300 win mag loading

[hvychev77]

hey guys/gals, new here to the firingline!! i just wanted to get a little advice if i may. i just started reloading for my 300 win mag and shot my first rounds today. my recipe is IMR7828-70 grains, under a 180 grain nosler partition, and i'm using a winchester large magnum rifle primer. My lyman manual states the starting load is at 69.0 grains for a starting load. My Richard Lee manual states that starting load and max. load is 74.5 grains. both have different bullet types, however, both manuals state that they used lg rifle primers, NOT magnums primers. What difference does it make? Anybody else use this recipe in their 300? I'm all ears to suggestins or advice. Also, i might add that the recipe i shot today gave me excellent accuracy, however, i do not have a chrono so i don't know the f.p.s. Thanks ya'll.....hvychev77

[mrawesome22]

Magnum primers are hotter and should only be used when called for. Your description of the Lee data states that the min and max are the same? Anyway, if it gives excellent accuracy and there are no signs of excessive pressure, such and hard bolt lift, then you are good to go.

[Crusty Deary Ol'Coot]

hvychev77, I have loaded for the 300 win. mag for years, and always used mag. primers.

Guess my books have called for that.

If you start at reasonable levels, they will not give any pressure problems.

For example if the "book" lists 70gr to 76gr max for XXXX powder and you start your tests at or close to the 70gr and work your way up, you will have no problems.

I might not start at the 70gr. if I had worked with a given rifle over a period of time, but for a unknown rifle I would probably take the safe route.

I'd probably go 3 at 70gr, 3 at 71, 3 at 72, and so on up to maybe 74gr where I'd go to 1/2gr jumps. If I see any pressure signs, I'd stop and back off. Pull the boolits

If you have the chance to also run the loads over a chronograph while firing for groups, look for any wildly fluxating velocities, which could mean it is time to again back off with that powder.

I have found RL22 to also be a good powder in the 300 as are H & IMR 4831.

I have a great RUGER Hawkeye 300 in the rack that is producing great groups and velocities, but due to the fact I decided to try cast boolits for hunting am currently using a RUGER #1 - 45/70.

If you have not used a chronograph before, do not be surprised to find your rifle is slower then the published figures. I have found that most rifles are slow, some meet the published figures, and even less exceed published velocities.

Also, once you have found a load your rifle likes, buy up a number of pounds of that powder ALL of ONE LOT# for just like changing lot #s of brass etc. those changes can have a sizable effect on groups/velocities.

I have seen a change of Lot#s with RL22 decrease velocity by close to 100fps in the 300.

In some tests I did with the 300 a couple years ago, my rifle gave a bit over 3300fps with a 165gr Nosler partition and IMR 7828 and the three shot groups were well below an inch at 100yds. This Hawkeye, seems to be one of the few "fast" rifles I have chronographed.

Keep em coming!

Crusty Deary Ol'Coot

[Clark]

The tricks I have learned for the 300 Win Mag, or 7mmRemMag, or 338 Win Mag or most belted magnums:

1) The first shot is headspaced off the belt. After resizing the firing pin may push the cartridge forward until it is stopped by the belt or by the shoulder. If you push the shoulder too far back, it will be working off the belt. The problem with that is that the factory rifles are head spaced more that .220" and the belt on the brass is less than .215". The brass is not going to last long getting worked like that. So for long brass life, push the shoulder back .001" or none at all and just neck size. This means the brass might get dedicated to one rifle.

2) The case right in front of the belt will expand, and the sizing will not resize it. The brass will fit back in the rifle that fired it, but to use the brass in more than one rifle, you may need Larry Willis' collet die. This means the brass might get dedicated to one rifle.

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

3) The parent case, the 1925 invention of the 300 H&H magnum is a little stronger than the 1889 7.65x53mm Mauser case head [30-06 type case head], but not much. Hot loads will make the primer pocket loose. The Mauser case head with large Boxer primer will have a threshold of ~ 71kpsi Quickload and the H&H case head ~ 78kpsi. Subtracting off a safety margin for a litany of variables will bring the loads down closer to 65 kpsi. This is expensive brass to be throwing away. A good measure of a load not being too hot, is that a piece of brass was fired 5 times with that load, in hot weather, and the primer seating still takes force. This means not only good note-taking is needed at the range as to what was the load, accuracy, and velocity, but good tracking of the history of each piece of brass. That is too complicated for me and too time consuming to drive to the range. So I walk from the reloading bench to out in the woods and shoot one in the dirt. Repeat, repeat, repeat, repeat. Then the safety margin must be subtracted from that proven load. Vernon Speer 1956 would reduce powder charge by 6%. Loads developed from this process are then the arrows shot into the fence and SAAMI registered max pressures are the target later drawn around the arrows in the fence. Load books are later loosely based on the target painted on the fence. Load book fundamentalists carry pieces of the fence in an ark and conduct rituals with strain gauges. These men, like Indiana Jones, will warn you, "Don't look at the brass!"

107kpsi on a belted magnum case... destruction..don't do this

[hvychev77]

thanks for the advice guys. I am definitely only using this brass for this one rifle. i only have one rifle chambered in 300 win mag. and i would not load this round for anyone else's gun either. I did only neck size my brass thus far. I am using Lee collect neck sizing die until i need to trim and full length size. Thanks for the info. I did myself a favor last night and ordered the Nosler reloading manual 6 for future info.

[Clark]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

The Nosler manual will say 77 gr IMR7828 max for 180 gr 300WM, 24" barrel = 3192 fps.

Quickload says 77 gr IMR7828, 180 gr Nosler Partiion, 3.34", 24"= 3045 fps 58,562 psi.

It takes ~ 49 yards for a Nosler 180 gr partition to slow from 3192 down to 3045 fps.

I usually find the threshold of long brass life at ~ what Quickload thinks is 78,000 psi, and I back off 4% powder charge from there as a safety margin for:
*powder temperature variations
*Shot to shot powder charge variation
*case to case volume variation
*Cartridge to cartridge over all length variation
*Bullet to bullet weight variation
*Primer to primer power variation
*Cartridge to cartridge neck tension variation

That load I then mass produce for hunting, and Quickload thinks it is 69,000 ~ 70,000 psi.
I am in excess of the SAAMI registered maximum average of 65,000 psi for selling ammo, but I am not selling the ammo to be used in a wide range of rifles, just one of my rifles.
I am smaller at 4% margin for my one rifle than Vernon Speer was at 6% for writing load books for many rifles.
It does not matter in absolute terms, what pressure Quickload think a loads is, I just have to know that what it thinks is 78kpsi is the threshold of long brass life in H&H case heads, and that helps me speed up my load development.

[Crusty Deary Ol'Coot]

hvychev77,

Yes, as Clark seems to indicate, do not over size your brass.

I learned this way back with my first "belted" cartridge rifle.

HOWEVER, that goes for all bottle neck cartridges! Go ahead and use a set of "full length" sizing dies, good to go, no problem, no need to buy anything else in most cases but ---------------------

Because of the manufacturing tolerences allowed, sizing dies and firearm chambers do very slightly. Sooooooo, lets say your chamber is on the large side and your dies are on the small side, you have a situation where "full length" sizingas per the directions supplied by many sizing die manufactures, will cause excess working of the brass, very short brass life and inconsistancy of your reloads.

DO NOT set a full length sizing die down to touch the shell holder at the top of the ram stroke or worse yet, until the ram "pops" over center at the top of the stroke as directed by some manufactures, UNLESS doing so is required for brass fired in YOUR firearm, sized in YOUR dies, and rechambered in YOUR firearm requires this much sizing for the reloaded cartridge to smoothly chamber in your gun.

Always, ALWAYS, size your brass to the minimum required for smooth/normal chambering. Even a slight crush fit/slight pressure on the bolt handle required to close the bolt, is not bad, just meaning you have zero slop/head space when the bolt closes on the loaded round.

Over time, you may find that a bit too much pressure is being required to chamber a reloaded round. At that point, VERY SLIGHTLY tweek the sizing die lower. Just enough to again have smooth easy chambering.

This may occur a time or two over the life of your brass, but at some point you will come to the optimum amount of sizing for your chamber/die combination.

At that point, you should never again need to adjust your sizing die unless you wish to resize brass fired in some other chamber that happens to be larger then yours.

It should go without saying, that sizing brass from different firearms, and using the same set of sizing dies - at the same setting - is likely not optimum, due again to manufacturing tolerences.

Keep em coming!

Crusty Deary Ol'Coot

[hvychev77]

thanks for all the info. on here guys. What a response!! Well, as far as sizing goes, i do have the Lee collet neck sizing die which does NOT full length size, so it's not overworking my brass. So, until my reloads start giving me problems chambering, i'll just neck size and ensure that my brass is at the right length. I did call Nosler today and spoke with a kind gentlemen about reloading their bullets and got some info. from him. It's nice to get somebody on the phone and just fire questions away. He answered all of them without a hiccup. So, that was nice. Plus i've ordered the Nosler reloading manual too. All in all, i'm getting ready to hit the range again this weekend!!! who's with me? Thanks again guys...........hvychev77

[Crusty Deary Ol'Coot]

Go for it hvychev77,

Not being overly a Lee fan, I have no experience with the collet neck sizer. Have used a bunch of RCBS and lately going with Hornady, plus a few others including Lee which I try to avoid in most cases.

Have had a few neck sizing dies or so over the years, and have never seen that they could do anything a properly adjusted full length sizing didn't do just as well.

Keep us posted.

Keep em coming!

Crusty Deary Ol'Coot

[Chris84]

This is the cartridge that made me get in to reloading, between the 22.00 price tag and the inconsistancy of factory ammo at the 1000m mark I started loading. I use No 9 remington large rifle primers works great.

My whole load data is winchester brass, Seria 180grain SBT bullet, 72.25gn H4835SC powder. No crimp. I can't remeber the oal right now sorry but it is seated way out there. I can't even put more then a single round in the internal mag. But this gives me 2.5 inch groups at the 1000m line out of my customized modle 70. But honestly the recoil is burtal since the bullet is just barely off the rifleing and I do mean barely.

When I was trying the magnum primers the best that I could get was around 5 inches at the same distance. I was use your data and play around a little find what works best for you. You maybe better with the mag primers. If the Lee dont have the load data the Speer manual does, that is the one I use.

[Crusty Deary Ol'Coot]

hvychev77,

One thing I don't recall seeing in your posts is, the use to which you intend to put your 300.

The last poster indicates he is into 1000yd shooting, and as such his bullet choice very well might be different then the person who used their 300 for a hunting rifle.

If not for target work at extended ranges or the desire of a hunting rifle with 400 + yard distant critter ability, and unless shooting reduced loads for increased trigger time, there is a great long list of more pleasurable and MUCH cheaper rifles to shoot.

If hunting is your reason for shouldering a 300, then do yourself a big favor and go with bullets haveing the integraty of those in the Nosler partition class.

Currently we are blessed with a good long list of high quality bullets, bonded, partition - Nosler/Swift, etc., a list far longer then the days when it pretty much came down to the Nosler Partition, the Bitterroot bullets and the Barnes.

Yes, these bullets are double the price of the old style cup and core offerings, but their integrity and in many cases the lessened meat damage makes them well worth the price.

In the days of 3 - 4 dollar gas, a bullet that costs 60 or 70 cents each is one of the smallest costs of your hunting trip.

Keep em coming!

Crusty Deary Ol'Coot