Chronographing Excaliburs

[Hester0305]

I recently bought and Excalibur Matrix 380's from one of my friends that he bought about 5 to 6 years ago, I decided to chrono both the Matrix 380
and my wife's Matrix 350 this morning. The Matrix 380 only shot around 336 fps with a 410 gr. Zombie Slayer and a Flemish string. The Matrix
350 shot 328 fps with the same arrow. The Matrix 350 is only 2 years old compared to 5 to 6 years old on the 380.

I guess my biggest question is does our limbs weaken with age on our crossbows. I was guessing the Matrix 380 should have be shooting
around 350-360 fps with that weight arrow and a Flemish string. Would anyone suggest getting a new set of limbs and trying those also.

[XB I GO]

my Matrix 380 shoots 363 fps with a 420 grain bolt on a chronograph 10 feet from the bow.

[frisky]

If I am not mistaken, Excalibur checks the FPS with a 350 grain arrow.

[Art-Man]

I shoot the Micro Raid 335, it has all the suppressor stuff on it and I just did a chrono on it with the factory quills and a 125 grain field point and it was shooting 316fps.

[Normous]

Your speeds seem about right give or take a few feet per second.

In the factory Excalibur uses a high end crono under ideal conditions to advertise speeds with a 350 gr arrow.

Most of us do not have the funds to replicate factory speeds and cheaper cronos under less than ideal conditions may leave us scrathing our heads with the results.

[wildcatter]

I have owned three chronographs, none over $200, and only one that gave false readings at a thousand feet per second that were off by more than 20 ft per second. The other two tested with a 3 screen Oller professional Chronograph known for its accuracy we're both within 5 feet per second of each other at 3400 feet per second.,

My proven shooting chrony Master gamma, has been calibrated or tested and was it is within 1 or 2 feet per second of the oler, in different lighting situations is Normous says they can be off some what but will be very close and within 1% deviation from actual speeds when properly setup and used. I have never owned any Xcalibur that did not give me it's estimated speed using a 350 green arrow. My 380 with a 390 grain Arrow, shoot 362 ft per second, with its 352 grain Arrow as close as I could get to the test are awake it shot 384 feet per second for a three-shot average. I never shoot these light arrows and blame them on a lot of the older limb damage but my Bow Shoot much smoother with the heavier arrows I prefer 425 to 450 grain.

When you state Flemish string that can mean a big difference in speed, I've had special strings built to absorb some of the shock and energy in a 405 compared to the factory string I lost 14 feet per second with that string, but it gave me much smoother and quieter results which is what I wanted. Depending on the string material and strand count this could be a lot of where your speed is being missed. But like Normous said, you have to know you have a decent coronagraph set up properly with the correct lighting and more than one shot to know if it's accurate or not, and the only true way to know if it's accurate is to have it calibrated with a proven model.

[Boo]

I have owned three chronographs, none over $200, and only one that gave false readings at a thousand feet per second that were off by more than 20 ft per second. The other two tested with a 3 screen Oller professional Chronograph known for its accuracy we're both within 5 feet per second of each other at 3400 feet per second.,

My proven shooting chrony Master gamma, has been calibrated or tested and was it is within 1 or 2 feet per second of the oler, in different lighting situations is Normous says they can be off some what but will be very close and within 1% deviation from actual speeds when properly setup and used. I have never owned any Xcalibur that did not give me it's estimated speed using a 350 green arrow. My 380 with a 390 grain Arrow, shoot 362 ft per second, with its 352 grain Arrow as close as I could get to the test are awake it shot 384 feet per second for a three-shot average. I never shoot these light arrows and blame them on a lot of the older limb damage but my Bow Shoot much smoother with the heavier arrows I prefer 425 to 450 grain.

When you state Flemish string that can mean a big difference in speed, I've had special strings built to absorb some of the shock and energy in a 405 compared to the factory string I lost 14 feet per second with that string, but it gave me much smoother and quieter results which is what I wanted. Depending on the string material and strand count this could be a lot of where your speed is being missed. But like Normous said, you have to know you have a decent coronagraph set up properly with the correct lighting and more than one shot to know if it's accurate or not, and the only true way to know if it's accurate is to have it calibrated with a proven model.

You can buy the very best chronograph, but if you get low readings of you don't shoot level with your sky screens. The most consistent performance I've had with chronographs is using lighting packages.

[wildcatter]

After 35 years shooting national benchrest competition I don't need instructions on setting up or using a chronograph. This is exactly why you will see in my comment I stated lighting and setup and yes very critical and yes very few capable of doing it consistently and properly.

[Hester0305]

Thanks everyone, I shot about 15 times with several duplicate readings on both the 350 and the 380. I haven't had any issues with my Chrono before
even not using lighting on it. That's good to know about the lighting situation. Looks like I need to purchase a light kit to get the most consistent readings. The 350 shot closer to the advertised speed with a Flemish string than the 380 did that's what had me puzzled.

It looked like I had the chrono pretty level but next time I'll put a level on it to make sure.

Thanks again.

[Boo]

After 35 years shooting national benchrest competition I don't need instructions on setting up or using a chronograph. This is exactly why you will see in my comment I stated lighting and setup and yes very critical and yes very few capable of doing it consistently and properly.

My comment was made to add to what you said.

[nchunterkw]

Thanks everyone, I shot about 15 times with several duplicate readings on both the 350 and the 380. I haven't had any issues with my Chrono before
even not using lighting on it. That's good to know about the lighting situation. Looks like I need to purchase a light kit to get the most consistent readings. The 350 shot closer to the advertised speed with a Flemish string than the 380 did that's what had me puzzled.

It looked like I had the chrono pretty level but next time I'll put a level on it to make sure.

Thanks again.

Hester
Try setting up outside on a nice "blue bird" sky and see what you get. Also, your chrony has a vertical window it wants the projectile to pass through. I put my chrony together and measure vertically to the lower and upper end of the window, then mark my rods with a red Sharpie. Then I set it up on a tabl;e, and set my bow up behind that. If you have one, use a laser bore sighter sitting on the rail to make sure the arrow will fly through the chrony at the proper height. Also, make sure the arrow will be completely free from the string before the front of it hits the first sensor. And finally, test with a bullet point and not something pointy like a BH.

So I said all that to say this....... I don't think it's your chrony setup.

Given all the other testing that has gone on, the rule of thumb for a Matrix is that you lose about 1fps/3gr. So 410-350 = 60gr --> should lose 20fps. The same would apply to the string weight difference from the Excal test string to your Flemish but sine we routinely see the marketing speed with a 350gr arrow, I don't think that is significant....maybe another 5fps? So you "should" be around 355fps on the Matrix 380 and around 325 with the Matrix 350. You are 20 fps away from that on the Matrix 380, and right on with the Matrix 350. So I am with you....something seems not exactly right with those limbs.

Give Danny a call and see what he says.

[RobD]

The 350 sounds good to me, the 380 seems a little weak. The 350 probably still has the factory string on it. If it was me, I'd put the 350 string on the 380 and chrono it to determine if it is the string or the limbs. You'll also want to double-check the brace height. Forum member xcalibur had a 380 that was shooting 340-something with a 400gr bolt in his thread (http://www.excaliburcrossbow.com/phpBB3/viewtopic.php?f=1&t=68217) and after working with Excalibur he got it up to where it should be.

[Boo]

You have to use a 350 gr arrow to check and verify.

[otisbrazwell]

switch the limbs from the 350 to the 380 that should answer your question

[XB I GO]

My Matrix 380 shoots 363 fps with a 420 grain bolt and the chronograph 10 feet from the bow.