.300 Win Mag and Retumbo

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Meph

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Hello gents and dames. I've been shooting some factory .300 Win Mag and I've upgraded my rifle (Mystic Precision is fantastic, he did 99% of the work. Highly recommended). As such, I got me dies, saved my brass and I have access to a press until I get my own (very soon).

So I did my brass prep. I deprimed and full resized the cases (as the Shilen chamber is very tight, some factory rounds wouldn't chamber due to the clearance from the belt to the shoulder). I trimmed, tumbled and reprimed with CCI large rifle magnum primers.

I got Retumbo powder and Matrix 210gr VLDs. Here comes the problem.

Hodgdon's doesn't list 210gr bullets. They list 200 to 220. That's not the biggest issue, as I can start halfway between the grains and go on the low end to work up.

The problem is even at minimum, 76gr of retumbo for 220gr bullet, the case is quite full. The powder is halfway up the shoulder, almost at the neck.

I HAVE NO IDEA HOW HODGDONS EXPECTS 81 GRAINS TO FIT IN THE CASE.

At 79 grains, the load is so compressed the bullet seized in my seater die and got pulled out of the case.

In any case, staying at maximum OAL is just impossible. I'm exceeding the OAL by .200" just to be able to seat the bullet past the ogive. I don't mind doing that but I'm getting into the rifling and that's not really good.



Am I just going full retard or is something not right here?

Finally, if anyone has a working load for the .300 Win Mag using retumbo and long bullets, I would be the most thankful person on the face of the earth. I can tweak the powder charge to be safe/accurate, I'm more concerned about bullet seating and min/max powder load for those VLD bullets.
 
What is the longest you can seat the bullet before you touch the lands in the rifling of your barrel? Seat the bullet longer and you should be ok. I was using retumbo with 190gr SMKs and had no issues, I was seating much longer than what my book said but it worked and I was 0.030" off my lands. My load was very close to yours so it can be done.
 
I have some 210 Matrix, so I thought I'd try it and see if I could find your problem. I used a once fired PMC .300 Winchester case, full length resized 2.625" long, and weighed out 81 grs of Retumbo. I tried various methods of dumping the powder in the case to get the most out of the powder capacity: just dumping it it in came half way up the neck, tricking it into the funnel came to the bottom of the neck, but trickling it into the funnel with a 12" drop tube did the trick, dropping the level to bottom of the shoulder. Seating the bullet I was able to get an OAL of 3.457", although compressed, I don't think it is compressed enough for the bullet to push back out.
 
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81C means 81grains Compressed ;)

Retumbo works best when it is compressed according to an article in Hodgdon Reloading Manual!
You might need to use a drop tube to get all the powder in the case and if you look in reloading manual, you'll often see load with 110% load density!
That's dense!

Alex
 
If your seating die catches your bullet hard enough to pull it back out of the case [even with a highly compressed load] you need to polish the inside of that seating plug.
Use 400 grit Wet or Dry and spin it inside the plug until it is nice and smooth. It should never grab the bullet.
FWIW, I use 81 grains of H1000 behind a 180 grain bullet in the 300 Win Mag. It is also well compressed, but works just fine.
Another is 79 grains of RL 25 behind the 200 AB in my 308 Norma Mag.
Regards, Eagleye.
 
I think the issue might be partly that I'm using a micrometer seating die that happens to have "bullet guide" (kinda like that reverse bullet ogive shape in the die that places the bullet) that makes it prone to seizing somehow. I noticed there was a scuff mark on the bullet where it had seized the bullet. The seating die is beyond mirror shine polished on the inside, it just seems to be shaped in a way that makes it grab onto the bullet...

I guess I shouldn't be afraid of compressing Retumbo - thank you for making that uncertainty go away. I know that the max load was listed as compressed, but I didn't know that near minimum would be compressed as well... I measure the powder loads one by one with a non-digital powder scale.

I'll trickle the powder in as it does make sense that it would arrange the powder more efficiently volume wise inside the case, that should reduce the heavily compressed problems.

Thanks a lot, you guys are great!

Last thing, I've been trying to find a way to accurately find how far away the lands are. It it just touch and go with a bullet that's covered in marker or is there an easier way?
 
Meph said:
. . . Last thing, I've been trying to find a way to accurately find how far away the lands are. It it just touch and go with a bullet that's covered in marker or is there an easier way?
Click to expand...

The system I use is a two step approach and required two dummy rounds. The first thing I do is seat a flat based bullet nose down in a cartridge case without a primer in place, then with easy gradual pressure, chamber the round. The flat base contact the lands and the bullet will push back into the case providing an accurate measure from the bolt face to the lands.

Secondly I take one of the bullets I intend to load and press it nose first into the muzzle of the rifle, then turn it with finger pressure which will etch a line at the ogive. If I seat this bullet so that the etched line is equal in length two the base of the flat nosed bullet in my first dummy round, I have have contact with the lands, from this point I can accurately adjust the distance off or into the lands, in your case with the micrometer bullet seater, or by knowing the thread pitch on my seating stem. RCBS uses 28 TPI and a quarter turn equals .009".
 
I use a length of smooth stainless rod that is near bore size, and two drill bit stop collars with set screws.

First I run the rod in from the muzzle until it contacts the bolt-face, then set one of the collars at the muzzle. Next remove the rod and push a bullet againstthe lands with a pencil and move the rod back in until it contacts the bullet tip. You can get a real feel for the tiny bit of resistance when the lands are just touched. Next, set the other collar and measure the distance between the collars with a caliper.The distance is the COL for that particular bullet.
Most methods based on useing a dented fired cartridge and bullet, and letting the lands push the bullet back into the case will consistantly give you a length that amounts to about 30 thousandths of jam.You can ram a tapered bullet into a tapered lead rather easily.
 
Meph; Last thing said:
I am using digital headspace gauge http://www.larrywillis.com/ and is very useful tool for checking seating depth.
For each bullet, cartridge combination I have dummy round created by pushing bullet (nose first) in to chamber and closing bolt forcing it in to lands
Now I can measure its length at ogive and work on different seating depth with good accuracy.

Andrew
Click to expand...
 
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