New US Military .300 Win Mag Match MK 248 MOD 1

#152
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Emouse, a military sniper rifle in 300 WM is not new... this particular load is.

BTW, does anybody kows what 300 WM load the germans use? </div></div>

I think its a 250gr bullet.
 
#153
Re: New US Military .300 Win Mag Match MK 248 MOD 1

still firing away with the mod 1s, no problems but trying to see if i missed the entire target... and i didnt, it was 220grs flying through the same hole... no pressure issues so far with the Savage...
 
#155
Re: New US Military .300 Win Mag Match MK 248 MOD 1

The only thing I can remember is that the Army wanted the 190 SMK pill to run out AT LEAST @ 2865 I think it was a 26" barrel. So take this number and with H1000 and see if you can run them higher. Should not be a problem with a 26 to get them out at even 3000 with no issue. Also a plus is that a H1000 is less temp sensitive.
 
#157
Re: New US Military .300 Win Mag Match MK 248 MOD 1

I wonder what powder they used for that load? From what I read is that they were temp sensitive versus the MK 248 Mod 1.
 
#158
Re: New US Military .300 Win Mag Match MK 248 MOD 1

This load is pretty much what I have been shooting in my 300WM for a few years now. I picked that load because many long range shooters were using it at 1,000 yds. Now paper at 1k is not like shooting critters at longer ranges. I have heard many good reports of the 220 working at very long ranges. My only complaint on my 300WM is it is not a 338LM. With that being said good killing shots have been taken with my rifle from 1,400 to 1,600yds. I have shot farther but wind was causing off center hits on game at longer distances. Granted on coyotes any hit is a good hit.
 
#159
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Take care, your barrel life with the 220 will be rather short. While the round bucks the wind better, it will cause throat erosion at a rather high rate.

The A191 we use, and there are two, a 185 and a 190, the Mod 0 runs between 2950 and 3010 depending on the weapon and barrel.
 
#160
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Rick, what is the expected barrel life for M24 rifles shooting A191 vs Mk248?

Is there any barrel that has a durability edge? Were chrome lined (or other internal coating), hammer forged with higher grade steel, etc., ever tried?

The finnish snipers here at SH reported a very long barrel life with the early Sako barrels in 338 LM (non coated IIRC, but made by hammer forging of high grade steel).
 
#162
Re: New US Military .300 Win Mag Match MK 248 MOD 1

I'm looking up the specs for the mk246mod1 as given. some critical specs are

-max pressure of 68100 at 70f
-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.
-The corrected average muzzle velocity of the cartridges conditioned at 70° ± 5° Fahrenheit (F) shall be 2,850 ± 50 ft/sec. feet per second
-The nominal overall length of the assembled cartridge shall be 3.500 inches maximum, 3.450 inches minimum
-The primer shall be a large match rifle primer, non-corrosive, nickel-plated, boxer type, and shall be of lead-styphnate type
-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
-The projectile for the MK 248 MOD 1 shall be the 220 grain Sierra MatchKing® Hollow Point Boat Tail (HPBT) bullet, commercial part number 2240
-The cartridge headspace shall be 0.212 inches minimum, 0.220 inches maximum
-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.

so there you have it, H1000 at about (minimum of) 4000PSI hotter than SAAMI specs
 
#163
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Im not even going to bother messing with the 220 much we can use the 208 A-Max and the Berger 210 to far better results. At the same time the 208 and 210 will not eat that much throat as the 220 SMK will. The military needs something that works in multiple rifles were as we shoot we can tweet our load until we find the sweet spot.
 
#164
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Hi,

A very informative thread.b I do have a couple questions though. I read the cautions of shooting this high pressure ammo through a normal rifle, so If I wanted to build a rifle around this MK248 mod 1 cartridge what type of action would I need to use? Also, I'm guessing that the other part of the equation is getting the correct reamer? Please forgive the newbie questions.

Thanks for the help!

Trevor
 
#165
Re: New US Military .300 Win Mag Match MK 248 MOD 1

I would personally not worry and shoot the A-Max 208. I learned this on my own and trying it even though I was told by a few people that its not worth messing with the 220 SMK. Also the 200 SMK will eat the barrel up faster.
 
#166
Re: New US Military .300 Win Mag Match MK 248 MOD

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sinister</div><div class="ubbcode-body">Conventional Army snipers have no Godfather</div></div>

What about Eisenhower, Berdan, and since your so humble...you! Lol. Seriously though we have SOME guys that we can look in the conventional army at but not alot.
 
#167
Re: New US Military .300 Win Mag Match MK 248 MOD

I got a bunch of this ammunition off of gun broker. they are very hot. i was comparing with hsm 220gr. i was just at a 600 yard range to shoot my fn scar for the first time, so i didn't really see what it could do at long range. after 2 shots with the mod 248 mod 1, the case would get stuck and i would have to pull out a cleaning rod to get the bolt back open. what was hitting with the hsm at 600 was air-mailing the target at with the mk248 mod 1. it was a warm day and my barrel was on fire!
 
#168
Re: New US Military .300 Win Mag Match MK 248 MOD

FYI im loading 208 amax to 3.520 (89.5mm), 77 grains H1000, 22 inch barrel, 2695 es 10. (factory weatherby mag box seems to be 90.5mm)

I cant figure out why its so slow, but I guess ill try retumbo, just ran out an hour ago of H1000.

Chris
 
#170
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jack-O</div><div class="ubbcode-body">I'm looking up the specs for the mk246mod1 as given. some critical specs are

-max pressure of 68100 at 70f
-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.
-The corrected average muzzle velocity of the cartridges conditioned at 70° ± 5° Fahrenheit (F) shall be 2,850 ± 50 ft/sec. feet per second
-The nominal overall length of the assembled cartridge shall be 3.500 inches maximum, 3.450 inches minimum
-The primer shall be a large match rifle primer, non-corrosive, nickel-plated, boxer type, and shall be of lead-styphnate type
-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
-The projectile for the MK 248 MOD 1 shall be the 220 grain Sierra MatchKing® Hollow Point Boat Tail (HPBT) bullet, commercial part number 2240
-The cartridge headspace shall be 0.212 inches minimum, 0.220 inches maximum
-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.

so there you have it, H1000 at about (minimum of) 4000PSI hotter than SAAMI specs </div></div>
Excellent info, thank you very much!

So, how much H1000 is loaded into each MK 248 MOD 1 cartridge?
 
#171
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ranger1183</div><div class="ubbcode-body">So, how much H1000 is loaded into each MK 248 MOD 1 cartridge? </div></div>
They change the charge weight for each lot of powder used.
The chamber pressure spec is used to determine the charge weight for each lot.
This negates any differences in the powder from lot to lot.
You should use a chronograph to find the charge weight required for the lot of powder you have.
(Unless you have access to equipment capable of measuring chamber pressures.)
wink.gif


I would be interested to see the same type of information for the MK316 MOD 0, MK318 MOD 0, MK319 MOD 0.
 
#172
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ranger1183</div><div class="ubbcode-body">
Jack-O said:
So, how much H1000 is loaded into each MK 248 MOD 1 cartridge? </div></div>

I use 77.0gr. to get the same velocity 2900+ FPS (from a 26" barrel). I heard other guys use the same charge to match the specs.

Its kinda Hot. Work up to this charge! Try at own risk!
Click to expand...
 
#173
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dodgefan</div><div class="ubbcode-body">We chronoed a MK13 w/A191 here a little while back and got right at 2990ish (don't have the data infront of me) w/o the can and a high of 3030 w/can. </div></div>

I don't have any experience with handloading so I do not mean to say my word has any validation beyond that of a messenger, but I ran into an active SEAL down here a while back shooting what was basically a 22" GAP MOD 5, and he told me that the two cartridges they were running were a 190gr and a 220gr SMK and that they pushed 3350fps and 3050fps, respectively. Those figures startled me to say the least, and while I may be incorrect on the bullet weights, he did mention a 190gr bullet for sure, and while I'm pretty sure he mentioned the 220gr MK248 MOD1 he definitely said one of the cartridges ran at 3350fps. Whether that was through the 26" MK13 or maybe he mentioned a 150gr or 170gr bullet, I don't remember exactly, I'm just curious to see what's really going on with this cartridge.
 
#174
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Why not? Great Britain holds the record right now. If it would help even a little our guys should get it.
 
#175
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Makes me start thinking about upping my charge from 79 GR to 80. I get 2862 FPS out of the 208 Amax, 79 gr of H1000, using CCI #200 primers and Hornady brass. I seat the bullets .010 off the lands and get 1 MOA. Thinking about using a little hotter primer and maybe 79.5 grain to see if I can get 2950 FPS and playing with my seating depth the get down past 1/2 MOA.
 
#177
Re: New US Military .300 Win Mag Match MK 248 MOD 1



What part of, a ton of "Long Action .30 Caliber Rifles" already in use don't you get ?

I am pretty sure people have explained in here, that since 1982 the US ARMY has used the M24 which has / had the ability to transition to .300WM. Back in that day the 338LM was just coming into it's own. In fact the 338LM was; what was considered a failed US Army project that was picked up by Lapua. Moving to 300WM is logistically easy, and frankly while they are absolutely going to the 338LM in the future, there is no reason for anything bigger, as in replacing the .50. Man portable is important... both the 300WM and 338LM are much more effective and practical.

The percentage of shots being taken beyond 1000 yards are very small, sure there are more lately because we are fighting in a remote location, but that can change on a dime. What happens when we need to fight an urban war and some who advocate a .375 or bigger have the guys carrying a super heavy ELR Rifle for engagements inside 400m. Then every one will say it is a waste. A 300WM is still effective and you can get away with shorter barrels in both that caliber and the 338LM. We have seen lighter 20" rifles in these calibers doing fantastic things.

Everything is a trade off and you shouldn't be decided on something simply because you are using it today, you have to think about tomorrow. [/quote]


I knew someone would sum it up properly. When we adopted the M24 and spec it to be magnum capable we were ahead of the curve.
The fact that conventional Army failed to upgrade sooner is not surprising. The members of this forum whose perspective
is that of the optimum single rifle are missing the point. The rifles and ammunition you desire can not be produced and fielded in the thousands. SMKs were a good choice for the reason others have pointed out. VLDs are rifle specific so are not acceptable for this purpose.Unless of course you provide each sniper with a personal ammo tech and gunsmith. Everything you adopt has to have some legs. I can remember when the Army didn't even have a sniper school and wouldn't consider having one. Took us a while but we've come a long way and are still moving forward.
 
#178
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MAT 4-82</div><div class="ubbcode-body">

What part of, a ton of "Long Action .30 Caliber Rifles" already in use don't you get ?

I am pretty sure people have explained in here, that since 1982 the US ARMY has used the M24 which has / had the ability to transition to .300WM. Back in that day the 338LM was just coming into it's own. In fact the 338LM was; what was considered a failed US Army project that was picked up by Lapua. Moving to 300WM is logistically easy, and frankly while they are absolutely going to the 338LM in the future, there is no reason for anything bigger, as in replacing the .50. Man portable is important... both the 300WM and 338LM are much more effective and practical.

The percentage of shots being taken beyond 1000 yards are very small, sure there are more lately because we are fighting in a remote location, but that can change on a dime. What happens when we need to fight an urban war and some who advocate a .375 or bigger have the guys carrying a super heavy ELR Rifle for engagements inside 400m. Then every one will say it is a waste. A 300WM is still effective and you can get away with shorter barrels in both that caliber and the 338LM. We have seen lighter 20" rifles in these calibers doing fantastic things.

Everything is a trade off and you shouldn't be decided on something simply because you are using it today, you have to think about tomorrow. </div></div>


I knew someone would sum it up properly. When we adopted the M24 and spec it to be magnum capable we were ahead of the curve.
The fact that conventional Army failed to upgrade sooner is not surprising. The members of this forum whose perspective
is that of the optimum single rifle are missing the point. The rifles and ammunition you desire can not be produced and fielded in the thousands. SMKs were a good choice for the reason others have pointed out. VLDs are rifle specific so are not acceptable for this purpose.Unless of course you provide each sniper with a personal ammo tech and gunsmith. Everything you adopt has to have some legs. I can remember when the Army didn't even have a sniper school and wouldn't consider having one. Took us a while but we've come a long way and are still moving forward. </div></div>

As I understand it the M24 was meant to be compatible with the .30-06 match ammunition then still in inventory. By the time the Army completed the project that ammunition was gone but .300WM was making inroads into the military.
 
#179
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RyanScott</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MAT 4-82</div><div class="ubbcode-body">

What part of, a ton of "Long Action .30 Caliber Rifles" already in use don't you get ?

I am pretty sure people have explained in here, that since 1982 the US ARMY has used the M24 which has / had the ability to transition to .300WM. Back in that day the 338LM was just coming into it's own. In fact the 338LM was; what was considered a failed US Army project that was picked up by Lapua. Moving to 300WM is logistically easy, and frankly while they are absolutely going to the 338LM in the future, there is no reason for anything bigger, as in replacing the .50. Man portable is important... both the 300WM and 338LM are much more effective and practical.

The percentage of shots being taken beyond 1000 yards are very small, sure there are more lately because we are fighting in a remote location, but that can change on a dime. What happens when we need to fight an urban war and some who advocate a .375 or bigger have the guys carrying a super heavy ELR Rifle for engagements inside 400m. Then every one will say it is a waste. A 300WM is still effective and you can get away with shorter barrels in both that caliber and the 338LM. We have seen lighter 20" rifles in these calibers doing fantastic things.

Everything is a trade off and you shouldn't be decided on something simply because you are using it today, you have to think about tomorrow. </div></div>


I knew someone would sum it up properly. When we adopted the M24 and spec it to be magnum capable we were ahead of the curve.
The fact that conventional Army failed to upgrade sooner is not surprising. The members of this forum whose perspective
is that of the optimum single rifle are missing the point. The rifles and ammunition you desire can not be produced and fielded in the thousands. SMKs were a good choice for the reason others have pointed out. VLDs are rifle specific so are not acceptable for this purpose.Unless of course you provide each sniper with a personal ammo tech and gunsmith. Everything you adopt has to have some legs. I can remember when the Army didn't even have a sniper school and wouldn't consider having one. Took us a while but we've come a long way and are still moving forward. </div></div>

As I understand it the M24 was meant to be compatible with the .30-06 match ammunition then still in inventory. By the time the Army completed the project that ammunition was gone but .300WM was making inroads into the military. </div></div>


Any M72 Match was already way out of date at that time. The .300Win capability was primarily a requirement from the spec-ops
side of the house.
 
#180
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Well, usually don't resurrect old posts, but had something to add to this one.

Got few pieces of this .... one was dented, and decided to collect some data and share.

The ingredients:

300WMpic2_zps7e8b1caa.jpg


The powder:

300WMpic7_zpsd63ec4b1.jpg


The bullet:

300WMpic10_zps3e7e76d6.jpg


Headstamp if you are not sure this is it:

300WMPic8_zpsa6741924.jpg


This is how much was in this one:

300WMPic11_zps2f7cd14f.jpg


It's seated pretty deep:

300WMPic9_zps7e28c2fe.jpg


About this much, if you need an actual:

300WMpic3_zpsefff9911.jpg


Hope this settles things for the curious....
 
#181
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Im assuming that this ammo would work well (without over-pressure) in a TRG42, which have loose chambers and long throats?

I put 40-rounds of SWA's version of the Mk 248 through my Rem 700 Custom build. Although I didn't have any crazy signs of over-pressure, just flatend primers, they were coming out of my Schneider 26" barrel at around 3000-fps with considerably more recoil them my 208 AMax loads.

Now I'm seeing pictures of Fed MilSpec brass (ie FC 10) and BHA brass. So is BHA a contractor for this ammo also? I purchased 500-ct of primed brass that were pulled due to QC issues (ie dents and scratches) with most being FC 10, a few from 09 and 08, and one so far with an 07 code.

Has anyone measured the cartridge from base to ogive yet?
 
#182
Re: New US Military .300 Win Mag Match MK 248 MOD 1

See a lot of questions in here as to rifles and ammo. I am active-duty Army and this has been what is going on lately.

Our M24s were not rebarreled to take .300WM. Instead they were taken away from us about 6 months ago. Then about 3 months ago we were issued the new XM-2010 system. The actions on our XM-2010s are clearly our old M24 actions reborn. Kind of sad to see the steadfast M-24s gone but glad to have the much more capable .300WM to shoot.

20130212_144228.jpg


As for our Mk-13s we have some that are based off Rem700 actions and some based of the Stiller action such as this MK-13 Mod 5.

20130212_144542.jpg


That being said, this thread started in 2009 in regards to the 220gr ammo coming out. It is currently 2013 and all I have is the A191 with a 190gr. SMK in it. Got to love the procurement system...
 
#183
Re: New US Military .300 Win Mag Match MK 248 MOD 1

A191 was (and is) a USSOCOM load.

Mark 248 is both a USSOCOM (bought with SOCOM MFP-11 money) and a standard Army (MFP-2) ammo item. By law Big Army is supposed to buy it for all USASOC and Conventional Army consumption. If you don't have 248 it's because your unit or post doesn't have it (or the S3 Ammo guy doesn't know to order it) or (if overseas) it didn't make it on last year's sea freight shipment.

Mark 13s are built to USSOCOM specification at one of two places. The Navy spec'ed Stillers because technically they didn't buy any M24s (so can default to a commercial receiver).

They drama behind SOCOM and conventional forces weapons buying would make Shakespeare blush. If you saw the reality behind the decision-making it would make soap opera writers cry as bush-league amateurs.
 
#184
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Who makes the reamer and is there a spec available for the chamber? What kind of accuracy are the 2010s and new MK13s turning out?
 
#185
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jack-O</div><div class="ubbcode-body">I'm looking up the specs for the mk246mod1 as given. some critical specs are

-max pressure of 68100 at 70f
-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.
-The corrected average muzzle velocity of the cartridges conditioned at 70° ± 5° Fahrenheit (F) shall be 2,850 ± 50 ft/sec. feet per second
-The nominal overall length of the assembled cartridge shall be 3.500 inches maximum, 3.450 inches minimum
-The primer shall be a LARGE RIFLE MATCH PRIMER, non-corrosive, nickel-plated, boxer type, and shall be of lead-styphnate type
-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
-The projectile for the MK 248 MOD 1 shall be the 220 grain Sierra MatchKing® Hollow Point Boat Tail (HPBT) bullet, commercial part number 2240
-The cartridge headspace shall be 0.212 inches minimum, 0.220 inches maximum
-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.

so there you have it, H1000 at about (minimum of) 4000PSI hotter than SAAMI specs</div></div>
Why, do we suppose, they are using a large rifle match primer instead of a large rifle magnum match primer?
 
#186
Re: New US Military .300 Win Mag Match MK 248 MOD 1

DETAIL SPECIFICATION CARTRIDGE, .300 WINCHESTER MAGNUM MATCH, MK 248 MOD 1, DODIC AB43, NSN 1305-01-568-7504, Revision A, 17 March 2009

"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. <span style="color: #FF0000"><span style="font-weight: bold">The primer shall be capable of meeting the ballistic requirements herein.</span></span>"
 
#187
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Remington brass fed 215 primer h1000 73 grns Smk 220. 32" Broghton barrel savage action 3 shoots 3/4" 500 yards... Swear it on my mothers grave! Sounds funny but we do it different in Pa. All cases sorted by velocity! I can shoot strings of duplicate velocities. Yea zero spread?!? Don't know why no body else doesn't do it that wat? That gun will do funny things at 1 K
 
#188
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lw8</div><div class="ubbcode-body">Who makes the reamer and is there a spec available for the chamber? What kind of accuracy are the 2010s and new MK13s turning out?
</div></div>

Standard SAAMI 300 Win Mag reamer.
 
#190
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lw8</div><div class="ubbcode-body">Who makes the reamer and is there a spec available for the chamber? What kind of accuracy are the 2010s and new MK13s turning out?
</div></div>

Standard SAAMI 300 Win Mag reamer. </div></div>

Are you sure about that? I do believe PTG makes the designated mk248 reamer and I dont think its a standard sammi reamer.
 
#191
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MattK287</div><div class="ubbcode-body"> I read that part. I guess I just don't understand how a large rifle match primer can function better in a magnum cartridge than a magnum primer. </div></div>

Please reread what Sinister posted regarding the primer.
 
#192
Re: New US Military .300 Win Mag Match MK 248 MOD 1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sharfshutze</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dave Tooley</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lw8</div><div class="ubbcode-body">Who makes the reamer and is there a spec available for the chamber? What kind of accuracy are the 2010s and new MK13s turning out?
</div></div>

Standard SAAMI 300 Win Mag reamer. </div></div>

Are you sure about that? I do believe PTG makes the designated mk248 reamer and I dont think its a standard sammi reamer.

</div></div>

The question was what reamer is used in the Mk13 and XM2010.
 
#193
Re: New US Military .300 Win Mag Match MK 248 MOD 1

I know what the question was, Kiff informed me this particular mk248 reamer used in the MK13 rifles is not a standard sammi spec reamer, its slightly tighter with more freebore.
 
#194
Re: New US Military .300 Win Mag Match MK 248 MOD 1

Ok. I'm not trying to be dense, it just works out that way sometimes. The reason is not obvious to me. It appears, by reading what Sinister posted, that ONLY a large rifle match primer is capable of meeting the ballistic requirements herein.
It's really no big deal, I just thought that if someone knew why a magnum match primer is not being used, they could offer an opinion as to why not. Like maybe more consistent ignition, or to keep excessive pressure down, or maybe, it just plain works better. Thanks anyways.
 
#199
Thanks Bryan, VERY interesting read...

I've heard that the 220 SMK was chosen because its tangent nose profile it was less sensitive to throat erosion than the higher BC 210 SMK (that can also be pushed a bit faster). Is this true? Can a different throat be used to eliminate this with mild secant ogives?

In the comparison of the 300 WM Berger 230 hybrid load to the 338 LM, what is the OAL of the 300 WM load? It looks quite long, does it fit into an M24 magazine?

Some very experienced finnish members have comented on very long barrel life with the 338 LM and 250 gr loads, at least with older Sako barrels. What can be expected with the new 300 WM loads such as the MK 248 MOD 1 ? What improvement in barrel life can be expected with the new melonite coatings, such as the new rem MSR?
 
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