Using MK248 Mod1 at sea level as a baseline......

[MontanaMarine]

.....Here's how my favorite 308, and 30-06 loads stack up, IN LOCAL ATMO.

Ran some calcs through JBM using Litz BCs.

MK248 Mod1, 220 SMK, 2980 fps, sea level, 1500 yards:

Vel: 1112 fps, 604 ft-lbs
El: 52 moa
Wind: 10.9 moa (10 mph f/v)
-------------------------------

My 30-06 load, 208 AMax 2720 fps, 4500' el, 1500 yds:

Vel: 1189 fps, 652 ft-lbs
El: 55.5 moa
Wind: 9.5 moa
-------------------------------

My 308 Win load, 208 AMax 2620 fps, 4500' el, 1500 yds:

Vel: 1125 fps, 584 ft-lbs
El: 60.8 moa
Wind: 10.2 moa
-------------------------------

So what does it mean? I'd say elevation equals cheap performance. And maybe, I'm not a loon for shooting the 308 well beyond 1000 yards (around here), if only in a recreational mode.

Obviously in local atmo the MK248 Mod1 would beat my loads by a good margin. But considering the military requirement of 1500 yards effective would mean at any elevation, I used sea level, standard atmo, as the lowest common denominator, for a baseline comparison.

 

[darthceadus]

Re: Using MK248 Mod1 at sea level as a baseline......

I'm in the process of giving upgrading my 300 win mag, where did you find the spec for the Mark 248 like brass, primer, powder ? I'm about to start reloading and want to use that as a baseline with Hornaday's new 225 grain bullet. I figured it would buck the wind a little better than the 220 smk. Since you are way more experienced than me if you were rebarreling would you still go with 300wm?

 

[darthceadus]

Re: Using MK248 Mod1 at sea level as a baseline......

I'm sorry mod 1 is the 190 grain I wasn't thinking. I'm using the Black Hills 190 match and love it. I just want something to help me cheat a little.

 

[jrob300]

Re: Using MK248 Mod1 at sea level as a baseline......

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sithlord</div><div class="ubbcode-body">I'm sorry mod 1 is the 190 grain I wasn't thinking. I'm using the Black Hills 190 match and love it. I just want something to help me cheat a little. </div></div>

Mod0 is A191, 190 SMK. Mod1 is 220 SMK.

Unless, you want to run a long (30") barrel to get your velocities up, you'd be hard pressed to beat the performance of the 208/210's. We've crunched the numbers over and over. The 225 wants more case capacity than the 300 can provide.

Run some numbers on 208 Amax at 3000 or 3050 fps. Hard to beat in a 30 cal, unless you step up to a 300 Hulk or the 30-375, etc.

John

 

[darthceadus]

Re: Using MK248 Mod1 at sea level as a baseline......

From what I've read on the backorder status of the 208 I was looking at something a little more readily available. That's why I was thinking of changing calibers since I'm rebarreling anyway or just stick with the 190's. What were your thoughts on the 208 hpbt? Please bear with me I'm a newbie and looking for advice from real guru's. I don't mean to hijack the thread. I was about to start a new one dealing with a possible caliber change unless you think I should stick with the 30 cal.

 

[jrob300]

Re: Using MK248 Mod1 at sea level as a baseline......

Sithlord, PM sent

John

 

[MontanaMarine]

Re: Using MK248 Mod1 at sea level as a baseline......

I gleaned the Mod1 performance data from the NavSea release, and the results Frank posted recently.