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.300 Winchester Magum Bullet Choice - Expanded

 
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  #8  
Old 01-13-2006, 12:04 PM
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Location: Houston, TX
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Re: .300 Winchester Magum Bullet Choice - Expanded

I have killed about 100 deer with my 3006 and 300RUM using 168gr SMK's in the 3006, and 220gr SMK in the 300RUM. I haven't lost a deer yet!!!!!! This has been anywhere from 10yds to 700yds. I use the 300RUM for elk, and have taken 7 elk now, anywhere from 350yds to my longest shot last year at 780yds. I've never lost an elk yet!!!!!!!! In my opinion, the 168's SMK's do blow up quick at short distance, but cause major tissue damage to a depth of about a foot....and the 220's do the same thing for about a foot and a half. But, at 500+yds, the 168's only penetrated the deer on a broadside shot about 9-10 inches. The 220's in the same scenario penetrate about 15 inches, and both are devastating from point of entry through the entire penetration.

hope that helps
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  #9  
Old 01-13-2006, 07:23 PM
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Re: .300 Winchester Magum Bullet Choice - Expanded

[ QUOTE ]
Unfortunately, they are not. You can't believe Barnes' advertised BCs. The 165 TSX is going to have a lower BC than the 165 BT/AB and it'll be a good shot lower than the 180 BT/AB.



If you want to stretch the legs of that rifle, the plastic-tipped 180's or 200 AB are going to make life much easier than the lighter, lower BC bullets.

I'm anxious to try the new MRX's though. Their actual BC's should finally be on par with the Ballistic Tips, Accubonds.

Of course when you want to get really serious, the heavier Wildcats, when available, will be excellent choices. The new 210 SMK might turn out to be a great bullet as well.

[/ QUOTE ]

I have shot the 180 Ballistic Tips at long range, and my results show their advertised BC to be Greatly exaggerated.... although they are VERY accurate... I was wondering if you had any data to back up (or refute) my results...?

The advertised BC is .507, I come up with more like .415 what say you?
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  #10  
Old 01-13-2006, 07:56 PM
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Re: .300 Winchester Magum Bullet Choice - Expanded

I haven't tested the 180 BT but I have the 200 AB. It came out a little lower than advertised but was fairly close--probably within the test's margin of error.

So I wouldn't expect a 180 BT to be anywhere near that low. How did you arrive at that number? I'd expect them to be right around the .5 mark in a good test, properly corrected for conditions, etc. That said, they don't have as efficient a shape as either the Hornady or Swift--both those will beat it (despite Hornady's more conservative rating).
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  #11  
Old 01-13-2006, 08:25 PM
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Re: .300 Winchester Magum Bullet Choice - Expanded

I have shot it from 0ft to 6000ft density altitude, I shot across a crony, I checked my scope to be sure it really tracks 1/4-inch per click, and ran my real-world results thru ExBal... in order to get my computer fantasy to match up with my real-world data, I had to fudge the BC down to .415 (no wonder my shots were hitting low @ long range)-Once I did that, my computer-generated drop charts are spot-on.

With the Berger 210's however, I entered all the data, used their advertised BC of .640, and BAM- a computer-generated drop chart that matches up almost exactly with the real world! Never off more than 1/4 MOA from my real results... impressive.

A recent Shooting Times article showed the 180 BT as having a BC of .440, a little better than my result.
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  #12  
Old 01-14-2006, 05:39 AM
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Re: .300 Winchester Magum Bullet Choice - Expanded

What brand of chronograph are you using? And are you chronographing under all these conditions at all the differing altitudes? (I recently found "temp insensitive" Retumbo and 50BMG did, in fact, drop the velocities in cold weather more than I thought they would.)

Rick Jamison should be highly commended for actually measuring and publishing BC's. Of all the thousands of pages of gun rags...you'd think more than one person would do it but he seems to be the only one who ever has. I'd like to personally thank him for his efforts....

That said, the BC's he measures are always low for all the bullets he measures. Correcting for environmental conditions, using the time of flight method (maybe his target is a fraction of an inch too far?), I don't know exactly the reason but they're always low.

What makes them useful, and what so many others miss, is that he doesn't just measure one bullet. He measures a bunch so if there are errors in his setup you can still compare them to each other relatively. Sort of the whole "control" part of the scientific method that many miss by simply posting anecdotal results from a single bullet.

I don't think I saw the article you're talking about, but a few years ago he measured the 180 BT at .443. But he also measured the SST at only .454 and Scirocco at .460. And those were the three highest out of all the 180's he measured in that test. The 180 X (advertised .511) only measured .370. The 200 X (advertised at .550) measured .405. None measured over .476, the highest in this particular test--which was the 200 Sierra Gameking, advertised .560.

His efforts testing and his results are great data if you just know how to look at it. So the numbers are skewed low--that's OK because they're skewed the same amount for all the bullets he tests so you can still compare bullet to bullet and see who wins the race.

In this particular test, he measured 14 different 180s. The BT was the 3rd highest, just a hair behind the SST and Scirocco. Just exactly where it should be from an Engineering standpoint looking at the bullets' shapes. So it's good data. Relatively speaking.

In the test you read, what other bullets did he test? How did they do?
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  #13  
Old 01-14-2006, 07:22 AM
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Re: .300 Winchester Magum Bullet Choice - Expanded

I have a PACT Chrony, which I have mainly used at sea level, so let's stick with sea level data for now.

180 Balistic Tip, .507 BC, 80deg F, Zero ft Density Altitude, 3080fps 100yd zero, 1.95 inch sight height.

My USO SN-3 adjusts in Shooter's minutes, not true MOA, so all my figures are in SMOA, or IPHY (inches per hundred yards) My reticle is in SMOA, as well- rather than mildots, and I have compared holding over with dialing, and the reticle and adjustments agree.

ExBal says 26.8 SMOA @ 1000 yards
My Data Book says 31.5 SMOA @ 1000 yards

Bullet hits 47 inches lower than ExBal says.
Fudge BC down to .415, and it agrees with my data book, every hundred yards, out to 1400 yards, the furthest I have shot them. I'm not a scientist, so all I can say for sure, is these are my results, with my rifle.

After fudging the BC, I printed out drop tables from zero to 6000 ft Density altitude, and used them with good success. Hits on steel out to 1000 yards with the 6000-foot data. (I was at 3500ft altitude, but as you may know- on a hot day, the density altitude can easily be 2-3000 feet more than your actual altitude.)

Rick Jamison should be commended for publishing real BC's- as you said- no one else will.

Here are some more of his results- he was loading for 30-40 Krag, hence the low(er) velocities.

180 TSX 2390 .394
180 NBT 2382 .444
200 NAB 1975 .491

marc
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  #14  
Old 01-15-2006, 07:21 PM
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Re: .300 Winchester Magum Bullet Choice - Expanded

Interesting, Marc. 47"--yikes! I guess that's why we actually shoot at these ranges to confirm the charts. [img]/ubbthreads/images/graemlins/wink.gif[/img]

You don't happen to be using a really, really slow twist do you? Other than that I think there must be some other error (or combination of more than one) to cause the discrepancy--in other words the BC of the bullet isn't entirely to blame.

Even Rick's data you posted shows the bullet doing much better. I measured the 200 AB at .550 and I'm confident that's a good, conservative number if anything as Brent Moffit here has also measured it numerous times higher than that--right up close to advertised. So if you scale Rick's data to that known control, his measurement of the 180 BT goes to .497 even using my conservative number for the AB. Trust me, if he measured the Berger he wouldn't get anywhere close to .640, it would be low just like all the rest.

I know many are happy once they have actual firing results and quit there but I'm too anal I guess. [img]/ubbthreads/images/graemlins/wink.gif[/img] I'm happier when I can find out exactly why the computer was wrong. It always comes down to me putting some garbage in.

The first thing I'd double check is the muzzle velocity. My 20 yr old Pro-Tach chronograph has served me well over the years, but it wasn't uncommon at all--especially under "funny" light conditions--for it to give me whacky readings. Sometimes 200-300 fps too high. But they'd be consistent and give me an average that was that high.

If I had believed those velocities and adjusted the BC in the program to match the actual trajectory I would have had to put in about .3 for some bullets. Two wrongs added to get the right answer.

That's why I just ordered my second Oehler. Getting a really accurate MV is highly important. So I'd try and shoot that load over another chronograph to see if that MV wasn't a bit optimistic. It happens, and if off far enough that could explain most of the difference by itself.

Then I'd measure the click value. If it was really only, say, .95" at 100 that might go unnoticed but could mean quite an error out at 1000. And of course, when things aren't adding up the 100 yd zero should always be re-checked. Sometimes scopes just don't track right and you find the error there.

Then there are conditions. If you were using a barometer, you might want to check it against another, etc. The weather can easily shift the density altitude close to 1000 ft without your noticing unless you're measuring. Enough to make a significant difference at 1000 yds.

These things or a combination could easily cause the required 31.5 SMOA. If it was more of an unknown bullet I'd be more likely to blame the BC but I really think we have enough data to show that this one's BC shouldn't be that low, and if you need to enter it that low in the program to make it match the real world, I really think it must be compensating for some bad data entered elsewhere.

Anyway, good luck.
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