Matrix 380 & A Tale of Two Strings

[Bigship]

Gents,

Spent some time looking at speeds and the comparison between the stock Excalibur string and a Jack Pine handmade Flemish string. I'm shooting the Zombies and the Diablos with different nocks and field points to achieve the weight variation. The Flemish string definitely imparts less energy into the arrow, but the bow vibrates less and the sharp, higher frequency "pop" at the shot settles into a lower frequency "boomp" (is that a word??) The numbers indicate that an arrow weighing 400 grains seems to be the sweet spot with either string. However, POI and repeatability count for something, and I have yet to see if my bow shoots an arrow with a 100 grain or a 125 field point/broadhead. Something tells me that these 18 inch arrows like a greater FOC, but we will see when I have the chance to shoot them (hopefully later today). One very good thing to know is that my Matrix actually exceeds factory speed spec. Board won't let me upload a 115k attachment. You can refer to this: post.http://www.archerytalk.com/vb/showthread.php?t=2473520

[nchunterkw]

The data on the stock string is very interesting. I have not seen arrow speeds increase as wt also increases. Your initial measurements at 350gr and 375gr correlate well with many other tests I've seen posted on here for the Matrix, where for every 3 gr arrow wt. increase you lose 1 fps. Your data comes out to 9fps loss for 25 gr = 2.77gr/fps. But at 400gr you gain 2 fps, over the 375gr speed, and at 421gr you gain 2 more over the 400gr speed, for a total of 4fps higher speed than the 375gr speed. Could it be a "sweet spot" of energy transfer? Maybe....but it did not carry over to the Flemish string. There you speeds steadily decreased with arrow wt. increase, to the tune of about 1fps for every 3gr, give or take.

It would be very interesting to see this data verified independently by other members. All you need is:

Matrix bow, stock EL string, Flemish string, arrows of 350, 375, and 400. I'd do it but I do not have a Matrix series bow.

[Bigship]

Yep, I noticed the anomaly also. I was shooting three shots per arrow thru the chronograph, but after about 10 "dup" indications, I just went to one shot. Its my first Matrix and I can believe how consistent it is. None of my other bows shoot as many duplicate readings thru the chrony. I'll probably stick with the Flemish string even though I lose a bit of speed. I like the smooth feeling and the lower frequency "thump" over the high frequency "pow" at the shot. If the 100 gn broad heads shoot well v.s. the 125 gn, my arrows will weigh a total of 395.3, which seems to be the best place to shoot the Matrix 380. Otherwise they'll be a bit heavier.

[nchunterkw]

What material is the Jack Pine string? B55?

[Kegbelly]

I would think something is amiss in the chrony results. I've shot a multitude of arrows at 350, 375, and 400 grains with the stock string and many flemish, and I have never gained speed with a heavier arrow. My 380 also shoots well above rated speed, and the heavier the arrow, the slower it shoots, no matter what string is on the bow including the stock string. I won't go so far as to say it can't happen, but I've never seen it happen in my own observations and never heard of that happening. I do agree I like the feel of a flemish vs the sharp snap of the stock string.

[Bigship]

What material is the Jack Pine string? B55?

Cal tells me his strings are made from, "36 strands of Brownell XS-2 [stands for extreme speed & extreme stability]. This is a fast, no creep material. I have not put the serving on yet, so I can serve to your custom length [5" is the usual], and have it in the mail today [postage included in price] if you like. I have .030 Halo, and .035 Majesty; your choice." I chose .035. Its a beautiful string and the camo color looks great with my Matrix 380 Extra.

[Bigship]

I would think something is amiss in the chrony results. I've shot a multitude of arrows at 350, 375, and 400 grains with the stock string and many flemish, and I have never gained speed with a heavier arrow. My 380 also shoots well above rated speed, and the heavier the arrow, the slower it shoots, no matter what string is on the bow including the stock string. I won't go so far as to say it can't happen, but I've never seen it happen in my own observations and never heard of that happening. I do agree I like the feel of a flemish vs the sharp snap of the stock string.

Yep, I just went back and looked. It looks like I must have transposed the column. I may put the stock string back on the bow and check the results again tomorrow if I can motivate my self to do it. I seem to remember one anomaly, not all of them.

[wildcatter]

I think that is a possibility but was doubting the consistent change. The only thing I ever checked mine with the factory string, I think, as I bought the lynx used and it came with a grey and black endless loop on it,, anyways. I got 379.8 av. w/112 ke shooting the 3 350 grain diablos, none over 351 grains and was happy. Then everything else was chronoed with a D97 Vixenmaster flemish. I shot 415 grain arrows and had a 5 shot string av. 358.3fps w/118 ke, the other arrow in the lynx I chronoed were the hunting arrows, 440 grains 5 shot string av. 352 fps w/121 lb ft ke then I made some heavy customs,, 620 grains @ 301.1 fps av,, and 125 lb ft ke.

My Mad Max the only arrows I chronoed were the 455 grain zombies @ 345 fps and 120 ft lbs ke.. this was with a boo flemish, I will be doing a lot of silencing modifications to it here shortly and will be testing 3 or 4 different types and weight arrows then. I have never even shot the mad max with the factory string,,,,

[Bigship]

Thanks for comparisons Catter. I'll look forward to your postings re. silencing the bow. The Excals are a blast to shoot. Still not giving up on the Orion or the Rebel, but the Matrix 380 is quickly gaining favor with me!!

[Bigship]

The data on the stock string is very interesting. I have not seen arrow speeds increase as wt also increases. Your initial measurements at 350gr and 375gr correlate well with many other tests I've seen posted on here for the Matrix, where for every 3 gr arrow wt. increase you lose 1 fps. Your data comes out to 9fps loss for 25 gr = 2.77gr/fps. But at 400gr you gain 2 fps, over the 375gr speed, and at 421gr you gain 2 more over the 400gr speed, for a total of 4fps higher speed than the 375gr speed. Could it be a "sweet spot" of energy transfer? Maybe....but it did not carry over to the Flemish string. There you speeds steadily decreased with arrow wt. increase, to the tune of about 1fps for every 3gr, give or take.

It would be very interesting to see this data verified independently by other members. All you need is:

Matrix bow, stock EL string, Flemish string, arrows of 350, 375, and 400. I'd do it but I do not have a Matrix series bow.

Well, I'm offended that someone would notice that I don't have a magic bow that defies the laws of physics. Really guys in my universe these things do happen. However, after returning from my most recent trip with Dr. Who, I have reshot all the arrows in the factory string and the chart has been reposted on AT below:

http://www.archerytalk.com/vb/showthread.php?t=2473520

These indications are in line with what you have so kindly stated. Thanks for noticing gents, and as my Asian friends say, "I'm sorry for any inconvenience caused." And from me, thanks for being so gracious with your comments. That speaks well for you.

[Bigship]

And one final thought. I reshot the 421 gn on the Flemish string and picked up 3 FPS. No diff in arrow drop or KE over the 413 gn arrow. However I did note that the 400 gn arrow drops 2 inches less at 50 yards yet retains 116 KE of the heavier weight arrows. So for you experienced guys with Matrix 380 or other, is an arrow weight around 400 gns the sweet spot for these bows??

[Kegbelly]

And one final thought. I reshot the 421 gn on the Flemish string and picked up 3 FPS. No diff in arrow drop or KE over the 413 gn arrow. However I did note that the 400 gn arrow drops 2 inches less at 50 yards yet retains 116 KE of the heavier weight arrows. So for you experienced guys with Matrix 380 or other, is an arrow weight around 400 gns the sweet spot for these bows??

Many have commented that 380-400 grain range seems to be the all-around best weight range for the M380 in terms of not sacrificing too much speed and flat trajectory but still noticeably reducing noise, shock ,and vibration. I'm shooting 400 grains with lumenoks installed and very happy with the way it performs.
Parting thought...one of these days I'm going to do some extensive testing with various weights above 400 grains and graph the results, I have a theory that the rate of speed loss decreases as arrow weight increases.... I think it's a sloped curve rather than X fps loss for every X increase in weight

[nchunterkw]

And one final thought. I reshot the 421 gn on the Flemish string and picked up 3 FPS. No diff in arrow drop or KE over the 413 gn arrow. However I did note that the 400 gn arrow drops 2 inches less at 50 yards yet retains 116 KE of the heavier weight arrows. So for you experienced guys with Matrix 380 or other, is an arrow weight around 400 gns the sweet spot for these bows??

Many have commented that 380-400 grain range seems to be the all-around best weight range for the M380 in terms of not sacrificing too much speed and flat trajectory but still noticeably reducing noise, shock ,and vibration. I'm shooting 400 grains with lumenoks installed and very happy with the way it performs.
Parting thought...one of these days I'm going to do some extensive testing with various weights above 400 grains and graph the results, I have a theory that the rate of speed loss decreases as arrow weight increases.... I think it's a sloped curve rather than X fps loss for every X increase in weight

Keg,
I'd love to see the results (y'all know how I love to crunch the ##s) and from some tests I have done on my bison arrows you are exactly right. There is a curve generated, not a straight line. If you use excel, you can plot the data points, then do a "curve fit" and have excel show you the equation of the line it is using to generate the curve. That gives you the ability to more accurately predict speed for a given weight going forward.

[nchunterkw]

BigShip...no worries. The new chart looks good. I have an F1 Chrony, and one thing I have found with it, is that you have to be careful that the arrow passes over the eyes within a specific window. On that one it is between 4" and 6" vertically above the eyes. What I did was install the guide rods, then measure straight up from the eyes, and mark the rods with red marker where the 4" - 6" window is. I then setup the bow and put a laser bore sighter on the rail and make sure my arrow will come off within the window. It has greatly improved my measurements. I also keep the bow, and chrony all lined up so the arrow passes over the center of the eyes, and just go move the target slightly so I don't always hit the same hole and ruin some fletchings.

[Kegbelly]

Keg,
I'd love to see the results (y'all know how I love to crunch the ##s) and from some tests I have done on my bison arrows you are exactly right. There is a curve generated, not a straight line. If you use excel, you can plot the data points, then do a "curve fit" and have excel show you the equation of the line it is using to generate the curve. That gives you the ability to more accurately predict speed for a given weight going forward.

I didn't know you could derive the formula like that Keith, thanks for the tip
I've wanted to do this since last year when I thought I spotted the trend but just haven't had the time to pursue it. It would be interesting...