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

[jwoolf]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">An exact copy of it. The charge weight is all I would need, and I should be able to figure that part out based on the velocity. I have some 220 SMK, so I may play with them and some H1000. </div></div>

I've been playing with this load lately.

I went up to 75.7gr of H1000 but, I was about .030 off the lands *(JBM said I was making 2860fps and I was at 27.0 moa at 1000 from a 100yd zero ).... moved down to 75.0gr at .010 off the lands and, it's showing pressure signs. I'm going to start off at 73.5 and move to 74.5 and see how that does at .010 off the lands.

75.0gr at .010 off the lands in a 26" 1:10 twist was giving almost 2900fps... It was dangerously hot. Brass looked ok but, the primers were having that nice moon crater and they were flat as hell.

This charge was only 26.25 elevation from a 100yd zero at 1000yds.

I shot them like that instead of pulling them... I'll probably have to throw away the brass now since the primer pockets are most likely too loose! LOL

If I had to guess ( and I do right now ), I'd say the 2850fps charge is somewhere around 74.0gr with the 220smk.

OAL ended up being about 3.52, win brass, rem 9 1/2M primers.

 

[sinister]

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

Conventional Army snipers have no Godfather, no patron saint with any rank, and no voice. They are a very, very small part of the community. "You will get what we give you and like it."

If it wasn't for guys like Brian Sain and the folks behind Americansnipers.org there'd be a whole bunch more guys with their stuff hanging out on a limb with no help at all.

Leg Army's reputation for common small arms development is in the toilet.

SOCOM has its problems, but it has more shooters per capita, with officers (from different services even) with some shooting background, and NCOs with extensive field and shooting experience who can write. Quite a difference.

Leg Army will ALWAYS try to catch up with SOCOM developments -- it is the nature of a big, uncaring, plodding organization. If there is trickle down we should be grateful for it.

Not the best situation, but what we're stuck with.

 

[ranger1183]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Does anyone know what charge weight of H1000 they are running with the 220 SMK?
The standard (SAMMI) 300WM is 62K PSI, and this new spec calls for 68K PSI, so it will be a little hotter round.
This cartridge set up will be top-notch for our military! I'm glad to see this! </div></div>
I'm interested in this load data as well as where to get a .300 Win Mag MK 248 MOD 1 reamer.

Sounds like H-1000 is the powder, the FGMM 215M is the primer and the 220 gr SMK is the bullet. How much powder, what is the overall cartridge length and where to get the reamer are the remaining questions.

Looking for data, not dogma.

Good shooting!

 

[jrob300]

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

Ranger,

Here is the spec. on the Neco site (you may have to override "trusted site"). I've never seen a powder charge quoted, but you could simply load til you get velocity. Be forewarned, the pressures are *stout*.

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

Or you could have Frank pull a bullet and weigh the charge.

They shoot it often at RO.

IIRC, the COAL is 3.55... I'm looking for the drawing and will put it up when I find it.

John

ETA: can't find the spec drawing, but the written spec. above lists COAL at 3.50"

 

[matthewusmc8791]

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

The best example of change is when the CMC went out on a field exercise many years back and realized that the current fleet was still using canvas tents and crappy boots and a poncho for rain gear did it change.... he got a wet ass and said this is BS we gotta do something...

He suggested that someone better get out and contact Danner Boots, Eureka tents and Gortex, etc. and get some ideas on some light weight high speed gear that WORKS...

Guess what they have now.. much better gear.... Same thing needs to happen if they want to switch to a different rifle....Problem is, if they have a 50cal the only other logical option would be a 300 win mag or 338... That way you can shoot it 100-1800yds very comfortably and for real long shots, use the 50cal... no need for two, three, four different weapon systems to buy, let alone train everyone on...Get rid of that Remy 308 and move into the 21st century...Times change, either you change with it or you get left behind..

Another example, LEO only had a dumb ass 9mm Glock or Baretta 92 and a 12guage pump for the longest…. Well if you remember the Bank of America robbery out in Southern California the found out, damn we might need more then our dicks in our hand if we want to stop this from happening again…. Now nationwide a lot of M4’s are being sent out and a lot better semi’s such as FN’s etc… Lets not forget the 40S&W as a side arm with 17rds… politicans arelike old people, very resistant to change!!!

Until there is a way for someone that has the decision making power to make money on a decicison or alot of people get hurt, it wont happen… Eveyone in here is more likely former military or LE so they know….. Until it effects someone of importance DIRECTLY good luck with getting anything done…

Sorry off topic, but most threads here are…

 

[ranger1183]

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"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Does anyone know what charge weight of H1000 they are running with the 220 SMK?
The standard (SAMMI) 300WM is 62K PSI, and this new spec calls for 68K PSI, so it will be a little hotter round.
This cartridge set up will be top-notch for our military! I'm glad to see this! </div></div>
I'm interested in this load data as well as where to get a .300 Win Mag MK 248 MOD 1 reamer.

Sounds like H-1000 is the powder, the FGMM 215M is the primer and the 220 gr SMK is the bullet. How much powder, what is the overall cartridge length and where to get the reamer are the remaining questions.

Looking for data, not dogma.

Good shooting! </div></div>

Back on topic, I'm looking for the powder charge. Anyone have some MK 248 MOD 1 that they (Rifles Only?) can pull a bullet on and weigh the charge? If you decide to do this, what is the H2O capacity of the brass they are using? QuickLoad has 5 different capacity amounts for .300 WM brass. Finding what MK 248 MOD 1 is using is actually very important.

 

[jrob300]

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

Ranger,

I had to enter custom H20 #'s for Federal, Nosler and Winchester brass... QL #'s did not work for any of it.

I suspect this is due to the fact that it changes over time (I have some old Win. 300WM brass that is nearly 20 gr. in weight heavier than the new stuff.

Somewhat off-topic, but FYI.

John

 

[ranger1183]

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

Do you still have those numbers? Can I "borrow" them from you?

 

[jrob300]

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

Ranger,

I didn't keep them, but I could get them again for you if you don't have the means...

It'll have to be tomorrow though, off to work.

John

 

[ranger1183]

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

I'd be very interested in those numbers, if you don't mind. That would be a great help for me. Thanks!

 

[oregon]

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

Has anyone seen if this ammo will work better in the 300 WM rifles so many of us already have or is a special barrel possibly with a specific twist / length necessary to gain full advantage? _9H said above, "A faster twist and longer throat barrel needs to be done up to work with this bullet versus a 190 or 200 but the effort seems well worth it." See the military is going to use a new barrel on existing long action guns. Does anyone know how this new 300 WM Match MK 248 MOD 1 ammo shoots in normal factory barreled guns around for decades such as Winchester Model 70, Remington model 700, ... specifically how far out does it provide 1200 ft lbs of energy? Is there any improvement in average hunting guns? Someone earlier in this thread gave an energy number then another questioned the calculation so still curious.

 

[ranger1183]

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

Well I know that someone has already spoken of a "MK 248 MOD 1" reamer so I'm guessing that whatever barrels are out there might need to have a new chamber cut. "Might" or "might not" being the important answer.

But as far as new barrels go, shooting a 300 Win Mag as much as possible in practice will no doubtedly cause barrels to be replaced on a regular basis.

 

[bohem]

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

I did some fiddling with Quickload at the min OAL specs and using the info included.

With a 24" barrel they're warm, around 65ksi, with a 26" barrel they're still not bad, only 62ksi. That 68ksi load would push the bullet over 3050 according to what I was playing with. I also used the smallest brass on file in QuickLoad, since there are several cases.

appx. 7<span style="text-decoration: line-through">5</span><span style="font-weight: bold">8</span>gr of H1000 was the point, so starting at 75 and working up for a specific rifle would be reasonable.

 

[Lowlight]

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

We have a some of the 220gr Mk248, we have chronographed in the Mk13 across a bunch of unit rifles, and the speed on the better rifles is 2950fps, we have seen as low as 2875fps, but no lower, as well the average SD is 8fps, the better deviation was 4fps, sampling more than 15 rifles.

I don't have any reloading stuff here, I know Jacob does, I can ask him to pull one apart... we mostly shoot it and not obsess over it.

I like it alot, huge improvement over the A191 which was good, but this is better.

 

[ChadTRG42]

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

We pulled some of the MK248 ammo, and the powder charge averaged 77.1 grains. I understand this to be H1000 powder. The charges were as low as 76.9 and high as 77.3 grains. This should be a hot round for most rifles, so work up to this load.

 

[ranger1183]

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

Thank you so much for this data Frank and Chad! That's extremely helpful! Chad, if you still have the brass, what was the H20 capacity of the brass?

You guys are great! Thanks again!

 

[ChadTRG42]

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

You're welcome! I no longer have any of the brass.

 

[jrob300]

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

Ranger,

Brass H20 capacities you requested:

Brass...Dry Wt..Gr. H20

Fed.....251......91.7
Nosler..249......91.2
Win.....240......93.1
WCC....241......93.6

I found Fed./Nosler to be interchangeable with no impact on group or ES.

Same for Win./WCC.

Loading difference between the two (driving 208's over H1000) was about 1 gr. for the same velocity.

I included dry weight as a control... if your brass is a different lot, it may start out at a different weight.

Good luck.

John

 

[jrob300]

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

Just a little PSA concerning Mk 248 Mod 1 fired from civilian rifles not designed specifically for it.

I heard from a guy this weekend that had an opportunity to shoot some from his custom WM.

"Shot about 10 rounds and quit! Very bad pressure signs and excessive mv. Gases flowing back through the primer and an mv in excess of 3050fps with 220gr bullet. I took about 10 apart and weighed the charge. Average: about 77.7 gr (H1000). Compressed load for sure, just beyond the shoulder in to the neck."

Just for comparison sake, pressure load in Federal brass in my rifle is 76.7g H1000, shooting <span style="font-weight: bold">208</span>'s *and* at a longer COAL of 3.65". That is a very stout load behind a 220.

Before anybody jumps down his throat, most of us wouldn't have given shooting a box of this stuff two thoughts either.

However, I have warned in these threads from the beginning that the pressures these are loaded to exceeds SAAMI. Peak pressures are way up there. It is clear that the US Military wanted a F1 car, not a Volvo station wagon and as such, designed a precision shooting *<span style="font-weight: bold">system </span>* around this loading. The .mil does not pick up their brass. They are not concerned about loose primer pockets or rapid throat wear. We've speculated about this before. This simply confirms in my mind that this is a temporary stopgap (or at least was intended to be so in the design and acceptance phase... who knows what will happen now with economy woes and cutbacks).

Ranger is asking the right questions about reamer specs, but I'd also be concerned about action strength, as this load will put it to the test. My guess is that practical minded shooters loading 220 SMK's will settle for a load that doesn't quite reach the velocities of Mk 248 Mod 1, but they'll be able to reuse their brass, their barrel will last over 800 rds. and they'll be able to see out of both their eyes. This does NOT mean that it won't work in some rifles. If you get lucky, good for you. But it's a crap shoot with a potentially high cost.

Clearly the *<span style="font-weight: bold">system</span>* works very well as evidenced by Frank's experience at RO. 4 fps ES and great downrange performance are not accidents. But just because MK 248 Mod 1 works so well in a Mk 13, does not mean we can blindly ignore the rules of reloading and just plug it in. Even with loaded ammo, because it was NOT designed for all of our rifles. Run some racing slicks on your Volvo wagon this winter and see how that works for you.

Soap box off.

John

 

[mgd45]

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

I'm still trying to grasp the concept that the military wants a longer range sniper rifle, but instead of going with the 338 Lapua, they decide on the 300 WM...? If what you want is the ability to "go long".....then why not do it right & get the best available system.....maybe even skip the .338 Lapua all together & upgrade to a .375 Cheytac.

I've heard the argument that the other rounds "cost too much" so that's why they are going with the 300 WM.....really...? Cost too much...? The US just lobbed 110 Tomahawk missles at Libya, basically a "blip" on the radar as far as military action is concerned. At $756,000 a piece that's roughly about $83 million bucks.

Someone posted earlier that the military put in an order for 34 million rounds. Even if they paid $8 per round (which they wouldn't) for the better long range round (.338 lapua or .375 Cheytac), we're talking about $170 million in spending. I seriously doubt that the military couldn't come up with a few extra hundred million to make it happen.....just seems like a "cop out".....

 

[Lowlight]

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

+100

What John has written has to be taken to heart. I saw this and decided to walk out the door and shoot our Accuracy International AWM in .300WM as well we have a GAP Barreled .300WM so it was easy to demonstrate.

Both rifles, Mk248 MOD1

Average velocity out of the GAP

You are not reloading the brass from the GAP, clearly signs of pressure.

The AI AWM was fine, no issue in fact lower velocities there, but here is a list of both rifles.

AI AWM

1. 2893fps
2. 2869fps
3. 2879fps
4. 2885fps
5. 2869fps

AVG = 2879fps
SD = 9.0

GAP Barreled 300WM

1. 2985fps
2. 2989fps
3. 2973fps
4. 2954fps
5. 2951fps

AVG = 2970fps
SD 15.4

Now, recently I have been wondering if my CED M2 has been running the numbers a bit low, maybe 50fps lower than it should be, but still, worst case add 50fps to what I have here.

Clearly not designed for your average custom rifle.

 

[Lowlight]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mgd45</div><div class="ubbcode-body">I'm still trying to grasp the concept that the military wants a longer range sniper rifle, but instead of going with the 338 Lapua, they decide on the 300 WM...? If what you want is the ability to "go long".....then why not do it right & get the best available system.....maybe even skip the .338 Lapua all together & upgrade to a .375 Cheytac.

I've heard the argument that the other rounds "cost too much" so that's why they are going with the 300 WM.....really...? Cost too much...? The US just lobbed 110 Tomahawk missles at Libya, basically a "blip" on the radar as far as military action is concerned. At $756,000 a piece that's roughly about $83 million bucks.

Someone posted earlier that the military put in an order for 34 million rounds. Even if they paid $8 per round (which they wouldn't) for the better long range round (.338 lapua or .375 Cheytac), we're talking about $170 million in spending. I seriously doubt that the military couldn't come up with a few extra hundred million to make it happen.....just seems like a "cop out".....</div></div>

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.

 

[jrob300]

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

Frank,

Thanks for the rapid confirmation. This is an interesting situation that I don't recall seeing before. Most .mil ammo that I recall is perfectly safe in civilian weapons (with the possible exception of some MK262 that I've heard through the grapevine can generate some high pressures on hot days in some chambers).

It will especially become an issue if the .mil ever decides to sell surplus to the public. I would think it not wise. In the mean time, I doubt that there are very many channels that puts this stuff into civilian hands.

Nevertheless, it would be prudent for those of us in the community to educate others of the potential risks. People tend to be enamored with all things military.

I think the thing that concerns me the most about this is that it is March. What happens to some poor sap that cooks a round on an August afternoon?

John

 

[ranger1183]

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

Frank,

Thank you very much, I greatly appreciate your help!

This load is very hard on brass, maybe to the point of being one shot only. And a MK 248 MOD 1 is not just any custom 300 win mag but a very specific rifle.

I wonder what mods the Army has to do to change their M-24's, basically a customized Remington 700/40XB into a MK 248 MOD 1? Obviously, a new barrel with the MK 248 MOD 1 chamber, and a new bolt but what else? Can the Remington 700/40XB's take such massive over pressures? Is there a special bolt design or is it "just" a custom chamber?

Sounds like one hell of a cartridge there.

Thanks again!

 

[Lowlight]

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

they didn't change anything I know of, it's still the same rifle used for the A191, or Mk248 MOD 0...

These are from Crane (Mk13), so nothing has changed yet, most are still fielding old rifles with new ammo.

The new M24E1 that was recently awarded might be different, but right now, nothing has changed.

Look at the AI AW, no pressure signs and manageable velocities, these chambers are not cut to Bench Rest Tolerances, but much looser to allow for dirt and debris. The AWM works fine, no adverse affects.

 

[lrs50bmg]

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

As Frank pointed out, the rifle the Navy uses, Mk13(Mod 6 now?) and others use, has not changed. Simply new ammo. The specs allow for it to be loaded to quite a high pressure, but the users are not planning on reloading this brass gents. They will not be using a new weapon until a choice is made in the PSR project. It is essentially an incremental improvement to the system to extend the range of the round. The Mk13, as is the M24, are built on Rem 700 platforms.

 

[stefan73]

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

Didn't someone split a .300 WM barrel at the best sniper comp a year or two ago at Benning?
I believe I saw something about it in the Army times.

 

[ChadTRG42]

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

Knowing some specifics of the powder charges and bullet used, this load is very hot for the average chamber in 300WM. I have noticed in AI rifles you can get away with stiffer loads. I would guess it's because of the larger chamber. Some custom 300WM chambers with tight necks and short thoats will show pressure much sooner than other rifles. So, chamber dimensions is a big part of the equation.
I personally have seen pressure with 76 grains of H1000 with a 208 A-max. So a 220 grain with 77+ grains is a very stiff load. But that's what this system was designed for. The military does not reload their brass. So, any pressure signs or case problems would be a non-issue. I think the 300WM with the 220 SMK is an awesome round for our military. I'm glad to see something like this. It is a good, lower cost (compared to your 338LM and CT stuff), option to use existing equipment.

 

[jrob300]

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

Does anyone know what reamer they use on the MK13, since it has not changed? Is it A191 (MK248 Mod 0)? This would answer Rangers question...


John

 

[darrindlh]

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

Ok first of all I am so glad that the gov went to a 300 wm. Being able to get these boys out at longrange and have them still make the shot will bo a great thing.
Second jlk bullets DO NOT have a .734 bc in thier 180 grn bullets. I talked with Bryan Litz and jlk sent him there bullets to test for bc. The jlk bullets have the same bc as the bergers. So that 2000yrds will not be.

the 7mm with the berger 180 at 3000 fps hits at 1500yrds=
1265 fps & 640 ftlb
the 300 the 220 match kings hit at 1500 1160 fps and 658 ftlbs

the 300 has more ft lb than the 7mm

Darrin

 

[JLM]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">Does anyone know what reamer they use on the MK13, since it has not changed? Is it A191 (MK248 Mod 0)? This would answer Rangers question...


John </div></div>

Did anyone perhaps think to ask Dave Kiff about this? Hrmmm...

 

[Tactical30]

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

Loaded some 220gr. SMK's over 74.0gr. - 77.0gr. of H-1000 tonight. I cant wait to test them and run them thru the chrony.

I used Winchester Brass/ Fed. 215M Primer/ Oal-3.500".

Barrel to be used: Bartlien 26" 1-10 Twist (Rem700 L/A Blueprinted Action).

I will post the results.

 

[Emilio]

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

I wonder if the over pressure caused by this round is the reason or part of the reason that the Navy is going with Stiller actions for the new MK-13.

 

[cjgassett]

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

I have shot 100 rounds of this wonderful round out of my savage 110 long range hunter. It is amazing. It shoots under a half inch at 100, and the longest period of constant shooting was a 15 rnd group... barrel was warm when i was done. it is a little over one hole at 100, cold barrel cold barrel shots...this gun has been good/above average with other ammo, but it LOVES this stuff...

 

[Oakland Tactical]

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

I would say the warnings on this one are not to be taken lightly. These rifles are chambered differently. Black hills made some A191 ammo for a while for the Navy (maybe still does). I tried to get some of it from them but they said it was not safe for regular 300WM rifles. They used 190SMKs but they were loaded substantially longer and IIRC were about 50FPS faster.

Heres a link to Cranes A191 development. They mention the COL at 3.5" with a 190 SMK at 3000fps using the "Navy match" chambered rifle. This stayed within SAMMI pressure which was part of the spec. The comparison that Lowlight did looks like the AI rifle was within SAMMI. A191 Development

 

[ida83704]

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

Do we know for sure it is H1000 not Retumbo?
All the Hodgdon Extreem powders I've seen really look the same.

In my Remy700 with 26 inch tube with Retumbo I'm averaging 3000fps with a 208amax.
78.0 grains of Retumbo

Minimal pressure signs.
(no change in bolt lift, no extracter marks, no masive case expansion measure at the belt, no firing pin flow, minimal flattened primers, 20% of the primers show some flattening)

2950fps with a 220SMK does not sound crazy with Retumbo

 

[ranger1183]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ida83704</div><div class="ubbcode-body">Do we know for sure it is H1000 not Retumbo?
All the Hodgdon Extreem powders I've seen really look the same.

In my Remy700 with 26 inch tube with Retumbo I'm averaging 3000fps with a 208amax.

Minimal pressure signs.
(no change in bolt lift, no extracter marks, no masive case expansion measure at the belt, no firing pin flow, minimal flattened primers, 20% of the primers show some flattening)

2950fps with a 220SMK does not sound crazy with Retumbo </div></div>
How much Retumbo did you use?

 

[ida83704]

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

just edited the post.

78.0 grains of Retumbo(max per Hodgdon)
COAL= 3.600

 

[jrob300]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ida83704</div><div class="ubbcode-body">Do we know for sure it is H1000 not Retumbo?
</div></div>

The spec says H1000

John

 

[slugfarmer]

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

wow

 

[winxp_man]

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

Im gonna try this combo with Retumbo powder and see what happens. Really like the info here.

 

[JFComfort]

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

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: winxp_man</div><div class="ubbcode-body">Im gonna try this combo with Retumbo powder and see what happens. Really like the info here. </div></div>

After shooting a bunch of Mk 248 Mod 0 rounds I developed a load with Retumbo and a 208 A-Max. The combo turned my 700P .300 WM into an absolute hammer!

 

[winxp_man]

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

Thanks for the info JFcomfort I will shoot some standard winchester 180 SP stuff this Saturday and then on Tuesday I will have some reloads for it

 

[ida83704]

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

Any idea why they picked the 220SMK when the 210SMK has a better BC?

The 210SMK has a BC of .640ish and the 220SMK has a BC of .625ish.

 

[TiroFijo]

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

The "old" design sierra MK 220 gr has a tangent ogive and is more forgiving than the secant ogive of the 210 gr and most VLD bullets.

 

[lw8]

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

Is there an actual Reamer for this new version that is available someplace?

 

[JLM]

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">Is there an actual Reamer for this new version that is available someplace? </div></div>

Email Dave Kiff and ask him?

 

[TiroFijo]

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

Probably one of the reasons the 220 SMK was picked over the 210 SMK (which has a higher BC and can be launched at higher velocity) is that one of the requirements was that all existing rifles in 300 WM should shoot the new load well without modifications. The bullet nose of the 220 SMK is identical to the old A191 190 gr SMK load, so no problems with throat angles and dimensions, etc.

 

[winxp_man]

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

So I got to measuring to see how far the lands are from my bullet seated at 3.340 and it came out to about .210 until the bullet hits the lands. So that gives me a total of 3.550. From what I read under the pdf link the MK 248 MOD 1 rounds has to be a minimum 3.450 and a maximum 3.500. I take it I would not need the chamber reamed to longer throat right ? thanks for any input guys.

 

[Emouse]

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

so this is supposedly all new?

The Germans have the AIAW as the G22

The G22 is in .300 win mag and they have used them since the AW first came out!