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New Barnes bullet testing.....

 
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  #22  
Old 02-20-2011, 06:52 PM
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Re: New Barnes bullet testing.....

See bold below:

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Originally Posted by Fiftydriver View Post
M.E.

That said, if you take two identical bullets, same weight, same dimensions, put an aluminum tip on one and leave the other as a HP, the length of the AT bullet will be MUCH longer then the HP and the resulting BC will be dramatically higher.

I am going to go with the thought that it is due to the smaller meplat and how it related to the form factor having modified slightly a meplat which demonstrated dramatic results. The bullet was only shortened a few thousandths so I know it was not a change in length that was the culprit rather the meplat.

You can go with your theory that its because of the meplat diameter, I can say its because of the added length...... In the end it could be either or both but both certainly effect BC.

Its similiar to the arguement that a larger caliber will drive a bullet of the same weight faster then a smaller caliber bullet of the same weight when used over the same case capacity.

Some will say that its because of the increased area of the bullet base so more force is applied to the base of the bullet per sq. inch.

Others, including myself will say its because of baring surface being much less with the shorter, larger diameter bullet and the ability to use faster burning powder.

My opinion here is that it is due to the increased bore capacity similar to that found when using a longer barrel for a given bullet weight. Just a thought.

Back to the bullets. Lets look at the Hornady 208 gr match bullets. The A-max with the tip has a BC of .650, the standard HP has a BC of .620... Yes the meplat is finer for the tipped bullet, yes the length is longer for the tipped bullet, in the end, the bullets weight the same, likely have very similiar form factor and yet the longer bullet has a higher BC.

The only real length increase comes from a plastic tip which in turn makes the meplat smaller.

Also the 180 gr Hornady SPBT and Interbond. The SPBT has a BC around .450, the tipped bullet in the .480 range. Yes finer meplat, yes longer bullet, higher BC same bullet weight and design.

Simply put, you take a certain bullet weight, no matter the bullet weight, if you add a tip for a fine meplat, use an aggressive ogive design, good boat tail design you will get the longest bullet possible for that bullet weight no matter what the bullet material is made of.

Very true. The part where you get the longest bullet possible for a given weight is also the highest possible form factor. See how they go hand in hand? I guess I am of the mind set that the only reason 'length' ever goes into a higher BC is due to the better form factor.

Again, I fall back on the comparision between the 300 gr SMK and the 265 gr AT RBBT wildcat bullets. The Wildcat is MUCH lighter and much longer and with a finer meplat. All of which adds up to a much higher BC bullet with the ability to be driven much faster then the heavier bullet as well.

Dont forget the fact that the ony reason it is longer is due to the more aggressive design, or form factor, if you will.....

Form factory certainly has alot to do with BC value but I still stand by the point that a longer bullet will always match of exceed a shorter bullet in BC. Now if we used a long aluminum bullet that weighted DRAMATICALLY less then a lead core bullet I would certainly believe that momentum would be dramatically difference. In the case of the bullets we are talking about, it will be very minimal. I am sure its there but in a very limited role.

If you take an aluminum bullet and a jacketed lead bullet both of absolutely identical demensions the BC's would be miles apart. Equal sizes and shapes, the jacketed lead bullet will have a MUCH higher sectional density period. Remember BC is largely made up of Sectional Density AND form factor. It is for this reason that 7mm bullets of the same weight and form factor as a 30 cal bullet will ALWAYS have a higher BC. It is the change in sectional density here that is the root of the higher BC.

Again, not flaming in any way, just saying that the resulting BC value is likely determined by both theories in conjunction with each other, not one apart from the other.

No flame here either. Just my point of view.
Technically, BC = (drag deceleration of the standard bullet) / (drag deceleration of the actual bullet). The reference of the standard bullet used is 1.000.

The below statements are not all there is to BCs. rather, the info below is BC in its most simple state used for comparison purposes to show the relation between sectional density and BC.

BC is (for the most part) a simple function of Sectional Density and Form Factor.

SD = Bullet weight (in pounds) / (bullet diameter * bullet diameter)

BC = SD / FF

Change the SD and not the FF and you change the BC plain and simple.

Two bullets of identical demensions where one is made of aluminum (specific gravity of 2.69) and the other is tungsten (specific gravity of 19.62) the tungsten will have a MUCH higher BC. If you have a jacketed lead bullet and an all copper bullet of identical demensions, again the jacketed lead bullet has a higher BC. You could have an aluminum bullet twice as long as a tungsten bullet utilizing the same form and the tungstun bullet will still win. It would take an aluminum bullet 7.3 times longer than a tungsten bullet to surpass the BC of the tungsten bullet. So if a bullet made of tungsten was 1" long, it would take an aluminum bullet of 7.3" to surpass the BC of the 1" tungsten bullet.

Granted there will be other factors at play where the BC is concerned such as bore quality, velocity, stability factor etc.........The above is geared towards the basic mathematical components where all other factors such as bore quality, velocity etc.... are equal. Also it should be noted that the above statements are based on the G1 drag model. It is somewhat difficult to compare ballistic properties of different bullets if the BCs are refering to different drag models. With all the computers in the world, as powerfull as they are and what knowledge of mathematics we have, there is no substitute for measuring BC accurately without firing tests. Be it doppler, TOF (by way of bullet activated relays), double chronies, or drop tests. We can predict them with a reasonable degree of accuracy. Accurate enough to get on a big peice of paper anyway to be fine tuned.

So in short, in a sense, bullet length has alot to do with a bullet's BC but not in and of its self. Only how it relates to the overall bullet weight which in turn gives life to the SD.

Respectfully,

M
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Last edited by Michael Eichele; 02-20-2011 at 07:02 PM.
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  #23  
Old 02-20-2011, 10:53 PM
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Re: New Barnes bullet testing.....

Jon,

No I did not say the nose was the same length. I said they had similiar ogive designs, nothing about nose length. Since the HP has a HP, its much shorter then the TTSX nose because it has a tip, both have similiar taper to the design of the ogive but I did not say they were the same length.

They have similiar body lengths, the SMK had a VERY slightly longer BT, 10 thou maybe but the TSX has a longer nose and finer meplat.

The numbers will come out in the end so all it takes is a bit of drop testing. If the weather was not 10 below zero right now, this conversation would not even be happening because I would have posted solid drop numbers for various ranges.
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  #24  
Old 02-20-2011, 11:28 PM
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Re: New Barnes bullet testing.....

Fiftydriver,

I will get some and try them down here. It is a nice warm 25 C here today.

Also they may shoot flatter down here seeing as they are flying upside down. LOL
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  #25  
Old 02-20-2011, 11:30 PM
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Re: New Barnes bullet testing.....

First off, let me state that I respect both of you guys tremendously. We have been involved in many debates over the years. Often, mostly on the same side, sometimes disagreeing, always respectful.

I also freely admit that both of you likely have far more experience on the scientific end of bullet design. I am not a bullet maker, I am not an external ballistic expert. The extend of my expertise is knowing how to make a rifle shoot a bullet to the same point of aim most of the time. I also know a bit about how drive that bullet faster then most averge chamberings. This is similiar to horse power in cars, the larger the displacement, the easier it is to make big HP. Same way with rifle chamberings, larger the case capacity, within reason, the faster you can drive bullets.

As far as ballistic testing, I take bullets set them side by side, take measurements and record them and then shoot them and record what happens while the bullet is in the air. Then do the same with other bullets and compare shape, design and ballistic performance. Simplistic in the extreme.

If the damn weather was not 15 below zero and snowing right now I would have offered plenty of solid drop test data and this conversation would not even be happening. Likely the results will lean closer to what you two are predicting. I simply hope that the longer TTSX bullet will offer at least as high of a BC as the SMK. IF it will, with its 200 fps velocity advantage and ability to survive impact velocities MUCH higher then the SMK for big game hunting, and also offer long range expansion, it could only be called a win for all of us.

Again, both of your advice, comments, opinions, facts and experience is more then welcome and thankfully accepted. I was not trying to prop up the Barnes bullets into something they are not, just that from the limited testing I have been able to do, they look promising for the hyper velocity chamberings which are very hard on conventional match bullets at the terminal end of their travels!!!

I freely defer to the ballistic experts, I just hope these bullets will perform like I think they will.
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  #26  
Old 02-21-2011, 12:45 AM
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Re: New Barnes bullet testing.....

Quote:
Quote:
Originally Posted by Michael Eichele View Post
Thanks for sharing.

I have been looking forward to testing the new 175LRX bullet. It is rumored that it will have around a .507ish BC. I was hoping for .525+ and that may be a tall order from barnes but it is doable for the right form factor. It is my opinion that a mono metal 175 bullet could be made to have up to about a .575 G1 if made right. I find that .638 for the GS 177 hard to believe but since they wont ever return emails or proccess orders, I cannot even try them to see for myself. It's too bad becuase it seems like even if .638 is too high, they probably have close to .58+ with a published expansion figure of 1500-1600 FPS. It would at least be nice to try them. I just ordered a 10x barrel just to run them but since they wont even accept may orders and emails I am about to just give up and cancel the order on the 10x barrel.

The last time I talked to one of Barnes techs, he said they should expand on game as low as 1400FPS. He said 1600' for water jugs and to subtract 200' for flesh for 1400'.

I find that very tough to believe especially scince the time before that they said 1800FPS for water filled jugs and 1600 for flesh.

In any event, it may be worth a good unbiased test. It may just be the best overall bullet for my 308s if the BC is near the .520 mark. Hopefully.

It would be interesting to see what the BCs of the 265 Barnes is at 338 Edge velocities.

Thanks again.

M

Thanks again.
Interesting Michael, I talked to Anthony from GS here in the states the week before last and he told me to make the order online. I ordered 4 boxes (200) 177's and got an email back the next day confirming the order. I'm expecting them in about 5 weeks.

On the BC of the 177... it's listed ad .638 @ 3300 fps. It's about .012 longer than the 210 Berger which Brian listed @ .631. I'm not sure what velocity range this is for, but I seriously doubt it's for 3300 fps. I'm guessing less than 3000. The Berger has a greater SD, but the GS is longer with a little better form factor. Just off the top of my head, I think the GS listed BC is probably fairly close... likely .6ish One of our members shot some a while back and his drops suggested the BC was correct. One set of drops isn't conclusive, but when all is considerd, I think it's probably pretty close. ...And definitely better than any Barnes bullets.

Did you try ordering online?

-Mark

Last edited by MontanaRifleman; 02-21-2011 at 01:07 AM.
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  #27  
Old 02-21-2011, 01:01 AM
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Re: New Barnes bullet testing.....

Quote:
Originally Posted by MontanaRifleman View Post
Interesting Michael, I talked to Anthony from GS here in the states the week before last and he told me to make the order online. I ordered 4 boxes (200) 177's and got an email back the next day confirming the order. I'm expecting them in about 5 weeks.

On the BC of the 177... it's listed ad .638 @ 330 fps. It's about .012 longer than the 210 Berger which Brian listed @ .631. I'm not sure what velocity range this is for, but I seriously doubt it's for 3300 fps. I'm guessing less than 3000. The Berger has a greater SD, but the GS is longer with a little better form factor. Just off the top of my head, I think the GS listed BC is probably fairly close... likely .6ish One of our members shot some a while back and his drops suggested the BC was correct. One set of drops isn't conclusive, but when all is considerd, I think it's probably pretty close. ...And definitely better than any Barnes bullets.

Did you try ordering online?

-Mark
I did place an order online at their website. Monday the 14th. I have not got a response. I have tried emailing their tech some time ago as well with no response.

M
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  #28  
Old 02-21-2011, 01:25 AM
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Re: New Barnes bullet testing.....

Quote:
Quote:
Originally Posted by Michael Eichele View Post
I did place an order online at their website. Monday the 14th. I have not got a response. I have tried emailing their tech some time ago as well with no response.

M
Call Anthony, I'm sure he can help you out.

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Gerard hasn't always answered my emails
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