The issues with the Mk248Mod1 in the M2010's has been pierced primers and stiff bolts (sometimes really stiff!). That is why it was pulled several years back from being issued OCONUS, the remaining ammo "in country" was still being used up.
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"High" pressure vs "Standard" pressure
- Thread starter THEIS
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Hello,
That is one of the reasons that JSOC just rewrote their new switch barrel sniper rifle requirements a couple months ago from:
308, 300WM and 338LM to 308, 300NM and 338NM....the NM cases can withstand pressure better since the NM cases are better at the unsupported area around the case head and extractor groove.
THEIS
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Ha ha ha. You got that right. We now have steel case and aluminum case. I'm sure there are other alloys that would work. Brass is a convenient metal alloy that could be made at all 150 years ago. Made pretty consistently. Most of all for a very long time, brass has been relatively inexpensive. Use and reuse after creation does not overly harm the environment. One of the ultimate recyclable materials as is aluminum and steel.
A multi-part case in order to strengthen the base but provide proper consistent release of the projectile seems plausible. Steel cases the size of CheyTac or 50 cal seems plausible. Steel cases are not a arena that as a wildcatter I would welcome. Like has been said, there are ways....
Right now, my contribution is to make shell holders for the Hubble Super Magnum. Followed by some forming process work and tooling/dies for that. Snuck in there is finishing my 375 Hubble Express and some research into alternative heavy material for jacketed bullets.
Hello Fred,
The "key" to making that work would be to ensure the case actually swells enough to "grip" the chamber in which the chamber can take some of the pressure instead of ALL the pressure being forced on the locking lugs.
That was ONE of the issues with the 338 Yellow Bastard from Bill R several years ago...his tool steel case caused all the pressure to be on the locking lugs.
Time to uncover the universal receiver system and see just how much pressure we can put onto certain cartridge cases.....
THEIS
Hello,
There are several ways that a more commercial entity could run this type of situation. The EASIEST would to do just as Shawn is doing with the 375 Terminator...it is only available in HIS weapon system.
So a deeper pocket entity that already manufacturers large caliber weapon systems and ammunition/munitions could easily implement "high" pressure cartridges that do not need "wildcat" forming, swaging, bushing, etc etc....(actually mfg the case) into their business plan by using that same thought process. Just as EDM Arms did with the 338 Yellow Bastard....it could only be gotten in their weapon system.
THEIS
J E Custom
Well-Known Member
Like everything else with firearms there comes a point of diminishing returns if you exceed SAMMI pressures. solve one problem and create two more.
As long as you stay within the pressure limits of "ALL" components firearms are fairly dependable and forgiving. when you increase the pressure different requirements are needed and the higher you go the more requirements are needed.
The best/classic solution to this would be a breach plug, Bag powder and projectile. This combination is used on the really big navel guns like the 16''
on battle ships. recoilless rifles/artillery use cases and projectiles like we do but the breach is stronger because of 'bolt/breach thrust' but the chamber is nit as high as some of the rounds we shoot.
A long time ago I set the maximum chamber pressure that I would work with at 63,000 PSI and have created some wildcats that will exceed high pressure loads with the same bullet weight and diameter with no heavy bolt lift or pressure signs on cases.
It is not mystical , magic or rocket science if you understand what causes pressure in the design and it saves all the problems and issues. The weakest link
always fails in any system so it is easier to use a reasonable pressure and eliminate all of the issues.
Just my opinion
J E CUSTOM
As long as you stay within the pressure limits of "ALL" components firearms are fairly dependable and forgiving. when you increase the pressure different requirements are needed and the higher you go the more requirements are needed.
The best/classic solution to this would be a breach plug, Bag powder and projectile. This combination is used on the really big navel guns like the 16''
on battle ships. recoilless rifles/artillery use cases and projectiles like we do but the breach is stronger because of 'bolt/breach thrust' but the chamber is nit as high as some of the rounds we shoot.
A long time ago I set the maximum chamber pressure that I would work with at 63,000 PSI and have created some wildcats that will exceed high pressure loads with the same bullet weight and diameter with no heavy bolt lift or pressure signs on cases.
It is not mystical , magic or rocket science if you understand what causes pressure in the design and it saves all the problems and issues. The weakest link
always fails in any system so it is easier to use a reasonable pressure and eliminate all of the issues.
Just my opinion
J E CUSTOM
Good Day J,
But how much of those "created" problems from exceeding SAAMI pressures is due to the "solution" created only took into account of changing a SINGLE component in the formula for the "betterment" of xyz cartridge instead of completely rewriting the formula?
So instead of just changing propellants to increase MV in which in turn increases pressure; in which in turn creates "hard" bolt lift...
So instead of just changing case dimensions and SIZE to get more propellant to increase MV in which in turn can create increased pressure; in which in turn creates pierced primers, etc..
WHY do we not change the entire formula by rewriting ALL the individual components of not only the ammunition but the weapon system too??
Action/Weapon system designed to operate at 250k pressure...
Case designed to operate at 90-100k pressure...
Projectile designed to greatly reduce friction force...
Primer used that can properly ignite the powder column but not so big it weakens the case head...
COMBINING all those components/thoughts would tend to solve the problem without creating additional problems, IMO!!!
We in this industry always work to improve this and that but we still have the mindset that 60-65k is the GOSPEL when in comes to "standard" pressure guidelines because SAAMI "says so".
YET SAAMI also says not to fire 9mm NATO ammunition in firearm chambered for 9mm parrabellum; as well as saying do not fire 5.56 NATO ammunition in firearm chambered for 223 Remington.....So if we pretty much disregard SAAMI on those, then why are we so "dedicated" to SAAMI pressure guidelines when we start improving cartridges...especially the ELR cartridges?
Thanks,
THEIS
Because people get injured, and then more bad things happen to everyone involved.
What MV do you seek?
Withe the endless amount of money available for research by all the countries in the world since WW1, I think we probably have what is economically feasible and safe for the masses.
What MV do you seek?
Withe the endless amount of money available for research by all the countries in the world since WW1, I think we probably have what is economically feasible and safe for the masses.
J E Custom
Well-Known Member
All good questions and I will try to answer in my opinion.
As I stated earlier, When we abide by the pressure limits set By SAMMI all things seem to work well
without failure. As discussed Brass is the week link with standard factory chambers or poorly cut custom chambers. With a good chamber design and careful loading most cases will operate above 65,000 PSI although shorter life can be expected. when brass is pushed to 70,000 PSI life will become short and other issues start to show up.
Powders create gas that creates pressure and that Is the reason we have so many different burn rates. Powders produce the same volume of gas for the same amount weight depending on whether
it is single base powder or double based powder. But change the pressure peak based of burn rates for the same amount of powder. So If you go with a slower burning powder and more volume and can use more grains of powder it will produce more gas by volume with no more pressure . As long as the barrel can utilize the extra powder, velocity will increase with no higher peak pressure.
There are other chamber dimensions that can increase velocity without increasing pressure.
Many years ago pressures were held to mid to high 40,000 PSIs of pressures because of the metallurgy and not the brass. As designs improved and the metallurgy got better and more consistent, the pressure standard was increased in modern firearms to 55,000. Now with some cartridge designs the pressure will safely handle 70,000 psi but brass will not survive very long
so we have reached the brass limit. On these cartridges barrel shank diameter becomes an issue because of expansion during firing. The chamber expands allowing the brass to expand but the chamber returns to its original dimension because it did not reach yield, but the brass does and the chamber compresses the brass making it hard to extract.(Heavy bolt lift).
I have many examples of increasing the powder charge and capacity with no increase in pressure but much more velocity. and these changes were more than One change. It takes many subtle change to push a 300 grain .338 bullet to 3,150 starting with a 300 rum size case and prevent heavy bolt lift. (Excessive pressure).
I am all for advancing the sport through innovation, but at some point you have to ask, is it worth the problems and cost.
Just my opinion
J E CUSTOM
coyotezapper
Well-Known Member
I have been handloading since the 70's. Does this make me an expert? No it makes me someone who has an opinion based on experience.
Up until the mid 90's I considered all of my loads to be on the safe side as they showed none of the commonly accepted pressure indicators like primer pockets and case head expansion etc. It was not until I bought my first two chronographs at this time that I realized how wrong my assumptions were. When using the Oehler 43 PBL I was able to measure chamber pressures and when testing my established loads found most all of them to be over pressured 5-7K in most cases. This was a very eye opening discovery. By no means did I feel any of the loads were dangerous but I did realize that if I had loaded to the common pressure levels where the pressure indicators were evident then I would have possibly been in that area.
It is for this reason I try not to give out load data on this or any other site. Too many variables to account for that would affect end results. Although with the larger case capacities of cartridges being used for LR there is a little room to work with. If someone asks for a QL prediction, I will give that out only after getting case capacity and OAL of cartridge - the two most important variables for predicting pressure. Most times the poster is too lazy to give these to me which indicates to me that he was only wanting free data - magic load with nothing else involved. This is the type of handloader that will end up destroying his rifle or worse yet hurting himself or someone else.
There are a few threads on this site right now where this issue is rampant. One is where the OP was complaining that he was only getting a few reloads out of his Nosler brass in 28 Nosler. He refused to even acknowledge that the problem might be that he is over pressured. I gave examples of using the same Nosler brand brass in 7RUM and 7STW and had no problems with the brass. He kept referring to the 28 Nosler load thread where people are listing velocities that are either made up or they are running way over pressured. I see velocities that are as much as 200 fps over what I have loaded for with two different rifles with different barrels. Small sample I know but you would have a hard time getting me to believe that any other rifle could produce those velocities without more pressure.
The two main things I have learned by being able to measure pressures is - one, there are no magic powders. Powders are generally designed to fill a broad scope of cartridges and not any one in particular. RL33 is the only powder that I have read where it was developed specifically for the 338LM, but will work with similar cases with the same capacity.
Number two is velocity = pressure. This goes right along with number one. There are some that think RL33 is the magic powder for the 28 Nosler because of the velocities they are getting. Peak pressure occurs in the first couple of inches of the chamber and then falls off as the bullet travels down the barrel. A good powder with a good burn rate for that cartridge will still have a good amount of pressure as the bullet exits. Its after the peak pressure where the burn rate really come into play. Its when you exceed that 65K or so pressure that adds that boost in pressure / velocity where some are claiming crazy velocities. Some will claim its the burn rate of the powder that gives that extra boost but have no pressure data to prove it. In two 28 Noslers I have developed loads for with 26" bbls using 195 Bergers and RL33 the velocities achieved were between 3020-3070 with both rifles at 63K pressure. Each rifle was developed with a different lot of powder and the charges for each were quite different but the velocity and pressures were almost identical. Just because you don't see a pressure indicator does not mean you are not over pressured. If you are over book velocities, most likely you are over pressured.
Up until the mid 90's I considered all of my loads to be on the safe side as they showed none of the commonly accepted pressure indicators like primer pockets and case head expansion etc. It was not until I bought my first two chronographs at this time that I realized how wrong my assumptions were. When using the Oehler 43 PBL I was able to measure chamber pressures and when testing my established loads found most all of them to be over pressured 5-7K in most cases. This was a very eye opening discovery. By no means did I feel any of the loads were dangerous but I did realize that if I had loaded to the common pressure levels where the pressure indicators were evident then I would have possibly been in that area.
It is for this reason I try not to give out load data on this or any other site. Too many variables to account for that would affect end results. Although with the larger case capacities of cartridges being used for LR there is a little room to work with. If someone asks for a QL prediction, I will give that out only after getting case capacity and OAL of cartridge - the two most important variables for predicting pressure. Most times the poster is too lazy to give these to me which indicates to me that he was only wanting free data - magic load with nothing else involved. This is the type of handloader that will end up destroying his rifle or worse yet hurting himself or someone else.
There are a few threads on this site right now where this issue is rampant. One is where the OP was complaining that he was only getting a few reloads out of his Nosler brass in 28 Nosler. He refused to even acknowledge that the problem might be that he is over pressured. I gave examples of using the same Nosler brand brass in 7RUM and 7STW and had no problems with the brass. He kept referring to the 28 Nosler load thread where people are listing velocities that are either made up or they are running way over pressured. I see velocities that are as much as 200 fps over what I have loaded for with two different rifles with different barrels. Small sample I know but you would have a hard time getting me to believe that any other rifle could produce those velocities without more pressure.
The two main things I have learned by being able to measure pressures is - one, there are no magic powders. Powders are generally designed to fill a broad scope of cartridges and not any one in particular. RL33 is the only powder that I have read where it was developed specifically for the 338LM, but will work with similar cases with the same capacity.
Number two is velocity = pressure. This goes right along with number one. There are some that think RL33 is the magic powder for the 28 Nosler because of the velocities they are getting. Peak pressure occurs in the first couple of inches of the chamber and then falls off as the bullet travels down the barrel. A good powder with a good burn rate for that cartridge will still have a good amount of pressure as the bullet exits. Its after the peak pressure where the burn rate really come into play. Its when you exceed that 65K or so pressure that adds that boost in pressure / velocity where some are claiming crazy velocities. Some will claim its the burn rate of the powder that gives that extra boost but have no pressure data to prove it. In two 28 Noslers I have developed loads for with 26" bbls using 195 Bergers and RL33 the velocities achieved were between 3020-3070 with both rifles at 63K pressure. Each rifle was developed with a different lot of powder and the charges for each were quite different but the velocity and pressures were almost identical. Just because you don't see a pressure indicator does not mean you are not over pressured. If you are over book velocities, most likely you are over pressured.
J E Custom
Well-Known Member
royinidaho
Well-Known Member
I've been following this bigger cartridge, reach further thing that is going on. I have cause to wonder.
I was shooting a 338 RUM, which began life as a 338 Win growing to the RUM due to it's negative sexiness.
I already had a 270 Allen Magnum.
The 338 Rum or even the 338 Win was big enough to serve all purposes except for ELR.
I gave to 338 RUM to a wounded warrior, think I was scammed on that one, and ordered a 375 AM as I'm confident a 338 AM wouldn't be big enough to keep me happy.
Then comes this KO2M thing. Huh
.
I'm pushing a 395 Hammer Hunter at a bit over 3100 with single digit ES more accurately than I can regularly shoot with less than 150 grains of RL-50, in a rifle that meets the Idaho 16# big game weight. Now I need 20 more grains of powder to compete? Guess I'm not going there but not saying I won't be stretching things towards the 2 mile mark.
@ 74 years of age it seems times to finally "settle for" what I have and go harvest stuff.
During the last 10 years I have lived in the over pressure world and my opinion it isn't worth the extra effort and expense. Thus I have as "big" a cartridge as I'm ever gonna need.
I'll be keeping watch on the progress that you all are making.
Keep it growing!
I was shooting a 338 RUM, which began life as a 338 Win growing to the RUM due to it's negative sexiness.
I already had a 270 Allen Magnum.
The 338 Rum or even the 338 Win was big enough to serve all purposes except for ELR.
I gave to 338 RUM to a wounded warrior, think I was scammed on that one, and ordered a 375 AM as I'm confident a 338 AM wouldn't be big enough to keep me happy.
Then comes this KO2M thing. Huh
.I'm pushing a 395 Hammer Hunter at a bit over 3100 with single digit ES more accurately than I can regularly shoot with less than 150 grains of RL-50, in a rifle that meets the Idaho 16# big game weight. Now I need 20 more grains of powder to compete? Guess I'm not going there but not saying I won't be stretching things towards the 2 mile mark.
@ 74 years of age it seems times to finally "settle for" what I have and go harvest stuff.
During the last 10 years I have lived in the over pressure world and my opinion it isn't worth the extra effort and expense. Thus I have as "big" a cartridge as I'm ever gonna need.
I'll be keeping watch on the progress that you all are making.
Keep it growing!
Danehunter
Well-Known Member
Re: "High" pressure vs "Standard" pressure (AI "upgrade")
How about an AI carrtridge for your favorite round?
The AI shoulders give more room for more powder (& more velocity).
AI cartridges are proven designs.
Worried about pushing yer bullet too fast?? Then get a heavier bullet with a VLD or Hybrid ogive for greater sectional density and better BC.
Eric B.
How about an AI carrtridge for your favorite round?
The AI shoulders give more room for more powder (& more velocity).
AI cartridges are proven designs.
Worried about pushing yer bullet too fast?? Then get a heavier bullet with a VLD or Hybrid ogive for greater sectional density and better BC.
Eric B.
coyotezapper
Well-Known Member
Re: "High" pressure vs "Standard" pressure (AI "upgrade")
Ackley cartridges are great but some benefit very little from case taper and shoulder angle change. I have two, a 7-08 AI and a 338-06 AI. The 7 was never able to reach 280 rem velocities within normal pressures as was the claim but is still one of my favorite 7mm's. It was supposed to gain 5-8% velocity over the straight 7-08 but never did. The 33 never produced velocities above its parent case the plain 338-06 but it did benefit from getting the 40* shoulder - minimal brass flow. Not a lot of case capacity gain with the 33 but some of that could have been the Lapua 30-06 brass I used which has less capacity to begin with. I probably could have gotten more case capacity with R-P brass.
Ackley cartridges are great but some benefit very little from case taper and shoulder angle change. I have two, a 7-08 AI and a 338-06 AI. The 7 was never able to reach 280 rem velocities within normal pressures as was the claim but is still one of my favorite 7mm's. It was supposed to gain 5-8% velocity over the straight 7-08 but never did. The 33 never produced velocities above its parent case the plain 338-06 but it did benefit from getting the 40* shoulder - minimal brass flow. Not a lot of case capacity gain with the 33 but some of that could have been the Lapua 30-06 brass I used which has less capacity to begin with. I probably could have gotten more case capacity with R-P brass.
