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6.2mm OCC

18K views 71 replies 7 participants last post by  noyb72 
#1 ·
I have been working on a new cartridge and have gone about as far as I can on my own. Who would be the right people/company to go to for further development and brass.

I have sent a prototype to Superior Shooting Systems Inc. for ballistics and measurements.

I would like some feedback and or replies

Here is a link to a pdf of my 6.2mm OCC

http://www.datafilehost.com/download-4a7c0ddf.html
 
#3 ·
Let me first say that I never served in the military, so I have no real-life understanding of what it means to rely upon your weapon, and the rounds you carry for it, to engage an enemy or to defend your life and lives of your comrades. I have tremendous respect for the men and women who have done so, and continue to do so, in the defense of this country and the freedoms we enjoy.

From the standpoint of ballistics and terminal performance, it has become obvious to me, over the years, that a projectile should be of a certain length, for its caliber, to provide good penetration. In direct terms, it should have a high sectional density (SD). A bullet of good construction, with a sectional density of around .220, driven at an adequate velocity, can be expected to penetrate well on thin-skinned, medium game animals. As hunting big game is the only experience I have, and I understand human beings are equally susceptible, this is what I will base my observations upon.

A .308 diameter bullet, weighing 150 grains, has a sectional density of .226, which can be expected to provide good penetration. However, the SD of the 52 grain .224 caliber bullet is only .148, while the .277 diameter 115gr Sierra HPBT has an SD of .214. Of these two, hunters would use the smaller bullet on varmints, with the expected result to be high bullet fragmentation and limited penetration. The heavier, .277 bullet, would be far better, at the correct velocity range, for penetrating larger game animals. This has been evidenced by the use of 6.8SPC rounds for hunting wild hogs, to great effect.

In order to retain the ability to penetrate, assuming an adequate SD, a bullet must have a significant muzzle velocity (MV) and ballistic coefficient (BC), such that the round has sufficient energy upon impact. For many years, in the various game fields of the world, a MV between 2500fps and 3000fps, with a BC of .300, or higher, have been proven to consistently and effectively harvest thin-skinned, medium game animals. There are many examples of cartridge/bullet combinations, in numerous calibers from .243 up to .458, which will provide this kind of performance from a shoulder-fired weapon of light to moderate recoil.

Both anecdotal and in-the-field results support the ability of the 6.8SPC cartridge to perform well on big game animals such as the whitetail deer and wild hog. With the 115 grain load most commonly used in this cartridge, it provides the MV, BC and SD expected of a big game hunting round. As such, I expect that it will be sufficient for the purposes of war, where the target is a human being. It recoils less than the 7.62x51 NATO round, while delivering more energy and penetration than the 5.56, allowing more rifleman to shoot the 6.8SPC accurately, and with good effect, than either.

While very few people can shoot a gun with a complete disregard for recoil, as Tang does, I think even he would agree that the 6.8SPC is a better choice than the .308, for sustained fire, or the 5.56, for effective fire. From what I can see, even though the OP has put together a good dissertation on the merits of the cartridge he proposes, it offers very little over the 6.8 round, if anything. I say this because nowhere in his comments does he acknowledge the importance of bullet WEIGHT, in this equation. A 90 grain bullet going slightly faster than a 115 grain bullet may be equally effective, but certainly not more so, making the proposed 6.2 OCC cartridge a lateral shift in performance, rather than a step up.

Also, I have never considered nomenclature of any significance, where a cartridge is concerned, and found that portion of the OP's paper frivolous, immaterial and frankly, juvenile. I can't see the point in quibbling over the naming of any device intended expressly for the killing of men and it is certainly nothing to be discussed when arguing the relative merits of such.
 
#6 ·
I say this because nowhere in his comments does he acknowledge the importance of bullet WEIGHT, in this equation. A 90 grain bullet going slightly faster than a 115 grain bullet may be equally effective, but certainly not more so, making the proposed 6.2 OCC cartridge a lateral shift in performance, rather than a step up.
"Nowhere"? 1/3 of my work stress the importance of bullet Weight. I have tried to design the optimum cartridge for the platform. 75gr(CR) was optimal for high velocity, and energy. 85-87-90gr(MR) was optimal for BC,SD, and energy. Giving the CR higher velocity for temporary and permanent wound cavitation. The MR for accuracy with better BC & SD. The 6mm will retain its ballistics far beyond that of the 6.8 giving each muzzle velocity. There are many factors into what the military wants. 6.8 looses 5 rounds per magazine from the 5.56 30 rounds. Ammunition weight is also a factor between the 5.56 and 6.8 . The 6.2mm will have flatter trajectory than the 6.8 . Finally and most importantly, D.O.D. has looked at the 6.8spc and determined it was NOT what the military wanted. This is why I stated that the 6.2mm was not intended compete with the 6.8spc or 6.5Grendel. My figures show the 6.2mm OCC as having 27-28 rounds compared to the 5.56NATO 30 magazine.
 
#4 ·
Deadduck, Like Tang said you have done your homework. But I have questions for you. What length of barrel do you plan on using to achieve your velocity goals ? And the second is a biggie. What does the 6.2 OCC achieve that a 6mm-223(6x45mm) can't do ?? The 6mm-223 can do over 3000fps with less than 50,000cups with 70gr bullets. And over 2800fps with less than 50,000cups with 85gr bullets. Admittedly these velocities are with a 24" barrel, hence the reason for my first question. Myself I've always wondered for a long time why the military just didn't chamber the m-16 in 6mm-223 shooting 85gr bullets for extra power with just barrel swaps, no mag or bolt changes and save lots of money instead of expermenting with new rounds. I must admitt the 6.8spc seems to be a fine round for the designed purpose. So what does the 6.2 OCC offer over the 6mm-223 besides a new case design ?? Dave
 
#7 ·
What does the 6.2 OCC achieve that a 6mm-223(6x45mm) can't do ?? I must admitt the 6.8spc seems to be a fine round for the designed purpose. So what does the 6.2 OCC offer over the 6mm-223 besides a new case design ?? Dave
Dave, As of right now I can only go by my figures and as they are mine may be bias, I will wait till I receive the results from the prototype I sent to SSS inc. The 6.2mm and 5.56mm case capacity are close, giving a few grains to the 6.2mm case(I dont have the info with the exact figures with me right now). But anything much heavier than 55-60gr in the 5.56 impedes into powder capacity, while the 75gr 6mm does not impede powder capacity in the 6.2mm case, and with the 87gr Hornady HPBT only 2mm(a little less) of the boattail impedes beyond the neck in the 6.2mm. How much do the 75-85-90gr 6mm bullets impede powder capacity in the 6x45 case ? I dont know, would like to though. I like the 6x45mm, I don't know why the military didnt go with it back in the 70's. May have had to do with velocity. ?
 
#8 ·
Here is a piece of trivia for all of you: The parent case for the 6.8 SPC is the truly venerable .30 Remington, which is actually a rimless 30/30. Literally. Loading data for the .30 Vs. the 30/30 is identical and the Speer #5 manual tells it plainly that the .30 Rem is in fact a 30/30 that was intended for the Model 8 autoloader and Model 14 pump action rifles.

What the British tried very hard to get adopted -: http://en.wikipedia.org/wiki/.280_British
This was a pretty good round.

5.56 basic comparison info -: http://www.thegunzone.com/556faq-nb.html
This is the top of the top 5.56 load for "best case" comparison. Some caveats do apply.
-- http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=1477&bullettype=0
Note the BC and SD numbers, they become very interesting later.

6.8 SPC information -: http://demigodllc.com/~zak/firearms/6.8SPC/loads.php
This guy has some good info.
-- http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=1815&bullettype=0
This is the Sierra 115gr SMK for 6.8 / .277. Note the BC and SD numbers in comparison to the 5.56 listed above.

6.5 Grendel information -: http://www.6mmbr.com/65grendel.html
This site straight up tells it like it is. Some truly great information.
-- http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=1715&bullettype=0
Take a close look.
-- http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=1727&bullettype=0
Take another close look, and read the linked article from 6mmbr web page listed above.

Good Shooting,
Gary
P.S. Now do yourselves a favor and *READ* The information is 100% solid and irrefutable! The ballistics do not lie. There are no magic Caliber Numbers in the world. Bullet Construction is Bullet Construction, *PERIOD*!! Things like BC and SD, are things of science that have been field proven over and over for decades. Ask any Professional Hunter in Africa what SD means to him, and of course bullet construction. Ask any top sniper from any big military.
 
#9 ·
Gary,

Those are some great articles, one of which I read quite some time ago. From where I stand, the 6.5 Grendel is a near-perfect compromise of recoil, weight and performance. There's no arguing with the BC of those long .264" bullets, or their outstanding history of terminal performance on big game. I can't see where the 6mm/.243 bullets are going to compete with a 6.5, except with lighter weight ammo, allowing more to be carried.
 
#12 ·
If we had the luxury of a new platform I would like see a newly designed cartridge with a 6.5mm or .257in. With the Grendel they did choose a great projectile, BUT then they had to try to find a case to fit the platform. The Grendel case was designed for bolt actions, it is a modified benchrest case, same is the .264 LBC-AR. The case diameter is even larger than the 6.8spc case. I believe the 6.5mm is most efficient in case lengths such as the 6.5 Creedmoor, 260 Rem and 6.5x47mm. We need to look for what the military wants and capacity and weight per round is a major factor here.
 
#10 ·
broom_jm,

Yes, the numbers are rather self explanatory.

Another interesting bit -: http://www.hornady.com/store/6.5mm-.264-123-gr-A-MAX-Grendel-LBC-Lapua/
Note the designations for this bullet. Now if you look at Hornady .277 bullets you do not see any SPC. I wonder why that is?
They make the cases for both
6.8 -: http://www.hornady.com/store/6.8-SPC/
6.5 -: http://www.hornady.com/store/6.5-Grendel-cases/

Now in fairness, the 6.8 SPC i am sure does make a pretty good hunting round for us civilians. I mean, it is basically a 270-30/30 Rimless short :) With todays powders and bullet tech, I can see it doing pretty well!

Now, take the .30 Rem, neck it down to 6.5 and move the shoulder forward, give it about .284 to .296 neck length, a 28 Degree shoulder or so, and Voila!! You would suddenly have a truly great "Little Hunting Round"!

Heh, another piece of trivia: 7/30 waters. This is the 30/30 literally necked down to 7mm, but with the rim still intact. It would seem Ken Waters had a pretty solid idea eh? Now just Drop the Rim, use .30 Remington as its basis and tinker just slightly and there ya go.

Good shooting,
Gary
 
#13 ·
I shoot the 7-30 Waters out of a Contender and find it to be a great blend of manageable recoil and good velocity, from a 14" barrel. The accuracy is nothing to sneeze at, either. I could see that case with a rimless design serving as a fine military cartridge...sort of a throwback to the 7x57, throttled down a bit.
 
#14 · (Edited)
@dd,

Sure, but you are not going to like the answer very much once you realize what the chinese round really is.

-- http://www.thehighroad.org/showthread.php?p=4335667
fairly decent discussion here,

Good shooting,
Gary
P.S. Pretty similar to the 6.8 SPC actually, though not exact. Case wise that is. The bullet is a very strange little animal.

Here is the link I was originally thinking of. This information is solid, and fairly complete. -: http://www.snipersparadise.com/articles/chinacomplex.htm

P.P.S. enjoy :)
I read this quite a long time ago, it took some fairly serious digging to find this thread. This thread has hashed out just about every single possibility known to mankind, including more info on the chinese round. http://www.65grendel.com/forum/showthread.php?t=1252&page=1&pp=25

P.P.P.S. DD357 I just caught up to and finished off that thread at 65Grendel.com and noticed that a few days ago you posted there. You should read through all 10 pages, a lot of info was hashed out. The short of it is, "there is no free lunch" a bullet of approximately 100gr in 6mm, or 120gr in 7mm is about as close to optimum as you can get more or less off the shelf. Meaning that you have to look at available non match bullets too. The 95gr 6mm SMK is a nice bullet, and the 130gr 7mm SMK is decent over all. All in all, No Free Lunch to be had anyplace. For match bullets in the right range, the 6.5mm 123gr bullets rule the roost for BC and SD.
 
#15 ·
@dd,

-- http://www.thehighroad.org/showthread.php?p=4335667

Here is the link I was originally thinking of. This information is solid, and fairly complete. -: http://www.snipersparadise.com/articles/chinacomplex.htm

P.P.S. enjoy :)
I read this quite a long time ago, it took some fairly serious digging to find this thread. This thread has hashed out just about every single possibility known to mankind, including more info on the chinese round. http://www.65grendel.com/forum/showthread.php?t=1252&page=1&pp=25

P.P.P.S. DD357 I just caught up to and finished off that thread at 65Grendel.com and noticed that a few days ago you posted there. You should read through all 10 pages, a lot of info was hashed out. The short of it is, "there is no free lunch" a bullet of approximately 100gr in 6mm, or 120gr in 7mm is about as close to optimum as you can get more or less off the shelf. Meaning that you have to look at available non match bullets too. The 95gr 6mm SMK is a nice bullet, and the 130gr 7mm SMK is decent over all. All in all, No Free Lunch to be had anyplace. For match bullets in the right range, the 6.5mm 123gr bullets rule the roost for BC and SD.
diriel, thanks. I read the one from David Fortier awhile ago.

I do agree with you that the 6.5mm bullet is great, just not optimal for the AR15/M16 platform. It requires to large a diameter case just to push at sufficient velocities(6.5Grendel). We all would probably agree that 25 rounds are sufficient for us civies but the military does not see it that way.
 
#17 ·
DD357,

There are at least 3 major factors and the unfortunate thing for any would-be cartridge designer is that no matter how great your idea might be, you WILL be compromising on at least one, if not all, of those three factors. The 308 has great bullet mass but higher recoil, lower mag capacity and higher ammunition weight. The .223 has very good velocity and low weight, but simply doesn't have the mass to retain velocity well or to have good terminal performance. I think you're on the right track by stepping up to the 6mm bullet, but the BC and SD of the 6.5 round is simply better, for any given bullet weight.

Put another way, if you were to take an average of the match ammo available for the 2 existing military rounds that you propose a replacement for, you would come up with (173+77=250/2) a round shooting a 125 grain projectile. If you take an average of the two bore sizes (.308+.224=.532/2) a rifle shooting .268 bullets would result. Something tells me if you were to average the ammunition weight of the 7.62 and 5.56, you'd get something along the lines of a properly designed 6.5mm cartridge.

If we can all agree on the basic "problems" inherent in the 2 cartridges currently being used by our military, then I submit that the 6.5 "something" is the solution. Maybe the Swedes had this all figured out 100 years ago? :rolleyes: In fact, if you did nothing more than shorten a 6.5 Swede to around 45mm, you might just have a perfect compromise round for the military...which would make it pretty dang close to the Grendel offering.
 
#18 ·
DD357,

http://www.lasc.us/RangingShotBullberry6.5TCU.htm
The 6.5 version of 223 necked up and improved

http://www.lasc.us/RangingShotVirginValley6TCU.htm
The 6mm version of the 223 necked up and improved

Read both of these very carefully. There is a ballistic lesson to be learned here that has a direct Field Proven Result ( making a steel ram fall over requires energy delivered on target ).

Believe me when I say that I have considered many many different things that would go into a combat cartridge. It is all about compromises, there are always "here are 3 choices - pick any 2". Which sucks. But here is a thought, Have you asked active duty service men about the weight of their ammo? Most I have met or talked to all said something along the lines of " if it will make **** drop NOW, **** yes I Wiill Hump It!!" And believe me some of those guys have one helluva lot of kit to hump.

I will say this, Look at the 95gr SMK in 6mm. The thing is, you have to look at non match bullets as well. The 95 is a pretty decent compromise, when you start typing in velocity and getting energy at range numbers it looks pretty good. Then when you look at the other non match bullets it suddenly don't look quite as good. I know "New bullets can be made" but man that is a LOT of hassle, it just does not happen over night.

Then to mix it up even more, look at the 7mm bullets that are around and plug in velocity at ranges and scratch your head some more. Suddenly its "****, choices choices".... I.E. ...compromise and more compromise. You can learn a **** of a lot by looking at Silhouette cartridges. For those guys it is about hitting a target and delivering enough energy At Range to make it drop, all in as small and easy to shoot package as can be managed. Is it a perfect analogy? No. But it is pretty **** similar is several ways.

Good Shooting,
Gary
 
#19 · (Edited)
DD357,

It is all about compromises, there are always "here are 3 choices - pick any 2". Which sucks.

I will say this, Look at the 95gr SMK in 6mm. The thing is, you have to look at non match bullets as well. The 95 is a pretty decent compromise, when you start typing in velocity and getting energy at range numbers it looks pretty good. Then when you look at the other non match bullets it suddenly don't look quite as good. I know "New bullets can be made" but man that is a LOT of hassle, it just does not happen over night.

Then to mix it up even more, look at the 7mm bullets that are around and plug in velocity at ranges and scratch your head some more. Suddenly its "****, choices choices".... I.E. ...compromise and more compromise. You can learn a **** of a lot by looking at Silhouette cartridges. For those guys it is about hitting a target and delivering enough energy At Range to make it drop, all in as small and easy to shoot package as can be managed. Is it a perfect analogy? No. But it is pretty **** similar is several ways.

Good Shooting,
Gary
Its good to get feedback from you, I think were thinking alike.

"compromise" = Bingo

I agree with Broom_jm that a 6.5mm projectile would be the best, BUT not while were restrained within the AR15/m16 dimensions.

Let me try to put this another way:
1) 6.5mm bullet = overall great choice
2) 6.5mm bullet with good BC & SD is a long bullet
3) Because the 6.5mm bullet is so long will require a short case to fit in platform
4) Because its a short case it will require large diameter for sufficient powder
5) Large diameter case = less magazine capacity, + weight per round (6.5 Grendel).

I really dont want to get into debating the 6.5 Grendel, I like the round, I just dont see the military ever going with it. The military is going to see the capacity loss & weight to significant.

OK, so whats has a larger diameter than .224 but is shorter in length than 6.5mm ? (bullet) So we can use a longer case but smaller in diameter for more mag capacity ?

I looked at .257 and really liked it also but still would require a long bullet to get good BC & SD.

He!! even a 6mm with great BC & SD would have to be quite long so thats one of the reasons why going with 75 - 90 gr. *Compromise* Yes 105 - 115 would be great But remember we are not trying to design a Benchrest round its a combat round.
 
#21 ·
You realize the TCU cartridge is a 5.56 case necked up to what ever caliber you wish and improved right? As for the 25, I really like the caliber. The thing about it is, it has relatively low sd and bc. There is a 90gr hollowpoint gameking bullet in 25 that just Kicks *** on game, but the sd and bc leave a good bit to be desired on it. There is a 110gr hornady bullet that has ok sd and bc but only ok, it is a **** fine hunting bullet however. Im not knocking 25, but for some crazy reason the bullets mostly all seem to lack in ballistics. I am not a huge 6mm fan either. I prefer 6.5 and 7mm for "the small stuff" and 30 cal or 338 cal for the larger stuff. Though that 95gr SMK in 6mm IS a fine bullet, very fine bullet in fact. Now if they would re-do it in FMJ battle bullet formula that would kick ***.

Do yourself a big favor, the link below is for an online ballistics calculator that is totally free to use. Use it to determine actual energy delivered at various ranges, guessing only takes you so far.
http://www.jbmballistics.com/calculations/calculations.shtml

Use this to get a GOOD LOOK at what your ideas can / will do. Then compare them to the ballistics of the actual combat 5.56 cartridges at various ranges. You can then extrapolate how "good" your idea is. Keep in mind by your rules you have to use the same 5.56 case so you can keep capacity up to par. Also keep in mind that the actual capacity is only 28 rounds not 30. No combat soldier in his right mind loads past 28, and some load 27 rounds. Rumor has it there are some new and improved mags coming into service that may allow a full 30 rounds to be used and not jam stuff up. Which would be nice. :)

Good Shooting,
Gary
 
#23 ·
Shall we assume for the sake of easy ballistics checking that this 6.45 SAW re-incarnation can at least equal a 6ppc? If so then you may be in for a pleasant surprise. As for info on the SAW, no not really. That is a different animal than the 6/223 (6x45) you see in the reloading manuals.

By the way, shame on you for listing BC's of VMAX bullets! I realize that they can be remade in that shape but usable by the military. Now if you can talk Tubb into a brass run for the SAW....wow?!?! That would solve numerous problems. I am going to assume for the sake of "idle chat" that this CAN equal the 6ppc at a minimum and shoot some numbers. The numbers I will give should all be 50k psi or less, absolutely no more than 52k psi.

Good Shooting,
Gary
 
#26 · (Edited)
Ok, so i changed it up. I went with Hornady 4th edition 6TCU information. This is MOST interesting as it gives velocity out of a 14" barrel. Ring any bells? This is approximately what your 75gr combat load would look like, only yours should beat this by a bit. JBM software was used for this information. BTW, shame on you for using Vmax BC :)

I am assuming 500 ft lbs as the max effective range, and will list the highest 100 yard increment at which it is still Supersonic.

Max effective: 300 yards @ 591 ft lbs (400 yards = 461 ft lbs)
Supersonic: 600 yards @ 1250 fps, with 260 ft lbs - (subsonic = 700 yards @ 1081 fps with 194 ft lbs energy remaining)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Shame on you again for using a Vmax. This is the 87gr marksman round.

Max effective: 400 yards @ 526 ft lbs (500 yards = 418 ft lbs)
Supersonic: 700 yards @ 1148 fps, with 254 ft lbs - (subsonic = 800 yards @ 1046 fps with 211 ft lbs energy remaining)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Fun with Numbers: Here is a 90gr Sierra Gameking FMJ bullet you mentioned, I use it here as the Combat round. (this should be usable for the military right now, and it may be cheap enough). *NOTE*: I used the 87gr information and knocked off 50 fps for the 90gr sierra bullet, this should be adequate for informational purposes.

Max effective: 400 yards @ 500 ft lbs (500 yards = 399 ft lbs)
Supersonic: 700 yards @ 1152 fps, with 265 ft lbs - (subsonic = 800 yards @ 1065 fps with 226 ft lbs energy remaining)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

More Fun With Numbers: This is an alternate version of the Marksman round. The information was "doped" from the Hornady 4th edition manual using 100gr information. We should be able to slightly better this. This being a 95gr SMK it is straight up usable by the military, the SMK is what they mostly use for this purpose.

Max effective: 400 yards @ 566 ft lbs (500 yards = 467 ft lbs)
Supersonic: 700 yards @ 1208 fps, with 308 ft lbs - (subsonic = 800 yards @ 1090 fps, with 250 ft lbs energy remaining)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Last little Fun With Numers: 107gr SMK Marksman round. I took the 100gr information from Hornady 4th edition and knocked off 100 fps for the 7gr difference and for lost capacity case intrusion.

Max effective: 500 yards @ 539 ft lbs (600 yards = 451 ft lbs)
Supersonic: 800 yards @ 1140 fps, with 309 ft lbs - (subsonic = 900 @ 1060 fps, with 266 ft lbs energy remaining)

Good shooting,
Gary
P.S. Remember this is a 6mm TCU with a 14" barrel, so these numbers are pretty good to look at and Think About.
 
#29 ·
From Rifle Shooter Magazine - shot show coverage -

"Black Hills introduced a 6x45 mm loaded with either a 100-grain Sierra Spitzer at 2600 fps, or an 85 grain Sierra GameKing at 2700 fps. The 6x45 is simply a .223/5.56 necked up to 6mm caliber. That means the cartridge is ideally suited to the AR-15 platform and allows the use of heavier bullets with no loss of magazine capacity. Lighter varmint loadings are expected to follow initial loadings"
-- Keep in mind they are listing velocity out of a longer barrel, probably an 18".

As for the differences, the TCU has just a little more capacity than the standard 6x45 listed above. Now the 6x45 SAW round is a totally different animal all together.
http://www.stevespages.com/page8d.htm
Go here and look up the 6x45, then the 6mm TCU. Then go look at your PDF file on the 6x45 SAW. Totally different animal, and a very rare one at that. You had people cringing at having Converted that round :)

Good shooting
BTW i modified that post, as it looked terrible. One more post coming
 
#33 ·
"Black Hills introduced a 6x45 mm loaded with either a 100-grain Sierra Spitzer at 2600 fps, or an 85 grain Sierra GameKing at 2700 fps. The 6x45 is simply a .223/5.56 necked up to 6mm caliber. That means the cartridge is ideally suited to the AR-15 platform and allows the use of heavier bullets with no loss of magazine capacity. Lighter varmint loadings are expected to follow initial loadings"
-- Keep in mind they are listing velocity out of a longer barrel, probably an 18".

As for the differences, the TCU has just a little more capacity than the standard 6x45 listed above. Now the 6x45 SAW round is a totally different animal all together.
http://www.stevespages.com/page8d.htm
Go here and look up the 6x45, then the 6mm TCU. Then go look at your PDF file on the 6x45 SAW. Totally different animal, and a very rare one at that. You had people cringing at having Converted that round :)

Good shooting
BTW i modified that post, as it looked terrible. One more post coming
From what I remember reading that velocity for the BH 6x45mm was taken with a 24" barrel.

I am familiar with the difference between the 6mmSAW & 6x45mm(6mm/223).
 
#30 ·
For the MK262 Mod1 ammo, barrel length is 18", the load data is theirs: 5.56x45 mil spec

Maximum effective: 400 yards @ 593 ft lbs (500 yards = 470 ft lbs)
Supersonic: 800 yards @ 1173 fps, with 235 ft lbs (900 yards @ 1074 fps, with 197 ft lbs energy remaining)

As you can see, the military has not sat on their heels.
 
#32 ·
6.8 SPC: This load is from hodgdon from a longer barrel than the loads I listed for the 6mm, so it should be A LOT faster than it would be out of a 14" barrel.

Maximum effective: 500 yards @ 526 ft lbs (600 yards = 390 ft lbs)
Supersonic: 600 yards @ 1236 fps, with 390 ft lbs (700 yards @ 1072 fps, with 293 ft lbs energy remaining)

Gary
 
#34 ·
Are you sitting down? These numbers are from Hodgdon online, so are comparable to the 6.8 numbers. Not so much to the 6mm atm,

6.5 Grendel
107gr SMK

Maximum effective: 700 yards @ 516 ft lbs (800 yards = 420 ft lbs)
Supersonic: 900 @ 1194 fps, with 339 ft lbs (1000 yards @ 1080, with 277 ft lbs energy remaining)
----------------------------------------------------------------------------------------------------------------------------

6.5 Grendel
123gr SMK

Maximum effective: 700 @ 583 ft lbs (800 yards = 486 ft lbs)
Supersonic: 900 @ 1213 fps, with 402 ft lbs (1000 yards @ 1104 - mach .989 - , with 332 ft lbs energy remaining)

Good Shooting,
Gary
 
#37 ·
Now for the Marksman in 6x45 out of a long barrel from Hodgdon online manual. Data is extrapolated as they do not have the 87gr, i used the 85 gr info instead. Actual velocity may be a bit high. For the 75gr bullet the info is as in Hodgdon manual.

6x45 with 75gr Vmax

Maximum effective: 400 @ 1913 fps, with 609 ft lbs (500 yards = 477 ft lbs)
Supersonic: 800 @ 1181 fps, with 232 ft lbs (900 @ 1076 fps, with 193 ft lbs energy remaining)
----------------------------------------------------------------------------------------------------------------------------

6x45 with 87gr Vmax

maximum effective: 500 @ 1744 fps, with 587 ft lbs (600 yards = 471 ft lbs)
Supersonic: 800 @ 1225 fps, with 290 ft lbs (900 yards @ 1085 fps, with 227 ft lbs energy remaining)

Good Shooting,
Gary
P.S. keep in mind these numbers are with a longer barrel than the posted TCU numbers. But they do represent a nice contrast between 14" barrel and the longer one used by hodgdon ( i think an 18 or 20 inch but not totally sure)
 
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