttingpractice points and checking straightness If not straight, I turn it 1/8th of a turn and recheck. I can always find a straight point. This makes the broadhead straight.

Last, I use one different colored nock so I know which one to put in the barrel for consistency. It may not matter, but with flat nocks, this may help a shooter consistently load arrows. If one is bad, it would be culled, checked for straightness,checked for spin balanceand rebuilt.

Right now, I don't balance inserts/shafts/broadheads to a single weight, but I could see the value in it if I wanted to shoot over 50 yards. Out to 50, these tricks get me ondeer. Now, how far would I shoot a deer, well. . .I need to prove this all works at 20, 30 and finally 40, before I consider going farther.

I can tell you that at 467 grains and 300 fps, I can shoot through a layered foam broadhead target. That's some penetration! A couple of grains heavier and I will need a second for back up!

RE: help gettin' crossbow sighted in
 

FOC is Foreard of center or Front of center and it is very important to good arrow flight.
The FOC % of your arrow indicates how much weight you have forward of center,opinions differ on the proper amount.
If your arrow balances in the center,you dont have enough weight FOC.
If you add a lighted nock to your arrow,the weight at the back will change your FOC and you may need a heavier BH or a brass insert with you regular head.
There are so many variables.

The original poster
Lucky Shot
That is very different POI (point of impact) between BH's and FP's There is most likely some other problem.
I use G5 Montec's while the POI is different from FP's it's not that much.
I rarely shoot FP's anyway,the Montec's are resharpenable so I shoot with them most of the time.
You could just sight in with you broadhead of choice,make sure it is shooting good at all ranges and go with it and not worry about the FP's for now.

Good luck and let me know how it turns out for you

RE: help gettin' crossbow sighted in
 

With all due respect, I believe you are mistaken. 3" diff = 15% FOC.

RE: help gettin' crossbow sighted in
 

First off, try a short 4 bladed broadhead like Slick Ticks. I found that out the hard way after missing 2 bucks with Thunderheads. Large heads make short crossbow arrows plane. FOC is very important in crossbow arrows. The extra weight up front, coupled with less weight in back, (I use 2" Blazers) actually 'pulls' the arrow to the same point more consistently:a.k.a accuracy. I use Gold Tip Lazer II's with 110 gr brass inserts and 2" Blazers. When coupled with 126 grn slicks it gives me nearlt 25% FOC and a very accurate arrow. They shoot essentially the same as my field point, I don't even bother to practivce with broadheads.
Mecahnicals are ok if they don't open in flight, which the sudden surge of 175 lb draw an easiely do. I've tried NAP Spitfires, they fly OK but not as close to same PIO as my slicks.

RE: help gettin' crossbow sighted in
 

Awshucks, can you please tell me how to calculate FOC. I seem to be having a brainfart.