• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

The Magic Number - What is it?

jgobbels

Sergeant
Full Member
Minuteman
Aug 5, 2007
115
9
54
Hoover, AL
Gents,

Looking to find your perspective on the Muzzle Velocity I should try to obtain in my .300 WIN MAG

In doing my research here, the overwhelming number is 2950 fps, but my question is how do you know where your number should be?

I've had some time doing the barrel break-in on my AIAW . 300 - I started at 67g and Im now at 68.6 with a resulting corrected velocity at the muzzle of 2881 fps.

My groups are good - Shot a personal best 5-shot of .252" today, and have recorded (12) 5-shot groups that gave me an average of .435". This should be the average +/- 12%, 95% of the time if I can do my part.


Here is what I want to do:

Im not a bench rest guy and as soon as I get my information and dope correct I'll be looking to just shoot steel. I'll probably shoot a few local matches so I'll need to be able to group, but that's not my priority for the rifle.

The gun will be used from 600-1000 yards 90% of the time and I'll be able to stretch it to 1300 yards twice a year.


SO....

Do I keep going and try to reach 2950 and watch to make sure my accuracy doesn't go south in the process or signs of pressure show?

Or:

Do I wrap it up now and start to get my dope?



Sorry this was so long...


Your thoughts are appreciated.



John~



BTW:

IMR-4350 - 68.6g (At this point)
Winchester Brass (Prep'd)
Winchester LRM Primer
Sierra 200g Match King
.010" off the lands

Out of a 26" 1:11 .300WM Accuracy International AIAW~
 
Re: The Magic Number - What is it?

There are only two possible answers.

One: It's a secret and those few who know won't tell.

Two: There is no magic, it depends on what your rifle gets and what you want.
 
Re: The Magic Number - What is it?

If your groups are averaging <1/2 moa, you need to record everything and just practice. When you can shoot 90% of your groups like that, at the range you're looking for, then go back and tweek your load.

But it sounds like a very decent load to me.
 
Re: The Magic Number - What is it?

Would help to know what bullet you are using but I will assume the 190 SMK from the load. There is no magic number. Figure out how far you want to shoot and look on a ballistics calculator at what velocity with that bullet will do the job and try to get it.

That said I would use a different powder. Something slower like H1000 or RL22. Also I liked the heavier bullets like the 208 AMAX in my 300WM. With some H1000 and the 208AMAX in a 26" barrel it would easily do 2950fps. I got away from the 190s as the heavier bullets have much better BCs and can buck the wind better at long range.
 
Re: The Magic Number - What is it?

I would start with running your current numbers through a ballistics calculator (biggameinfo.com has one), if you haven't already. Will it preform on paper out to where you want it too? Now run the numbers again at your target velocity (2950). I think you will be surprised by how little 70fps will change your numbers.
You can still work your load up to see if you can safely get your velocity while maintaining your accuracy.

BTW my Sierra manual stops at 67.0 grains with IMR 4350 @ 2900fps using the 200gr SMK. Only IMR 7828 makes 3K per the book.
I think you will see that most saying 2950 are running 190gr SMK, IIRC.
 
Re: The Magic Number - What is it?

I think it's a good question.

My interest comes from a concern for copper fouling. I think I see a linkage between increased velocities (and the pressures that spawn them) and copper fouling accumulation.

When I do my load development, some of the goal involves sustained accuracy. Unless there's some especially compelling reason to do otherwise; if more than one accuracy node emerges, I will often choose the one at the lower velocity. It saves things, like components, throat degradation, and sometimes (I think) allows copper deposition to occur more slowly, over a longer string of accurate rounds. My primary concern about velocity is that the rounds arrive ontarget supersonic at the intended distance. If that distance is not critical, velocity seems less of a goal to me.

Greg
 
Re: The Magic Number - What is it?

John,

I have had good accuracy using IMR 4350 in the 300WM with the lighter bullets. When you go to the heavier bullets, IMR 4350 is a little too fast of a powder, and will not yield the highest velocities. I would look at H1000, R22, and even Retumbo. I have been experimenting some with Retumbo, and am getting more velocity than H1000.
For 800-1K, the 200 SMK is just ok. The BC on the 200 SMK is .565. If you go up to the 208 A-max, it's .648 BC. This will make a huge difference at 800+ yards. The 210 Berger is very similar to the A-max. The IMR 4350 load shoots good in your rifle, but if you want more velocity, you will need to switch powders. Hope this helps.

Chad
 
Re: The Magic Number - What is it?

Guy's,

All great information. I wanted to start my load using the 200g SMK's and that's where I'm at now.

I also have standing by a few pounds of RL-22 and a few hundred 190g SMK's.

I'd like to end with trying some 210 Berger's and take a perspective on what will give me the best accuracy and terminal velocity at the ranges I'll be shooting.


Appreciate everyones responses.


Best,

j
 
Re: The Magic Number - What is it?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">I think it's a good question.

My interest comes from a concern for copper fouling. I think I see a linkage between increased velocities (and the pressures that spawn them) and copper fouling accumulation.

When I do my load development, some of the goal involves sustained accuracy. Unless there's some especially compelling reason to do otherwise; if more than one accuracy node emerges, I will often choose the one at the lower velocity. It saves things, like components, throat degradation, and sometimes (I think) allows copper deposition to occur more slowly, over a longer string of accurate rounds. My primary concern about velocity is that the rounds arrive ontarget supersonic at the intended distance. If that distance is not critical, velocity seems less of a goal to me.

Greg </div></div>

Wow, it's refreshing to hear some say this. I know there are people out there that like those screaming-ass velocities and give little concern as to the effects of those velocities on the rifle. Then they get pissed when their rig goes south in a very short period of time.

I concur with what you said about high velocity and copper fouling. I'm not an old fart yet, but I do have the opportunity to run through several different calibers every year and even develop handloads for them.

In just about every super-crazy-mega-magnum I've had my hands on, copper fouling gets more severe as velocity goes up. I've found that dropping just 100-200 fps below max velocity can decrease and even eliminate copper fouling in these rifles.

Something else I've noticed that's very interesting is that sometimes switching to a slower burning powder than what you currently use will allow you to reach max velocity and pressure without copper fouling.

I don't know why this is, but I have witnessed this on several different magnums I've worked with. Anyways, I hope this info helps someone out there having issues with excessive copper fouling.
 
Re: The Magic Number - What is it?

often i don't even measure MV. i just seat to the lands, load up to pressure signs i'm comfey with, and if said load meets my accuracy needs, i just rock that load. seriously, i've spent less than an hour developing .5 moa loads for a rifle capable of such. when i work up my range cards, i get MV by matching bullet drop to ballistics calculator. seems more accurate than my chrono.

i've found fouling is more a product of barrel finish and bullet material than velocity.
 
Re: The Magic Number - What is it?

that seems just to simple sikpupi.but if it works well do it.there is so much imfo available on these sites.i generally go through posted loads and pick one that seems to be close to what i am looking for and just go from there.and of course i always verify the imfo.this site has great imfo along with 6mmbr.com,the guys over there are very scientific ,maybe a little fanatical with load development.
 
Re: The Magic Number - What is it?

This is the same question I have... I am shooting 178gr AMAX now with 69.5g IMR 4350, Now I am manily shooting around 800yds, So should I consider tring the 208g AMAX with a slower burning powder???

Thanks
Richard
 
Re: The Magic Number - What is it?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrservices</div><div class="ubbcode-body">This is the same question I have... I am shooting 178gr AMAX now with 69.5g IMR 4350, Now I am manily shooting around 800yds, So should I consider tring the 208g AMAX with a slower burning powder???

Thanks
Richard</div></div>

Save the 178s for the .308 and get some 208 AMAXs and push them with some H1000. You'll get a load that will work out to a mile. Also will buck the wind better with it's .647 BC compared to the .495 of the 178 AMAX
 
Re: The Magic Number - What is it?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrservices</div><div class="ubbcode-body">This is the same question I have... I am shooting 178gr AMAX now with 69.5g IMR 4350, Now I am manily shooting around 800yds, So should I consider tring the 208g AMAX with a slower burning powder???

Thanks
Richard </div></div>

As long as you're satisfied with the accuracy of 4350 and copper fouling is not an issue I wouldn't worry about it. But, if 4350 is the only powder you've tried I would give other powders a look. You might be very happy with the results, I was.
 
Re: The Magic Number - What is it?

All this talk about load development is bullshit, just get a Browning BOSS installed and be done with it.
 
Re: The Magic Number - What is it?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Outsydlooknin75</div><div class="ubbcode-body">All this talk about load development is bullshit, just get a Browning BOSS installed and be done with it. </div></div>

I'll be sure to do that.
smile.gif