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Caliber of the month club...

kopcicle

kopcicle

Obfuscation Engineer
Full Member
Minuteman
Feb 11, 2022
109
89
Covington Wa
...or what can the .308 do to keep pace with the 6.5 creedmoor ad nausea

If I may make an open ended suggestion.





There has been a very long winded debate about the various 6.5 caliber offerings vs the .308/7.62 NATO/30 Cal as of late.


Some of the more ridiculous comments have included the fact (yes, fact) that the 6.5 Creedmoor retains enough velocity at extreme range to still be supersonic to nearly 1,400 yards while the .308 is passing through the transonic barrier somewhere between 900 and 1,000 yards.


Add to this the complaint that the 6.5 terminal ballistics are abysmal with all but what I would call boutique projectiles and ineffective on larger game such as elk.This was stated without any discussion about range of engagement .


Now lump this all into one post. I wish I could find that rant again but I have such a convoluted and lengthy browsing history across many machines that I , squirrel ! ………………..


FFS


I do not know of any projectile capable of even moderate performance over a span of nearly 2,000 feet per second. On the high side they blow up on contact and on the low side they pass through without expansion. It’s physics FFS.

Part of the equation is the reduced cross sectional area of the 6.5 plus its greater length to diameter ratio for the same given weight. Sectional density is easily confused with the length to diameter ratio as the former is more closely related to terminal ballistics and the later more closely associated with external ballistics.

Since this is the comparison between the two calibers it would seem that for the .308 to keep pace with the 6.5 it would need to be longer. This becomes a mass equation. The length can’t be added without making the bullet heavier. The answer is to eliminate the lead and create a bullet that is longer by the addition of copper to it’s length to replace the mass of the lead. Seems easy now doesn’t it? Not so fast. First there is barrel wear which is actually a fairly simple problem in metallurgy. Guilding and or bearing metal alloys are well known in industry and this seems to be the only straight forward part of the thought. Next is stability of the bullet which is also fairly well understood. Note here that most BTHP (actually open tip rather than hollow point) target bullets are mostly void (air) behind the ogive with most of the mass at the base. So now we’re at a longer bullet with more sectional density and a better ballistic coefficient because of it’s length. So far so good. Now on to terminal ballistics. Prior to closing the tip of the bullet score the inside of the forward cavity. This will of course take large sample size of experimentation. Then anneal the forward section of the bullet to make it malleable and promote expansion without disintegration at higher velocities while predictably expanding at lower velocities.

What to do with the extra length of the bullet? At some point you run out of magazine length and are single loading. This is fine for the paper puncher but not so much for the hunter or other shooter. So the bullet gets seated deeper in the case. In my case it’s fortunate that I kept all my reloading and range information for decades past. I had more than a few loads that were not full capacity with 147gr or 168gr for that matter that were bypassed possibly because they did not fill the case leading to inconsistent pressures and velocity. Now not all of these loads will show promise either because of powder availability or pressures or other variables but I’m sure there is a gem or three in there somewhere.

In the end it’s a worthy thought experiment at the very least. It’s environmentally friendly by eliminating the lead. The bullets can be made with not much more than a lathe and an arbor press from 5/16″ and 3/8″ copper bar stock with minimal waste. Those in the manufacturing industry can see the possibilities of coining, drawing, trimming, reaming, scoring, forming, sizing and annealing, all on a modified punch press and draw line.

All this to keep up with the latest caliber of the month club.On the surface it seems a bit silly to gain another few hundred yards of supersonic velocity out of the .308. However the capability of making your own high performance projectiles has some appeal. Getting rid of the lead is not only environmentally sound but it’s also one less raw material to source.


This is only somewhat more than a thought experiment at this point. I will gladly accept any and all suggestions.


YMMV





Kudos if you read it.
 
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MinnesotaMulisha said:
There’s no fucking way you’re going to get 3160fps with that bullet out of a 308 to achieve a .620 BC. Ain’t happening.

And if the bullet was tested at 3,160, who knows how well it performs on game, target, at distance, etc at 308 velocities.
Click to expand...
yup

shows a 300WM in the pic even

but @bohem can for sure chime in about shooting his Seneca (and prior Warners) solids from a 308
 
kopcicle said:
I do not know of any projectile capable of even moderate performance over a span of nearly 2,000 feet per second. On the high side they blow up on contact and on the low side they pass through without expansion. It’s physics FFS.
Click to expand...
Monos are the answer to this conundrum. Other than the ones that are specifically designed to be frangible, monos designed for terminal performance will hold their bases together at just about any realistic rifle velocity. The expansion portion will tend to fragment away at higher speeds, but you should still get penetration. The main downsides of the monos are cost, lower BC, and higher minimum expansion velocity. A lesser downside is the lighter bullets, but that's mostly a BC issue, and saying "you can't get XYZ weight in such-and-such cartridge" is true of any bullet, you just hit that limit at lower weights with monos.

I think this is about all the energy I'll spend on yet another "308 can compete" discussion. Have fun.
 
Many have tried to get a .308 solid to perform better than a cup core. Just doesn’t work out so well.

Even in one of Litz Q&A videos he said AB has unsuccessfully tried and just can’t either get it to perform better or at least better enough to make it worthwhile over a regular Berger cup core.

I’ve personally not had much luck with .308 solids. They do ok. But haven’t had the success I’ve had with larger and smaller solids.
 
Feniks Technologies said:
Many have tried to get a .308 solid to perform better than a cup core. Just doesn’t work out so well.

Even in one of Litz Q&A videos he said AB has unsuccessfully tried and just can’t either get it to perform better or at least better enough to make it worthwhile over a regular Berger cup core.

I’ve personally not had much luck with .308 solids. They do ok. But haven’t had the success I’ve had with larger and smaller solids.
Click to expand...
I'm not thinking "solid" so much as "more cup, no core" .
I have a small amount of experience with .475 solids in bronze so I'm not a complete stranger to the idea.
Most of the commonly available Cu alloys are not guilding metal so there's that.
The punch and draw line is mostly tied up with making HVAC contacts.
I have a lathe with a crude but accurate collet chucking system.
Nothing to stop me from pushing copper down an old milsurp chrome lined barrel.
Once pressures/diameters/wear stabilizes I can get these pills into the "chassis" and see what gives.
Chassis=Lead sled. Doesn't even resemble a rifle. Just an interrupted thread breach with barrel of choice threaded in.

Somewhere down the line there is the "miss the downrange chrono, wheel of misfortune" game.

Back to work...
 
kopcicle said:
...or what can the .308 do to keep pace with the 6.5 creedmoor ad nausea

If I may make an open ended suggestion.





There has been a very long winded debate about the various 6.5 caliber offerings vs the .308/7.62 NATO/30 Cal as of late.


Some of the more ridiculous comments have included the fact (yes, fact) that the 6.5 Creedmoor retains enough velocity at extreme range to still be supersonic to nearly 1,400 yards while the .308 is passing through the transonic barrier somewhere between 900 and 1,000 yards.


Add to this the complaint that the 6.5 terminal ballistics are abysmal with all but what I would call boutique projectiles and ineffective on larger game such as elk.This was stated without any discussion about range of engagement .


Now lump this all into one post. I wish I could find that rant again but I have such a convoluted and lengthy browsing history across many machines that I , squirrel ! ………………..


FFS


I do not know of any projectile capable of even moderate performance over a span of nearly 2,000 feet per second. On the high side they blow up on contact and on the low side they pass through without expansion. It’s physics FFS.

Part of the equation is the reduced cross sectional area of the 6.5 plus its greater length to diameter ratio for the same given weight. Sectional density is easily confused with the length to diameter ratio as the former is more closely related to terminal ballistics and the later more closely associated with external ballistics.

Since this is the comparison between the two calibers it would seem that for the .308 to keep pace with the 6.5 it would need to be longer. This becomes a mass equation. The length can’t be added without making the bullet heavier. The answer is to eliminate the lead and create a bullet that is longer by the addition of copper to it’s length to replace the mass of the lead. Seems easy now doesn’t it? Not so fast. First there is barrel wear which is actually a fairly simple problem in metallurgy. Guilding and or bearing metal alloys are well known in industry and this seems to be the only straight forward part of the thought. Next is stability of the bullet which is also fairly well understood. Note here that most BTHP (actually open tip rather than hollow point) target bullets are mostly void (air) behind the ogive with most of the mass at the base. So now we’re at a longer bullet with more sectional density and a better ballistic coefficient because of it’s length. So far so good. Now on to terminal ballistics. Prior to closing the tip of the bullet score the inside of the forward cavity. This will of course take large sample size of experimentation. Then anneal the forward section of the bullet to make it malleable and promote expansion without disintegration at higher velocities while predictably expanding at lower velocities.

What to do with the extra length of the bullet? At some point you run out of magazine length and are single loading. This is fine for the paper puncher but not so much for the hunter or other shooter. So the bullet gets seated deeper in the case. In my case it’s fortunate that I kept all my reloading and range information for decades past. I had more than a few loads that were not full capacity with 147gr or 168gr for that matter that were bypassed possibly because they did not fill the case leading to inconsistent pressures and velocity. Now not all of these loads will show promise either because of powder availability or pressures or other variables but I’m sure there is a gem or three in there somewhere.

In the end it’s a worthy thought experiment at the very least. It’s environmentally friendly by eliminating the lead. The bullets can be made with not much more than a lathe and an arbor press from 5/16″ and 3/8″ copper bar stock with minimal waste. Those in the manufacturing industry can see the possibilities of coining, drawing, trimming, reaming, scoring, forming, sizing and annealing, all on a modified punch press and draw line.

All this to keep up with the latest caliber of the month club.On the surface it seems a bit silly to gain another few hundred yards of supersonic velocity out of the .308. However the capability of making your own high performance projectiles has some appeal. Getting rid of the lead is not only environmentally sound but it’s also one less raw material to source.


This is only somewhat more than a thought experiment at this point. I will gladly accept any and all suggestions.


YMMV





Kudos if you read it.
Click to expand...

I don’t see much point when the 308 is a quarter
The price and at even 800 yards you essentially have an expensive barrel eating round, that wont kill or hit a target any better. For a hunter or average target shooting its a bust for me. People love buying them in the AR platform, if want to be the cool kid you show up with a 300 winmag or 7mm-08. Or really confused someone with an AR in 45-70. And ill bet 1 in a hundred know you can get one.
 
This is the worst 308 vs Creedmoor thread I've read yet
 
@is
JaoeyP said:
This is the worst 308 vs Creedmoor thread I've read yet
Click to expand...

In the real world, explain the benefit of a 6.5 over a 308, if i set up body size target at 8-900 yards theres nothing a 6.5 will do the 308 wont. And if im gonna spend 3x the price or
More for ammo im be shooting my 300wm
 
ebbiv said:
@is

In the real world, explain the benefit of a 6.5 over a 308, if i set up body size target at 8-900 yards theres nothing a 6.5 will do the 308 wont. And if im gonna spend 3x the price or
More for ammo im be shooting my 300wm
Click to expand...
why do you feel the need to legit argue every thread you post in?
 
ebbiv said:
@is

In the real world, explain the benefit of a 6.5 over a 308, if i set up body size target at 8-900 yards theres nothing a 6.5 will do the 308 wont. And if im gonna spend 3x the price or
More for ammo im be shooting my 300wm
Click to expand...
Eye roll, sigh.

6.5 Creedmoor is not 3x the cost of 308. If it were your argument might have merit.

Shoot whatever you want. Just try to do so without making arguments based on fallacies about why you're doing it.
 
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ebbiv said:
Here's the thing, if you want to dispute it, try doing it with data, otherwise you're talking shit. I own many guns in many different calibers, and while the 6.5 is superior in certain situations, technically flies flatter and so on at the end of the day the performance isn't enough to claim you would have missed the shot with the 308. And there's more than enough test to prove the point. so go out and shoot both and bring me back some targets from the 2 identical platforms you obviously own that prove your point.
Click to expand...
b6graham said:
why do you feel the need to legit argue every thread you post in?
Click to expand...
Boston huh? Well here's one nobody will argue. Boston is ranked #1 in the nation as the most annoying accent that exists. lol
 
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ebbiv said:
Here's the thing, if you want to dispute it, try doing it with data, otherwise you're talking shit. I own many guns in many different calibers, and while the 6.5 is superior in certain situations, technically flies flatter and so on at the end of the day the performance isn't enough to claim you would have missed the shot with the 308. And there's more than enough test to prove the point. so go out and shoot both and bring me back some targets from the 2 identical platforms you obviously own that prove your point.
Click to expand...
I didn't argue for either caliber, I pointed out your false claim that 6.5 Creedmoor is 3x the cost of 308. It's not. They are similarly priced, with either sometimes being slightly (less than 10%) more/less expensive than the other.
 
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Data? At 900 yards?

At 900 yards, In a 5 mph wind, a 175 gr FGMM 308 load drifts 0.5 mil further than a 147 gr ELD-M 6.5 CM load (1.2 vs 0.8 mil). That is the entire width of a standard IPSC universal rifle target.

At 900 yards, a 308 drops 2.4 mil further than a 6.5 CM (9.4 vs 7 mil). That is 2.5x the height of a IPSC Universal rifle target.

The 6.5 CM gives the shooter substantially (measurably and meaningfully) more error budget both in range and wind estimation.

Between the 6.5 CM and 308 win, the 6.5 CM is the better long range cartridge, and it isn't even close.
 
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hlee said:
Data? At 900 yards?

At 900 yards, In a 5 mph wind, a 175 gr FGMM 308 load drifts 0.5 mil further than a 147 gr ELD-M 6.5 CM load (1.2 vs 0.8 mil). That is the entire width of a standard IPSC universal rifle target.

At 900 yards, a 308 drops 2.4 mil further than a 6.5 CM (9.4 vs 7 mil). That is 2.5x the height of a IPSC Universal rifle target.

The 6.5 CM gives the shooter substantially (measurably and meaningfully) more error budget both in range and wind estimation.

Between the 6.5 CM and 308 win, the 6.5 CM is the better long range cartridge, and it isn't even close.
Click to expand...
Your argument reads just like a Camaro is better than a Mustang because you only turn the steering wheel to the left by 7* in a Camaro, where in a Mustang you have to turn it by 9.4* for the same corner....
 
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MadDuner said:
Your argument reads just like a Camaro is better than a Mustang because you only turn the steering wheel to the left by 7* in a Camaro, where in a Mustang you have to turn it by 9.4* for the same corner....
Click to expand...
Real world, 1000yd shot will have wind estimation errors, complex crosswinds, inconsitent angles/directions and all of that...you have a 1 second flight time. Run the math with stocastic error in your wind or elevation measurement. Thats why he said 'error' budget. Without errors...different story....
 
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ma smith said:
Real world, 1000yd shot will have wind estimation errors, complex crosswinds, inconsitent angles/directions and all of that...you have a 1 second flight time. Run the math with stocastic error in your wind or elevation measurement. Thats why he said 'error' budget. Without errors...different story....
Click to expand...
Hit at 1000 first shot many times with .308.... then struggled mightily in a gusting 20-30mph crosswind at the same exact target and distance.
If I had an "error" budget - it broke the bank in the wind.
 
MadDuner said:
Hit at 1000 first shot many times with .308.... then struggled mightily in a gusting 20-30mph crosswind at the same exact target and distance.
If I had an "error" budget - it broke the bank in the wind.
Click to expand...
It is useful to understand the difference between luck and skill when estimating repeatability of events.

 
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What a dumb thread. I guess 22lr is also as accurate as 308 if I properly predict the wind up to the 1/10 mph gust.
 
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MadDuner said:
Your argument reads just like a Camaro is better than a Mustang because you only turn the steering wheel to the left by 7* in a Camaro, where in a Mustang you have to turn it by 9.4* for the same corner....
Click to expand...
Let's assume you are aiming at the center of a IPSC Universal Rifle target, set at 900 yards. That target is 0.9 mil tall at 900 yards. Using the 308 win load above, a range estimation error of 25 yards or more in either direction will send your bullet off course by 0.5 mil high or low. Assuming you are aiming at the center of the target, you have a range estimation error budget of less than 25 yards at 900 yards with the 308 win load posted above.

The 6.5 CM suffers the same, but at longer distance. The target is 0.7 mil tall at 1100 yards. A 25 yard estimation error leads to the bullet going high or low by 0.35 mil.

Now wind. At 5 mph, the 308 is being blown 1.3 mil off course. The 6.5 is being blown 0.8 off course. At 7 mph, the 3.0 is being blown 1.8 mil off course, while the 6.5 is experiencing a 1.1 mil deviation. A 2 mph error in wind estimation will lead to the 308 bullet missing wide, while the 6.5 will still nick the edge- (a IPSC URT is ~0.6 mil wide).

Get back to me when you can call 5 mph v 7 mph at 900 yards.

It is not about the gross numbers, it is about the error in estimations.

The better analogy would be between cars that exhibit either tight or sloppy steering.
 
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JaoeyP said:
Dude is seriously Buddly reincarnated. Watch what you say to him, or he'll buy that Z28 right out from under you, and within weeks he'll be screwing your girlfriend and your sister!
Click to expand...

I believe he invented the story in his mind as a way to score his own sister…
 
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