I am working on a low recoil load for my 300 Win mag. I'm using 45 grains of Hogdon 4895 with a 130 gr Hornady flat base bullet. My COL is failry short (right out of the Hornady book"). I'm getting 1.25" groups at 100 yards. I get lots of groups with one flier, and I'm wondering if filler material might help.

Does any one use filler in reduced loads? Do you see any increase in accuracy? If you do use filler what kind do you use and how much? Has anyone had a pressure problem or catastrophy from using filler?

Do you think I should try to "tune" this load by changing COL or powder charge? Which should I try first?

I have used kapox as a filler in reduced loads with both cast and jacketed bullets. It' worked well with a couple of .375's and the charges were similar to yours.

With the 220 Swift the kapox coated the necks of the fired cases even though the load was accurate.

The NRA publication "Handloading" warns against the use of Dacron as a filler.

In general I have had better results with standard primers vrs magnum in these light loads.

The easiest and safest way to do what you want to do is to use IMR's SR 4759. That powder is made for what we are doing and is high in bulk. Note that a 1/2 pound of it is packed in a one pound can.

The reason for this is that with some light charges, but not your 4895 load, a double charge is possible. The faster burning 4759 will get the pressures up and perhaps that will improve consistancy.

My formula for a good light bullet load using 4759 in any cartridge that I have tried has been 1/2 the charge weight of what that cartridge would use with conventional powders.

Thus if a 300 WM would take 80 grs of conventional powder then the 4759 load is 40 grs. Most rifles give about 2700 to 2800 fps with that load and a light bullet.

Youth Loads

I could not find a 300 WM load for 4759 on IMR's new site. However smaller similar cartridges can be used for work up starting data. Here is the 300 H&H data.

Elkhunter, I've used fillers with very slow milsurp. powders (WC 860 & IMR 5010) and cast bullets in cals. from 7.5 Swiss to 8mm Mau. The filler was either Grex or powdered bran (via a coffee mill), but never more than 1cc and sometimes (in the 8mm Mau.) as little as .3cc. What's different when using these fillers is that you use less powder to achieve the same velocity, but you gain cleaner burning and lower ES's & SD's. This doesn't detract from accuracy and may, in fact, improve it. ...Maven

Pardon my ingorance, but what is Grex?

Grex is a granlated plastic filler that is used for filling in the gaps between shot in shotgun shells.

I would be very cautious about using fillers in a case that has a relatively large dia vs the neck dia, especially with a granulated filler. With a straightwall case, evrything gets blown down the bore no problem. In the 300, the shoulder is quite a constriction for powder to flow through at very high velocities.

Are your groups 3 shot or 5 shot? 1 1/2" at 100 yds isn't at all bad for a plinker load, in fact it's quite good. Use a chrono to see if you're getting wild velocity swings. You also might want to try different primers. Sometimes a hotter primer works better for low load density loads, sometimes a cooler primer helps.

The groups I mentioned are three shots at 100 yards. I can usually get two that are very good and one flier. Some of the fliers open groups to 2.5". I'm not sure what the practical accuracy of a reduced load is. I'm sure that some (if not all) of the fliers are shooter error. I'm just looking for ways to trouble shoot this load.

Would cornmeal or cotton (from a Q-tip) make an effective filler, or am I asking for trouble?

I'd try to stay away from fillers if possible.

You can use very reduced loads and get good accuracy and consistant velocities. In my 350 Rigby, which has about identicle powder capacity to your 300, I use 20 gr of Unique under a 200 gr cast bullet, and for a ten shot string, my average velocity was 1410 fps, and the extremem spread was only 20 fps. It would print 5 into 1" at 50 yds.

Some powders simply won't burn consistantly at reduced levels, and hence won't produce the best accuracy. I do know from personal experience that Unique and 2400 do work quite well with reduced loads, but their velocity might be lower then you are after.

Don't use Dacron!

I ringed the neck of the chamber of my 9.3x62 using dacron as the NRA advice said I might. I read the advice, had a look at my brass, saw the ring, got it bore scoped and replaced the barrel.

Probably about 20 rounds of 95gr 0.365 bullets fired under a few grains of unique and dacron.....