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Discussion Starter · #1 ·
Hey I know you would know pretty good about the MK 248 MOD 1 round JF.

My questions is if I have a throat length total of 3.550" am I good to go for this round ? I know they run out to 3.500".
 

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You should be good. The 220 SMK is a large bullet and not super sensitive to jump. I wouldn't worry so much about the specs of the mod 1 and just work up the load for your rifle. Make the COL as long as your mag will allow to leave room in the case and help drop pressure just a hair. Using a large rifle primer instead of a magnum will help keep pressure in check too. The Mk 248 mod 0 stuff I shot up a couple years ago was loaded in Winchester brass. WCC head stamp "Western Cartridge Company". The load was hard on brass just like I'm sure the mod 1 load is.

I'll dig around and see if I have any of that stuff left. I included a lot of it when I sold my .300 WM.
 

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The load I ended up loving was one I worked up with a 208 A-Max. I used Retumbo, WCC brass, FGMM 210M primer with a 3.62" COL. They were leaving my 700P .300 WM @ 3,000 fps. That load turned my rifle into a hammer, it would reach out to 1,550 yards with very little drama. I should have kept that rifle :-(
 

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Discussion Starter · #4 ·
Im going to get some 220 SMK's and also some H1000 aside from the Retumbo I already have. I will also get some Hornady 208 A-Max rounds online cause I cant find them locally.
 

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Discussion Starter · #6 ·
I sure will. I just got me some Retumbo, H1000, 220 SMK, and a neck sizing die. I found some Winchester brass 27 shipped which is a pretty good deal.
 

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Some Mk 248 mod 0 stuff. I'm trying to track down some measurements I took from the brass and loaded rounds. Its been a long time since I've shot magnum rifles and all this Mk 248 mod 1 stuff has been getting me excited. I'm considering tracking down a 700P in 7mm Rem Mag but we'll see I get easily distracted.



Its pretty cool researching the loads the military develops. It started as a Navy project I believe and worked out handy because the Army M24's were build on long actions since the original chambering was going to be .30-06. As we all know they ended up going with .308 Win.



I dropped the magnum rounds in favor of efficient short action rounds but sometimes I have to admit I miss it.
 

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Discussion Starter · #8 ·
Dont get distracted and get one :D

I have a 7mm the 69 model and when the barrel goes out I will supe it up for long range with a trued action and a nice barrel. I was messing with the ballistic calculator and the Swampworks JLK VLD .284 180gr bullets and they are the craziest thing I have ever ran on the ballistic calculator. This dam bullet runs supersonic out to 2000 easily at 3000 FPS. I wonder how much beating that 3000 FPS will give the barrel.
 

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Discussion Starter · #9 ·
Ok so I went out yesterday the 6th of May, and shot 50 various loads of 220 SMK and 208 A-Max. Here are the numbers and they kinda pissed me off.

Alt- 151 sea level.
Temp ranged from 79.9* to 83* when I was done shooting for the day.
Humidity started at 31.8% and came down to 25%
Bar Pressure started at 29.920 and ended at 29.870

220 SMK
76.0 H1000
Winchester Brass @ 2.610 (New case capacity was 89.48)
CCI 250 Mag Primer
COAL from Ogive 2.880 (Which should = 3.450 COAL for the 220 SMK that is)

2729
2748
2769
2766
2759

76.5 H1000

2802
2729
2724
2826
2826

77.0 H1000

2789
2770
2773
2785
2794

This is the same setup with Retumbo powder.

78.0 Retumbo

2836
2823
2807
2845
2800

78.5 Retumbo

2800
2807
2806
2822
2830

I dont get the variation in the numbers ? I wonder if the primer had something to do with it. I just got some Federal 215M maybe this will give me better consistent numbers.

Here I changed the bullet to the Hornady 208 A-Max COAL from the ogive was 2.880 but from the tip it was about 3.650

76.5 H1000

2842
2803
2845
2835
2838

77.0 H1000

2825
2846
2818
2845
2833

These loads are with Retumbo but same 208 A-Max

79.00 Retumbo

2958
2838
2968
2884
2990

79.5 Retumbo (These loads all had a pretty bad sticky bolt)

2950
2869
2909
2913

Again not very consistent with FPS at all. I will try all these loads again with Federal 215M primers and see what happens.

Joe maybe you can look up some of your old info and give me some input :)
 

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I used a 210M primer instead of the 215M to help drop pressure just a hair. My COL was 3.62" putting the 208 A-Max just off the lans. My brass OAL was 2.62". What scale are you using? How did the neck tension feel when you were seating the bullets?
 

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Discussion Starter · #11 ·
The scale I'm using is the RCBS CM w/out the dispenser and the Lee Scoop cups. I know that is working good because for my .308 the RL-15 powder gave me a deviation of 16 FPS..... John (jrob300) over at snipershide said to try to anneal the cases and see what happens he had the same issue with the Winchester brass. While seating I had just a few that seated kinda ruff. I think that annealing will solve this issue. Then again I might get pissed and go and get some Lapua brass ;)
 

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Winxp_Man said:
The scale I'm using is the RCBS CM w/out the dispenser and the Lee Scoop cups. I know that is working good because for my .308 the RL-15 powder gave me a deviation of 16 FPS..... John (jrob300) over at snipershide said to try to anneal the cases and see what happens he had the same issue with the Winchester brass. While seating I had just a few that seated kinda ruff. I think that annealing will solve this issue. Then again I might get pissed and go and get some Lapua brass ;)
Do they make .300 WM brass? The brass I was using was the WCC Mk 248 mod 0 brass.
 

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Discussion Starter · #13 ·
They did, but not any more, I have seen it for sale from other people at a decent price.
 

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Discussion Starter · #14 ·
So what was your pet load for your 300 WM with the 208 A-Max ? What powder did you find really good.
 

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Winxp_Man said:
I sure will. I just got me some Retumbo, H1000, 220 SMK, and a neck sizing die. I found some Winchester brass 27 shipped which is a pretty good deal.
Bass Pro has some Win. brass at pretty good prices, found some 308 for 22 bucks.
 

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Winxp_Man said:
So what was your pet load for your 300 WM with the 208 A-Max ? What powder did you find really good.
The loaded ended up being;

208 A-Max
WCC brass 2.62"
80 grs Retumbo
FGMM 210 primer
COAL 3.62"

H1000 worked well but Retumbo was slightly slower burning and I was able to push the A-Max faster with less pressure.
 
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