Home Forums Hunting & Shooting Hunting Rifles Tissue Damage - .270 vs. 6.5x55

Exactly.Bullets in flight and terminal ballistics are not the same thing.Numbers don't explain everything, a common trapping among those who have not hunted a lot with a wide range of cartridges and bullets.

If they do, maybe someone can give us a formula for why a bullet can fly apart in mid air once the jacket integrity is compromised,and it spins itself apart? The problem with energy numbers is that (like SD numbers), they never take bullet construction and materials into consideration.

No one is saying that forward velocity isn't a major contributor to expansion of bullets. We all know that it is. What is being said is that with tough bullets, the faster twist will aid expansion.And those same fast twists may cause a standard bullet to over expand and come apart completely.

Bullets are not the same;a Nosler Partition (as one example, along with a BT, AB, and just about anything else in the standard bullet lineup)is built differently, and from different materials than a Barnes X or a BBC for that matter. The Partition is built (far as I know) from a guilding metal jacket,and alloy core.The jackets are tweaked caliber to caliber but they expand easily from standard cartridges, are somewhat brittle,and shatter (fragment). Only the midsection partition keeps a NPT from behaving just like any other C&C bullet.

OTOH a Barnes is made form pure copper; so is a BBC, along with a pure lead core. Jackets on the BBC are very heavy, much heavier than any Partition of comparable weight. The materials are more malleable and will bend under stress rather than shear. With the BBC the expanding petals are supported by the heavy bonding to the lead core,so the petals do not normally shear (see Scotty Beretz thread showing a 150 gr 270 fired into water jugs).

Both bullets, due to the materials, design, and construction are harder to expand than "normal" bullets.This is why both are known for withstanding very high impact velocities. They do not behave the same as thin jacketed C&C bullets. Fast twist helps facilitate expansion of these tougher bullets.But that same faster twist will tear a standard C&C bullet apart; they are not built to take the stresses of higher speeds and faster twists.

I have not used Barnes, but I can say from personal experience that 130-270,140-7mm,and 165-308 BBC's, spun fast and started at high velocity, are about the fastest killers of BG animals I have personally seen.Ditto a 250 gr 375.

I can't recall the issue, but in Rifle Magazine(late 70's early 80's),a ballistics guy did an article on this twist thing. As part of his tests he fired (IIRC) a 154 Hornady from a 7 Rem Mag into clay blocks which "held" the wound cavities. First, he fired reduced loads that duplicated the long range velocity ( maybe 300 yards, can't recall) and showed the results of the wound cavity in the clay.

Then, he fired full velocity loads into the same clay blocks at actual distance. The bullet expansion was greater, and the size of the wound cavity was larger, in the blocks shot with the full power load at actual distance.

How come? The author felt the differences were not the velocity( which was pretty much the same for both), but the increased rpm's of the bullets fired at full velocity.The differences in the wound cavities was pretty apparent.

In subsequent issues the naysayers showed up with the graphs, formula's, and gobbldigook-hyroglyphics explaining why what the actual shooting showed, could not be true..they, however,had fired "nothing" into "nothing", depending on the "formula's"......I laughed then,30 years ago, and I'd laugh now.

Those inclined can go look up the article if they have back issues.

If you watch the slo-mo videos of bullets hitting ballistic gelatin, it's interesting how some bullets make a smooth expanding temporary wound cavity. But on other bullets, when they hit you see big rips and tears in the cavity, and sometimes a helical rip that matches the spin of the bullet. It's almost like a spinning buzzsaw entering the tissue. It makes sense that increasing the bullet spin increases distortion of the wound cavity, increases trauma, and speeds the desired end result.

Bob,

I remember the original Failsafes had to be redesigned because when they built them they used reduced velocity to simulate long range expansion and found that bullets were not expanding reliably at long range when actually fired at full muzzle velocity. Not sure how that works out since I would think the bullet would have been spinning more slowly at similar impact velocity with the reduced loads. Maybe I can find the article.

Another interesting test would be does the same 90 grain bullets spin apart at 6.5x55 velocities as may actually be spinning similar or faster than a 264 Win Mag if an 8 twist vs 9 twist (both are at ~295k RPM if started at 3300, 3700 fps respectively). Otherwise is the air friction at the increased velocity causing the bullet to come apart or is it really the spin (any bullet would fly apart at 200k+ rps once jacket ruptured i would think).

All that being said, I agree that it looks like certain bullets types benefit from twist more than others. In terms of the big game bullets, the petal type bullets with the cutting edge make the most sense. I cant see it helping much with the rounded frontal area of traditional mushroom, however more spin should keep bullets going in a more straight line in game with less yaw so maybe hitting things more square as well vs better chance of glancing off. Otherwise, no down side.

I've tried justifying the mental gymnastics in my mind of doing a fast twist .270 barrel on one of my existing guns but they all shoot well so at least have to have a semi-rational reason to spend money:)

Lou

Lou presently my factory tubes are twisted 10"....cause that's what they came with....but when I order new, I get a 9". Does not cost extra and since I still have 130 BBC's that's how I roll. I'm sure it isn't going to hurt anything.

That's interesting about the Failsafe. Sort of the opposite from what I saw. But just goes to show that these hard/fast rules get tricky and hard to apply across the board when we have so many bullets constructed so differently.

Your point about keeping the bullet nose forward after impact was something Steigers always mentioned as a side benefit to higher twist rate,as "nose forward" is how the expanding bullets were designed to perform.

texncal: People seem to hate that buzzsaw analogy.... but I get what you are saying and agree.One thing for sure from the slo-mo videos....those bullets do NOT stop spinning after impact.

The kinetic energy theory ignores the effect of centrifugal force on the bullet.

Those that havent seen it probly wouldnt believe what the stubby little 6.5 Creed 1/8 does to critters.

Great little cart.

Dang this forum. I have a nice commercial Mauser action, stock, dies, brass, bullets and all it needs is a barrel to scratch the 6.5X55 itch. It'd be cheaper just to give it all away but I'm thinking this'll happen soon.

Like lots of things in life, too many folks get hung on the WHY.

You don't need to know WHY the sun sets in the west, you just need to know that it does.

I don't know or care about the WHYS of fast twist/buzz saw etc. What matters is that I do know what a Barnes spun hard does to stuff.

My wife and I are just back from Deer and Elk hunting. Wife had either sex deer and either sex elk tags. I had nothing tag wise so I was the step and fetch it. Wife shot a 5X5 Bull Saturday and a 5X5 Buck Sunday Morning. Both were shot with her 270 Win. loaded with 140 grain Hornady SST's driven with 59.7 grains of RL-22 with WLR primers Winchester cases. Both animals were shot in front of the shoulders and both dropped in their tracks. Meat damage was minimal. The elk shot took some of the lower vertebra process as it went through. Deer shot was lower and broke the sternum and sucking out a goodly portion of the lungs. I can't comment on the 6.5 X 55 as I have never owned/used one.

Higher RPM & softer Barnes bullet is my guess.
After trying to figure out this Barnes bullet stuff...faster lighter etc. And having a lot of phone conversations with Barnes, I finally got them to admit they do make some of their bullets harder and some softer. My guess is the 6.5 bullets are softer and open faster creating a better wound channel.

I also remember reading some military reports on twists and wounds. The conclusion of those studies were a higher rpm caused a higher distructive wound....BUT the bullets also didn't track as straight as a slower rpm.

I know that one of the reasons I switched to monometals in my 270's was to get away from the destruction that I have witnessed by C&C bullets.

I don't find lead fragments/smears in the venison while processing anymore.

Can't comment on the twist thing, but it makes sense to me.

I have felt that GMx's are softer as they expand into nicer mushrooms, with softer edges, while the TSX's have sharper, jagged edges after expansion.

CRS;
Good afternoon sir, I trust the weekend has been treating you well.

While I'm somewhat reluctant to post photos of "samples of one" - I happen to now be in possession of exactly one recovered 130gr. TTSX and one recovered 130gr GMX.



So they both started out from my 22" barreled .270 at about 3000fps, but the impact velocities would have been different in that the GMX landed at less than 100yds and the TTSX at over 250 I'd guess. Both weigh just a bit under 129gr now - virtually identical weights as close as I can measure.

Anyway again though they are only one of each they do most certainly show the tendency that you've mentioned.

We don't miss the lead smears in venison either - though the cats seem to be getting less blood shot burger so they aren't big fans of the monometals at our house.

Hopefully that's of some interest to you or someone out there tonight sir. All the best to you this fall and good luck on your remaining hunts.

Dwayne

Plus, when bullet expands this wide..





And retain this sorta weight (225 BBC from a 338 Win Mag)



They have got to really tear up innards. I have shot a piles of jugs and NEVER seen the carnage left behind..

Seems like as others have mentioned a million times, its more about the bullets than the cartridge.

Wished I had some on game footage for this bullet, but it is up to bat in a few weeks.. More to follow.

Long ago in college I read Don Zutz Handloading for Hunters.
He talked about this very subject, and how twist was responsible for a Swede doing more radial damage than a 270 on deer.

The Good Old Swede by Robert Sherwood, 1970 Handloaders digest 5th edition. He test various twist Swedes for penetration and expansion.

10th Edition 1984 - Just one good bullet by Robert Masters, discusses the Swede/6.5-06, 264 WM and 6.5 RM and 125 Partition, deadly combo on deer thru elk.

Suffice to say, every deer I hit with a 6.5x55 dropped in its tracks. 120 corelokt and 130 NAB. It works

I'll throw this out just for grins. I shot over 20 caribou over a 3 year span with a Ru 77V 25-06 at ranges of 70 -500 yards, using hand-load 140 grain Speers. All but the first were one shot bang flops- and he just didn't know he was dead with that quartering shot. The second broadside thru the ribs did knock him flat.
Tissue damage wasn't all that bad, but the blood shot between muscle groups (trimable) was pretty extensive.

The next few caribou shot after that was with a '98 30-06 using 180 gr factory plain-jane - probably Corelokts - don't remember. Range on the first was about 200 yards, broadside, high thru the lungs. He just stood there for a good 20 seconds until he fell over. I knew where I had hit him, so just waited. My hunting partner said I had a rather surprised look on my face - which didn't stop him from whacking the other bull right after.

That and other caribou shot with the same '06 all showed less tissue damage/blood-shot between tissues and less bang-flop than that .25, which I foolishly sold.

So yeah, I'm a bit surprised that the .270 seemingly shows less tissue damage/blood shot than the Swede. My Rem 725SA .260 with 140 grain factory Corelocts at 2750 advertised shows about the same kind/amount of damage as the 150 factory Corelokts from a '98 '06 (different from above '98) at similar placement and ranges- mostly beyond 300 yds, over the last 4 years. Pretty much all bang-flops, either gun, which is kinda surprising, but welcome. 3 for the .260, 5 for the '98, 2 others for a Ru77 '06.

I've no idea of twist rates. The Ruger ("Stub") has a 17 inch barrel that I'm guessing gives .308 velocities... original manufacture, bobbed. The Rem wears a take-off ightweight 22 inch 700TI stainless barrel, the '98 has a heavy 27 inch bbl. All shoot PDG!

140 gr in 25-06?

3,000 fps/130gr 270 10" ROT = 216,000 RPM

3k mv/120 6.5x55 8 ROT = 270,000 RPM

Interesting we see 270 in a 6.5 equation

I believe faster RPM induced bullet upset, all else equal matters, AND it could be overall 6.5 bullets have thinner jackets made for slower impact/launch speeds.

Now MONO changes that above, and it seems faster RPM's just slice more per distance traveled. No doubt physics tells us the KE from spin is minute.

The 6.5 stands on it's own merits, regardless of why, it is proven in the field. Low recoil is always a bonus

TTSX's are not often recovered, so here is a 7mm 120 TTSX that finished a young boar. The pig had been shot first in front of one shoulder and downed. It lay kicking longer than I liked so I hit it with a finisher. This one went into the spine, between the shoulder blades, and was later recovered. The range was close, maybe 10 yards, and mv was about 3050 fps. 7mm-08 Montana.

65BR;
Good afternoon to you sir, I hope this finds you well on this last Sunday in October.

I've just now got off the phone to a recently retired gunsmith who's opinion and knowledge I've learned to trust a whole lot. As usual after talking or corresponding with him I'm a bit smarter now....

So one of the things he told me about the question at hand is that the military barrels were faster than 1:8 - more like 1:7.5" - AND they had very deep rifling as compared to most commercial barrels.

He felt that perhaps that's why the military barreled rifles are so hard on cup and core bullets - that the deep rifling weakens the bullet jacket somewhat or that was his hunch.

As mentioned previously in this thread, our daughter's rifle was indeed tough on some 120gr bullets we tried way back when it was my late father's rifle.

He agreed that fast twists and mono bullets seem to be a match made for each other from all reports in his district (Kootenays, BC) too.

Anyway, as well he's given me some ideas as to where and what to look for in a 6.5 barrel so we'll see now what comes of it.

Hopefully that was of interest to you or someone out there this afternoon sir. All the best to you and good luck on your remaining hunts this fall.

Dwayne

I would guess that this has more to do with different shooters using the rifles at hand. I would guess (again) that your daughter aims more for the shoulder while you are more in the rib cage looking for the vitals.

Just my rather ignorant opinion.