Loads for my new .300 win mag


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brianr23
February 3, 2013, 10:20 AM
Looking for a little advice for loads for my new CZ550 I picked up. I have access to H4895 and IMR 4350. I have hornady 180 btsp and 220 rn bullets. I do not have magnum primers. I am going hog hunting next weekend and would love to use the 220 grain RN at about 2500 fps. Any 4350 or 4895 recipes would be appreciated.

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Jim Watson
February 3, 2013, 10:31 AM
I don't have a .300 Win Mag and therefore no "recipes" to share.

I am reluctant to copy something out of a manual with risk of a dangerous typo, but the information is in the books. 4350 will be the powder to use, 4895 is too fast for the case volume.

brianr23
February 3, 2013, 10:56 AM
I figured 4350 was the way to go and have a good idea of the charge to use. I'm concerned about magnum vs regular large rifle primers. Would there be a major difference between the two? Some manuals use magnum and some don't.

briang7511
February 3, 2013, 11:02 AM
i have tried imr 4350 and have had luck with lighter bullets at lower velocities. Nothing i really was looking for. I do load reloader 22, 74 gr with the same 180 gr hornady btsp. Holds about 1 to 1.25 groups at 100yds with the book recommeded seating depth so it fits in the magazine. That is the only hunting round i have had success with. I havent tried alot of hunting rounds either.

My best load comes with 74gr H1000 208gr hornady bthp or amax loaded .030 off the grooves, way to long to put in the magazine. holds 1/2 in groups at 100yds and is great at 1000 yds. My rifle is a rem 700 sendaro with a 1in 10 twist. As always start light and work up.

Using fed gmm 215m primers

Presto
February 3, 2013, 08:54 PM
Neither of those are my go to powder for heavy (180gr. and up) bullets. I tried 4350 when I first started with 300 Win Mag, and never could get consistency in my rifle. I tried just about everything on the market and settled on H1000 and RL 22 for heavy bullets. I don't have my data at hand, but I think the 180 gr. Hornady BTSP load is around 74 gr. of H1000 with a Winchester LRM primer. This was my go to hunting load before I switched to the 180gr. SST.

My target load is a 225gr. Hornady BTHP over 73.7gr of H1000 with the same primer as above. That should be close to a max load, so take it with a grain of salt.

A 300 Win Mag takes some work at the bench and range to get right. You most likely won't luck up on the perfect load on the first try. The challenge is why I went with a 300 in the first place.

Again, I don't have my data at hand, so you really should check on those loads before trying them. I sure wouldn't rely on my faulty memory to load by!

Be safe and have fun.

Cougar71
February 3, 2013, 11:53 PM
Have had good luck with RL22.

TooManyToys
February 4, 2013, 01:05 AM
Working with what you have, 4350 & 180s should be ok for you.

critter
February 4, 2013, 07:03 AM
I have a Win M70 in .300 mag. I use IMR 4350 in it (usually with 150-`65 gr bullets). Regular primers worked quite well but I found the groups were smaller with magnum primers.

Heavier bullets should work really well with the 4350. Give 'em a try. Betcha they will bring home the pork.

Trent
February 4, 2013, 10:53 AM
From my spreadsheet

Test of Sierra at same (max) seating depth - bullet 0.001 from touching lands
1/14/2012 H4831SC 65.8 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4831SC 66.8 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4831SC 67.8 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4831SC 68.8 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4831SC 69.8 220gr Sierra MK Neck Turn 3.448 5 100 yd
Test of Sierra MK w/ H4350 powder - bullet remains .001 from touching lands
1/14/2012 H4350 61.0 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4350 62.0 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4350 63.0 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4350 64.0 220gr Sierra MK Neck Turn 3.448 5 100 yd
1/14/2012 H4350 65.0 220gr Sierra MK Neck Turn 3.448 5 100 yd

Trent
February 4, 2013, 10:55 AM
Those are all pretty mellow loads, "within the book" specs, although the 64 and 65 gr loads of H4350, in my rifle, flatten the primers out pretty good, but there's no cratering on the pin. I recall H4350 having a pretty narrow range when you're loading 220gr pills.

EDIT: Also those are for 220gr matchkings, not round nose, so you might want to be careful. Not sure how switching to round nose 220's would affect the load.

briang7511
February 4, 2013, 08:10 PM
I agree with presto, alot of trial and error to get a good load. While were on the subject has anyone tried the sierra mk 240gr HPBT with a 1 in 10 barrel? The box has the recommended twist at 1 in 9 keeping me from trying them.

Trent
February 4, 2013, 09:18 PM
Briang;

They won't stabilize.

Also you REALLY need a custom throat to shoot 240 grain pills. If you don't have a bit of freebore you won't be able to load those long enough. They'll sit so far in to the case that A) you'll lose a LOT of capacity, and B) they won't be accurate for crap.

The more the base of a bullet sits down in to the case, the more issues you'll have with velocity spread and run-out because that base will start to tip before the bullet is fully engaged in the rifling.

Also at the pressures of 300 win mag, that copper and lead turn to (what amounts to) jello; so that base expands and then gets forced back to bore diameter. That's what causes (my theory of it anyway) the wider velocity spread, it never happens the same way twice, to the bullet never starts out at the same rate, which causes different muzzle velocity, etc.

briang7511
February 5, 2013, 01:04 PM
That makes alot of sense why i have alot of issues in the beginning trying to find a load. The throat depth of my rifle is rather deep. I measured the FED GMM with the 190 SMK bullet and it had about .260 jump to the grooves causing them to group about 2.5 in at 100yds. The COAL with the 208 amax is 3.630 to the grooves. Any where from .010 to .030 off the grooves gives good accuracy. The last batch was 3.600 to 3.605 and they held 1/2 groups.

If throat depth is a major concern i probably have enough. I will research later and try to find OAL of that sierra.

Trent
February 5, 2013, 08:05 PM
On my rifle, the lands start at 2.845". This is a touch too short for SMK 220 grain, or 210 grain Berger VLD, I've got a bunch of 180 /185 grain bullets that just came in so I can try to get a better match to my lands.

300 Win Mag is one of those rifles that's kind of "Blah" until you get that load dialed in. Then it's OH MAN can this thing shoot.

Good luck on your quest, you aren't alone. I went through all this once with my old barrel, worked up countless variations until I finally came across a load that averaged .3 MOA.

Unfortunately that old load shoots like crap in my new barrel so I'm starting all over again.. :)

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