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6.8 SPC Bullet Performance

634443 Views 614 Replies 159 Participants Last post by  Guts
There is useful information spread throughout this topic regarding six8 bullet terminal performance. As it has grown in length, these links have been added to take you directly to pages where new bullets and additional testing were added.

100 Yard Terminal Testing; Barnes 85gr TSX & 95gr TTSX, Sierra 90gr HP, Hornady 110gr V-Max & HPBT and 120gr SST
starts with this post below the links.

100 Yard Terminal Testing; Nosler 100gr and 110gr Accubond
6.8 SPC Bullet Performance

200 Yard Terminal Testing; Barnes 85gr TSX & 95gr TTSX, Nosler 100gr & 110gr AccuBond, 120gr Hornady SST
6.8 SPC Bullet Performance

300 Yard Terminal Testing; Barnes 95gr TTSX, Nosler 100gr & 110gr AccuBond, 120gr Hornady SST
6.8 SPC Bullet Performance

100 & 200 Yard Terminal Testing; Barnes 85gr TSX, Nosler 85gr E-Tip, Sierra 110gr Pro-Hunter, Berger 130gr VLD,

Round 2 -> 100 & 200 Yard Terminal Testing; Hornady 110gr HP and HPBT, Nosler 115gr Match
6.8 SPC Bullet Performance

Round 2 -> 300 Yard Terminal Testing; Nosler 85gr E-Tip, Barnes 95gr TTSX, Sierra 110gr ProHunter, Nosler 110gr AccuBond, Federal 115gr Fusion MSR
6.8 SPC Bullet Performance

Comparison: 100gr & 110gr Nolser AccuBond with 115gr Federal Fusion MSR
6.8 SPC Bullet Performance

Round 2 -> 200 Yard Terminal Testing; Sierra 90gr HP, Hornady 110gr V-Max & HP, Sierra 110gr ProHunter, Federal 115gr Fusion MSR
6.8 SPC Bullet Performance

Round 2 -> 300 Yard Terminal Testing; Sierra 90gr HP, Hornady 110gr V-Max, HP & BTHP, Nosler 115gr Match
6.8 SPC Bullet Performance

Federal Fusion MSR/GD Bullet Performance Comparison - 90gr Gold Dot, 115gr and 120gr Fusion MSR
6.8 SPC Bullet Performance

Benefits of Ballistic Tips (or what happens when you remove them on monolithic bullets)
6.8 SPC Bullet Performance

100 Yard Terminal Performance Testing; 110gr Barnes TTSX
6.8 SPC Bullet Performance

100-300 Yard Terminal Performance Testing; 110gr Barnes TSX
6.8 SPC Bullet Performance

All Copper Bullet Comparison; 85gr Nosler E-Tip, 85gr Barnes TSX, 95gr Barnes TTSX, 110gr Barnes TSX

What Defines Bullet Expansion? An analysis of monolithic and lead-core bullet performance.

Effects of Barrel Twist Rate on Bullet Expansion.

Round 3 - > 130gr Bullets
130gr Bullet Testing; Hornady SST, Sierra Pro-Hunter, Nosler Ballistic Tip and E-Tip http://68forums.com/forums/showthre...et-Performance&p=471451&viewfull=1#post471451
130gr Berger VLD http://68forums.com/forums/showthre...et-Performance&p=416533&viewfull=1#post416533
130gr Nosler Partition http://68forums.com/forums/showthre...et-Performance&p=533428&viewfull=1#post533428
130gr Sierra GameKing http://68forums.com/forums/showthre...et-Performance&p=562847&viewfull=1#post562847
130gr Federal Fusion, Remington Core-Lokt, and Speer Hot-Core http://68forums.com/forums/showthre...et-Performance&p=616848&viewfull=1#post616848
130gr Speer BTSP http://68forums.com/forums/showthre...et-Performance&p=628630&viewfull=1#post628630
130 Hornady InterLock and Woodleigh PP SN http://68forums.com/forums/showthre...et-Performance&p=681588&viewfull=1#post681588
130 Federal Flat-Base http://68forums.com/forums/showthre...et-Performance&p=946545&viewfull=1#post946545
130 Cutting Edge MTH http://68forums.com/forums/showthre...et-Performance&p=959122&viewfull=1#post959122

400 Yard Terminal Performance Testing
  • The Challenges of Longer Range Shooting
  • Varmint/Target Bullets: 110gr Hornady HPBT & V-Max, 115gr Nosler Match CC
  • Hunting Bullets: 90gr Gold Dot, 95gr Barnes TTSX, 110gr Barnes TSX, 110gr Nosler Accubond, 120gr Fusion MSR, 120gr Hornady SST

Comparison: Nosler 90gr Bonded Core vs Federal 90gr Gold Dot

GS Customer Bullets for the 6.8 SPC: 80gr and 99gr HV

Hornady's New 100gr GMX

Comparison: Hornady 100gr Soft Point vs Remington 100gr Pointed Soft Point

Sellier & Bellot 110 FMJ

Remington 115gr Ultra-Bond

Lehigh Defense 100gr Controlled Chaos (CC)

Comparison: 110gr Hornady V-MAX and Sellier & Ballot Plastic Tip Special (PTS)

Cutting Edge 120gr & 130gr Match, Tactical, Hunting (MTH)
Speer 90gr TNT HP

Cavity Back Bullets 105gr & 120gr MKZ

Nosler 110gr Flat-Base Soft Point (FBSP)

Cavity Back Bullets 95 CB Tech

Winchester 115gr XP


Original Post

I had the opportunity to take six 6.8 SPC bullet combinations to the range and test terminal performance. My goal was to verify the bullet I would be using for deer and hogs. I tested performance using a bullet "trap" that I have refined and used for a couple of years. The trap consists of a gallon jug of water (typically an empty milk jug) in front of a box of phone books and magazines. The water jug provides the hydraulic medium to effect bullet expansion/mushrooming. The box catches the bullets and provides relative penetration performance. I've used this bullet trap with .223 Rem to .300 Win Mag and have seen similar terminal performance results on elk I have harvested with a .270 Win. With that said, I realize this method of testing is not as good a medium as ballistic gelatin but that's a whole other story and not very convenient to use. More details on the bullet trap can be found in this on-line article. Note, I now use a single phone book in front of multiple magazines like G&A, Shooting Times, etc.


These are the bullets and their respective muzzle velocities shot from and 18-inch PSA SS SPR barrel. There was a 15+ mph headwind and the temperature was 48F.
85gr Barnes TSX - 2815 fps (31.0gr AA2200)
90gr Sierra HP - 2775 fps (30.5gr AA2200)
95gr Barnes TTSX - 2805 fps (29.6gr AA2200)
110gr Hornady V-Max - 2615 fps (factory)
110gr Hornady HPBT - 2640 fps (factory)
120gr Hornady SST - 2525 fps (27.5gr AA2200)

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

Here is a link to a picture of the 6.8mm (0.277") bullets used with some .270 Win bullets I typically load on the right side for reference.
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There have been several prior posts on 100 CX Testing (#573-582, 596) that have led to this conclusion.

Thank jawjaboy for pulling 100 CX bullets from factory Hornady ammo (Lot # 949179) and contributing them for testing. His lot of factory 6.8mm SPC ammo had the same crimp/finishing marks just below the ballistic tip as the component bullets. Macatac also confirmed his factory Hornady ammo (Lot # 3221532) had the crimped just below the ballistic tips. Testing with jawjaboy’s bullets, minimum velocity expansion was consistent with the component 100 CXs tested so far where velocities 2210 fps and below did not expand and yawed like an FMJ. Testing at a higher speed of 2290 fps, the 100 CX finally did open up with expansion deep into the expansion chamber. The expanding petals did break away but I will have to test further to determine if that is due to the CX being a softer copper than the GMX or the testing method used. Note, a 6.8mm CX on-line review from another shooter stated he was getting failure to open at mid-range velocities and loss of petals when speeds were high enough to effect expansion.

So, what is going on. After impact, a bullet must shorten and expand to a larger diameter to remain stable. Anything the delays expansion, as is happening here, will cause the bullet to be unstable in the denser medium, yaw, and fail to expand. The previous tests with the BTs removed showed proper expansion at speeds below 1600 fps so the expansion cavity is not causing any issues. The remaining factor(s) that could be delaying expansion would be the bullet’s copper gripping the BT to tightly and/or the increased hardness of these new tips. I found some .308 150gr CX bullets that do not have the crimp and will test them and then smaller calibers to further determine the details of why Hornady’s new CX bullet is not providing optimal expansion.

Meanwhile, what does a hunter do with a good bullet that turns into an FMJ after 150 yards (or closer to 100 yards with a shorter barrel). I suggest one of two options. You could resort to shoot hogs through the shoulder blade to create bone fragments that will improve terminal performance (not easy to do if they are running). Or, remove the obstruction that is preventing expansion, e.g., the bullet’s ballistic tip. This will give you a bullet with good expansion to 350 yards and beyond depending on your muzzle velocity. Good medicine for hogs and even better for coyotes. I tested two configurations: 1) with the BT removed but stem still in-place, and 2) BT removed with the stem pushed into the expansion cavity. As you can see in the test results below, leaving the stem in place did not impede expansion. Even with the lower BC (G1) of 0.230 vs 0.303, there is less than an inch difference in trajectory at 200 yards. I did a quick accuracy test with two 3-shot groups at 100 yards. POI did not change and accuracy was not degraded with the tips removed. Below is a link to a new thread on how to accomplish BT removal if you want to recover the performance potential of your 6.8mm SPC 100 gr CX bullet and ammunition.

(38) Hornady’s New CX Bullet: How to Restore Terminal Performance | 6.8 SPC Forums (68forums.com)

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The chrono results for the lot of ammo (Lot # 949179) from which I supplied the pulled bullets for Xman's test is attached.

The particulars are:

Rifle: PSA 6.8 SPCii 18" 1:11 twist
Suppressor: SilencerCo Omega 300
Chronograph: Oehler 35p
Distance from muzzle: 10 feet
Altitude asl: 295 feet
Temperature: 51 deg F
Humidity: 58%
Pressure: 30.10 inHg

I will add my anecdotal observations from the field on several hogs and a coyote with the Hornady 6.8 SPC CX 100 grain are consistence with Xman's findings. The one deviation with my observations from his results is it appears that the 6.8 SPC CX 100's failure to expand may occur at shorter distances, under 150 yards, possibly because hogs / coyotes flesh may have less obstructive media effects, from Xman's test media, on the CX 100 hence less expansion and lethal terminal performance. Once again this is anecdotal but to my eye I've noticed a difference in shot hogs' and coyote's reactions from Hornady 6.8 CX 100 versus both S&B 6.8 SPC PTS (Red Tip) 110 grain and IMI Systems Razor Core 5.56 77 grain HPBT-Match (Sierra MatchKing) ammo. They just seem more like a poor shot placement or FMJ pass through than with the other ammo I've used.

Bottom line: I will be removing the tip from the CX 100. When I run out of these I'll be using the S&B Red Tips until I get my reloading online with the Hornady 120 SST bullets.

JBM - Calculations - Trajectory JBM - Calculations - Trajectory 1/1

Input Data
Ballistic Coefficient:0.303 G1Caliber:0.277 in
Bullet Weight:100.0 gr
Muzzle Velocity:2648.0 ft/sDistance to Chronograph:10.0 ft
Sight Height:3.00 inSight Offset:0.00 in
Zero Height:1.75 inZero Offset:0.00 in
Windage:0.000 MOAElevation:0.000 MOA
Line Of Sight Angle:0.0 degCant Angle:0.0 deg
Wind Speed:10.0 mphWind Angle:90.0 deg
Target Speed:10.0 mphTarget Angle:90.0 deg
Target Height:12.0 in
Temperature:51.0 °FPressure:30.10 in Hg
Humidity:58 %Altitude:296.0 ft
Vital Zone Radius:5.0 in
Std. Atmosphere at Altitude:NoPressure is Corrected:Yes
Zero at Max. Point Blank Range:YesTarget Relative Drops:No
Mark Sound Barrier Crossing:NoInclude Extra Rows:No
Column 1 Units:1.00 inColumn 2 Units:1.00 MOA
Round Output to Whole Numbers:No
Output Data
Elevation:9.678 MOAWindage:0.000 MOA
Atmospheric Density:0.07709 lb/ft³Speed of Sound:1107.8 ft/s
Maximum PBR:315 ydMaximum PBR Zero:272 yd
Range of Maximum Height:159 ydEnergy at Maximum PBR:718.5 ft•lbs
Sectional Density:0.186 lb/in²

Calculated Table

Font Finger Material property Paper Thumb


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Further comment to my post above. From a quality standpoint, excepting the bullet expansion issue, the chrono results and accuracy, sub MOA, demonstrates Hornady is really producing a fine product. This level or consistency in chrono results is approaching long range match quality.

So don't think I'm bashing Hornady with my comments about the CX 100 terminal performance. If they can fix the bullet expansion issue, I wouldn't hesitate using it and be very happy doing so.

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I wonder if Hornady could switch to the softer FTX tip similar to that used in the 30-30 bullet would solve the problem?
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I think just going back to the softer GMX tip would return the CX to better performance. I'm trying to test with a GMX tip installed but 1) its difficult to get the harder CX tip and stem completely out. I've been able to get a tip completely out from one of the .308 150gr CX bullets but 2) I cannot get the GMX tip to fit into the CX expansion cavity. The opening to the CX's expansion cavity is 0.084" and I cannot get the GMX tip to fit which is a 0.088" diameter. The harder CX tip has a larger stem diameter of 0.090" but is tapered. The tight, compressed fit of the CX tip is leading me to believe that the crimp, or finishing mark as Hornady calls it, is not the primary cause of the lack of expansion in the 6.8mm 100gr CX bullet.
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I think just going back to the softer GMX tip would return the CX to better performance.
You are probably right. I am just curious to see if a softer tip would further reduce the velocity needed for expansion. I remember stories of hunters who would fill "hollow points" of bullets with vasoline to increase expansion. Hornady, for example, has been using the soft FTX polymer in a fair amount of pistol and subsonic ammo for rifles.
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Completed a full test series on the 100 CX and compared it to the 100 GMX. Results were:

The 100 CX lost at least 480 lb-ft of capability. Minimum velocity for expansion increased 560 fps or more compared to GMX.

100 GMX min velocity is 1670 fps, 620 lb-ft of KE*
100 CX min velocity is 2230 fps, 1100 lb-ft of KE

There was also an “Opening Shock” when the 100 CX began to expand where it was shedding petals between 2230 to 2400+ fps. Others have reported this also.

* Minimum opening velocity for 100 GMX is likely lower. Testing was not conducted below 1670 fps which still produced effective expansion.
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I did further testing of the 100 CX last weekend in order to more precisely measure the minimum velocity required to begin bullet expansion. The test media was good size boar shot 15 minutes prior. I've had all the necessary equipment in the truck for the past 2 weeks waiting for an opportunity like this. I've used hogs in the past for testing but never at night using a chronograph. There was a phonebook/paper bullet trap placed on the far side of the hog in-line with the expected shot. A spotlight was used to illuminate the desired point of impact since the rifles I was using were not night scope equipped. A 1/4" foam board took a "snap-shot" of the bullets as they exited the hog. The minimum opening velocity is 2100 fps, slightly better than the other two test methods. This is still a significant loss of low-energy expansion capability compared to the 100 GMX which expanded at 1650 fps and potentially lower. This is a 200-yard loss of capability so plan on the 100 CX performing like an FMJ beyond 175 yards with a 16” barrel. BTW, the .308 CX bullets (150-180gr) faired a little better losing 125 yards of low-energy expansion capability. Basically, making a .308 Win a 300-yard rifle which, in my experience, is limiting for hunting pronghorn and elk.

As shown in prior posts, this loss can be recovered by clipping the CX's new, heat-resistant ballistic tip which is harder than the BT used on the GMX. There was no lose in accuracy or change in POI at 200 yards.

Hornady’s New CX Bullet: How to Restore Terminal Performance

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Hornady was contacted regarding the degraded terminal performance of the new 100 CX compared to the 100 GMX it replaced. The driver behind the new CX product line that replaced the GMX was to develop capable monolithic bullets for their line of PRC cartridges, e.g., 6.5, 7mm, and 300 PRC. For CX bullets that had a GMX-lineage, there were no engineering changes other than using the new copper and inserting the new “heat-resistant” ballistic tip which is a harder plastic than used in the GMX. Hornady stressed that the tip of a bullet gets extremely hot when traveling at high mach numbers and longer distances. In their POD casts, they say that this new “heat-resistant” ballistic tip benefits bullets with high BCs that are shot at distances greater than 500 yards.

Multiple discussions with Hornady ended up being a one-way exchange of test data. Hornady was unwilling to share any data or specifics regarding their testing that could have disprove the results posted here. Communication concluded with Hornady stating they have no intention of changing the new “heat-resistant” ballistic tip on the 100 CX because the bullet could be used in cartridges significantly more powerful than the 6.8mm SPC. It did not matter that Hornady only uses this bullet for their 6.8mm SPC factory ammunition. They further stated that 6.8mm SPC users were fortunate that the 100 GMX performed as well as it did because it exceeded their design objective to have a minimum velocity for expansion in the 2000 fps range. This begs the question why Hornady would design to a goal that was not competitive with other monolithic bullets from major manufacturers?
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As shown in the test rests above, the 100 CX required velocities greater than 2100 fps to generate expansion compared to 1650 fps for the 100 GMX. This 450 fps increase in minimum velocity for expansion results in is a 175+ yard reduction in effective range, i.e., over a 50% reduction. Using Hornady’s published data, that equates to the 100 CX turning into an FMJ at 150 yards. Clipping the tips off the 100 CX restores the bullet’s expansion to that of the GMX it replaced.

To better understand the capabilities of the new CX product line, I have continued testing with the 80 and 90 CX (0.243); and 110, 150, and 190 CX (0.308). This is a summary of those results.
  • The bullets all have different expansion cavities both in depth and diameter, even if they use the same diameter ballistic tip.
  • CX bullets may experience more petal lose than their GMX counterparts due to the softer copper.
  • The new additions to the CX line (90 CX, 190 CX) measured more precisely than CX bullets with a GMX lineage. The 190 CX was so precise it was in the “match” category.
  • The 190 CX may be made for rifles capable of shooting longer ranges, but I would not classify the 190 CX as being designed as a long-range bullet. Its expansion cavity is not very deep and bullet expansion is less than the other .308 CX bullets for the same energy level. Bullets designed for long range typically have a lower minimum velocity for expansion where the 190 CX does not have effect expansion below 2000 fps. This bullet was a beast when fired from a 300 Win Mag. Expect deep to over-penetration without as much transfer of energy to the game compared to the other .308 CX bullets.
  • The 6.8mm 100 CX had the most negatively affected by the addition of the heat-resistant BT.
  • The 6mm 80 CX expansion was not significantly impacted. The 90 CX had excellent expansion.
  • The 110 CX designed for the 300 BO had excellent expansion, well beyond 2x bullet diameter.
  • The 150 CX expansion was significantly degraded losing 125 yards of effective range resulting from a 225 fps increase in minimum velocity for expansion compared to the 150 GMX. For the typical .308 Win hunting rifle, this reduces CX’s effective range from 425 yards to 300 yards, a 30% reduction. This degraded expansion should also apply to the 165 and 180 CX bullets because they are identical in every way to the 150 CX expect for added weight due to the longer bullet tails. Clipping the 150 CX’s tip will restore its expansion potential and actually improve it to lower velocities than the 150 GMX.
Hornady’s New CX Bullet: How to Restore Terminal Performance

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A number of photos show Hornady 120 grain SST's with core separations. I was watching a Hornady podcast about terminal performance and one of the bullet designers had some interesting points. One was about weight retention and jacket separation. He points out that jacket separation is particularly bad if it happens early, before the bullet reaches the heart. This is because neither the core nor jacket tend to travel straight and might miss the heart. After that point, it is less of a problem. The attached video is set to start playing at the point where they discuss this.

A couple minutes later in the video, somewhere around 1:03:30, they discuss an odd property of some Hornady bullets, especially the ELD-X, and to a lesser extent, the SST and Interlock. This explains what we often see with the 6.8 120gr SST: a fairly intact rear piece of jacket and a separate lead mushroom.
As the bullet is penetrating, the jacket peels back but since it and the lead core are not bonded together, the outer edge of the lead mushroom abrades away, exposing fresh lead. They rely on the loss of the outer edge of the lead to keep the mushroom from expanding so much that penetration gets reduced excessively. This is what they call "continuous expansion" on the ELD-X, but it seems to happen somewhat with the 6.8 SST as well. The interesting part is that the continuously forming mushroom pulls on the core and the lead actually flows forward inside the jacket. As this happens, the lead core shortens and pulls away from the base. Even though these bullets have a mechanical "interlock ring", with deep enough penetration, the core can pull past it and separate from the jacket. This happens regularly with the 120gr SST.

FWIW, they mainly talk about the newer ELD-X design which is an evolution of the SST. The ELD-X design is currently mainly used on longer, high-BC bullets (the .277 version is 145gr, for example). The front part of the jacket is thinner (to open sooner) and the back part of the jacket is thicker. This allows it to stay intact for deeper penetration over a large speed range.

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This is what they call "continuous expansion"
I've seen this with Sierra Gameking 130 #1820 270 bullets on whitetail deer. Never worried me as I had dead deer. An memorable example was a diagonal transverse shot from front of shoulder quartering to me to behind the last rib on the opposite side just under the skin perfect mushroom with the core separated but in perfect position on the jacket.
Nincomp, thanks for sharing this podcast. I've hunted and tested 120 SSTs for some time now. I've experienced multiple lead-core separations from the copper jacket. I have even recovered an SST at long-range that started to expand/open up but then stopped. The lead core freely slide forward and aft within the swelled copper jacket. From these tests and recovered copper jackets from game, it appears to me that, as the bullet begins to expand, body fluid gets inside and causes the jacket to swell freeing the lead-core to then fragment in "grenade" style, i.e., the copper jacket can act just like a sabot. This can happen very rapidly within the first inch or two of penetration. I know this to be the case, because I have recovered multiple copper jackets during bullet testing with dirt inside the copper jacket. The only way for that to happen is for the water "slug" from the bullet's impact on the gallon water jug to splash up dirt from the ground in front of the already separated copper jacket as it enters the bullet trap. A water "slug" can have a lot of energy. I have had the water slug from 300 Win Mag tests destroy my wooden frames holding the testing components.

I recently experienced what I believe was a failure of an SST while hog hunting that led to a 200-lb wounded sow charging me. Things got up-close and personal (see link below).

(33) Constant Bearing – Decreasing Range | 6.8 SPC Forums (68forums.com)
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I’m a little skeptical on Hornady‘s explanation. I tend to agree more with Xman.

Hornady claims the core is sucked slimmer as the front erodes away. Similar to a low pressure collapse of a straw when sucking on a milkshake. Or somehow the lead core is wicked up like liquid (kerosene) in a lamp. Either scenario requires a very low pressure in front of the bullet.

Xman’s explanation is much more plausible. Like Xman finding dirt inside a jacket, all the recovered SST jackets I have found have animal tissue and even bone fragments inside the jacket often with the core still in the jacket. Adding to Xman‘s observation, to some extent it could be caused by the hydrodynamic or acoustic shockwave from the collapse of the temporary wound cavity.

As the bullet enters the animal or test media, it creates a high-pressure temporary wound channel blowing debris, tissue and fluids about the cavity. Like Xman indicated, the jacket can pick up some of the debris is compressed into what little space is available as the temporary cavity collapses. There might even be a small steam explosion inside the jacket/core cavity. Squishing the lead and bulging the jacket. The same phenomenon that causes dieseling, propeller erosion from cavitation and “sonoluminescence“.
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