.300 Win Mag Velocity in 30 inch barrel


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LR Sarge
September 12, 2013, 01:05 AM
Quick question to all you reloader super freaks. I am in the middle of a build, based off the .300 win mag.
Trued Remington 700 action
Pac-Nor 30" super match grade, #8 (heavy contour) barrel (3 lands-3 grooves)

Barrel has not been chambered yet, but I have to develop a round that will fit the magazine of some quality bottom metal, and my velocity needs are 3057+ fps with a hornady Amax in that specific barrel. Once I have the round made up he will chamber to my loads specs. From there he will cut the leade and neck just perfectly to match. My machinist suggests .020 off the lands to start, and I can work forward and back looking for pressure signs.

My question is, is 3060 fps doable with a 208 gr Amax in a 30" lapped barrel with 3 lands and grooves?

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Markm87
September 12, 2013, 10:01 AM
I would expect so. You might even go 26"-28"... I think 30" is past the point of velocity gain.

We're around 2900 and change out of a 24" Krieger.

Outlaw Man
September 12, 2013, 12:07 PM
Yeah, I'm not an expert on the 300 win mag, but I'd also expect your charge has done all the accelerating it's going to do before it gets to 30". I would think you can reach your mark, though.

What are you planning to use the rifle for? A 30" barrel with any kind of thickness sounds like a beast of a rifle to carry.

MtnCreek
September 12, 2013, 12:28 PM
FWIW, 26", H1000/208 amax is around 2,900 and burps a decent fireball in the dark. 3057 may be tough to get. I assume you came about the 3057 by plugging numbers into a ballistic calc, correct? What are you trying to accomplish? If you're looking to really stretch the distance, a different bullet may be the solution.

Good luck w/ the new rifle.

dprice3844444
September 13, 2013, 12:50 AM
get a good chronometer

Ridgerunner665
September 13, 2013, 01:04 AM
Need to get the groups tight before using the chrono.

Powder is scarce...do both at the same time, shoot for groups over the chrono...saves time and money.

LR Sarge
September 13, 2013, 03:54 AM
Interesting... My purpose in the barrel weight, bullet weight, velocity, etc. is to stay supersonic to 1 mile. If I can get away with the Hornady 208 grain with a BC of .648, a 30 moa scope base, NSX 8-32x56, I have enough BC and velocity to stay supersonic for a mile while having enough adjustment in my optic to mannage a 100 yd zero at 0 minutes of adjustment, and enough adjustment to get me to 1 mile at 62.5 moa. I am maximizing my scope potential and barrel bullet combination at the same time. If the 300 win can't do it, I'll have to go 300 RUM or larger caliber.

MtnCreek
September 13, 2013, 09:18 AM
You're putting a lot of faith in the stated BC of the a-max.

Good luck.

Ridgerunner665
September 13, 2013, 09:23 AM
Bryan Litz tested the 208 Amax.... Its actual BC is a little HIGHER than it is advertised.

MtnCreek
September 13, 2013, 09:27 AM
Do you have a link to the testing?

Thanks.

Medusa
September 13, 2013, 09:33 AM
.338 Lapua Magnum and 300 grain Scenar (HPBT) with G1 0.736. It will get you to a mile and more, while eating the barrel a tad less. 300 WM is still a .30 cal. I have shot the 300 WM to 1 kilometer regularly and 1200 m sometimes, but the bullet is struggling with the wind. It depends on the bullet used, true, but 30 cal meets the limits sooner than bigger ones (.338 etc).

Ridgerunner665
September 13, 2013, 12:35 PM
Do you have a link to the testing?

Thanks.

I have it in PDF...but its easy to find on google.

Ridgerunner665
September 13, 2013, 07:42 PM
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA554683

JimKirk
September 13, 2013, 10:00 PM
That report would not give Nosler the best grade for reported B.C. accuracy ...

Good reading...

Ridgerunner665
September 13, 2013, 10:08 PM
That report would not give Nosler the best grade for reported B.C. accuracy ...

Good reading...

Yep...but I still shoot Ballistic Tips...I've made my own BC calculations.

Dthunter
September 15, 2013, 11:15 PM
LR Sarge:

Even if you got 3100 fps out of the 300 Win mag, (you wont/ don't try) your bullet will cross into the Sub sonic realm at around 1620-1640 yards. Well short of a mile (1760 yards).

But the real question I have is:

Why do you need the bullet to be supersonic at a mile?

The bullet does "not need" to be super sonic to be accurate at that distance. If your twist rate is sufficient,(1:10" is fine) the bullet should remain stable at/to that distance.

I have shot nearly 500 of the A Max 208Gr. bullets to a mile over the last two years with a 300 Win Mag.
They do just fine at the 2940fps my rifle barrel gets. A great combo In my eyes.

The last time I shot at a mile, my MOA adjustment was (69.0)
The time before that it was 71.0 MOA.
The time before that, it was 75.8 MOA. (different temperatures and atmospheric conditions).

Mtn Creek: seems to be correct in saying, that It sounds like you have too much faith in the "Published" B.C. value. (no insult, what-so-ever meant).

I say this because, "I" have found that the "advertised" B.C. tends to be a little generous/high when shot from my rifle.

I believe that individual variances in barrel finish/dimensions/copper fouling, etc. are some of the reasons for this tendency.

The next lot/batch of A-Maxes I get "MAY" result in a slightly different BC value.


The absolute best advise I feel that I can give is to use the manufactures values as a start, and use them to get the impact points "close" to your points of aim at multiple ranges (at least 5 different ranges, at least 100 yards apart, and starting at 200 yards or more). The differences will be more pronounced the further you go out, and making it easier to quantifiably/qualitatively measure the results. Record the "ACTUAL FIELD RESULTS", and adjust the ballistic software to correspond to your measurements at ALL the reference measurement distances, and with your specific Atmospheric conditions on THAT DAY.

I have reached a mile with 4 different calibers this way.

Good luck, and have "LOADS of fun!

I hope this information can help in some way.

jerkface11
September 15, 2013, 11:24 PM
I think 30" is past the point of velocity gain.

You're kidding right? It's a .300 Win Mag not a .300 Blackout. However if you're going for the most velocity why not go with .300 Weatherby?

Dthunter
September 15, 2013, 11:33 PM
jerk face:

Soooo TRUE!

The 300 Win Mag is more than enough to reach a mile.

If a shooter hasn't (actually) done/shot the experiment as in the "stated thread comment", he/she has no idea what kind of results ACTUALLY happen.

LOL!

And yes, I have done experiments with 30" barrels and progressively shorter, as in the thread comment.

Bart B.
September 16, 2013, 10:42 AM
Many folks have shot .300 Win Mag 28 and 30 inch barrels and got 3000 + fps with 200-gr. bullets.

Leaving at 3100 fps, that AMAX bullet will be subsonic at about 1350 yards. A mile down range, its moving about 670 fps according to Berger's software.

USSR
September 16, 2013, 01:10 PM
Leaving at 3100 fps, that AMAX bullet will be subsonic at about 1350 yards.

Not sure where you're getting that data from, but Point Blank external ballistics software calculates the the 208gr Amax bullet is still going at 1485fps at 1350 yards, well above subsonic.

Don

Speedster00
September 16, 2013, 01:47 PM
I have no experience shooting this distance but I do have a 300 win mag. Out of curiosity, why go with such a heavy bullet? Why not a 168 gr? From my little knowledge that seems to be an awfully popular weight for 30 cal extreme distances.

USSR
September 16, 2013, 02:55 PM
I have no experience shooting this distance but I do have a 300 win mag. Out of curiosity, why go with such a heavy bullet? Why not a 168 gr?

You go with a heavy bullet because they have a higher BC (Ballistic Coefficient, or in layman's terms, they are more streamlined). The 168gr Sierra MatchKing has a 13 degree boattail, and was designed for 300 meter shooting. It is a terrible long range bullet.

Don

MtnCreek
September 16, 2013, 02:58 PM
Out of curiosity, why go with such a heavy bullet? Why not a 168 gr?

Higher BC = less drag / drift. At a point in the bullets path, the heavier 208 amax will give less drop (and more importantly less drift) than the 168 gr bullet.

Not something I have experience with, but if I were looking to shoot 1 mile + on a regular basis, I would consider something like a 230 gr Berger or maybe 220-240 gr SMK.

Edit: I type slow. :)

Speedster00
September 16, 2013, 03:01 PM
Higher BC = less drag / drift. At a point in the bullets path, the heavier 208 amax will give less drop (and more importantly less drift) than the 168 gr bullet.

Not something I have experience with, but if I were looking to shoot 1 mile + on a regular basis, I would consider something like a 230 gr Berger or maybe 220-240 gr SMK.

Edit: I type slow. :)
gotcha. thanks.

jerkface11
September 16, 2013, 03:01 PM
If it were me I'd set the rifle up as a single shot so I wouldn't be limited by the magazine.

MtnCreek
September 16, 2013, 03:05 PM
If he's having it cut to a specific bullet, that won't be a problem.

Bart B.
September 16, 2013, 04:55 PM
As stated in my post, I used Berger's software; the latest version using G1 BC of .648.

Across all the ballistics software available, you'll easily get a 200 yard spread about the range bullets go subsonic.

MtnCreek
September 16, 2013, 05:09 PM
Were you plugging conditions to simulate worst case conditions for your area? (In a valley in mid-winter)?

Dthunter
September 17, 2013, 09:08 PM
In order to shoot a mile with a 300 Win Mag, you do not need to go with the 230 grain Berger. But they are great for it!

The 210gr VLD does awesome for me! I managed to win an informal competition at a mile a few years ago (20+ Experienced Shooters). I managed to post a 5 round,14" group at a mile. It was a great day indeed!


Using a G1 BC to figure out your trajectory is nearly pointless. The G7 is the standard which a highly profiled bullet trajectory can be predicted much more accurately.
Have fun with it!

Bart B.
September 17, 2013, 09:27 PM
I used a balmy, sunny day at sea level with the temperature at 70 deg. F.

'Tis interesting that at a mile down range that AMAX bullet leaving at 3060fps has a vertical impact change of about 1 inch for every 10 fps of muzzle velocity. It also drops about 1.3 inches per yard of horizontal range.

And a bit over 2 feet of drift for every mph of cross wind speed. The bullet's maximum height above the line of sight will be about 38 feet at 1100 yards where the wind will be blowing 20 to 40 percent faster than at ground level depending on the terrain.

Ran the same bullet numbers with Sierra Bullets software using a .648 BC and it said the bullet went sub sonic at about 1,500 yards. Sierra's bullets have five different BC's for different velocity bands; BC's for their 30 caliber 210 gr. HPMK range from .530 @ 1400 fps and below to .645 @ 1800 fps and above. I think that AMAX also has different BC's for different velocity bands and .648 may be its highest. Therefore, I believe that unless good BC numbers versus velocity bands are taken into consideration when calculating the bullet's path with any decent degree of accuracy, the numbers you get may well be off quite a bit.

After getting a "shooting boresight" for the sights and muzzle velocities for the loads, I've used Sierra's software with G1 BC standards calculating drop at different ranges up to 1000 yards with all their 30 caliber HPMK bullets shot from two .308 Win. rifles and two 30 caliber magnums. Calculated sight settings versus reality to get zeros at 300, 600, 800 and 1000 yards was within 1/4 MOA. I don't think Berger's software is any better with their G7 BC standard.

Dthunter
September 18, 2013, 12:59 PM
If you have ever shot much at ranges like 1000 +, you would see immediately a difference when using the G7 standard.
Some reading of Brian litz "Applied Ballistics" would be beneficial.

Ridgerunner665
September 18, 2013, 01:43 PM
Lmao

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