26 Nosler necked down (a modern equivalent to the old 244 H&H)?
Gentlemen, I present... the ".220 REDLINE"
- Thread starter fredo
- Start date
Glad to see you're back! I've missed the updates on your adventures.
I'm going to guess it needs to be bigger than a 257 Weatherby. My first instinct was that you'd grab a 300 PRC and neck it down, but I don't think that is big enough, so I'm going to say that you'll be using a 300 Norma Mag, necked down and blown out?
Good guesses!
In my prior post, I neglected to add one pertinent factor for scheming a .240Redline. Same as the .220, I’m making use of components I already have. Dies, brass, bushings, boolits, etc. This both streamlines the wildcatting process, and minimizes the initial startup cost (cuz imma need that $$$ for barrels!)
Given the history of sooooooo many crazy 6mm wildcats, my .240Redline isn’t anything really wild. More so, think along the lines of having a more practical version of something like the ol’ .244 H&H (hint), which has been called the ‘pinnacle’ of 6mm wildcats...
Regardless, the .240 is gonna be fun to mess with! Given the bc edge of same weight .22 cal caliber boolits, the .240 is gonna hafta really bring the heat to overcome the sheer ballistic awesomeness of the .220Redline...
Rest assured, the .240 is already a ‘thing’...looking at the reamer print right now (grin)!
And my last write up for the .220 is near finished, complete with some neat-o (terribly edited) ‘in field’ vids. It’ll be posted up where the first 3 installments are...
Good shooting!
In my prior post, I neglected to add one pertinent factor for scheming a .240Redline. Same as the .220, I’m making use of components I already have. Dies, brass, bushings, boolits, etc. This both streamlines the wildcatting process, and minimizes the initial startup cost (cuz imma need that $$$ for barrels!)
Given the history of sooooooo many crazy 6mm wildcats, my .240Redline isn’t anything really wild. More so, think along the lines of having a more practical version of something like the ol’ .244 H&H (hint), which has been called the ‘pinnacle’ of 6mm wildcats...
Regardless, the .240 is gonna be fun to mess with! Given the bc edge of same weight .22 cal caliber boolits, the .240 is gonna hafta really bring the heat to overcome the sheer ballistic awesomeness of the .220Redline...
Rest assured, the .240 is already a ‘thing’...looking at the reamer print right now (grin)!
And my last write up for the .220 is near finished, complete with some neat-o (terribly edited) ‘in field’ vids. It’ll be posted up where the first 3 installments are...
Good shooting!
Fredo,
With the new announcement of the .257 heavies, I think it's a new kid on the block so to speak. Gives new life to the .257. Lots of big case options too. Good luck with your new project. I'll be following. John
Thanks John!
Let’s get this 6mm flavor hashed out first, LOL
Truthfully, I’m just not a fan of going uber-heavy on pill size. I get that some guys like hitting car hoods at a mile, and I’ve had a ‘boomer’ or two that could manage real well at extended distance. That’s where the super high bc stuff shines...
But, the thing is, super heavy, high bc bullets just don’t come into their own until they fly beyond a certain given distance...
As a hunter, most times, a slightly less than massive pill, and slightly more modest twist rate will excel in point blank range, and still haul the mail for when things stretch a bit. The .220Redline 1:9 twist /69-75gr bullet marriage is a great example. Wicked flat for 5-600yds, and still impressive well beyond that...
Sure, a super fast twist tube to support an ultra heavy (sometimes solid) projo might sound like all the rave right now. But simply stated, their performance window tends to fall beyond where I’m shootings most often. Not to mention the fact that ya really paint yourself into a wall when ya throat long and twist fast, specifically for super heavies. And that limitation is only exacerbated when a hotrod is involved...
You’ll see what I mean when the .240 is born. I used the same logic in designing the .220. Just think, if you were mainly into killin’ critters, doesn’t an 87gr crowdin’ 4K fps sound, or an 80 @ 4150+ sound better than a 105 @ 3650? It does to me! The rpm generated will be significantly more friendly in the former. And any ol’ ballistic calculator will tell the tale of short-mid range superiority...
Just something to think about!
Let’s get this 6mm flavor hashed out first, LOL
Truthfully, I’m just not a fan of going uber-heavy on pill size. I get that some guys like hitting car hoods at a mile, and I’ve had a ‘boomer’ or two that could manage real well at extended distance. That’s where the super high bc stuff shines...
But, the thing is, super heavy, high bc bullets just don’t come into their own until they fly beyond a certain given distance...
As a hunter, most times, a slightly less than massive pill, and slightly more modest twist rate will excel in point blank range, and still haul the mail for when things stretch a bit. The .220Redline 1:9 twist /69-75gr bullet marriage is a great example. Wicked flat for 5-600yds, and still impressive well beyond that...
Sure, a super fast twist tube to support an ultra heavy (sometimes solid) projo might sound like all the rave right now. But simply stated, their performance window tends to fall beyond where I’m shootings most often. Not to mention the fact that ya really paint yourself into a wall when ya throat long and twist fast, specifically for super heavies. And that limitation is only exacerbated when a hotrod is involved...
You’ll see what I mean when the .240 is born. I used the same logic in designing the .220. Just think, if you were mainly into killin’ critters, doesn’t an 87gr crowdin’ 4K fps sound, or an 80 @ 4150+ sound better than a 105 @ 3650? It does to me! The rpm generated will be significantly more friendly in the former. And any ol’ ballistic calculator will tell the tale of short-mid range superiority...
Just something to think about!
Heck yes Fredo! It’s about time of flight.
Looking forward to the updates.
I feel a disturbance in the force...........
AckleymanII
Gold $$ Contributor
Many people would love to hear of your trial an success in this cartridge!!
snert
Silver $$ Contributor
Gentlemen, it is my honor to present the fourth installment of the 220 REDLINE.
Enjoy
Snert (for Fredo)
Enjoy
Snert (for Fredo)
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Well done' Sir!I like wildcats.
And being an avid predator hunter, I've gravitated toward 'hotrod' type cartridges...fast & flat is where it's at!!! Maximum point blank range and terminal performance on critters are key elements for a 'hotrod' to improve upon, over factory available cartridges. Ideally, the performance gains should justify the extra time, effort & expense of wildcatting. That's never set in stone, we all like what we like...
Several years back, I built a .22-243Win. The 1:7.7 Krieger launched 75Amaxs nearing 3500 fps, and they sure can fly at that launch speed! But then, I saw a friend's (slow twist) .22-243AI, and couldn't stop wondering what that "Improved" case could do with a faster twist??? So, built a .22-243AI on a 1:8 Brux, and that has been my 'favorite' predator cartridge for a while now. Fireforming brass on summer 'chucks & LR steel targets was good fun, and the AI'ed case allowed for another 100+ fps gain over my previous straight .22-243Win. A longer throat & full case of slow burn H1000 allows my .22-243AI to run 'cooler', mitigating throat erosion for this overbore cartridge. Have a coyote killin' friend who swapped a new barrel on his .22-243AI after 1500 rds of 80Amaxs, and it still shoots under well 3/4moa as a fireforming barrel. Lots to like about the .22-243AI!
So, where's this all going, you might ask???
Well, the same 'wildcat' itch has begun to fester & I kept looking at all this SAUM brass & those Redding 7SAUM dies...wondering "what if"...
What if I necked a SAUM case down to .224?
That question has been bouncin' around in the brain bucket for a few years now. Well, a wild hair grew from my azz, and decided to spend some time on what this monster might behold???
First thing to consider is: bullet integrity. My .22-243AI is throwing a 75Amax @ 3600fps from a 1:8 twist barrel, generating ~324,000 RPM. Needless to say, that is ALOT of spin! Every bullet handles RPM differently, depending on its design & construction. Going over the edge on RPM may result in bad things happening, from inconsistent penetration, "splashing" on animals, to outright "poofs" where the bullet never even makes it to the target. So, keeping a bullet intact & happy is of paramount importance! With the huge increase in case capacity, a .224 caliber SAUM is prolly gonna push a 75-80 fast enough to make 'em quit...
So, easy answer to address excessive RPM? Slow down the twist rate! Let's assume 3750fps as an MV for a 75gr bullet from this .224 caliber SAUM wildcat. From a 1:8 twist barrel, that 75gr bullet would be spinning over 337,000RPM!!! NOT GOOD, that number kinda scares me. I sure don't wanna invest all this time, effort & expense to start blowing bullets up after only a few hundred rounds down the pipe. And I sure don't want the bullets that can handle that stress to be "splashing" on a coyote!!! The whole idea is to kill them with extreme prejudice & authority where they stand! Otherwise, this just ain't worth it. BUT...if ya drop down to a 1:9 twist, that 337,000 RPM magically drops to 300,000. Still ALOT of RPM, but despite a 150fps gain in MV, its actually considerably less RPM that my present 1:8 .22-243AI. That bodes well for keeping bullet jackets intact, and coyotes in the dirt. Me likey...
However, there are some things that need to be checked to insure a given bullet will fully stabilize from less twist. Enter: Berger's wonderful Stability Calculator!
http://www.bergerbullets.com/twist-rate-calculator/
Given that same MV of 3750 fps, a 75gr VLD is "marginally stable" from a 1:9 twist barrel, with a factor of 1.2. That is @ sea level & 30°F, atmopsherics toward the lower end of intended use. Given the conservative MV estimate, I'm OK with a stability factor of 1.2, so that finalizes the twist rate for this .224 SAUM @ 1:9...
Now, what brass should I use? Necking down from .300SAUM is not practical, especially given that there is 7SAUM and 6.5(SAUM) 4s brass on the market. Just happened to have some brandy new Norma 7SAUM brass, so let's go with it! I used bushing I already own, and got brass necked down in three steps. Before doing so, I did remove the stem from my Redding Type S FL 7SAUM die, so it would not interfere with the decreased neck ID. A bit of Imperial Sizing Wax, and here we go!
1st bushing: .291
2nd bushing: .270
final bushing: .258"
That was easy!
(.252 bushing at right will be final tension bushing, as you'll see later)
I decided on that last .258" bushing, as it would allow for a close fit for getting that necked down brass onto a .224" mandrel. Turns out, my K&M ExpandIron only had to open the necked down brass about .001"...nice!
After truing ID on the .224" mandrel, I checked neck thickness & concentricity. Concentricity was not bad, given all that squeezin', but they did measure .018-9" That's a bit thicker than I'd care to run, so...time for the K&M turner! But first, have to address case length, as all that necked down brass has to go somewhere. Case length increased over .010" from virgin 7SAUM (~2.023--->~2.034") So, a quick trim got them all uniform @ 2.025", and now the shoulder will index true on the neck turner...
Set the K&M up and got to shavin'!
I did feel the cutting mandral take a bit of material from inside the neck, and I turned juuuust slightly into the shoulder to keep any potential issue of 'donuts' at bay. Viola, a nice, true .015" neck thickness...
Final thing, pick a bullet & find a seating depth! Seeing as how those finished cases ended up with nice, long necks, and this is gonna be a fire breathin' dragon, I didn't want to start too long on OAL. Basically, I eyeballed an 80Amax up & went from there. Here's an 80Amax @ 2.770", base of bullet is just above the shoulder, and there's plenty of bearing surface to chase lands. this length isn't set in stone, just wanted to get a baseline 'dummy' round sent out to JGS to get a reamer print worked up...
Here's what a loaded .220 REDLINE looks like!
Since this sucker is gonna run right at/beyond the redline of any .224 caliber I'm aware of, the name seemed appropriate
Loaded round measurement of .254, (.224 + .015 + .015)
That .252 bushing in the pic above will allow .002 tension upon re-sizing, should work OK for the time being. If this monster shoots & yields intended performance, I can see a set of custom dies in the future...
So, there ya have it! A .22-7SAUM...aka the .220 REDLINE. For reference, heres the REDLINE next to a 6.5SAUM4s /140JLK...
That about does it, for now!
Dummy is off to JGS, I'll await a print to confirm specs, then get a reamer ground! In the meantime, will be impatiently waiting to get this monster throttled up. ~71grains of capacity under a .224 caliber boolit is gonna make some heads spin, I hope!!! Quickload predicts both H1000 & Retumbo to have great potential at modest case pressure...
Until then, thanks for coming along on this wildcat ride!!! Will keep y'all updated...
Please let us know how it performs!
Correction: I just watched the videos. All I can say (again) is, Well Done, Sir!
I've been wacking varmints for 50 years and in my experience within 99% of field shooting conditions time of flight is so critical that I don’t use the best grouping 300 yard load I use one that's 1/4"bigger but 600 FPS faster.
Fredo -
Howdy !
Back when you first started writing about the ".220 Redline ", I made a reply to the post wherein I mentioned
rifle' " Expansion Ratio ". You asked me for a definition of expansion ratio back the, but I only responded by refering you to some website. I apologize for that, and intend to make amends for it now, and also include other pearls from Homer......
I have appreciated ballistician Homer Powley straight-forward form oftechnical writing. What follows are excerpts from the Homer Powley's " Powley Computer Handbook "......
...." expansion ratio determines how much of the chemical energy is converted into kinetic energy "
" The expansion ratio is simply the ratio of the total volumne of the gun to the case capacity ".
" It is the number of time the gas will expand by the time the base of the bullet reaches the muzzle."
" Lower expansion ratio guns are lower in efficiency than higher expansion ratio guns ".
" The ballistic efficiency inside a gun is determined by the pressure. Therefore, we can say that efficiency in any gun is necessarily going to be limited by the limit of pressure which can be used ".
" High pressure is high temperature, and therefore; fast erosion. It is as simple as that ".
"Barrel life does not depend upon the velocity of loads, as such. If high velocity has been obtained by running high pressures, then the cause is still the high pressure; and not the velocity ".
Max velocity:
" For our conventional guns, there are only 3 ways by which higher than ordinary levels may be obtained " :
1. " Increase pressure. This is usually unsatisfactory, because a 10% increase in pressure increases the velocity by only 1/2 such a percentage increase; namely 5% ".
2. " For a given bullet wt, increasing the total volumne of the gun by increasing the Expansion Ratio.
For a given cartridge, you have to increase barrel length ".
3. " For a given bullet wt, increasing the total volumne of the gun by decreasing the Expansion Ratio.
For a given gun [ barrel ] length, the chamber is increased in size ".
" Acceleration is force divided by mass. The greater the Sectional Density, the slower the [ bullet ] acceleration ".
" Density of loading is the ratio of the weight of powder used, to the weight of water which will fill the powder space ".
As previously mentioned, Powley provided an " Expansion Ratio " ( ER ) graph his " Powley Papers " article, printed in the " Guns & Ammo 1974 Annual ". The graph was listed a variety of calibres and case capacities, and all were listed for a 28" barrel length ( his chosen example ). When I mentioned this chart as regarded
" .220 Redline " expansion ratio in a notional .28" barrel, the chart appeared to give an ER of 4.5 . And also as previously noted, his chart did not graph expansion ratios lower than 4. His Powley Computer Handbook offered this comment: " If expansion ratio is below 4, you probably will not realize satisfactory performance ".
From you recent comments on the impending " .240 Redline ", it sounds like you will be staying away from the lower level of efficiency a rifle w/ a built-in ER of 4 would feature. A commendable notion !
FWIW -
To reach an ER of 4 in a 6mm rifle w/ an ( example ) 28" barrel, the powder charge would be an estimated 120gr. Your " .244 H & H updated " would feature a case capacity that would hold less powder than that ( IMHO ).
Great to have you back, and keeping us updated on your leading edge thinking for hyper-velocity rounds !
With regards,
357Mag
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