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Discussion starter · #421 · (Edited)
FightFireJay said:
I never seriously thought about twist rates affecting terminal performance, other than a quick look at and dismissal about spin rates stabilizing bullets in flesh (according to several sources who could do that math and proved it wouldn't stop a 5.56 from tumbling no matter what your barrel twist).
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Barrel twist rate only stabilizes bullets enough for flying through the air, not during the terminal phase penetrating through flesh. For a bullet to remain stable and penetrate on-course after impact, the bullet has to shorten and increase/expand in diameter on contact. If not, the bullet will immediately tumble and 1) break in the middle (fragment), e.g., 110 BTHP, 115 Nosler CC, and other OTM bullets ... or ... 2) yaw 180 degrees and penetrate tail first, e.g., 130gr VLDs. Even if the bullet expands and shortens it might not be enough to remain stable during penetration. If you take a recovered bullet, measure its length and diameter, and run it through a stability calculator using velocity at impact. The stability factor is around 40 after impact vs 1.5 for stability in-flight. More centrifugal force (faster twist rate) can increase that diameter of expansion for some bullets which should result in a higher rate of energy transfer and likely reduce penetration.
 
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#422 ·
You Still Rock

All I can say is that you are still rocking the boat! This type of testing is FAR more valuable than any manufacturer's data will ever be. You deserve the 27 caliber lifetime achievement award, my brother!
 
Discussion starter · #423 · (Edited by Moderator)
Lehigh Defense 100gr Controlled Chaos (CC)

The picture below shows the Lehigh Defense 100gr Controlled Chaos (CC) in a line-up with other 6.8mm bullets. The Lehigh Defense 100gr CC is a lead-free bullet made of brass. According to the Lehigh Defense website "the idea was to burst the bullet into numerous particles at a predetermined depth creating many wounds and a large temporary cavity". Testing will determine how well this bullet met these design objectives. Thank chefmatthew for contributing the Lehigh Defense 100gr CC for testing.

From 6.8 SPC II - 18" ARP 1:11 barrel, 60F
100gr Lehigh Defense CC - 2820 fps (29.5gr AA2200) [1.080" BC 0.323] - 2.295" COAL

Caution - these loads worked in my rifle but this is no guarantee that they will work safely in yours.

Image
 
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Discussion starter · #424 · (Edited by Moderator)
Lehigh Defense 100gr Controlled Chaos (CC) Terminal Testing Results

The Lehigh Defense 100gr CC is the first all-brass bullet I've done terminal performance testing with. Terminal results with a 6.8mm did not meet the stated design objectives nor was the minimum velocity anywhere close to 2000 fps listed on their website. Only the highest velocity bullet tested at a range of 25 yards expanded enough to break into recoverable pieces. That bullet broke off five pedals with a remaining mass of 83.6 grains. Expansion for this highest velocity round was close to the bottom of its expansion cavity (which was not very deep to begin with). However, the shorten bullet shank was still too long to remain stable and it tumbled. Reaction with the water jug was limited. Duplicate testing with the alternative bullet trap yielded the same expansion results with the bullets over-penetrating and blowing out the back of the bullet trap. Indications of a temporary wound channel in either test method were minimal (equates to limited energy transfer). All bullets test yawed, 1:10 twist did not help at these 6.8mm velocities. Lehigh Defense has some interesting bullet concepts but it appears not be have been applied effectively for this bullet to be used in a 6.8mm SPC. I will retest at .270 velocities (3400 fps mv) but the highest velocity test during these test sessions was equivalent to a 200-yard impact minus the additional spin that would be imparted if shot from a .270.

Contrary to Lehigh Defense's design statement, expansion depth of any bullet cannot be predetermined. As discussed in post #427, a bullet must expand immediately on impact to a larger diameter and or shorten significantly in length to prevent the bullet from yawing. This bullet accomplished neither which is why it tumbled (the recovered bullet shank on the left had a stability factor of 3.5 vs 40 of a typical expanding bullet). For use in a 6.8mm, this Controlled Chaos' expansion cavity needs to be deeper, take less energy to open, and have fragments that are heavier than 3 grains.

Update 11 Apr 2015:

From .270 Win - 23" Tikka T3 1:10 barrel, 60F
100gr Lehigh Defense CC - 3247 fps (60.0gr IMR 4350)

When shot from a .270 Win and an impact velocity of 2920 fps, the recovered 100 CC looked the same as the bullet recovered at 2750 fps from the 6.8. Its weight was 80.9 gr. Reaction with the water jug was limited compared to other bullets with this impact energy. One fragment was recoverd in the outwash of the water jug and weight 3.8 grains. The most significant difference was the penetration of the remaining bullet shank. With the faster twist and higher muzzle velocity, the spin of the .270 bullets was 234,000 rpm compared to 180,500 fpm of the bullet fired from the 6.8mm. With the greater stability, the projective from from the .270 did not tumble and bore through the 1500 pages of phonebook, 15 magazines and 5-inches of white paper. The overpenetration of this bullet was more than any I have tested and would have never been recovered if shot into the alternative bullet trap (soaked wet newspaper).

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#426 ·
I've tried searching to no avail. I've read in other threads on here that the Barnes TAC line up is the exact same as the corresponding TSX or TTSX counterpart, and that Barnes differentiates to keep track of LE sales. The 85 grain TSX (#30254) is similar to the 85 grain TAC-X (#30257), the 95 grain TTSX (#30271) is similar to the 95 grain TAC-TX (#30253), and the 110 TSX (#30260) is similar to the 110 grain TAC-X (#30259).

Barnes' website indicates that the SD and BC of each "pair" are the same, but the literature of the TAC line speaks to "tracking better through barriers" and "controlled" expansion, while the TSX/TTSX literature speaks to "razor-sharp cutting petals" and "instant expansion".

Have you done any testing with the TAC lineup that confirms that they are the exact same projectile?
 
Discussion starter · #427 ·
ncorry said:
Have you done any testing with the TAC lineup that confirms that they are the exact same projectile?
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No I have not. I have asked Barnes and they told me they were the same.
 
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#428 ·
150 fed rn

Great info on this thread Xman!

I received 500 fed rn about the same time you did. I've loaded some up and settled on 32 grn of blc(2) which gave me ~2330 fps and very adequate hunting accuracy.
I'm looking at using them on mule deer and maybe elk this fall. The one in my avatar haunts my dreams!
Have you considered testing these for velocity vs. expansion? Seems like they could be hell on wheels at the proper range!

Thanks again for all your work!
 
Discussion starter · #429 · (Edited by Moderator)
spyglass, I did a preliminary test with the 150gr Federal Round Nose (RN) using the alternative bullet trap (wet soaked newspaper) a couple of weeks ago. I was doing a min-max velocity test with the two 100gr GMXs I had left. When testing the .223 55gr GMX, I found that the GMX bullets were always loosing their pedals going through the phonebook and had to switch to using the alternative bullet trap. This experience made me question whether this was the case with the 6.8mm 100gr GMX which had also lost pedals in prior testing. Testing the 100gr GMX in the alternative bullet trap did show near perfect weight retention at high energy levels (no pedal loss) and also verified successful expansion in the 1600 fps range. Measured expansion between both bullet trapping methods was within 0.015" which is essentially the same result.

I also wanted to see how the 100gr AB would do when driven at higher velocities using the alternative bullet trap. Weight retention was identical to prior tests using the water jug/phonebooks and expansion was within 0.010".

To answer your question, I had one 150 RN remaining after a CFE powder vs velocity ladders so launched it into the alternative bullet trap. When recovered, the 150 RN had mushroomed nicely and showed good weight retention. It's copper jacket was thin and peeled away like the 130gr Rem CoreLokt. I will accomplish a full test series on the 150 RN but it will be a couple of months before I get back to the range. This will have to do for now.

From 6.8 SPC II - 18" ARP 1:11 barrel (65F)
150gr Federal RN - 2260 fps (31.3gr CFE223) [BC 0.261]

Caution - these loads worked in my rifle but this is no guarantee that they will work safely in yours.
Go to the First Page for Quick Links to all the bullets tested

Image
 
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#431 · (Edited)
Xman said:
The alternative bullet trap comprised of just water soaked paper sounds simple but has some complications. It gets pretty heavy and can become too much for one guy to handle. I have tried just 12 inches of wet paper with phonebooks behind that. However, bullet deformation still occurred when the softer lead-core bullets entered the phonebook. At least 18 inches of water soaked paper is need to capture most 6.8mm bullets. To make the trap easier to handle, I have had to break the wet papers down into sections contained in Walmart bags. A Phonebook and or foam core is still required as an emergency backstop in case a bullet's penetration goes all the way through the wet newspaper stack.

I started out testing at 100 and 200 yards but now have settled at 25 yards and down load powder charge to stagger velocity, e.g., 33 gr CFE, 29 gr H335, 25 R10x and 23 R10x. For shot velocities below 2000fps, the .270 and 25 gr of TrailBoss are use. The .270's 1:10 twist makes sure the bullet is still stable enough to remain true on impact. I typically shoot 4 to 6 bullets into the trap before disassembling to search for the bullets. I have to work front to back in 2-inch sections or less to see if the bullet yawed or veered off a straight course. This way I make sure I know which bullet is which when I get to them. This process also gives a good view of how large and long the wound channel was. It has been essentially impossible to recover fragments from the alternative bullet trap, even when 90 grains of copper and lead have been left behind as was the case with the 150 AB LR.
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Xman, love reading your test results. Fwiw, I have been testing hunting & sd bullets for decades using wetpack. It compares very well to ballistic gel & animal flesh in expansion. Penetration is about 75% of gel & neither really can judge penetration in factual flesh. Back in the day, bullet manuf used a lot of wetpack to develope good bullets.
Wet phone books are about perfect. I line a cardboard box, that copy paper comes in, with a simple plastic trash bag. Then stuff in the wetpack. It's 18" of wetpack. If you need more, put two boxes end to end. I use a workmate with simple 2x4 "table" clamped in it & just set the boxes on it. 36" of wetpack will stop any expanding bullet, even my 404 Jeffery with 400gr softs. As you note, shooting carefully, I can get 4 large caliber bullets or 5 smaller caliber. I too load down for testing & shoot at 25yds, just easier. Keep up the good work. I hope to do some testing of my own on the new 100gr GMX in my new 6.8 upper.
 
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Discussion starter · #432 · (Edited)
Fredj, thanks for your tips. Some of my challenges so far with wet-soaked paper in a copy paper box are (after collecting enough paper to fill it with)
1) time to saturate the paper. It will often take a day or more to saturate the paper if packed tight. If loose, then I can't squeeze the excess water out easily.
2) weight when it is saturated. The weight of one wet-soaked copy box of paper is heavy enough that I have to be careful lifting to avoid back strain.
3) finding the bullets after testing. When the papers are all in the copy box, I have to unload the paper stack from the copy paper box then separate the wet stack of newspaper from the beginning moving aft to trace the bullets back to where they stopped. Their paths aren't always parallel, especially if the bullet yaws, and I want to make sure I don't mix up the bullets.
4) it near impossible to find fragments in the wet newspaper though it's easy to measure and graph the amount of fragmentation with respect to impact velocity/energy based the bullet's recovered weight.

As an alternative, I started soaking newspapers stacked about 4" thick in individual Walmart plastic bags. They soak in the cooler full of water on the drive to the range where I squeeze out the extra water from each bag. I'm up in testing in minutes (advantage 1). The second advantage of the 4" thick plastic bags is their individual weight is easy to manage. To hold them as a group, I have a loading tray made of 2by4s and plywood. I originally made the trays to hold the water jug and bullet trap on the berms at distance. The trays also make it easy to stack the plastic bags of wet paper in a column/row. I do take the bullet traps/trays down range via a red wagon with pneumatic wheels. The third advantage of the plastic bags is its quick & easy to find the bullets and see where they stopped penetrating. In no time, new bags can be add as needed to set-up the tray for another round of testing (I often will run 20 bullet tests with the original bullet trap process and a dozen or so with the alternative bullet trap). The temporary wound channels are also highlighted as the plastic disintegrates showing a nice round boundary of cavity. I can only stack up to 24" of wet paper in the tray so if to prevent over-penetration out the back of the trap, I place a dry phonebook in the rear to catch the few bullets that don't transfer energy well enough to stop inside the wet paper stacks.

I have found bullets with significant expansion on impact that transfer a large amounts of energy rapidly seem to destroy the bullet traps in short order. With the wet soaked paper (alternative trap), a .270 150gr AccuBond Long Range is so explosive it was one & done. The 150 AB LR doesn't penetrate much but the front of the trap is nothing but a large empty cavity (full of lead fragments). I haven't tested the .308 bullets in the alternative trap yet and will be apprehensive when I do. I've been testing .308 bullets with water jugs and phone books (original bullet traps) using a .300 WinMag because a .308 Win doesn't have the energy level to fully expand the monolithic bullets, e.g., drive to the bottom of their expansion cavities. The copy box with the phonebook, magazines, and paper lasts one sometimes two shots (3 maybe 4 with good .270 Win bullets). The water jugs pretty much disappear when hit with full-power .300 WinMag loads. The energy transferred to the water has torn the wooden trays apart. My second iteration still failed and I'm trying to figure out a third iteration for the trays that might stand up to the .300 Win Mag's impact force.
 
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#433 ·
Xman- if the monolithic bullets aren't expanding well in 308 Winchester , what seems to be a better bullet for expansion and penetration without too much fragmentation in 308 winchester? Maybe something like an accubond?

Have you tested many in 30 cal yet? I'd be interested in results with speeds below 2600fps as that's what my 16" next gen is getting at the muzzle with 150's ( I haven't tried 165's yet but they would be close ) I have heard that SST bullets are a lot less explosive in 308 win than the 6.8 has proven to be .
 
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Discussion starter · #434 ·
THM, I didn't mean to leave you with the impression that monolithic bullets don't expand well in a .308. The .308 doesn't have enough energy to fully open the bullets and drive them down to the bottom of their expansion cavities. From terminal performance testing, I've found the monolithic .308 bullets are designed to still function with the full power of the .300 Win Mag which makes sense (why would they make .308 caliber bullets that came apart in a .300 Win Mag). Using the .300 Win Mag, I've even found the energy level were structural failure occurs (pedal separates from the bullet shank).

Here is a specific example. The 150gr GMX with a muzzle velocity of 2650 fps will expand/mushroom to a diameter of 0.522" at 60 yards (2030 ft-lbs of kinetic energy). That is respectable expansion and you still can see the some of the expansion cavity in the center of the bullet. From a .300 Win Mag with a mv of 3140 fps, expansion is 0.629" with an impact at 100 yards and is at the bottom of the expansion cavity (2780 ft-lbs). When launched at 3340 fps and a 25-yard impact (3580 ft-lbs), expansion is 0.725" and the crown of the bullet separates as one piece from the bullet shank (no pedals like a Barnes). I'm still trying to determine the minimum velocity/energy where the bullets don't expand anymore. I'm having to develop low-power loads with H4895 as TrailBoss just doesn't work well with copper jacketed bullets.
 
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#435 ·
Xman said:
THM, I didn't mean to leave you with the impression that monolithic bullets don't expand well in a .308. The .308 doesn't have enough energy to fully open the bullets and drive them down to the bottom of their expansion cavities. From terminal performance testing, I've found the monolithic .308 bullets are designed to still function with the full power of the .300 Win Mag which makes sense (why would they make .308 caliber bullets that came apart in a .300 Win Mag). Using the .300 Win Mag, I've even found the energy level were structural failure occurs (pedal separates from the bullet shank).

Here is a specific example. The 150gr GMX with a muzzle velocity of 2650 fps will expand/mushroom to a diameter of 0.522" at 60 yards (2030 ft-lbs of kinetic energy). That is respectable expansion and you still can see the some of the expansion cavity in the center of the bullet. From a .300 Win Mag with a mv of 3140 fps, expansion is 0.629" with an impact at 100 yards and is at the bottom of the expansion cavity (2780 ft-lbs). When launched at 3340 fps and a 25-yard impact (3580 ft-lbs), expansion is 0.725" and the crown of the bullet separates as one piece from the bullet shank (no pedals like a Barnes). I'm still trying to determine the minimum velocity/energy where the bullets don't expand anymore. I'm having to develop low-power loads with H4895 as TrailBoss just doesn't work well with copper jacketed bullets.
Click to expand...
Gotcha , I didnt understand....when you find the minimums I'd be interested...thanks once again !!! In spades!!
 
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#436 ·
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#438 ·
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#439 ·
Ammunition Attrition said:
Hold an 85 Tac up to an 85g Triple shock and there's a difference, physically, I can see. Less of a beveled edge before the first groove on one of 'em, for instance. So....
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I wonder if this was a difference between TSX and Tac, or just a difference made to both and one is an old batch and the other a new lot of bullets? The world may never know.

I also recall hearing that the two bullet series are identical, minus extra inspection/testing that is used to determine consistency of the mil/le projectiles. But for the life of me I cannot remember where I got that information, so maybe I dreamed it.
 
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#440 ·
Xman,
did you consider soft clay or gelatin as an alternative you could put easily into molds?
Some clay is quite soft and easy to work with. not sure about recovering any of the small fragments.
 
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