Reloading the 300 WIN MAG for long range accuracy using Sierra #2230 HPBT MK

[tomtomz]

I have a P14/M17 Military action made by Remington and used in WWI which was sporterized
by my long dead ancestors to have a 26" medium weight 1:10 right twist barrel chambered for
300 Win Mag.

I inherited this rifle, which has taken it's share of coyotes at or past 300 yards as a Great Plains ranch
working rifle, and has also taken its fair share of Mule deer, Elk, and Antelope across canyons at that range
with an old Bausch and Lomb scope which appeared to be an 8x fixed power scope installed in 1957.

After having a very good gunsmith check it out and confirm that headspacing was within tolerance, and that it is
in good working condition, he installed a new Millet scope and it has been an accurate range rifle out
to 300 yards, and is untested beyond that range.

I am about to see how it does with custom rounds loaded especially for it using IMR7828 powder and
the #2230 SMK from the latest Sierra reloading handbook.

I want to learn if it is truly a long-shooter, so I:
-Researched and obtained the Sierra #220 MK bullet
-Fired Winchester Factory rounds through it (some of which were too hot and blew out the primers and ruined the brass!)
-Took those useless brass and loaded only the #2230 MK into it, COAL 3.7" (no primers or powder charge)
-Carefully chambered the dummy round in my rifle.
-Closed the bolt with some mild resistance, locking it into place.
-Removed the dummy round, observing the slight shadow of rifling lands.
-Rechambered the round a few times, which barrel marked the bullet very slight more.
-Measured the round to be COAL 3.530"

So I repeated these steps with another sized, unprimed, uncharged dummy brass and bullet,
and I measured 3.532" and supposedly COAL for this is round 3.340" per Sierra's
current reloading handbook.

I want to find the appropriate COAL to handload rounds for my rifle, and my rifle only.
My rifle feeds both 3.53" rounds without any problems. And since this is a custom-built rifle that
is a fine shooting firearm, I am wondering if a) the throat of this barrel is burned out, or
b) this barrel has quite a bit of freebore to it.

Upon close examination, the leade is not damaged and the lands appear to be in
good or better condition. I could believe that the barrel has some freebore to it,
as the 300 WBY is reputed to have.

But I can't believe that I should build rounds with a #2230 MK with a COAL of 3.50 or longer.

Please share your thoughts with me on developing an accurate round for this rifle.
Is my measurement method flawed?

[geezerbiker]

I would reduce the length .002 or .003" off the test dummy round and go with it.  I have a .308 Winchester built on a 1909 Argentine action that's like that.  My rounds are way longer than the books say but shoot very well... 

Tony

[SHOOTALL]

At one time I believed that a bullet started in the rifling was the best way to accuracy. I have a 2506 that fed that belief. I have over the last 30 years learned different. My sons 300 Wby mag will not shoot well with bullet touching the rifling or even if to close. That 2506 shoots just as well backed off a wee bit. I have seen different rifles shoot better with the bullet adjusted to different COL. So the first two things I try when first loading anything but a Wby mag is seat a bullet backed out the rifling a bit and then try some with the base of the bullet flush with the bottom of the neck on rounds that permit it. Which ever shows the most promise I work the COL both ways from there to find the best load.
 With the 300 Win Mag keep in mind it has a short neck .

[drdougrx]

That action is a long one...I have a stock P17 made by Winchester that I was going to use for a custom until I figured that the cost could not be justified.  The mag well is huge and I believe could even handle a 375HH length cartridge.  No matter...in the days when your rifle was sporterized, a long "weatherby" type throat was all the rage.  Shootall gave good advice.

[tomtomz]

Shootall, are you saying "try both ways to find the most accurate?"

[Lloyd Smale]

I used to go through all of that too. I found that going through it all to put the bullet in a certain place relitive to the rifling was about a waste of time. Ive seen many guns like weatherbys with long throats that did there best with a big jump and some that needed about everything in between. So now what i do is work up loads at max overall lenght suggested by the loading manual. Once i zero in on the load that the gun shoots best i then may take it and try differnt seating depts but rarely have i had a problem getting moa or better without even fooling with it.

[shot1]

What you need to understand is that the COAL given in a loading book is not the MAX COAL for your rifle. That is just a COAL that will work in most any rifle. It is usually waaaaaaaaay off the lands. This is my experience of over 30 years of precision handloading and shooting. Start with your COAL 10 thousands off the lands with Sierra bullets. Do a ladder test of groups working up to your max powder charge to find your most accurate load at 100 yards. Duplicate that load and move out to 300 yards and see how it shoots. Then you can start fooling with seating depth to see if it improves accuracy. You usually find your best accuracy around 1 gr below max loads. There are so many variables for finding accuracy in a load. Your rifle might not like IMR7848 powder and shoot all over the place but shoot like a house a fire with another powder like one of the 4350s. It will shoot better with one make of primers that it will with others. Little things like case prep do make a BIG difference. Deburring the inside the case primer flash hole where the hole was punched through has really made a difference in accuracy for me. It all boils down to trial and era. We will not even get into proper mounting and handling of the rifle. If you don't do it the same EVERY TIME at long range you will not hit the same spot. Then there is the wind to deal with. I could go on and on but want. Good luck in your quest for accuracy.

[roper]

I have a P14/M17 Military action made by Remington and used in WWI which was sporterized
by my long dead ancestors to have a 26" medium weight 1:10 right twist barrel chambered for
300 Win Mag.

I inherited this rifle, which has taken it's share of coyotes at or past 300 yards as a Great Plains ranch
working rifle, and has also taken its fair share of Mule deer, Elk, and Antelope across canyons at that range
with an old Bausch and Lomb scope which appeared to be an 8x fixed power scope installed in 1957.

After having a very good gunsmith check it out and confirm that headspacing was within tolerance, and that it is
in good working condition, he installed a new Millet scope and it has been an accurate range rifle out
to 300 yards, and is untested beyond that range.

I am about to see how it does with custom rounds loaded especially for it using IMR7828 powder and
the #2230 SMK from the latest Sierra reloading handbook.

I want to learn if it is truly a long-shooter, so I:
-Researched and obtained the Sierra #220 MK bullet
-Fired Winchester Factory rounds through it (some of which were too hot and blew out the primers and ruined the brass!)
-Took those useless brass and loaded only the #2230 MK into it, COAL 3.7" (no primers or powder charge)
-Carefully chambered the dummy round in my rifle.
-Closed the bolt with some mild resistance, locking it into place.
-Removed the dummy round, observing the slight shadow of rifling lands.
-Rechambered the round a few times, which barrel marked the bullet very slight more.
-Measured the round to be COAL 3.530"

So I repeated these steps with another sized, unprimed, uncharged dummy brass and bullet,
and I measured 3.532" and supposedly COAL for this is round 3.340" per Sierra's
current reloading handbook.

I want to find the appropriate COAL to handload rounds for my rifle, and my rifle only.
My rifle feeds both 3.53" rounds without any problems. And since this is a custom-built rifle that
is a fine shooting firearm, I am wondering if a) the throat of this barrel is burned out, or
b) this barrel has quite a bit of freebore to it.

Upon close examination, the leade is not damaged and the lands appear to be in
good or better condition. I could believe that the barrel has some freebore to it,
as the 300 WBY is reputed to have.

But I can't believe that I should build rounds with a #2230 MK with a COAL of 3.50 or longer.

Please share your thoughts with me on developing an accurate round for this rifle.
Is my measurement method flawed?

When you have something build you have it done like you wanted and I'm sure who ever had that rifle build did just that.  It's called custom throating and I have it done on my rifles.  If you look at the 30-06,300mag,338mag,35 Whelen etc all have 3.340"  COAL.  My 35 WhelenAI is at 3.510" and my last 300mag was at 3.500" and I'm about 25 thou off the lands.

The Wby freebore was put in for a reason so it's lot different if your custom throating.  You might find that rifle was chamber for the 180gr/200gr Partition and they wanted at least bullet dia .308" inside the neck and  that rifle would of been build early 60 as the 300mag was SAAMI spec 1963.

[tomtomz]

My Grandpa made this rifle. After WWII he bought "fifty military actions for fifty bucks."
Most were Mauser 98 long actions with an inch or two of barrel left, with the stock
cut off.  He died when I was 16, and I wish I could ask him so many things...like this.

This rifle was his favorite, which makes it very special to me. He was a terrific marksman
and a tireless rancher. He tended herd through the toughest storms with a rifle, Thermos,
and an old Chevy Apache pickup.

I wish I could do anything as well as he did.  I have time to get there.

If I don't blow my rifle and my face off.

[SHOOTALL]

How do factory loads work ? if they work why change ? if not work out from there a wee bit at a time.

[tomtomz]

It likes 180 grain flat bottomed bullets in Federal Power-Shok, but I want
better performance since I'm already a handloader. I want more distance,
which this rifle should be capable of.

[SHOOTALL]

If you are going long distance you might find a boat tail bullet works better. You may also notice your bullet is more accurate at 300 yards over 100 yards . Some say the bullet has to go to sleep. Most say it has to settle down. Then at some point the bullet goes from super sonic to subsonic. There may be some noticeable changes here also. Some say the boat tail helps stabilize the bullet as it slows .

[roper]

It likes 180 grain flat bottomed bullets in Federal Power-Shok, but I want
better performance since I'm already a handloader. I want more distance,
which this rifle should be capable of.

When that rifle was built by your grandfather they didn't have lot of bullet choice that we have today plus that barrel may be short lived at that upper end velocity.  Barrels have come long ways since the 60's

My first build was 1967 and I still have that rifle with same barrel.

[Grumulkin]

It likes 180 grain flat bottomed bullets in Federal Power-Shok, but I want
better performance since I'm already a handloader. I want more distance,
which this rifle should be capable of.

So, how much distance do you want?  What do you plan to shoot at that distance?


It does very little good to use a bullet with an excellent ballistic coefficient if it doesn't shoot accurately enough to consistently hit the target you're shooting at.  I think you'll also find that if you calculate the drop at various yardages between 180 and 220 gr. bullets you'll find there isn't a whole lot of difference even in the 400 to 600 yard range between the two bullets.  If I had a gun that liked 180 gr. bullets better than 220 gr. bullets, I would be shooting 180 gr. bullets.  It turns out that my 300 Win. Mag. likes 200 gr. Nosler Accubonds over H4831SC for what it's worth.

[Lloyd Smale]

I agree. Ive been shooting the 300mags of various sizes for years and never have found a need for a bullet over 180 grain. If i want a heavier bullet i step up to my 8mag or 338. As to the boat tail vs flat base id go with the one that shot better as at under 500 yards the differnce isnt much. A 300 win pushing a flat based 180 in the hands of a good shot will easily take deer out to 500 yards and thats about as far as i want to shoot live targets anyway.

[tomtomz]

I'll take a pot shot at a coyote if it isn't near livestock. When I understand how this rifle shoots, I
may use it around livestock. I can't shoot over livestock if the bullet tumbles, or I will likely hit a cow.

I have a 30-378 WBY that shoots well at long range, but is far too nicely finished to knock around
on a four wheeler. This rifle is shorter, lighter, and better all around for tending herd.

[Larry L]

Hard to believe that nobody has given you the benchrest answer to accuracy. You'll want to develop the loads over a chronograph but you're looking to push that bullet at 2700-2750'ps. That's going to be something like 70-72.0 grs of IMR7828. Once you've hit that node, you dial in absolute accuracy with the OAL in .005 increments starting at max OAL. Most of the guys will shoot either the 200 or the 190gr pills from a 300 Win Mag but velocity is the same. Accuracy is normally a tiny cloverleaf at 100 yds with groups at or less than 3/4" at 300 yds. Considering that the 300 Win Mag goes against everything a benchrest guy looks for in a cartridge, it's been in the winners circle a lot.

[SHOOTALL]

Of course we could offer the military loads for snipers where a A191 load is a 190 gr, Sierra match king bullet going 2900 fps
OR a MK2008 mod. 1 load , 220 Sierra match king bullet at 2830 fps.
 

[Roach68]

Here's Berger's take on length.



The folks at Berger Bullets have just released an interesting technical bulletin that describes methods for optimizing bullet seating depths with Berger VLDs. The document explains how to find the OAL “sweet spot” for VLDs in your rifle. Interestingly, while VLDs commonly work best seated into the rifling .010″ or more, Berger’s research indicates that, in some rifles, VLDs perform well jumped .040″ or more. This is a significant finding, one that’s backed-up by real-world testing by many shooters.


The key point in Berger’s report is that: “VLD bullets shoot best when loaded to a Cartridge Overall Length (COAL) that puts the bullet in a ‘sweet spot’. This sweet spot is a band .030″ to .040″ wide and is located anywhere between jamming the bullets into the lands and .150″ jump off the lands.”


CLICK HERE to download Berger VLD Tuning Tips


Writing in the report, Berger’s Eric Stecker observes: “Many reloaders feel (and I tend to agree) that meaningful COAL adjustments are .002 to .005. Every once in a while I might adjust the COAL by .010 but this seems like I am moving the bullet the length of a football field. The only way a shooter will be able to benefit from this situation is to let go of this opinion that more than .010 change is too much (me included).”


For target competition shooters (for whom it is practical to seat into the lands), Berger recommends the following test to find your rifle’s VLD sweet spot.


Load 24 rounds at the following COAL:
1. .010″ into (touching) the lands (jam) 6 rounds
2. .040″ off the lands (jump) 6 rounds
3. .080″ off the lands (jump) 6 rounds
4. .120″ off the lands (jump) 6 rounds


Berger predicts that: “One of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005.”


OBSERVATION and WARNING
Berger may definitely be on to something here, and we applaud Berger’s testers for testing a very broad range of seating depths. However, we want to issue a STRONG WARNING to reloaders who may be inclined to try the 4-step method listed above.


Be aware that, as you load your cartridge progressively shorter, putting the bullet deeper into the case, you will be reducing the effective case capacity dramatically. With smaller cases, such as the .223 Rem and 6mmBR, moving from .010″ into the lands to .080″ and .120″ off the lands can CAUSE a dramatic pressure rise. So, a load .010″ into the lands that may be safe can be WAY OVERPRESSURE with the bullet seated .120″ off the lands (i.e. .130″ deeper in the case, the difference between .010″ in and .120″ out).


To illustrate, using a QuickLOAD simulation for the 6mmBR cartridge, moving the bullet 0.130″ deeper into the case can raise pressures dramatically. With the Berger 105 VLD seated .010″ in the lands (with 0.220 of bearing surface in the neck), and a charge of 30.0 grains of Varget, QuickLOAD predicts 60,887 psi. (This is using ADI 2208 data, and a 5500 psi start initiation value). If we move the bullet back 0.130″ further into the case, QuickLOAD predicts 64,420 psi (even after we drop start initiation pressure to the “default” non-jammed 3625 psi value). The 64,420 psi level is way higher!


Cartridge & LoadCOALJam/Jump*Start PressureMax Pressure
6mmBR, 30.0 Varget
Berger 105 VLD2.354″+0.010″ in lands5500 psi60,887 psi
6mmBR, 30.0 Varget
Berger 105 VLD2.324″-0.20″ JUMP3625 psi59,645 psi
6mmBR, 30.0 Varget
Berger 105 VLD2.264″-0.80″ JUMP3625 psi62,413 psi
6mmBR, 30.0 Varget
Berger 105 VLD2.224″-0.120″ JUMP3625 psi64,420 psi
* As used here, this is the variance in OAL from a load length where the bullet ogive just touches the lands (first jacket to barrel contact). Loading bullets to an OAL beyond that point is “jamming” (seating bullet into lands), while loading to an OAL shorter than that is “jumping” (seating bullet away from lands).