Good all in one Black Bear to Deer in a factory 10mm?

[Roguer]

MI resident myself. Always got a chuckle out of the DNR's position on this. Dead deer parts and cougar tracks on the Lake Superior shoreline and lots of sightings for the last 20 years = nothing to see here people. Just misidentification caused by big house cats..........

Nope. MN. 

I found my old stash of 10mm DT 200 grain HC Lead solids. I'll have to see if there is a feeding issue with my LWD barrels for it. It appears the feed ramps might be to small for the broad bullet flat nose from what I Googled-Fued. Since we are going to have some cold weather the 416R LWD barrel will be going in it for the lead ones.  When I had money I invested in a few "On sale LWD barrels" seems my idea was a good one, even got one with a comp. They make the same type of barrels under double diamond brand of the LWD ones I have, not the Alpha Wolf ones.

Good added info I see. Very informative.

[Rojo27]

Bullets stabilize based on their length and diameter when using the classic Greenhill formula.

twist = 150*(projectile diameter^2/projectile length)

But, this simplistic formula assumes a lead bullet traveling at velocity around 1900 fps.

In all reality we are looking for gyroscopic stabilization, which is determined by the spin rate (revolutions/time), projectile geometry, projectile density.  Given the modern complexity of bullet shapes and composition, we are lucky that averages of these last to attributes work just fine for the most part.

The Bowman equation extended Greenhill to account for the impact of velocity on spin rate.  Increase velocity (distance/time) for a given twist (revolutions/distance) and the spin rate goes up, increasing stability.  This equation assumes that velocity is in inches per second:

twist = (sqrt(velocity)) * (projectile diameter^2/projectile length)

However, since we usually measure velocity in feet per second, and the square root of 12 is 3.4641, Bowman's equation is usually simplified to:

twist = 3.5 * sqrt(velocityFPS) * (projectile diameter^2/projectile length)

As different materials are used in bullet construction, the specific gravity (SG) of the bullet changes, usually going down since very few elements available to reloaders are more dense than lead.   As SG goes down, the bullet has to spin faster to compensate.  Different shapes also impact this as long boat tail hollow point bullets are longer than their mass would suggest, but in general these factors do not play heavily into handgun bullets.

Barrel length has no bearing on stabilization except as it impacts velocity.  Increasing barrel length usually increases velocity and therefore spin rate, allowing bullets to better stabilize.  But this really only applies if you have a bullet the is barely stabilized.  In general twist rates are faster than needed because there is a big delta between the minimum spin rate to stabilize and the maximum spin rate before the bullet rips itself apart. (Although that can happen if you shoot super-light varmint bullets out of a fast twist barrel meant for heavy, long range target bullets.  Think 36 grain .224 bullets out of a 22-250 in a 1:7 twist barrel meant for 90 grain bullets.)

Increasing barrel length does not impact twist rate.  A bullet fired from a 1" barrel and a 30" barrel in a 1:16 twist will both rotate 1 full revolution for every 16" of travel.  The rifling does not accelerate the spin the longer the bullet is in the barrel.  Unless it is gain twist rifling or the bullet is skidding in the rifling.

When talking about 10mm and doing the math assuming a 200 grain bullet of about .625" of length, any twist faster than 1:20 should be more than fine for any velocity above 600 fps. 

So, we are left with the mystery of why a longer barrel on a Glock seems to make a difference but the same bullet stabilizes fine in other guns with similar length barrels.  On the face of it, the Glock's faster twist should provide for success with even shorter barrels and corresponding velocity and spin rate reductions.

I personally think three factors are at play here and I think they are resulting in some bullet skid in the rifling.

Factor one is the ridiculously fast twist in the Glock barrel.  1:16 is pretty standard for pistols in 9mm and larger.  As we have said, 1:20 is fast enough for even the most anemic 10mm loads in long bullets, and shorter bullets require less spin to stabilize. So, the Glock spin is more than twice as fast as needed, and more than three times as fast as needed at 10mm velocities (1:31 at 1200 fps)

Factor two is the loose Glock groove diameter.  Every Glock I am aware has slugged at .402" give or take.  I have not measured bore diameter, but the excess groove diameter provides some slop.

Factor three is the polygonal rifling that Glock uses.  This results in less abrupt, sharp, grabby rifling.

I think these three factors together allow the bullets a significant amount of skid that you don't see in a 1:16 cut rifled barrel.  As a result, spin is not being fully imparted to the bullet at the time of engraving, and the bullet behaves more like it is being fired from a gain twist barrel

my 2¢

And some citations:

Here are some twist calclulators.  Note that none of them ask for barrel length.

http://bergerbullets.com/twist-rate-calculator/
https://thebarreloutlet.com/twist-calculator/
https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

And finally, another calculator with sources and additional info about Greenhill Bowman and others twist formulas:

http://kwk.us/twist.html

WOW!  Where else anywhere on the internet can you ask a question and get that kind of knowledge, information, logic, reason, experience annotated with citations and source material laid out for you?

AMAZED!!

[Roguer]

Since black bear attacks are fantastically uncommon, and black bears are not particularly hard to kill, I'd recommend the OP concentrate on whatever cartridge they think will work best for deer. Whatever that is will be MORE than enough to deal with any bear issue.

If it's accurate out of the OP's gun, I'd look no further than the Federal Trophy Bonded 180 grain.

All most didn't see this one.

I been around black bears to know what to expect about them. I helped my old man when he was a game warden "return" bears to nature for years. I've lost many a food pack and other things to them. But a few times they never wanted the salami and cheese sandwiches or the Doritos and kept doing the huff huff trying to get closer and closer with a predator lock on. Break in to the old farm house with me in it. I want to be ready for that just in case again. Bears are like people, most just want your tastie tidbits, some want more. My rule of thumb is NEVER shoot a bear unless your hunting it or HAVE to shoot it. Being on the business end of a bear a few times taught me to have enough to over kill when it comes to a gun for them.

My last encounter was when I was steel head fishing he climbed down the rock cliff I did (there were steel rings in the cliff some one put there), huffed to try and steal my steel head. The Doritos and sandwiches seemed to buy him off, his patients told me he made his living off of tourists. Hint spread them out so they eat one by one and takes longer. I climbed up poured out the second bag of Doritos and got the heck out of there! I had a 44 mag I could of used, but he showed no signs of wanting to get me. He could of had me if her wanted me so I knew it would be dumb to put a hole in him. I still lost the steelhead though...took the over 20 pounder I think to show off my my uncle and my aunt came with her walker saying "Oh you brought us a steelhead!" and put it in the fridge. How could I say no to two people who gave me free medical care for a while when I needed it?

[SPDSR]

Actually, it would be the extra velocity the length imparts.

So a 4.6" Glock has issues with the 220gr hardcast but similar barrel length 10mm like the Tanfolio don't? 

Hadn't heard same issue plaguing 5" 1911 pistols.  Does it?

220 grain hard cast stabilization gets even weirder. The Underwood 220 won't stabilize in my G20, but the Buffalo Bore 220 do and even shoot quite accurately. They do have a slightly different profile.

For deer and smaller bear or hogs I'd almost say an expanding round would be better, like the Buffalo Barnes 155. The heavy solids don't come to mind unless we are talking quite large animals.

[4949shooter]

For what it's worth, I have fired the Underwood 220 grain powder coated hard cast load out of my G40 and they stabilized just fine. They were powerful too.

YMMV. Always best to test your carry loads in your weapon of choice prior to serious social, hunting, or animal defense work.

[SPDSR]

I haven't tried the new coated ones. I'll have to get some of the 220 and see if it changes anything. Either way does the coating seem to reduce leading potential in a Glock as advertised?

[4949shooter]

I haven't tried the new coated ones. I'll have to get some of the 220 and see if it changes anything. Either way does the coating seem to reduce leading potential in a Glock as advertised?

I believe it does. I only fired a box of it, but there was no leading in my G40 barrel that I could see.

[SPDSR]

Thanks I'll have to try some out. Do they seem like the same exact bullet profile as the old ones? Same meplat and all?

[4949shooter]

I don't have any hands on experience with the old ones. But they do look similar to me....just powder coated.

[SPDSR]

Thanks

[Thebear_78]

My last encounter was when I was steel head fishing he climbed down the rock cliff I did (there were steel rings in the cliff some one put there), huffed to try and steal my steel head. The Doritos and sandwiches seemed to buy him off, his patients told me he made his living off of tourists. Hint spread them out so they eat one by one and takes longer. I climbed up poured out the second bag of Doritos and got the heck out of there! I had a 44 mag I could of used, but he showed no signs of wanting to get me. He could of had me if her wanted me so I knew it would be dumb to put a hole in him. I still lost the steelhead though...took the over 20 pounder I think to show off my my uncle and my aunt came with her walker saying "Oh you brought us a steelhead!" and put it in the fridge. How could I say no to two people who gave me free medical care for a while when I needed it?

Feeding the bear is the worst thing you could possibly do!    A black bear shouldn't be that aggressive.  Any black bear that will force the issue like that needs to be put down.   Your just reinforcing the bad behavior to reward that bear with food. 

Black bears aren't really that tough to kill.  Any good factory load that will work for whitetails or hogs will do fine on black bears as well.   Any of the 180-200 gr JSP or JHP loads are good, placement trumps bullet.

I generally carry 200gr TMJ @1250fps.  Buffalo bore or hand loaded copycat.  Our bears come in bigger sizes than most black bear and the solids tend to penetrate better.  I saw the blazer 200gr FMJ go thru a 6' black bear neck shoulder junction exited out back leg, two shots.   Broke neck and spine vertebrae shutting him down on the spot.



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