I've been looking for a load to take with me to South Africa in my 300 Win Mag using the Barnes 180 gr TSX.

I was at my gunsmith's place the other day looking for a few answers. I was getting 3 shot groups in the 1-1.5" range, which I was acceptable with, however, the groups were not consistent from one range trip to another. Many of the groups were in a vertical line, perhaps 2 touching, or near touching, with the 3rd off from 1" to 1.75". So, I was asking some questions about the gun, etc. He suggested I needed to use a faster burning powder versus the IMR7828ssc, RL22, Magnum and MagPro, I'd tried thus far. His suggestion was when getting vertical stringing, the fix is to try a faster burning powder.

He suggested a load that he uses with 180 gr bullets in all of the 300 Win Mag rifles he builds. He mainly shoots Hornady, Sierra and Speer bullets, but said he didn't see why the Barnes wouldn't do the same. His comment was, "If the rifle didn't shoot this load, then we need to work on it." He also stated the load should be shooting around 3100 fps.

I was a bit skeptical because the load he suggested is over current published recommendations. However, I worked up to the suggested load and here are the results. There were absolutely no over pressure signs, heavy bolt lift, etc.

Three shot group with Barnes 180 gr TSX average speed was 3096 fps with 22 fps deviation.

What powder did you go to? Also, if you are using the Barnes manual I have found that their max loads are pretty conservative. The load I run through my 300saum is also over the published max in the barnes manual, with no signs of excessive pressure.

Share what this magical powder is.

Probably H 4350.
Always works well in the .300 WM case.

Powder was IMR 4350, but he said you could use either IMR or H, whatever I had on hand.

Charge was 72 grains, which is well over published max. I started at 5% from book max (69 grains) and worked up in 0.5 grain increments. I would suggest you do nothing less than what I've done for your rifle.

I have always achieved slightly better accuracy with H4350 than IMR4350. don't think you will though looking at your group!
nice!!!

That is a nice group, although I might be a bit leery of that load in really hot temperatures, when the the rifle and ammo have been out in the sun.

How warm was it when the load was developed?

From what I've learned, IMR-4350 is one of the most temp sentitive powders.

For a 4350 powder, I'd for sure use H-4350, Extreme series.

DF

Temp was about 66 F.

That will make a guy smile.

Going to a faster burning powder to get better groups is an old trick that still works well.

Back when I got my Browning Eclipse in 300 WinMag, in 2001, I had an old Speer #8 manual that I had been using for years, and it had always worked fine. My go to powder for the 30-06 was IMR4350, so I found a load for the 300 Mag with that powder. My manual had a suggested starting load of 71 grains with a 180 grain bullet. I stopped at 73 grains of IMR4350 with a chronoed result of 3140 ft/sec. No pressure signs and good brass life. I was surprised when I got a newer manual where it showed a max charge of 69 grains of IMR4350.

That73 grain load shot 3/4" groups pretty consistently.

shootist: IMR4350 may be on the quick side for the 300's today, but it still works.

I don't use that load anymore. Changed powders when I discovered Barnes TSX bullets. Also 'discovered' RL-22 powder. A match made in heaven for the 168 TSX and '22.

I have always used 71 gr I-4350 with the 180 PTs.

Nice group. I'm happy to see you got your gun shooing good.

I'm getting brass ready for some loads using 175 gr. Barnes LRX with H-4350 in my 300 Win. Mag.

Don't discount RE-17 in place of the 4350's. ITs similar in burn rate, but will typically give higher velocity. Great shooting ther, though. Very well indeed.

I like RL-17 in several rounds. It doesn't seem to have the accuarcy nodes with ladder testing as do many conventional powders. It just shoots good as the loads are increased. It doesn't seem to show pressure signs like others, probably due to it's progressive pressure peak.

As other have reported, when you DO see pressure signs with RL-17, you're WAY over where you need to be. So, be careful.

DF

I loaded up some RL17 this afternoon for my 375 H&H. I hope it shows some promise!

RL-17 works real well in my 30-06 with the 200gr. Nosler Partition.