New GSC 338 LRH bullets.

[BryanLitz]

Mr. Schultz,

I've got no interest in continuing this debate with you. My live fire test results are published, and they indicate typically 20% to 30% lower BC's than you provide. None of your explanations of how or why I'm wrong explain this drastic gap between theory and reality.

Arguing one theory vs. another theory is OK. Even arguing which test results are more valid is reasonable. However, you're arguing that your 'theoretical' BC's are more accurate than my 'tested' BC's. This is not a reasonable position which is why I'm not interested in continuing the debate.

I'm further inclined against this conversation given your pattern of enticing these kinds of debates in various internet forums. You've been proven wrong many times but continue to persist. My hope is that readers can discern between credible test results and computer predictions. There's enough misinformation on the internet which makes it difficult for new shooters to learn.

Mr. Schultz, there are very specific design features which explain why your bullets' actual flight performance falls short of the predicted performance. As chief Ballistician for Berger Bullets, you can understand that I'm not at liberty to advise on competing bullets' design. My point is; there's a good reason why your predicted performance falls short of actual, and it's none of the things you're addressing. In other words, rather than trying to make everyone believe in the inflated estimates, you should address the design issues which are responsible for the estimates being optimistic to begin with.

-Bryan

 

[BryanLitz]

Tim,

It's good that you've had a positive experience with these bullets. It is very nice when a bullet maker can offer flexibility; this is one aspect of machined bullets that conventional cup and core bullets cannot match.

I've got some questions on your experiences. You stated:

I weighed 200 and never had a variance over .001 grain.

My question is; what kind of scale were you using to measure bullet weights to 0.001 grain? Most digital scales can resolve within 0.1 grains, some high end ones can get to within 0.02, and I've even seen some resolve to 0.01 grains. But outside of a laboratory environment, I've never heard of scales that can resolve weight to 0.001 grains.

Another statement that piqued my interest:

I lost my BC numbers from my testing of the 99 gr SP 6.8 bullets but they did allow us to keep the bullet super sonic thru 1K from a 18" and sometimes even a 16" barrel but in that is was in the transonic range.

A 6.8 SPC magazine length 99 grain 270 caliber bullet that's supersonic to 1000 yards in a 18" barrel is hard to believe.

Even with a G7 BC of .2 (which would require a form factor of 0.88, which is better than nearly any bullet) and a MV of 2800 fps (very optimistic for an 18" barrel 6.8 SPC), the supersonic range is less than 900 yards.

The only way I could see this round making 1000 yards supersonic is at very high altitude.

It would be interesting if you could locate your records on this bullets BC and MV from the mag length 18" SPC, as well as the altitude of the test. Also, how did you determine the bullet was supersonic at 1000?

-Bryan

 

[Gerard Schultz]

Mr Litz

I am not saying that your results are wrong, only that you are interpreting my technical information incorrectly. A good example of how you are seeing this is if I would say the predicted temperature is -10 and you assume -10F. I may mean -10C and those are two very different things. Or if I say that I built an F-Open rifle with a 76 cm barrel and you say "76 inches, that is incredible". You are interpreting it wrong and making some basic mistakes. Taking your toys and going home, is not the way to handle this. I have said Centigrade and centimetres several times now and you keep on thinking Farenheit and inches.

I'm further inclined against this conversation given your pattern of enticing these kinds of debates in various internet forums. You've been proven wrong many times but continue to persist.

Name one instance or give one link to such an example. It will be most welcome.

My hope is that readers can discern between credible test results and computer predictions.

Everything that I have done in bullet making since 1982 and turning bullets since 1992 has been the result of intense testing on the range, in the field and in ballistics labs. Just because I am not as prolific a writer as what you are, does not mean that what I do is sucking my thumb. However, I do have an opinion of any person who averages G1 BC numbers.

you should address the design issues which are responsible for the estimates being optimistic to begin with

Every so often one bumps into someone that, perhaps has more depth of experience or knows something that one does not know. Perhaps this is such a time?

Should you change your mind about continuing this discussion, even by e-mail or here, I will be available of course.

 

[MudRunner2005]

One box. That could be 50 bullets or 25, depending on the size of the bullet. You give the details and application and we design the bullet.

Mr. Shultz, do you have any designs for heavier .284 projectiles, such as around the 168-180gr range?

I have been told that with copper monos that a lighter bullet can produce almost the same affects as a heavier one, but with more velocity. I don't know how true that is, since I am not a ballistician, but it would seem like if that were the case, then heavier mono bullets with greater BC that are stable in the proper twists to their cup & core counterparts might produce a bullet with extreme capabilities, compatability, and user friendly familiarity.

I have been told similar weighted monos require a faster twist to spin them... If there is a way to design a LR high BC 180gr 7mm mono that is capable in a 1:9 twist, why has nobody produced one yet? I would think it would be a big seller...

And don't take this as anything more than questions, because that's all it is. I am just curious to know a bit more about the mono vs cup & core game, because there seems to be a schism where on one side people say you can shoot the same weight monos in the same twist as a cup & core, and on the other side, people say that you need a faster twist to shoot a mono that is the same weight as the comparable cup & core.

 

[BryanLitz]

Mr Schultz,

My BC's have units of lb/in^2 which is the universal standard in the small arms industry even for countries which primarily operate in metric. If your BC's are expressed in units other than lb/in^2, then please say so.

While we're clarifying such things, when we talk about G1 BC's, what I mean is, BC's referenced to the G1 drag standard; A poor choice for modern LR bullets, but since that's all you show for your bullets, it's our only common language for performance measure. Here's a representation of the G1 model I use: http://www.jbmballistics.com/ballistics/downloads/text/mcg1.txt

This is the G1 drag model that ballistics programs use when you enter a G1 BC. If you're using a different G1 model, please say so.

Furthermore, my BC's are corrected to standard ICAO sea level atmosphere. This is the international standard atmosphere model. If you're referencing a different atmosphere model, please say so.

Of course none of the above potential misunderstandings explain why my measured BC's would be so much lower than your predicted BC's. See below example of your .375 cal 355 grain SP. I chose this bullet because it was tested in a 1:10.5" twist rate that produces your recommended SG of 1.2+. In my test conditions, the SG was actually 1.67. It was even one of the cartridges you recommend: .375 CT.

As you can see, the measured BC falls short of your predicted value at all speeds. Yes, the error changes with speed, and I can see your issue with averaging BC's especially G1 BC's. G7 BC's are not perfect for your bullets, but they're much better than G1's in most cases. But you don't provide G7 BC's, so averaging is a bigger problem than it has to be. However, that's not the big picture here.

The big picture is that you're way over representing the actual performance of your bullets.

-Bryan

 

[jonthomps]

To a certain extent, I view published BC's only as a guideline. When in doubt, believe the bullet. I would much rather believe actual BC's than published.

 

[tim_w]

Tim,

It's good that you've had a positive experience with these bullets. It is very nice when a bullet maker can offer flexibility; this is one aspect of machined bullets that conventional cup and core bullets cannot match.

I've got some questions on your experiences. You stated:



My question is; what kind of scale were you using to measure bullet weights to 0.001 grain? Most digital scales can resolve within 0.1 grains, some high end ones can get to within 0.02, and I've even seen some resolve to 0.01 grains. But outside of a laboratory environment, I've never heard of scales that can resolve weight to 0.001 grains.

Its completely understandable why you would question that resolution. I would have asked the same thing. I should have included the scale I used to prevent questions and what many might just assumed an exaggeration as I would not blame you if you had. I have personal interests in chemistry and pharmakonetics and as such have acquired a number of rather high end lab pieces ( At least for a individual not worth 100s of millions). As sometimes I am dealing in very small measurements of extremely small and or low density quantities ( dosing in mcg) I have a Ohaus balance scale ( they run about $2K+ but I purchased my used for 1/3 of that but still not cheap)
The scale above has resolution to 0.1 mg but the linearity in real world is closer to 0.2 from what I have seen. 1 gr = 64.80≈mg 0.001 grains = 0.00154≈mg. Now while the scale read to that it is certainly possible it could have been off by .001 grains, as I stated, either way from bullet to bullet. So this true. I should have been more accurate and given a tolerance range but it was very late (3am ish) when I posted if I recall and I was being a bit lax. More correctly it should have been 0.001 +/- 0.001 With that said I rarely use it unless needed as its a pain to setup and has to be on a extremely solid surface. It has sealed weighing box over the platform as even the smallest air movements can throw it off.


Another statement that piqued my interest:


A 6.8 SPC magazine length 99 grain 270 caliber bullet that's supersonic to 1000 yards in a 18" barrel is hard to believe.

Even with a G7 BC of .2 (which would require a form factor of 0.88, which is better than nearly any bullet) and a MV of 2800 fps (very optimistic for an 18" barrel 6.8 SPC), the supersonic range is less than 900 yards.

The entire commercial development of the SPC was a mess as the very short free bore print was sent to SAAMI by Rem and was the not the one used to do the dev work but was a match chamber. That caused most all ammo companies to have downloaded ammo compared to what could be done with the longer free bore. Very similar to the .223 vs 5.56. If you look at the vel of SSA ammo combat loads of the time the vel were a good bit higher but had to be in the proper chamber. The load we used was hot but according the calibrated PT 65K (obviously not definitive) Certainly not a round to be shot at a high rate of fire, blowing thru a mag, for sure, but hunting would have been fine.
The barrel was a nitrocarborized (melonited) 5r rifling with BSC % 18-20% ( I can not recall offhand which we went with on the button design. Either way its on the much lower side of things compared to what many barrel makers use as default which usually is in the 30% range if I am not mistaken. Then again we scoped a pac nor 4 groove and I swear it could have been over 50%. The lands were huge!!
COAL set to max allowable by PRi 6.8 mag 2.30" Typical AR mags have a COAL max around 2.6"
3000 fps on average.



The only way I could see this round making 1000 yards supersonic is at very high altitude.

You are correct about the altitude as that was shot in CO at in the high plains so maybe 6K
To people out there is not very high I guess as a old friend was hunting IIRC @ 11K I am no mountain goat so the airs to thin for me LOL

It would be interesting if you could locate your records on this bullets BC and MV from the mag length 18" SPC, as well as the altitude of the test. Also, how did you determine the bullet was supersonic at 1000?

I will try to get the info and in fact I think I am still have some of those exact bullets. The data is on an old laptop and I have been needing a good bit of other data on there as well so hopefully I can get it off there. Look I do not have remotely close to not only your skill and knowledge but in all liklehood the vast amount of high end equipment. You are not going to see me renting doplar radar time for bullet tracking. I have two CED M2 [they were no longer making Oehler at that time and my only one had broken beyond repair (was run over by my Excursion, do not ask as I will look as stupid as I still feel)] the that I put on ridge aluminum square tubing that was checked to be straight and square to the best the machine shop I used could check it.

I also tried to be as precise as I could measuring the distance between them. I usually used a surveyors measuring wheel that had a manf claimed accuracy of 3" per 100 feet so that's roughly 0.2% but unless its the salt flats or pavement its not perfectly flat. It areas that were rough we used reel tape measure. Honestly now posting this I do not know why I did not use the transit I picked up. That would have ensured accurate angle of incline/decline if any. Anyways in no why could I every compare this to a properly setup testing lab such as you have built there at Berger.

-Bryan

Not to get on any side of the "debate"? that has sprung up in this thread I want to make something clear. From my shorter vel tests of the various bullets the BC were higher than what I got shooting across two chrono. I did not think much of this as it was a few years ago and basically most everyone BC that were computer derived all seemed to come out high compared to drops. ( I recall some botique bullets that were popular on here having extremly high BC published) Thus, your findings do not surprise me. I did not know they got that extreme and again I am no expert and you most definitely are, I recall them being in the 15-20% overage range.

As I think you have eluded to, the drive bands have to be taken into account and that maybe one of the issues. Other than eliminating them the other thought I had was possibly to have gain twist barrel that ended in rapidly increasing twist rate to "smooth out" the drive bands as it goes down the bore. I had noticed in a few bullets we were able to recover how the bands had been smoothed out somewhat which was one thing that, among others, lead to that idea (as ridiculous or not as it maybe.) The higher vel allowed by the soft copper and lower bearing surface area I would "think" would also help to this end. Again this would obviously be in the frame work of a very specialized setup i.e one bullet or at least one design of bullet setup.

I always try to give accurate information. Sometimes I screw the pooch and mess up but its never my intent. The facts are the bullets I received from GSC were very consistent and well made. I do concur the BC were elevated. I can only speak to the specific ones I used and were no where near those with no limit on OAL. As my interests were only in that very specific area I have no idea if the BC depart even more or not. I also do not have the data in front of me and do not like to make rock claims without solid backup of those claims. Thus I can only say what I recall from memory and noted as such.

I greatly respect the work and quality of it that you do, not to mention, the large amounts of data you freely publish on the net for the edification and benefit for all who care to take the time to learn from it. I have learned a great amount from your posts and that which is contained in your books. I very much enjoyed the recent post on popular chronograph performance testing. I had asked a question in there but I think it got lost in the rest of my ramblings in my post. It was dealing with changes in vel in the short distance after exiting the muzzle.

 

[Kiwi Greg]

A while ago now I shot the .375 414 GSC against the 425 CEB with the same velocity at 2050 yards.

Both were within 0.5 moa at 100 yard zero, the 414 fell 8 moa lower than the 425 at 2050 yards.

Sorry that the video is so long but it was the first time I had shot them at ELR.



The 414 were extremely accurate but clearly their BC was much lower than the 425 even though it was advertised as much higher.

I could have got a little more velocity from the 414 which would have increased their performance but they would still have impacted much lower than the 425s.

Interestingly my custom tipped ex 425, 417 when tipped, fell 2 moa lower than the standard 425, even though their velocity increased, obviously the plastic tip "hurt" their BC, their accuracy was as good or better than standard.

The Lazers I have tested, 425 & 450, also show their BC as being lower than their non tipped siblings for ELR shooting.

 

[Gerard Schultz]

Mr Litz

The big picture is that you're way over representing the actual performance of your bullets.

I use the same units as everybody else does and say this about the GSC BC numbers on our bullet technical profile pages: "BC values are calculated at standard Metro values using a G1 profile. Any comparison with the BC values of other manufacturers is not valid as there is currently no standard method in use between manufacturers. Enter these values into an external ballistics program to calculate BC for your launch speed and distance. For exact values, shoot drop tables at the elevation and temperature for your location."

I am going to say this once more:

1. As long as you average G1 BC numbers, you have lost before you started because your averaged number will be wrong. It cannot be done. If you wear a #10 shoe and buy a #8 for the left foot and a #12 for the right, on average you have the right size but neither is going to be the correct fit.

2. BC changes with speed and our BC numbers are intended to be used to calibrate a ballistics program so that it calculates correctly. For example, have a look at this page: GS CUSTOM USA - Bullet Technical Profile How do you propose getting a 500gr 416 caliber bullet to 4300fps? It cannot be done. The numbers we give are purely to calibrate ballistics programs and nothing else. We even say that it cannot be used for comparison with other tested methods because everyone uses a different method. Why do you do this then, unless it is to 'advertise' the correctness of your method?

Your method, or Kiwi Greg's method is not wrong, that is what you found on the day, but it does not mean that the numbers we give are wrong, as you state. We do not 'advertise' BC numbers, we give them purely to calibrate ballistics programs. Your figures may be right on the day but your statement that our numbers are inflated is wrong.

This is why we say: "For excact values, shoot drop tables at the elevation and temperature for your location."

Let me know if there is something that you do not understand in this, I would be happy to try to explain.

 

[Kiwi Greg]

Mr Litz



I use the same units as everybody else does and say this about the GSC BC numbers on our bullet technical profile pages: "BC values are calculated at standard Metro values using a G1 profile. Any comparison with the BC values of other manufacturers is not valid as there is currently no standard method in use between manufacturers. Enter these values into an external ballistics program to calculate BC for your launch speed and distance. For exact values, shoot drop tables at the elevation and temperature for your location."

I am going to say this once more:

1. As long as you average G1 BC numbers, you have lost before you started because your averaged number will be wrong. It cannot be done. If you wear a #10 shoe and buy a #8 for the left foot and a #12 for the right, on average you have the right size but neither is going to be the correct fit.

2. BC changes with speed and our BC numbers are intended to be used to calibrate a ballistics program so that it calculates correctly. For example, have a look at this page: GS CUSTOM USA - Bullet Technical Profile How do you propose getting a 500gr 416 caliber bullet to 4300fps? It cannot be done. The numbers we give are purely to calibrate ballistics programs and nothing else. We even say that it cannot be used for comparison with other tested methods because everyone uses a different method. Why do you do this then, unless it is to 'advertise' the correctness of your method?

Your method, or Kiwi Greg's method is not wrong, that is what you found on the day, but it does not mean that the numbers we give are wrong, as you state. We do not 'advertise' BC numbers, we give them purely to calibrate ballistics programs. Your figures may be right on the day but your statement that our numbers are inflated is wrong.

This is why we say: "For excact values, shoot drop tables at the elevation and temperature for your location."

Let me know if there is something that you do not understand in this, I would be happy to try to explain.

Mr Schultz

Your BC data here for the 375 414 SP clearly says BC 1.247, max 3400fps, 1.109 - 2300fps, 0.819 - 1200 fps

GS CUSTOM BULLETS - 375414SP256 Technical Data

This was the reason I got some of your 414SPs to try, which wasn't an easy thing to do.

Using the 414 GSC my muzzle velocity was 3140 fps, calculated impact speed for POI at 2065 yards was 1330 fps which works out to an average G1 BC of 0.83

This is a fair way away from the advertised BCs

This is why in the video, I was surprised I couldn't see the strikes, I was looking above the 425 CEB impacts when I needed to look 8-9 moa below them.

Using the 425 CEB my muzzle velocity was 3140 fps calculated impact speed for POI at 2065 yards was 1590fps which works out to an average G1 BC of 1.03

Incidentally the G1 BC of 1.03 is what CEB advertise their BC as for the 425.

CEBs BCs might not be absolutely right/perfect but clearly they are more accurately represented than yours.

At a closer range I may have achieved closer results than I did at 2065 yards, but considering the high BC 375 projectiles are for shooting ELR comparing them at 1000-1500 yards is pointless.

 

[Bob lee]

My expericene with the gs bullets mirrors what has been stated here, i am no ballistics expert but what i do know is that to get my drops to match my ballistics program i had to lower the bc number i entered into the app, quite a bit lower than advertised. They were very accurate but when you pay what theese cost and the bc isnt there its disappointing. Just my .02.