300 Rum Loads and Pressure or Head Space problems

[George Koch]

I've been reloading now for 15 years and have never run into this problem, I've checked the forums on several different sites and decided to post on this one. I purchased a 300 RUM Sendero in August of this year. (First mag I have ever owned or reloaded for) worked some loads up that the gun liked.

Rem Brass- Fed GM215M primer, IMR-4350, 80.5 grs, sitting under a 180 gr Accubond. The powder vol. is only about 84 or 85% of the case capacity which is less then I like vol. wise. I loaded up 15 more for hunting season in October, same load and decided I would shoot them. Prior to shooting them I ran across a loading manual that listed the max powder load for the 4350 at 80 grains. I've been using the Nosler 6th addition for my cookbook and they listed the max load of 4350 at 82 grs.

I had some concerns however since I had already been using 80.5 grs with no problems , I sent them down range through the chron. and the velocity was within 9 fps of book values with the exception of the last shot which spiked about 40 fps. On the last shot the bolt stuck a little and I assumed that I had heated her up a bit as there was not any downtime cooling off period for the last 3 shoots.

After inspecting the brass at home I noticed that all 15 casings had the primer backed out a thousand or two. These cases had been fired once before and this was their second outing, trimmed to 2.840 and neck sized only. Bullet seating same as before.

Anybody got any opinions, I've seen a few, indicating primer pocket problems, a few indicating low pressure, and head space problems. In light of that other reloading manual that listed the max load at 80 grs I'm sort of at ground zero.

I was getting to ready to work another winter load up with this powder and jump it a little closer, Its had 65 rounds fired through her from day 1 total.

I've got some RL 25 and some magnum powder that would fill the case I just don't like taking more pounding then I have to. I'am not concerned with the fraction of a second or a 100 fps slower vel. The deer nor the paper could ever tell the difference and I have plenty of vert adjustment left in the scope to fix that.

Anybody got any opinions or loads they would like to share it would be nice, I have no problems using another powder or bullet for that matter.

 

[highridge1]

I am running 200 gr accubonds with RL25,fed 215 primers and it has been a great load with my 300 rum.I am running 92.0 grs but you should work up to that, I have no pressure signs and great accuracy.I am not saying 4350 won't work but it isn't a powder I would consider for the 300 RUM. I went to 200gr bullets because the 180 were a mess on game to much blood shot etc.

 

[300 ultra]

My pet load was 87.5 gr of RL25 with a 200 accubond which Nosler shows as a starting load and I get sticking bolt and flattened primers. I am now playing with retumbo to see what happens. I am also switching bullets because I was not impreesed with what it does to animals. Which was not much.

 

[300 ultra]

Oh and Nosler stated they got near benchrest groups using 4350 with medium weight bullets. Ive thought of trying that also.

 

[Derek M.]

While IMR4350 is one of my favorite powders of all time, it is NOT a great powder for a 300 RUM in my opinion. The case is just too big and 4350 is a medium burning powder. Sure you can get good loads with it but you are talking about a more narrow range of powder volume where pressure spikes are more likely.

My suggestion: Get a slower powder more suited for this caliber. Re22, Re25, H1000, Retumbo, WC870, Magnum, or similar.

Generally speaking, I think you are better off with a load where powder is 94% or higher. I prefer closer to 97% or higher myself.

Good luck

 

[Kevin Thomas]

Hi George,

Sounds to me like a combination of a relatively mild load, and a bit of a headspace issue. May be that neither is a real problem, but you're seeing indications of both here. If the primers backing out like this, then there isn't enough pressure to cause the case to stretch to fill the gap that amounts to headspace. That's why you're seeing protruding primers, rather than flattened primers. The 4350 is a great powder for most of the magnums, but it is a bit on the fast side when compared to some of the newer powders and the more recent cartridges. Truly a great powder in 300 Win Mag, probably a bit too fast for optimum performance in a RUM. Several others have mentioned some options here that would be worth a try.

On the second issue, reloading manuals should be treated as a simple report saying "we tried this combination, and these are the results we got." This is why you see the various differences you do from one manual to the next. None are "wrong" (at least that I've ever seen), but they are different. As they say, your milage may vary.

 

[George Koch]

Thanks to all, I'll be trying some of the suggestions, I thought I might have been using a marginal powder for the RUM

 

[conn338rum]

I played around with a number of powders for my 300 RUM and bullets
Ended up with the same powder I use for my 338 RUM
Retumbo 94 gn with VLD's 210gn for the 300 RUM
H1000 did not shoot as well but that's my gun
May try some 168's with Retumbo in the 300 RUM
Just a note H4850 at 59 gn with 168 VLD's worked very well in my 30-06

 

[eismccc]

I like the 200 grains myself, along with Magnum powder to 90%, sometimes a little higher. I've recently been using the 180 grains with Magnum up to 100%, it works great. I don't know if a lot of people measure and weigh loads completely during the reloading process, but it definitely helps with avoiding pressure problems and blowouts at the rear. I'll use the painted bullet method to help determine the proper seating level, as well as a chronometer for backup.

 

[BIG MO]

Yep, slower powders such as RL25, Retumbo, and H1000 with the 180 and up bullets, will probably solve your issues. Keep us posted.