Velocity question?s

[darrindlh]

You beat me to it. Lol. That is the article i have. Awesome stuff.

Darrin

 

[diriel]

I studied that information quite a while back. I ended up considering buying a Magnum Length action, so I could build a Real Deal .308 bullet diameter Magnum of some kind. I was actually leaning towards a 30-375 Ruger of some kind.

Right at the moment, I have decided to run with a Sinarms Brux barrel in 7mmRM, with Devin doing all of the work to my Savage 111. I figure that by having a REAL smith sort out any action problems I may have, and a REALLY GOOD Chamber job I will save myself from my previous Savage Pre-Fit situation. Devin @ Sinarms seems to take his reputation pretty serious, and he seems very comfortable smithing a Savage.

Sorry for the OT part of the post...just telling why I had closely viewed the mk248 mod 1 information. Some day I may very well roll up a 30 cal mag of some variety... then again, if i want a Shoulder breaker, I may roll with a 375 cal Long Range Built Magnum of some kind Now THAT is where .... some interesting "Things" have been going on

Have a good one,
Gary
P.S. the Mil Spec 300WM has very little in common with a Commercial OEM 300wm... I would think even attempting to shoot a Mil. Spec 300wm piece of ammo might be a bad idea... just postulating.

 

[darrindlh]

Gary, i to respect sinarms. Those guy are doing some great things, ive been keeping up on there 338sin. Pretty awesome.
What is the difference in a mil spec 300 and a 300 that has been trued up and accurized? I thought that the military were using the same 700 action?

Darrin

 

[diriel]

Average working pressure is more, and COAL is longer than any commercial cartridge. I posted about it... the info is there sir Working COAL on a 300wm is 3.340 for commercial ammunition.

Gary

 

[darrindlh]

Intresting indeed. In My factory 300wm rem 700 i reload to a coal of 3.60. Which is according to your post is longer than the mark240 which has a coal of 3.50. 3.34 is not where accuracy is found, for example berger bullets like to be seated .20 off the lands. That short of coal is reducing case capacity and is no where near the lands. Therefore obtaining the best accuracy is not found.

Darrin

 

[diriel]

You can put a 3.6" round through a standard long action remmy? Or do you single feed? My savage will most definitely not feed a round that long.

Have a good one,
Gary

 

[darrindlh]

Yup . That is in my standard remmy. I agree with you my savage could not go that long in overall length. I need to figure out now they can load to 71,000 psi. You know what i thought was interesting accuracy for that rifle is 4.5 inches at 300yrds
have a great day

Darrin

 

[ken snyder]

It's still not a goal for a 300 WM. The military version (specs.) are asanine. Metal cohesively bonds ( welds itself together ) at about 92,000 psi this one is allowed a maximum of 78,900. It's not a 300WM, It uses the 300WM case. This is definately an ocassion that the cartridge should have a clear, descripitive name such as 6.5-284 vs. 6.5-284 Norma and probably another suffix like 6.5-284 Norma T. this is an example of Government cheapness, lots of money saved by pushing something past its limit instead of re-barreling and rechambering a zillion rifles, I guess in the military its better to have a few blow up rather than to try and keep track of who has what rifle and sending the wrong ammunition. We in the civilian sector do not need to play the games of a Jack *** movie. Want that vel. with that heavy of a bullet, then use a larger cartridge or star in your own movie, could be the new Darwin Awards.

 

[Trickymissfit]

This is the information straight from the Neco.navy.mil PDF document:

https://www.neco.navy.mil/upload/N00164/N0016409RJN30000209RJN30_0002_att.pdf

"" 3.
REQUIREMENTS
3.1 Classification of characteristics. Where critical or major
characteristic requirements are listed in this specification, they
are annotated by a "C" or "M" and sequential reference number
starting with "1" for critical and "101" for major. The letter and
number are contained in parentheses. The main verbiage of the
requirement is then surrounded by brackets, "[ ]". Minor
characteristic requirements contain no annotation. Reference DOD-
STD-2101.
3.1.1 Critical characteristic. One that analysis indicates is
likely, if defective, to create or increase a hazard to human
safety or to result in failure of a weapon system or major system
to perform a required mission.
3.1.2 Major characteristic. One that analysis indicates is not
critical but is likely, if defective, to result in failure of an
end item to perform a required mission.
3.1.3 Minor characteristic. One that analysis indicates is
significant to product quality but is not likely, if defective, to
impair the mission performance of the item.
3.2 First Article. When specified in the solicitation (see 6.2g),
a sample shall be subjected to First Article inspection in
accordance with 4.2.
3.3 Government-loaned property. Government-loaned property (see
6.2e and 6.4) might be used for performing tests as specified in
Section 4 and Appendices A, B and C of this specification.
Government-loaned property shall be described in the contract where
applicable.
3.4 Components. MK 248 MOD 1 cartridge components are the
projectile, the cartridge case, the propellant, and the primer.
3.4.1
Projectile.
The projectile for the MK 248 MOD 1 shall be
4
DS/JXNN/C08/1604A
the 220 grain Sierra MatchKing® Hollow Point Boat Tail (HPBT)
bullet, commercial part number 2240, manufactured by Sierra
Bullets, (Drawing 53711-8330251). The bullet shall have a lead or
lead alloy core and copper or copper alloy jacket. The bullet
shall have a nominal weight of 220 grains, with a tolerance of ±0.5
grains. The bullet diameter shall be 0.3086-0.0005 inches. The
bullet shall be of the reverse drawn, Open Tip Match (OTM) type
capable of meeting the accuracy requirements as specified in
paragraph 3.6.4.
3.4.2 Cartridge case. The cartridge case shall be .300 Winchester
Magnum constructed of copper alloy in accordance with ASTM B19, and
shall not be plated. The cartridge case shall meet the external
dimensional requirements of ANSI/SAAMI Z299.4-1992. (C1) [A vent
hole shall be present in the primer pocket of the cartridge case].
3.4.2.1 Headstamp. The cartridge case headstamp marking shall
consist of the identification code of the manufacturer, last 2
digits of year of manufacture and the notation "300 WM" or "300 WIN
MAG" in accordance with drawing 53711-8330252.
3.4.3 Primer. The primer shall be a large match rifle primer,
non-corrosive, nickel-plated, boxer type, and shall be of lead-
styphnate type. The primer shall have a brass anvil and brass cup.
The primer shall be capable of meeting the ballistic requirements
herein.
3.4.4 Propellant. (C2) [Each cartridge shall contain Hodgdon
H1000 propellant.] The propellant loaded in this cartridge shall
contain flash reduction additives or coatings, and shall meet the
temperature stability and ballistic requirements detailed in
Section 3.6.
3.5
Complete cartridge.
3.5.1 Cartridge assembly. The cartridge assembly shall be
manufactured and inspected in accordance with drawing 53711-
8330252.
3.5.2 Primer seating depth. The primer shall be seated in the
cartridge case to a depth of (M101) [0.000 to 0.008 inch below the
face of the cartridge case head.] The primer shall not be staked
or crimped in place.
3.5.3 Cartridge overall length. (M102) [The nominal overall
length of the assembled cartridge shall be 3.500 inches maximum,
3.450 inches minimum] in accordance with drawing 53711-8330252.
The distance from the cartridge case head to the 0.300 inch
diameter datum on the projectile ogive shall be controlled to
within ± 0.010 inches. The nominal overall length and the distance
5
DS/JXNN/C08/1604A
from the cartridge case head to the 0.300 inch diameter datum on
the projectile ogive of the assembled cartridge shall be
established, within the above limits, by the manufacturer to meet
performance requirements.
3.5.4 Cartridge headspace. (M103) [The cartridge headspace shall
be 0.212 inches minimum, 0.220 inches maximum], in accordance with
drawing 53711-8330252. Cartridge headspace shall be measured from
the base of the cartridge case to the opposite surface of the belt
of the cartridge case.
3.5.5 Primed case sensitivity. Primed Case Sensitivity tests
shall be conducted on empty primed cases in accordance with 4.5.5.
Primed case sensitivity shall be as follows:
a. b.
3.6
(C3) [The mean critical height minus two standard
deviations ( H -2σ) shall be 3.0 inches minimum.]
(M104) [The mean critical height plus four standard
deviations ( H +4σ) shall be 22.0 inches maximum.]
Cartridge ballistic performance.
3.6.1 Velocity. (M105) [The corrected average muzzle velocity of
the cartridges conditioned at 70° ± 5° Fahrenheit (F) shall be
2,850 ± 50 ft/sec. feet per second (fps)]. The standard deviation
of the corrected muzzle velocity at 70° ± 5° F shall not exceed 15
fps. This test shall be conducted in accordance with paragraph
4.5.6.
3.6.2 Chamber Pressure. (M106) [The corrected average chamber
pressure shall not exceed 68,100 pounds per square inch (psi) at
70°F.] Neither the chamber pressure of an individual sample test
cartridge nor the average chamber pressure plus three standard
deviations of chamber pressure shall exceed 78,900 psi. This test
shall be conducted in accordance with paragraph 4.5.7.
3.6.3 Operational Temperature Stability (High and Low). The
velocity and pressure of sample cartridges conditioned and fired at
the temperature extremes specified below shall be in accordance
with 3.6.3.1 and 3.6.3.2.
a. Conditioned at 165°F - 5°F for not less than 2 hours
immediately prior to firing.
b. Conditioned at -20°F + 5°F for not less than 2 hours
immediately prior to firing.
6
DS/JXNN/C08/1604A
3.6.3.1 Velocity. (M107) [The average corrected muzzle velocity
of the sample cartridges conditioned at -20°F shall not vary by
more than 75 fps from the average corrected muzzle velocity of the
sample cartridges conditioned at 165°F.]
3.6.3.2 Chamber Pressure. (M108) [The average corrected chamber
pressure of the sample cartridges conditioned at -20°F and 165°F
shall not exceed 71,500 psi.] Neither the chamber pressure of an
individual sample test cartridge nor the average chamber pressure
plus three standard deviations of chamber pressure shall exceed
78,900 psi.
3.6.4
Accuracy.
3.6.4.1 300 yard accuracy. (M109) [The extreme spread of any
individual 10-shot group shall not exceed 4.5 inches at 300 yards.
The average extreme spread of ten, 10-shot groups shall not exceed
3.5 inches at 300 yards.]
3.6.4.2 600 yard accuracy. (M110) [The extreme spread of any
individual 10-shot group shall not exceed 9.0 inches at 600 yards.
The average extreme spread of ten, 10-shot groups shall not exceed
7.0 inches at 600 yards.] This test shall be conducted in
accordance with 4.5.8 and Appendix B, except that the range to
target shall be 600 + 1 yard. This test shall be conducted as part
of the First Article Sample or if a First Article Sample is not
part of the contract, as part of the first production lot of a new
contract.
3.6.5 Function and Casualty. (M111) [There shall be no weapon
stoppages due to the cartridge.] The cartridge shall meet all
function and safety requirements of Table I. Misfires shall be
considered separately in accordance with Table I. Function and
causality testing shall be conducted using the rifles as specified
in the contract.
""

Please read and note that 68K psi +- a good bit is what they are running and their COAL is like 3.5".... it is all there... read and enjoy.


Have fun,
Gary

Kinda looks like they are playing with 77 grains of H1000 and a 230 grain bullet. Gonna be real hard on the actions with 68K+ chamber pressures, and I wouldn't want to shoot it in a generic two lug action. Case head thrust is going to be a major factor with that kind of pressure. But that's our government idiots in action. The data you supplied is typical DASCMA stuff written by non users. Doubt barrel life will exceed 600 rounds, so somebody over there must have a stock option with a certain barrel maker. They'd have been better off with a generic .300 Weatherby at 63K PSI using the same bullet and a longer barrel life. I could write a book about government contracts specs.
gary

 

[Trickymissfit]

I studied that information quite a while back. I ended up considering buying a Magnum Length action, so I could build a Real Deal .308 bullet diameter Magnum of some kind. I was actually leaning towards a 30-375 Ruger of some kind.

Right at the moment, I have decided to run with a Sinarms Brux barrel in 7mmRM, with Devin doing all of the work to my Savage 111. I figure that by having a REAL smith sort out any action problems I may have, and a REALLY GOOD Chamber job I will save myself from my previous Savage Pre-Fit situation. Devin @ Sinarms seems to take his reputation pretty serious, and he seems very comfortable smithing a Savage.

Sorry for the OT part of the post...just telling why I had closely viewed the mk248 mod 1 information. Some day I may very well roll up a 30 cal mag of some variety... then again, if i want a Shoulder breaker, I may roll with a 375 cal Long Range Built Magnum of some kind Now THAT is where .... some interesting "Things" have been going on

Have a good one,
Gary
P.S. the Mil Spec 300WM has very little in common with a Commercial OEM 300wm... I would think even attempting to shoot a Mil. Spec 300wm piece of ammo might be a bad idea... just postulating.

why they chose the .300 win case seems odd to me. The case design is not good for bullets much longer than a typical 200 grain spitzer. But a .308 Norma mag would be a better combo. A much better case design that handles the 230 grain bullet better. The Norma mag will do the same velocity with less pressure and have a longer throat life in the end. Most folks that shoot 1000 yard competetion these days are using .300 Weatherbys and the sharp shouldered clones (.300 Ackley and .300 Jarrette are a couple). Somebody in the Navy must have got a major reward for this one!
gary

 

[diriel]

@ darr,

4.5" for a single 10 round string out of TEN 10 round strings, 100 rounds down range total. Which is actually pretty decent for ammo that is cranked out in mass.

"" 3.6.4.1 300 yard accuracy. (M109) [The extreme spread of any
individual 10-shot group shall not exceed 4.5 inches at 300 yards.
The average extreme spread of ten, 10-shot groups shall not exceed
3.5 inches at 300 yards.] ''

The thing about the 71k pressure is.... A LOT of Magnum reloaders hit that pressure range quite commonly. They just do not realize it. The max pressure they list as allowable is actually not to exceed 78k psi... just ouch!

Have a good one,
Gary

 

[Trickymissfit]

4.5" for a single 10 round string out of TEN 10 round strings, 100 rounds down range total.

"" 3.6.4.1 300 yard accuracy. (M109) [The extreme spread of any
individual 10-shot group shall not exceed 4.5 inches at 300 yards.
The average extreme spread of ten, 10-shot groups shall not exceed
3.5 inches at 300 yards.] ''

The thing about the 71k pressure is.... A LOT of Magnum reloaders hit that pressure range quite commonly. They just do not realize it. The max pressure they list as allowable is actually not to exceed 78k psi... just ouch!

Have a good one,
Gary

I know where comming from, but think they are asking for trouble right from the get go. I see lots of my tax dollars being wasted. As for chamber pressures, I think they're nuts! When your talking 210 grain and up bullets; the .300 win mag starts to fade fast. I would use a .300 Weatherby with a standard throat, and cut those groups by a third at the miniumum with a longer barrel life and much less chamber pressure.
glt

 

[diriel]

Trickymissfit,

I hear you! If it were me, I would base off of RUM or Ruger Mag case. Personally I like the design and look of the 30-375 Ruger long neck that steve123 over on the hide had built. Pretty reasonable case capacity, a nice long neck, and seems as though he enjoys it.

As you say, there are better options out there for a go fast 30 cal magnum. Lots of better options. I can tell you for sure I would like to see some of their Once Fired 300wm brass! Note, I did not say USE any of it I would think it might be a one use scenario.

Gary

 

[Trickymissfit]

Trickymissfit,

I hear you! If it were me, I would base off of RUM or Ruger Mag case. Personally I like the design and look of the 30-375 Ruger long neck that steve123 over on the hide had built. Pretty reasonable case capacity, a nice long neck, and seems as though he enjoys it.

As you say, there are better options out there for a go fast 30 cal magnum. Lots of better options. I can tell you for sure I would like to see some of their Once Fired 300wm brass! Note, I did not say USE any of it I would think it might be a one use scenario.

Gary

I honestly think they have folks buying contracts that are listening to people that have an inbred ideal with no basis to back it up. Honestly they'd be much better off with the .338/375 Ruger case, or simply goto the .338 Lapua.

But my constant gripe is that 85% of the KIA's on a battlefield are under 50 yards, and 90% are under 100 yards. Of all the KIA's on the battlefield, 85% come from Field Arty and another 10% come from air strikes. A sniper is a true non factor when you look at the whole scheme of things! After two or three actions blow up in some folks faces the program will quietly be shut down
gary