Test results on 264 cal 150 & 160 gr Matrix Bullets

[BryanLitz]

A while back there was a thread where some people were asking about the BC's of the Matrix 150 and 160 grain bullets. Marshal was kind enough to send me some bullets for testing and I've got the results.

In exchange for sharing these test results, I'd like to ask a favor. I'd appreciate any feedback on the data sheets shown below. This is the format I'm settling on for my new book which will basically just be all bullet data (similar to the appendix in Applied Ballistics For Long Range Shooting but expanded to ~400 bullets).

My aim is to provide the top level info like useful bullet dimensions, G1 and G7 BC's, minimum and recommended twist information as well as details for those who want to dig deeper.

Here's the data sheet for the 150:

And the 160:

Regarding the bullets, the only twist I shot them from was a 1:6" .260 Remington. Even at somewhat depressed MV, the bullets were fully stable from this twist, and I feel the results are a good representation of long range performance. My hunch was that these long dudes would need much more than a 1:8" but that's not really the case; 1:8" gets you most of the BC there is to be had.

Another note; the meplats on these bullets are relatively large; something I see a lot on longer bullets. Based on what I've seen pointing the 7mm 180 Hybrid (which also has a larger-than-normal meplat), I suspect you'd see anywhere from 7-9% increase in BC if you pointed these bullets. However, beware of what effect the closed meplat might have on expansion.

Appreciate any feedback on the data sheets.

Thanks,
-Bryan

 

[jonthomps]

Excellent information! I like the layout of your bullet diagrams. The information is clear and concise. Not sure I'd change anything. Side note: I found it fascinating that the G7 BC actually increased at the extreme outer limits of velocity.

 

[Len Backus]

Thanks, Bryan.

 

[elkaholic]

Well done Bryan! This is the kind of cooperation and precision data that we all yearn for. This will be very helpful! I was pleased to hear that twist rate did not change the b.c. much provided it was sufficient to stablize. I look forward to testing this out in the field when I get done selling business', homes, etc.......thanks again/Rich

 

[bigngreen]

Very nice Bryan, big Thanks for giving them the once over and putting it in a nice yet full layout of info, looking at my Applied Ballistics data we were getting dialed in pretty close. The elk don't dig them gun)

 

[BEEMAN]

Thanks. This should help my load development.

 

[Deleted member 46119]

I love the format.

When can I get the book!

Data. data, DATA!

 

[stomp442]

Awesome format and looking forward to the book. I am not real familiar with these bullets, how do your numbers compare to advertised or estimated numbers?

 

[BryanLitz]

Awesome format and looking forward to the book. I am not real familiar with these bullets, how do your numbers compare to advertised or estimated numbers?

It depends on how the advertised or estimated numbers were generated.

One common scenario is that advertised numbers are based on short range testing (100-200 yards) where the bullet velocity is high. Well, at high speed, the G1 BC is higher, then decays at low speed. The manufacturer advertises a number based on high velocity which isn't wrong, but it's not representative of the bullets performance over long range.

Take the 160 grain 6.5mm bullet from Matrix. They advertise a G1 BC of .685. My measurements indicate a G1 BC of .687, but only for velocities over 3000 fps. As velocity slows down, the G1 BC drops, a lot, and over the course of a long range shot, the BC averages more like 0.646, which is the number you'll need to accurately predict drop.

This is one reason why the G7 BC is so much better; it doesn't vary as much with speed. So if everyone tested and used G7 BC's, it wouldn't matter (as much) if you tested over 100 or 600 yards, the G7 BC would be more or less the same.

I'm not picking on Matrix here, they make good bullets and do their best to provide the most accurate ballistic performance data they can. But to really nail it down takes a serious effort which isn't really practical for the size company they are.

So, to answer your question directly, my BC's are quite often lower than estimated or advertised BC's for two reasons:

1. Using the G1 BC tested at 'high speed' only, uncorrected for long range decay
2. Deliberate inflation (probably less common than #1)

Most people don't realize how easy it is to estimate BC's with very good accuracy. It's just sectional density divided by form factor.

Sectional density is a known, from weight and caliber. A .308 caliber 175 grain bullet has a sectional density of 175/7000/.308/.308 = .264. That's every .308 caliber 175 grain bullet.

The other element is form factor, which is related to the drag.

Bullets with 'average' drag will have form factors of 1.00, so their G7 BC is equal to their SD.

Bullets with 'low' drag will have form factors lower than 1.00, but usually not lower than 0.90.

Bullets with 'high' drag will have form factors around 1.10, sometimes much higher but much higher than 1.1 aren't even considered for long range (think of a Barnes TSX flat base or a Swift A-Frame).

So looking at any bullet and making a guess about it's form factor being 0.9, 1.0, or 1.1, if you're right, it will get you within 10% of the actual BC.

Using the 150 and 160 grain Matrix bullets for example again, the sectional density is:

150 grain: 150/7000/.264/.264 = .308
160 grain: 160/7000/.264/.264 = .328

Now we just have to take a guess at the form factors.

Based on looking at these bullets (the nose and tail matter most to form factor, length of bearing surface matters little). My guess would be they would have a form factor close to .95.

So based on this, the G7 BC's would be:

150 (SD/Form Factor) .308/.95 = .324
160 (SD/Form Factor) .328/.95 = .345

As it turned out, the form factors on these bullets were .992 and .989. So the actual BC's are:

150 = .308/.992 = .311
160 = .328/.989 = .332

These actual numbers are only 4% different from what was actually tested.

Granted I may be better at guessing form factors than average, but with a little practice, and knowing form factors of similar bullets, you can get pretty good.

Sectional density gets you most of the way to a good G7 BC, the form factor just modifies it, and you can estimate that pretty close.

I often use this as a sanity check for BC claims. You can calculate what the form factor would be for a bullet of that weight, caliber and BC, and decide if it seems reasonable. Often times BC claims infer an unrealistic form factor (like 0.7) for a bullet which look like others having a known form factor of .95.

Wow, I didn't mean for this to get so long, just got on a roll.

Take care,
-Bryan

 

[Cold Trigger Finger]

Brian ; I really appreciate the class!!

 

[stomp442]

Thank you Brian for the response. I have read your books a few times and feel like I grasp the concept of estimating BCs fairly well and I know the G7 is the better model to use. I just like to know what the manufacturer actually advertises. How close they are let's me know they are doing more than simply advertising the highest number possible like Nosler has consistently done. Again thank you for your response and the time and effort you put into your work.

 

[elkaholic]

Very good explanation which people can understand. Hopefully, everyone will read this and use it accordingly when people throw out these outrageous b.c. claims........Rich

 

[bigngreen]

You can easily go the the Matrix Ballistics web site, but the 160 is listed at G1 .685 which would have come from guys shooting them and I know a bunch of us push them hard but I was running a G1 of .680 in Applied ballistics. He does not have the 150 even up as it just got into the hand of guys to shoot this summer, any BC numbers thrown around are from those of us who shoot them and we were getting dialed in very close to what Bryan is listing.
Many Matrix bullets are still listed with the calculated or "static" BC's which we all know will run high, as they get feed back from shooters the BC numbers are getting refined and certainly this will refine them even more!

 

[elkaholic]

Very good explanation which people can understand. Hopefully, everyone will read this and use it accordingly when people throw out these outrageous b.c. claims........Rich

When I speak of outrageous b.c.'s, I am not referring to Matrix. Marshal was good enough to donate the bullets to Bryan to help all of us. Unlike some other bullet makers, he is not afraid of the truth and makes some darn good bullets.......Rich