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Very Hot Topic (More than 25 Replies) Bullet Designs and Specs (Read 178629 times)
frnkeore
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Bullet Designs and Specs
Apr 30th, 2013 at 2:03am
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I bought a bullet design program about a year ago and I have found it to be very accurate in calculating mathematical ballistic coefficients and I thought it might help people on this forum to make choices and decisions of what they may want to try.

My main area of interest is spitzers and most of these will be in that area but, not all. 

I will start with the Ideal/Lyman molds that I have and then go on to target molds that I own, as well as bullets out of molds that I have obtained from friends.

Frank

  

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frnkeore
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Re: Bullet Designs and Specs
Reply #1 - Apr 30th, 2013 at 2:18am
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SSShooter
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Re: Bullet Designs and Specs
Reply #2 - Apr 30th, 2013 at 7:36am
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Very nice. What is the program name and where did you purchase? Thanks.
  

Glenn - 2x CPA 44 1/2 w/22LR (Shilen ratchet-rifled & Bartlein 5R rifled), 38-40RH & 38-55WCF (Bartlein 5R rifled) & 40-65WCF (GrnMtn 'X') barrels
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MikeT
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Re: Bullet Designs and Specs
Reply #3 - Apr 30th, 2013 at 4:58pm
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frnkeore,

Have you tried these bullet designs against each other to see if the calculated BC holds up in the real world?

Keep on hav'n fun!
MikeT
  
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frnkeore
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Re: Bullet Designs and Specs
Reply #4 - Apr 30th, 2013 at 6:22pm
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Mike,
All that I can tell you right now is, Lymans # 4, Cast Bullet Manual, lists the 257420 at a BC of .129 and the 319247 at a BC of.208. 

One thing that you have to remember about bullet shapes and BC's is that velocity can make a very big difference. i.e. flat nosed and round nose bullets generally have a higher BC at lower velocities <1200 fps and extremely sharpe points give higher BC's at over 22-2400 fps. 

If you can look on page 98 of the 46th Lyman reloading manual it shows the differances in BC's for different velocitys of the same cast bullets. I believe Sierra give simular info on their jacketed bullets.

I don't know what velocity that the BC's are calulated at in this program but, you can use it to see what happens with the change in bullet shape and make comparisons to other bullets. 

I have two other programs that calulate BC and this one compares well with them. But, only velocity differances over a given distance, as gaged by caliberated chronographs will give the actual BC and you have to factor in air dencity on any given day along with that. 

In the end it is just a tool to be used in designing bullets with the hope of reducing wind drift. BC never won a match all by itself Smiley

Frank
  

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frnkeore
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Re: Bullet Designs and Specs
Reply #5 - Apr 30th, 2013 at 8:24pm
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Part 2.
First is a no name mold that I have.
Even though the picture shows no taper. all the below molds are tapered by various amounts.
« Last Edit: Mar 16th, 2015 at 9:10pm by frnkeore »  

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ole7groove
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Re: Bullet Designs and Specs
Reply #6 - Apr 30th, 2013 at 9:11pm
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Frank- I've tested just about every conceivable spitzer design cast bullet, many times the BC's of the bullet design software do not come close to the actual BC's determined by actual ballistic testing. Most software programs assume that the bullet is stable for its entire travel to the target, this is NEVER the case (The Bullets Flight by FW Mann), therefore the BC's tend to be higher than actual test firing, this is especially true in the case of the 100 and 200 yard ranges fired by schuetzen rifles. For instance the software of your bullet design program is for longer ranges per BPCR shooting. What my ballistic system allows me to do is find the optimum stability velocity for each bullet/rifling twist combination.
Regards-
Barry
  
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gunlaker
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Re: Bullet Designs and Specs
Reply #7 - Apr 30th, 2013 at 10:31pm
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That looks like a pretty nifty piece of software.

It would be interesting to compare the B.C. Of the bullet as it was cast with it's B.C. after it gets bumped up upon firing.  I know that smokeless is different than black powder, but I've seem pictures of many slender nosed bullets whose noses looked entirely different after being shot over a case of black powder.  Perhaps the change in shape due to bump up is one factor in the differences obtained via simulation and "real life".

Chris.
  
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ole7groove
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Re: Bullet Designs and Specs
Reply #8 - May 1st, 2013 at 8:38am
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Chris- I've noticed the bump/slump also with smokeless powder loads and I suspect that some spitzer designs  may also allow the larger ogive radius noses to have a tendency to slump off center due to rotational acceleration while confined in their travel down the barrel. Remember that BC is only an indicator of a bullets efficiency (time to target) and not an indicator of its consistent accuracy at any given range. Currently I believe a 5r ogive to be about optimum for efficiency and structural strength.  Prior to 1978 spitzers were rarely, if ever, used in ASSRA matches, with all the testing I've done over the past 10 years I still believe a flat nose bullet has an edge in accuracy for calm condition shooting. An accurate, higher BC spitzer has the advantage with its reduced wind drift. The spitzer style bullets became popular after the first Coors Match in 1982 and 200 yard shooting, prior to then most SS matches were at 100 yards. 
Barry
  
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Aonghas
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Re: Bullet Designs and Specs
Reply #9 - May 1st, 2013 at 9:02am
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Quote:
Frank- I've tested just about every conceivable spitzer design cast bullet, many times the BC's of the bullet design software do not come close to the actual BC's determined by actual ballistic testing.
/snip/

Test-firing comes upwith a lot of surprises. Some years ago I made a series of aluminium moulds to cast bullets for a little rifle. Nothing so grand as calculations - it was pure suck-it-and-see. The first few were too light, and at 130 yds (FP to sand in butts) the bullets made (approximately) a ten-foot group...

In the end I just used 9mm and .38 bullets whose weights I knew (or I'd weighed). It shot perfectly with, if I can remember that far back, 126 grain Luger cast bullets - about three times the weight of the first of my first batch from the home-made moulds.

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frnkeore
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Re: Bullet Designs and Specs
Reply #10 - May 2nd, 2013 at 1:31am
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More Ideal/Lymans
« Last Edit: May 2nd, 2013 at 1:44am by frnkeore »  

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frnkeore
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Re: Bullet Designs and Specs
Reply #11 - May 2nd, 2013 at 1:35am
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frnkeore
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Re: Bullet Designs and Specs
Reply #12 - May 2nd, 2013 at 1:38am
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Even more
« Last Edit: Mar 16th, 2015 at 2:49pm by frnkeore »  

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frnkeore
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Re: Bullet Designs and Specs
Reply #13 - May 4th, 2013 at 9:51pm
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Some more custom bullets
« Last Edit: Aug 2nd, 2015 at 10:04pm by frnkeore »  

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frnkeore
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Re: Bullet Designs and Specs
Reply #14 - Jun 1st, 2013 at 4:54pm
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JLouis wrote on Apr 30th, 2013 at 6:44pm:
Without the use of a sofisticated and state of the art ballistics system it would be next to impossible to verfy real life BC's. I was fortunate to be able to do so last Thursday and it was a real eye opener. The results were not close to any of those guess and by golly computor programs offered on the net, including the bullet design software Frank has shared and that comment is not meant to be offensive, just real comparative results from the same program.


So far my program has shown it's self to be very conservative. I talked to Barry and he had results for my borrowed 33 cal Ron Long bullet that was shot in the Modesto match by it's owner. The program predicted a BC of .395 and in actual firing at 200 yards the BC was .44. With another less areodynamic bullet my program predicted a BC of .282 and that bullets actual 200 yard BC was .32 and change. So, it maybe inaccurate but, in the direction at I preffer Smiley

Frank
  

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