Grouping issue

[Downunder]

Hi guys, well I eventually received the 380 after a Paper War with NZ customs, have it now set up with a single stage Trigger Tech and Hawke XB1 scope.... one very sweet bow ... awesome to shoot
I sighted in at 20 yards as instructions stated with Diablo bolts and 150gr field points, moved out through the various distances to 60 and 70 yards. At 60 yards I noticed the group opening up to 3" and at 70 yards a much larger group.. 6 to 7" approx.
At 50 yards and below, 1 to 2 inch groups easily obtainable.
My question is, what is the reason for the sudden opening up of groups ?
I dont think there is any issue with bow or scope or mounts, all is tight.
Is it at greater distances, a greater FOC is required to stabilize the bolts ?
I have tried some dear I say it.. Horton Carbon Strike MX 20" with 120mm long vanes and these are worse, even at short distances.
I'm after a bolt and broadhead combo for use on small game at the longer distances. The Black Eagle Executioners seem to have a good following.... looks like PayPal might get another hiding
Thanks all for any input !

[Cossack]

First make sure your bow is rock solid (as are you) and bow isn't resting on something hard that would cause deflection from recoil...which becomes more apparent at increased distances.

[Downunder]

First make sure your bow is rock solid (as are you) and bow isn't resting on something hard that would cause deflection from recoil...which becomes more apparent at increased distances.

Thanks for that, I'm laying in prone position using a Harris series S, Model L bipod for sighting in, holding as level as possible but without a "level". The spread in grouping is more of a straight drop but a little sideways.
To be honest I'm not sure what to expect in grouping at the longer distances !!

[vixenmaster]

Is yer scope vertically plumbed ? Next is usin one arrow & mark each vane as you shoot to see if'en it hits the same. Put a dot on one vane stick it down as cock vane shoot it 3 times to see if'en it hits the same hole area at 20yds. If'en it don't mark next vane wid 2 dots shoot it 3 times to see if'en it hits same spot. If'en it don't go mark last vane wid 3 dots n shoot it 3 times. It can very well be ye arrows don't hit the same area at 20 yds let alone 70yds. Make sure you don't cant yer Excal when shootin

[Michiganhunter]

Well just my opinion here. First off give yourself a little time getting used to the bow. Technique is more important at longer distances. Just picking up the bow and expecting one inch groups out to 60-70 yds isn't going to happen not by any of us, well at least by me...lol You checked everything for tightness already so thats a good start. Arrow and broadhead combinations are also important so you may have to experiment, but thats all part of the fun. Wind can change a group from one day to the next. Brace height etc. At 50 yds I was getting 1 inch groups off a rest with my Exomax. at 60-70 yds the groups opened up and that is normal as very small movement during the shot will not make a huge difference in a group at 20 -30yds but will multiply the error the farther from the bow the arrow has to travel. In other words a 1/32 (example)of an inch movement at the shot and you will still get 1 inch groups at 20 yds The same movement at 60 yds will be much more exaggerated giving you a 3 inch group. This is just a guess in terms of actual measurement but you get the idea. I believe these Excal bows are capable of 1 inch groups at 60-70 yds but it takes time and a lot of practice to achieve that level of proficiency.
Another note is that the arrow is slowing down much quicker at longer distances so that 150 gr field point is starting to have more negative effect on the trajectory as gravity takes its toll on the arrow. Do you have a helical on your vanes or are they straight or straight offset?

[Tom]

First of all I think I am leaning to agree with Mike and for you to check that the scope is plumb. The results you are getting is similar to what would happen if the vertical crosshair in the scope is not straight up and down when the deck of the crossbow is horizontal.

A crosswind will also put a wrench into your grouping at distances. When you said that the larger fletched arrow was worse, this might be from a cross wind. A cross wind would push arrow to the side and also take away speed from the arrow, all depending on the speed of the wind at a time. Also remember that the wind at where your sitting might not be the same as 60 yards down range.

Check your scope for being plumb and then check wind the next time you shoot.

Good luck Tom

[paulaboutform]

Hi Down under, congratulations on your new bow. I have the same bow and you're going to love it. They are scary accurate when set up and equipped properly. If you're interested in long distance shooting I can tell you that off the bench I'm getting 2" - 3 1/2" groups from 80 yards to 110 yards. The trigger tech trigger is a great start. In my opinion a MUST HAVE is a level bubble mounted on your riser on your'off' side so you can check your level from a shooting position. You may also want to invest in some Black Eagle Zombie Slayer arrows with either 92gr or 110gr brass inserts and 100gr points. I'm using the 92gr.. Also, the 2" blazer veins fletched with a Bolt EZ Fletcher jig gives great helical and works flawlessly. I also buy the bullet points 100 at a time and weigh and sort each point. This allows me to weigh my finished arrows and weight match them with the points. This is just the method I've used for years and I've had very good results. I also recommend plastic nocks just because they're much easier to change out quickly. It's also very important to make sure your scope is mounted perfectly square and plum. Good luck and happy shooting. You've got a great piece of equipment.

[Downunder]

Well its 6.15am here and have go to work, some great comments here, gona get a level for start , thought I was careful to hold level but cant be a 100 on that.... And more practice for sure!! I dont profess to be an expert just experienced a big change between 60 and 70 yards, windless conditions also.
Thanks all for the input and will read all again tonight

[paulaboutform]

In all fairness, I'm no pro either. My bench shooting is using a lead sled DFT to avoid human error. It's fully micro adjustable so it's just the equipment that's shooting super well. I'm just the loose nut behind the bow.

[Normous]

In all fairness, I'm no pro either.

Soon to be...

[Downunder]

Do you have a helical on your vanes or are they straight or straight offset?

Yup, the 18" Diablow arrows are the ones that came with the bow, helical fletched I would call them.
The 20" Horton Carbon MX are about 6 years old, also helical fletched. I use them on my Vixen.
I am very keen on the Black Eagle Zombies, they read good. Twenty inch seems to be the preferred length I read.

Thanks all for your comments, absorbing all

[Downunder]

Do you have a helical on your vanes or are they straight or straight offset?

Yup, the 18" Diablow arrows are the ones that came with the bow, helical fletched I would call them.
The 20" Horton Carbon MX are about 6 years old, also helical fletched. I use them on my Vixen.
I am very keen on the Black Eagle Zombies, they read good. Twenty inch seems to be the preferred length I read.

Thanks all for your comments, absorbing all

Just done a Google on helical and straight offset ( I'm learning !!) ... I'm sure the Hortons are straight offset but not sure the Diablows are ???

[paulaboutform]

The Diablo arrows are perfectly fine for hunting and will kill whatever you shoot through the vitals. However, if you're looking to play at some looong range that changes the game a bit in my opinion. I've shot some crazy tight groups out to 110yards and I believe to do that consistently you'll need super consistent arrows. I grain match all my arrows, number or letter them, and make sure they all hit the same spot at 20yards, 30yards, and so on. I need to know they're all hitting inch and a half spots at 60yards. Some of the arrows will shoot outside the main group repeatedly and that's when I try using a different vein as the cock vein. If that works I mark the new cock vein with a sharpy pen and if it doesn't work it gets separated and put in the penalty box. It all depends on what you're looking for, how much time you have to invest, and how much you like to tinker. Good luck.

[one eye joe]

I posted a reply a day or so back, bu somehow it never got listed.

A lot of guys shooting distance swear by spine indexing their shafts (and weight sorting components). Seems that if the shafts are indexed, they all "bend" basically the same so that it is easier to keep them together as distance increases. For my shooting out to 50 yards, I don't see the need, but can understand wanting to do everything possible for extended distance shooting.

Just one more possibility to throw into the mix.

[paulaboutform]

I posted a reply a day or so back, bu somehow it never got listed.

A lot of guys shooting distance swear by spine indexing their shafts (and weight sorting components). Seems that if the shafts are indexed, they all "bend" basically the same so that it is easier to keep them together as distance increases. For my shooting out to 50 yards, I don't see the need, but can understand wanting to do everything possible for extended distance shooting.

Just one more possibility to throw into the mix.

Absolutely agree.