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Ballistic coefficient. Educate me.
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Picture of Karoo
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I am wanting to get two different bullets to shoot as close as possible to each other.
A Barnes TTSX and a Hornady Interlock.
The Barnes is frightfully expensive for us on this side of the ocean but Hornady very much more available.
Am I right in assuming that the Hornady Interlock 168 gr would be a better match to the Barnes 165 gr than the Interlock 165 gr, because their ballistic coefficients are reasonably close, due to the longer-for-weight Barnes? All else being equal.
Any other suggestions for a cup-and-core bullet that does well with a 300 WSM.
I am blessed that my 270 shoots many different bullets to the same point of impact and wish the same for my 300 WSM.
The truth is that only for about 20% of the time do I need the Barnes quality and for the rest a conventional bullet will do just fine.
Thanks.
 
Posts: 779 | Location: Eastern Cape, South Africa | Registered: 24 December 2006Reply With Quote
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Picture of Rapidrob
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There will be several factors that come into play that will allow/disallow the Hornandy bullet to shoot with the same accuracy.
1. Bullet diameter
2. Hardness of jacket material
3. Length of bullet body that contacts the rifling
4. The shape of the bullet base.
The latter being of most importance. How the gasses effect the bullet as it leaves the muzzle pushing on the base of the bullet is critical for accuracy.
That being said most Hornandy bullets are very accurate. You may have to alter your load,seating depth and crimp force to achieve the same accuracy but you should be able to do it.
I have shot the Hornandy bullet out to 800 yards with very good results.


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Posts: 442 | Location: Albuquerque | Registered: 28 March 2013Reply With Quote
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You need to read the book Applied Ballistics by Brian Litz. This is too big a can of worms to open here.

At reasonable hunting distances say under 500 yards you wont see much of a differance.

Know this BC is varying constantly because it is velocity dependant.
Manufactures exaggerate their BC, and Barnes is one of the worst about doing so.
You must shoot the bullet and let it tell you what it is doing out of every gun.
 
Posts: 154 | Location: N. Texas | Registered: 26 February 2014Reply With Quote
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Picture of Karoo
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Thanks Rapidrob and Abbispa,
Regarding the shape of the base, then would two boattails match better than two flatbases, all things being equal?
(All hypothetical, I understand.)
 
Posts: 779 | Location: Eastern Cape, South Africa | Registered: 24 December 2006Reply With Quote
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quote:
Originally posted by Abbispa:
You need to read the book Applied Ballistics by Brian Litz. This is too big a can of worms to open here.

At reasonable hunting distances say under 500 yards you wont see much of a differance.

Know this BC is varying constantly because it is velocity dependant.
Manufactures exaggerate their BC, and Barnes is one of the worst about doing so.
You must shoot the bullet and let it tell you what it is doing out of every gun.


I agree. Bullet makers constantly exaggerate their ballistic coefficients because it sells. You can only trust what you see on paper. And, out to 300 yards, BC has not seemed to matter as much as bullet weight in changing point of impact. But the bottom line it, you have to zero the rifle at distance when ever you make a bullet, powder, change. The dynamics of recoil change and that will change point of impact.

Most of my hunting rifle shooting is at 100 yards, 200 yards, 300 yards, at CMP Talladega. I wish they had a 400 yard target. I know 500 yards is 8 MOA up from 300 yards with most cartridges. But I am going to say, those who think they are going to hit something at 500 or 600 yards, you are far too optimistic. Maybe if you walk the misses to the target, but 500 yards is a long way to hit the X ring first shot.
 
Posts: 1195 | Registered: 10 October 2005Reply With Quote
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I am a little like Karoo in wanting different loads to shoot close to or on the same Point Of Impact. I like to have back up loads to counter occasional component shortages and to be able to keep shooting with either no, or minimal scope adjustment. For my .300 WM ( I know, not quite the same as the 300 WSM, but maybe close ? ) the standard I used was Barnes TTSX 180 gn. I had to experiment with different bullet makes to find the one that shot closest. Initially these were Hornady SST and Interbond 180 gn. Hornady GMX, Nosler Accubond, Swift Scirocco, Sierra Pro Hunter were not as good. More recently I tried Hornady ELD-X 178 gn which shoots so well I am going to switch to this bullet. It doesn't shoot to exactly the same point as Barnes TTSX 180 gn but it's not far off.
As other posters have said I wouldn't rely extensively on BC figures to match up bullets. Making up loads to range shoot at various distances will reveal the truth. Good luck with your endeavours.


Hunting.... it's not everything, it's the only thing.
 
Posts: 1994 | Location: New Zealand's North Island | Registered: 13 November 2014Reply With Quote
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Couple things. If you want the long discussion of bullets and bullet making there are two brothers, formerly in business together, but not now. Dave Corbin, corbins.com, swage.com, etc.; and his brother Richard, rceco.com. Both have books they have written on line on the web site. Sans pictures but can't have everything.
--At times like these I am reminded of an old saying: "lures are not designed to catch fish, but to catch fishermen." My intro were the writings of the late Jack O'Connor via Outdoor Life magazine. Quite late I came to understand that he was in ROTC during WW I. No colorful plastic tipped bullets in those days.
--For some reason beyond my limited math/engineering background, the match bullet of .308 caliber was 168 grains. People not concerned about highest score punching paper ... 150 was the all around for the '06. Then, .308 took over in the military and the 150 grain match bullets came on.
--Yes, I have a point. In the old, pre plastic tip days, if the bullet had a lead tip, usually it was for hunting/game. If there was no lead showing, often it was a match bullet. The more durable tip w/o lead showing was, I am told, to make the tip deform less in the rapid working of the action in competition. I had a friend whose son was quite a competitor until he hurt his back. He was also a gunsmith. He told me that one competitor competed exclusively with Nosler Partition bullets. These got him the groups although costing more. On well. I hope the ELD X works out for you. As said, the ballistic efficiencies are guidelines and only shooting the round will tell the final story. Barnes started making round nosed bullets out of copper pipe. Fouled more, or so said Mr. Ackley, but expansion was very dependable. Fred sold out many moons ago and now they are doing a whole lot more. Happy Trails.
 
Posts: 519 | Registered: 29 August 2007Reply With Quote
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karoo could you provide a little more info about the point of impact of the two bullets you are trying. Is one bullet grouping say 3 inches higher than the other @ 100 100yds or to the left or right ??? What distances are you normally shooting at ? Do you have access to other brands of bullets other than Barnes and Hornady ? In my experience each barrel seems to have some preferences as to what bullet it shoots best. First thing I would try would be 180 gr Hornady bullets and the 165 gr Barnes bullet.
 
Posts: 2432 | Location: manitoba canada | Registered: 01 March 2001Reply With Quote
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I've found similar weight Hornady Interlocks and Nosler partitions shoot very close to one another in my 30/06 and .338 Win.mag. Other than the bullets the loads are identical in each caliber.


Tom Z

NRA Life Member
 
Posts: 2286 | Location: Pennsylvania | Registered: 07 January 2005Reply With Quote
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Picture of Karoo
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Thanks for the comments.
Snowman, I have not started loading yet, so want to start with the ones most likely to succeed.
Also, the Interlocks and TTSXs are the perfect combination, being the cheap/strong respective duo.
I do have access to most other brands of bullets. Hunting distances would be 300 yards and under.
Hope this makes sense. As stated earlier, I do have this ideal combination with my 270.
 
Posts: 779 | Location: Eastern Cape, South Africa | Registered: 24 December 2006Reply With Quote
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Karoo I have been loading for over 50 years and in my experience every rifle seems to be a law onto itself. Some rifles will shoot several bullets to near the same point of impact while others have quite different points of impact. You have to try some bullets that are availible and see what the POI is with each bullet. I have never seen any correlation between BC and POI
 
Posts: 2432 | Location: manitoba canada | Registered: 01 March 2001Reply With Quote
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Picture of youngoutdoors
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In my experience BC changes with velocity. Any body else feel this way. A very pretty popular bullet maker told me this years ago when I couldn't get the numbers to come out right with the distances and velocities I was shooting. I changed the BC until it matched the drop I was experiencing and my drop charts suddenly worked.

God Bless, Louis
 
Posts: 1368 | Location: Mountains of North Carolina | Registered: 14 January 2008Reply With Quote
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Sierra's Pro Hunters, and Nosler Partition will shoot to the same impact point.
I dont look at BC's. Out to Normal distance, it does not matter
 
Posts: 188 | Location: Las Cruces, NM | Registered: 31 March 2002Reply With Quote
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Depends on the rifle.

Some will shoot several types close together.

Others will throw them like a shotgun patern.


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Posts: 66765 | Location: Dubai, UAE | Registered: 08 January 1998Reply With Quote
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quote:
Originally posted by Saeed:
Depends on the rifle.

Some will shoot several types close together.

Others will throw them like a shotgun patern.


So far, in my two rifles, 140 grain TTSX does not shoot to the same point of aim as 140 grain Partition bullets.
I am changing over to copper on account of our new rules in California, will peddle the ones with lead.


TomP

Our country, right or wrong. When right, to be kept right, when wrong to be put right.

Carl Schurz (1829 - 1906)
 
Posts: 14332 | Location: Moreno Valley CA USA | Registered: 20 November 2000Reply With Quote
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