HD Ammo - Will Black Hills 5.56x45 50 grn Barnes TSX be over-stabilized in a 1:7 twist 10.3" barrel?

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[ARCHIVED THREAD] - HD Ammo - Will Black Hills 5.56x45 50 grn Barnes TSX be over-stabilized in a 1:7 twist 10.3" barrel?

Posted: 6/14/2018 5:27:34 PM EDT

I'd like to buy some 5.56 ammo for HD, and the Black Hills loaded 50grn Barnes TSX seems like a great performer. However, I'd be shooting it out of a 1:7 10.3" long barrel, both with and without a dedicated 5.56 can. Will the bullet be over-stabilized suppressed or unsuppressed, and do I need to worry about baffle strikes on the can?

TIA.

Posted: 6/14/2018 7:18:04 PM EDT

[#1]

out of that barrel I highly doubt it.

Posted: 6/14/2018 7:43:29 PM EDT

[#2]

What is “overstabilized”?

Posted: 6/15/2018 7:37:58 AM EDT

[#3]

Attached File

Posted: 6/15/2018 8:27:09 AM EDT

[#4]

No. I still get sub 2moa 10 shot groups from 1/7 barrels with it.

Posted: 6/15/2018 9:41:29 AM EDT

[#5]

With modern production .224 bullets... you are VERY hard pressed to "over stabilize" any of them. Especially monolithic solid bullets like the Barnes.

Mid '80's era production thinly jacketed bullets made for slower twist rates ( 1n14 twist, 22/250 ), have been known issues when fired in new 1n7 twist barrels... but those bullets are long gone.

Photo from the internet, showing a bullet spinning and breaking / failing apart on target.... just an FYI.

Posted: 6/15/2018 10:48:51 AM EDT

[#6]

Is MK318 mod 0 the same Barnes TSX ?

Posted: 6/15/2018 11:48:20 AM EDT

[#7]

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Quoted:
Is MK318 mod 0 the same Barnes TSX ?

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No, but very similar. I guess. They are both solid base copper IIRC, but the MK 318 has been designed to fracture the petals instead of mushroom.
Over stabilized is pretty much a misuse of the term. As noted, some would fall apart because of thin jackets, and some don't shoot well because of the barrel not liking then. Lighter bullets seem to be touch and go with a 1:7, but that may be outdated wisdom in itself as many here do very well with light rounds.

Posted: 6/15/2018 9:17:22 PM EDT

[#8]

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Quoted:
Is MK318 mod 0 the same Barnes TSX ?

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Nope, it is an OTM with a lead core.

There is a "brown tip" military load now using the 70gr TSX though. A lot of people confuse the two.

Posted: 6/16/2018 12:13:12 AM EDT

[#9]

Quoted:
I'd like to buy some 5.56 ammo for HD, and the Black Hills loaded 50grn Barnes TSX seems like a great performer. However, I'd be shooting it out of a 1:7 10.3" long barrel, both with and without a dedicated 5.56 can. Will the bullet be over-stabilized suppressed or unsuppressed, and do I need to worry about baffle strikes on the can?

TIA.

View Quote

https://www.policeone.com/police-products/firearms/accessories/ammunition/articles/7251807-Why-Black-Hills-Barnes-TSX-is-the-first-purpose-built-police-patrol-rifle-load/

Posted: 6/16/2018 4:53:38 PM EDT

[#10]

Overstabilizaton and spinning bullets apart are two separate things.

You will never spin apart a monolithic copper bullet. You need thin jackets and high RPMs to spin a bullet a part.(MV * (720/twist rate) Use just the denominator of your twist rate. So 720/7 for a 1/7 twist and not 720/(1/7)

Overstabilization occurs when your combination of twist rate and MV take a bullet above the minimum RPM to keep it stable. The higher you go above this, the more small differences in bullet homogenity like jacket run out will cause your groups to open up ever so slightly. There is a formula to determine the average increase in group size based on how overstablized a bullet is an the average amount of jacket run out. The amount is so small that unless your are shooting 0.1" groups in bench rest competition it doesn't even matter.

Posted: 6/17/2018 9:55:52 AM EDT

[#11]

There is no such thing as over-stabilized. A bullet can't be too stable. Davetrader is spot on about how slower twist barrels can produce smaller groups at the extreme, but I think over-stabilized is a terrible word to use to express that idea. It makes people think fast twist barrels are unsuited for light bullets. They are not.

Posted: 6/18/2018 11:26:58 AM EDT

[#12]

At HD distance, it wont matter...AT ALL!!!

Posted: 6/18/2018 9:04:35 PM EDT

[#13]

Quote History

Quoted:
At HD distance, it wont matter...AT ALL!!!

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This

The group will open up a little, maybe.

Posted: 6/18/2018 10:24:05 PM EDT

[#14]

I have some 50gr TSX from BH that I could test in my 10.5" 1:7 twist barrel. What yardage would you want to see it shot at?

Posted: 6/19/2018 5:22:36 PM EDT

[#15]

Thanks guys for all the great info.

Quote History

Quoted:
At HD distance, it wont matter...AT ALL!!!

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Agreed, shot group size won't matter at HD distance. I was only concerned about baffle strikes on the suppressor or the bullet disintegrating. From the responses above, it sounds like I don't have to worry about it.

Posted: 6/19/2018 5:34:34 PM EDT

[#16]

Quote History

Quoted:
I was only concerned about baffle strikes on the suppressor or the bullet disintegrating. From the responses above, it sounds like I don't have to worry about it.

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Nope, I fired 45gr TSX out of my 18" 7twist at 3350fps and 50gr TSX at 3175fps. The 45gr shed all their petals, the 50s fully expanded in gelatin.

(These handloads were developed for my 7" pistol.)

Posted: 6/19/2018 9:35:56 PM EDT

[#17]

Quote History

Quoted:
What is “overstabilized”?

View Quote

This.

A bullet is either stable in flight or it isn’t. If it isn’t, it won’t hit the target consistently.

If a bullet has a VERY thin jacket that is designed to fragment, like a very light varmint bullet, then you CAN over SPIN it and make the jacket disintegrate. That’s not going to happen with the bullets you’re talking about. Not at all.

Posted: 6/21/2018 9:30:43 AM EDT

[#18]

No.

And

No.

Posted: 6/22/2018 12:33:04 PM EDT

[#19]

Quote History

Quoted:

If a bullet has a VERY thin jacket that is designed to fragment, like a very light varmint bullet, then you CAN over SPIN it and make the jacket disintegrate. That’s not going to happen with the bullets you’re talking about. Not at all.

View Quote

Thanks, that's really interesting. So what about modern 55 grain plinking ammo out of a 1:7 twist? Would the jacket disintegrate? I'm thinking like 100 round bulk packs of Federal .223 etc.

Posted: 6/22/2018 1:32:28 PM EDT

[#20]

Quote History

Quoted:

Thanks, that's really interesting. So what about modern 55 grain plinking ammo out of a 1:7 twist? Would the jacket disintegrate? I'm thinking like 100 round bulk packs of Federal .223 etc.

View Quote

No, not out of my 18" anyway.

Posted: 6/22/2018 9:23:43 PM EDT

[#21]

Quote History

Quoted:
Thanks, that's really interesting. So what about modern 55 grain plinking ammo out of a 1:7 twist? Would the jacket disintegrate? I'm thinking like 100 round bulk packs of Federal .223 etc.

View Quote

Nope. The kind of bullets I mentioned are the extra-light (35 grain or so) bullets specifically designed for varmint hunting. Think “varmint grenade” or “varmageddon.” They have very, very thin jackets to have the “explosive” terminal effects on very small animals like prairie dogs.

Now with such light bullets, you can really push them fast, nearing 4000 fps if you’re brave. The rate of spin at 4k fps out of a 1:7 barrel is really, really fast, and it’s the centrifugal force that disintegrates the bullet.

Basic 55 grain bullets, either FMJ or soft point, have pretty sturdy jackets, and they’re heavy enough that you’ll stay much closer to 3000 fps. Not much chance a properly made bullet like that will come apart just because of spin and velocity.

[ARCHIVED THREAD] - HD Ammo - Will Black Hills 5.56x45 50 grn Barnes TSX be over-stabilized in a 1:7 twist 10.3" barrel?

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