New guy loosing his mind from load data

Ok it is my understanding that the MK248MOD1 round the military is using is a 220 gr SMK at 2850. And isn't that out of like a 26 or 27 inch barrel?? And that its such high pressure that the brass is not reloadable because the primer pockets are looser than my first girlfriend after the first firing.

The barrel on the M2010 .300 WinMag isn't 26"... try shorter. From what we've been told the MK248Mod1 isn't being issued in the states any longer and when the supply in certain countries dries up they will be getting the MK248 with the 190 matchkings. The Mod1 certainly can have high pressure signs in issue rifles, I've seen extractor marks and such but nothing as bad as primers falling out. I think it is also loaded a little longer than SAMMI spec...would have to confirm that. The good thing about you loading your own is that you get to decide (to a point) how long to load them and that can be a deciding factor in pressure.
 
I was under the impression that the reason the military picked the 220 smk for their 300 win mag sniper round was because at the time it was done that was the highest bc 30 cal bullet out there.

Didn't say it was not a good bullet for the 300WM. It is probably a very efficient, effective, and accurate bullet for a 300WM and that is why the military uses it for a 300WM.

What I am trying to convey here is that it is not a very efficient bullet for a BIG 30 magnum like a 300 RUM, and 300 Wby. Probably would not be an efficient bullet for a 30 Nosler either.

The 220 SMK has a BC of .629 and the 240 SMK is .711. The 220 is a decent bullet but there are better. From what I've been told is that it is easier to get to shoot to standards out of a series of rifles and that's why it was chosen. The 220 does have a long bearing surface, basically look at most Matchkings of any caliber and to up the weight and BC all they do is increase the length of the shaft (bearing surface), the ogive and boat tail profile pretty much stay the same with a few exceptions. Most bullet manufacturers do this.
 
Ok I am a new guy. I have made several new posts lately looking for information. I have been shooting a 243 and a 300 win mag for a while now. But I am thinking about moving up to something to spend more money on. So I have a new 300 wby mag on the way and gonna send it off for a new barrel.
So this is why I am loosing my s**t a little. I ordered some Ramshot magnum, and last night I was on there website looking at load data, and saw this....

300 win mag 24'' barrel 220 gr SMK

accurate mag pro 80.1 gr 2875 63,396 psi
ramshot magnum 80.9 gr 2868 63,412 psi

300 wby mag 24'' barrel 220 gr SMK

ramshot magnum 83.0 gr 2840 62,500 psi

300 RUM 24'' barrel 220 gr SMK

ramshot magnum 91.0 gr 2870 62,940 psi


Ok it is my understanding that the MK248MOD1 round the military is using is a 220 gr SMK at 2850. And isn't that out of like a 26 or 27 inch barrel?? And that its such high pressure that the brass is not reloadable because the primer pockets are looser than my first girlfriend after the first firing.

So am I loosing it? Is this info wrong? More velocity from 300 win mag than a 300 rum?!

I know that every rifle is different. And I know companies can't conduct all of their tests on a day when the temperature is the same, but WTH???

MAYBE I SHOULD TAKE UP GOLF.

I hear ya, brother. I was in the same boat going down the same non-navigable, tortuous, river of confusion and expense. Muddying the river's waters were introductions of new powder that nuanced a cartridge's performance; well, at least that's how reloading component manufacturers sell it to us. Keep in mind that fishing tackle intent is to catch fisherman. Manufacturers want to separate us from our $$$.

I'm a hunter, not a target shooter. So my conclusions are based upon killing big game.

My two primary cartridges are .270 Win and 7MM Rem Mag.

There are infinite loading combinations for each of these cartridges: brass, primers, powder, and bullets.

I've figured out that within reason, accuracy is more important than velocity. A couple hundred FPS ain't gonna affect a bullet's destruction of vital organs.

A 400 yard shot is rare. 200 yard shots are far more common, at least they are where I hunt. However, the exception is I've shot two big game animals at distances that have at least double the 200 yard norm. But I never allow an exception modify the rule.

Figure out most accurate bullets for the game you intend to hunt, assuming you're a hunter. The same reasoning will hold true for target shooting. I've produced very tiny groups with Sierra GameKing bullets (for deer), and very good groups using Partitions for elk. But I've bought a few boxes of AccuBonds. The unknown factor is whether Accubonds equal the legacy of Partitions.

Federal match primers seem to be the gold standard. But I'm sure that others will work just as well.

I've used just about all brands of brass. I used to use W-W exclusively. However, W-W quality seems to be less than what it once was. I've since gone with Norma brass. A hundred of each ought to last me a lifetime of hunting.

Powder is the irascible variable. H-4831 still works as advertised. I've gotten very tiny groups with IMR-4350. RL-19 & RL-22 might have both beaten in accuracy and velocity. While I've never tried it, IMR-7828 has a huge following.

So, here's my advice: start with components that ought to work in your rifles. The best place to start here is reading what shooters of your cartridges have written about various powders. I use loading manuals as reference only. They are not definitive. No one hunts in laboratories. I give much more weight to shooters who have actually fired cartridges in the field and on ranges. If a hunter were to tell me that 62 grains of RL-22 in a .270 Win with 130 grain bullet produces dangerous pressure, I'd stay away from that load. If another hunter writes that 58 grains of RL-22 in a .270 Win gives decent velocity and incredible accuracy, I'd be all over trying that load.

Put together five loads of powder charges, increasing by .5 grain. This could take a lot of time, which is why I've researched the heck outta hand loading before I've sunk money on components. For instance, considering the .270 Win, the gold standard load is 60 grains of H-4831 and a 130 grain bullet. Many hunters have said that if this load is not accurate in a .270 Win, sell the rifle. So I will forever have H-4831 on hand. If all else fails, I'll know that I can put together a load that has proven itself where it matters: in the field.

I don't get nutted up over a new powder that'll allegedly give me a hundred FPS increase. I would try a new powder if hunters who have actually used it have written that it will shrink groups. After all, a speeding bullet is useless if it can't hit squat.

I'd guess that RL-22, IMR-7828, and H-4831 will work very well in all three cartridges for which you load. I'm sure that others will work as well if not better. But it will boil down to cost, how much time you're willing to spend experimenting, and how you define the best load for your rifles.

I wish you the best of luck. Heck, I needed a lot of luck when I was in your shoes.
 
smithjasona1978,

I've forgotten to recommend this excellent source of hand loading info:

https://www.amazon.com/dp/1879356643/?tag=lrhmag19-20

If you don't own a copy of Pet Loads I'd recommend that you buy a copy. Mr. Waters has extensive data of the three cartridges you're loading contained within his thorough magnum opus. Even better, Mr. Waters has expended considerable effort actually shooting his loaded cartridges on ranges, not in laboratories, and documenting his results.

Of all the loading materials I have, I use Pet Loads most often for loading info.
 
+1 for what SansSouci had posted. I have used retumbo in a 300win mag before with good results also. It bumped up the velocity and was sub MOA. I have since went to the 300RUM in a Sendero. I have been testing the 220 ELD-X bullets that also have a long bearing surface as well. Running 87 grains of RLL 26 which is about all I want to run and getting 3023fps. Currrently my group has reduced over my retumbo load. I am currently in the process of trying to back it down to see if I can reduce it more. I would like to keep it around 3000+ fps with the hopes of shrinking the group posibally to .5 MOA. Any ways its a lot easer to dial up on the scope then to spend countless hours of chasing the highest node of accuracy and velocity even though I still do this a little Because I get bored but on my RUM it not been worth the cost...Also if doing it again the cost and time spent trying to find Remington Rum brass can be exhausting. I currentlu have 100 new brass and after about 5 reloads on these I figure the barrel will be shot out by then and the brass should be ready for the waste benn.
 
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