300RUM reloading experts needed

[Augustus]

Gentlemen, I have just finished wrestling with the same symtoms with my 338/408. Even with very mild loads the cases get progressively tighter with each firing. I FL sized between each firing, the shoulder was bumped and was not the problen. As it turned out my chamber is just a smidge tighter than my FL die just above the case head. Part of the case is not being resized at all and is simply getting tighter with each firing. This seems to be a fairly rare occurance, I have never seen this happen before. I did a little research and the cases with the least amount of taper are more inclined to have the affliction. I have a 375/408 die that cures the problem but accuracy goes to pot. This may or may not be the cause in jons case but it certianly could be. Changing factory dies probably wont help because it is probable the chamber is a little tight. I pulled my barrel and polished the chamber which helped somewhat. I am trying to decide to polish more or try to get a set of dies that will work.

[Eaglet]

Gents,

I have two 300 RUM Remington Factory Rifles. I am getting close to using

up about 12 lbs of Retumbo of about 3 or four different Lot Numbers. I have

Nothing but a lot of respect and good things to say about Hodgdon Retumbo

Powder. In the Cold and in Hot temps; on my first load or my fifth load...

The problem that's taking place here is very interesting but I don't see the

Retumbo Powder having anything to do with it. Bullets? They change in diame-

ter as well as in hardness and that easily could change the amount of the

charge. That's just normal. Your solution, IMHO, is something else. Check your

powder measuring scales and make sure that not air drafts are moving through the room

while reloading.

[Varmint Hunter]

Originally Posted by Augustus

Gentlemen, I have just finished wrestling with the same symtoms with my 338/408. Even with very mild loads the cases get progressively tighter with each firing. I FL sized between each firing, the shoulder was bumped and was not the problen. As it turned out my chamber is just a smidge tighter than my FL die just above the case head. Part of the case is not being resized at all and is simply getting tighter with each firing. This seems to be a fairly rare occurance, I have never seen this happen before. I did a little research and the cases with the least amount of taper are more inclined to have the affliction. I have a 375/408 die that cures the problem but accuracy goes to pot. This may or may not be the cause in jons case but it certianly could be. Changing factory dies probably wont help because it is probable the chamber is a little tight. I pulled my barrel and polished the chamber which helped somewhat. I am trying to decide to polish more or try to get a set of dies that will work.

Augustus - you may be on to something. I emailed a copy of my reamer specs to Redding and then called them. They suspected that the chamber was a bit too tight for their standard dies and offered to make a set of custom dies from a few fired cases. The price was very high. They also suggested that I may want to polish out the chamber a bit. However, my smith along with one of the board regular smiths highly recommended against doing this because you "run the risk of ruining a precision cut chamber". Rechambering to a standard (non-minimum spec) chamber was suggested by one of them.

I opted to try the Forester FL die which appeared to be a bit tighter but to no avail.

I'm taking the rifle to North Carolina in 10 days for some deer hunting. For now, I just loaded up some new brass with my accuracy load and will work on this problem when I get back. The new brass always extracts smoothly. Hmmmmmmm????

[tjonh2001]

guys i have changed powder and i have even used a different scale. i am thinking that i might have a tighter chamber and the dies arent resizeing them all the way i have tried redding and rcbs dies. the one thing is that we did polish the chamber one more time and it has made it better but not fix the problem and i am worried that if we polish more might oval the chamber and that would be a shame.

[Augustus]

VH, same thing here I fireform and the extraction is smooth until the third firing which is becoming tight. By the fifth the bolt lift is sill OK but I cant pull the bolt back w/o pecking on it with something.

[J E Custom]

Originally Posted by Varmint Hunter

Augustus - you may be on to something. I emailed a copy of my reamer specs to Redding and then called them. They suspected that the chamber was a bit too tight for their standard dies and offered to make a set of custom dies from a few fired cases. The price was very high. They also suggested that I may want to polish out the chamber a bit. However, my smith along with one of the board regular smiths highly recommended against doing this because you "run the risk of ruining a precision cut chamber". Rechambering to a standard (non-minimum spec) chamber was suggested by one of them.

I opted to try the Forester FL die which appeared to be a bit tighter but to no avail.

I'm taking the rifle to North Carolina in 10 days for some deer hunting. For now, I just loaded up some new brass with my accuracy load and will work on this problem when I get back. The new brass always extracts smoothly. Hmmmmmmm????

I would vote for the rechambering Instead of polishing because polishing is not exact and you
run the risk of ruining the chamber.

This is a very good post for all to learn and it will be interesting to find out exactly what the problem is.

I believe in treating the problem not the symptoms and the chamber sounds like the problem
at this time.

J E CUSTOM

[Dano1]

Guys,

I just had a thought run though my head while reading this thread. Another possible problem may be powder residue buildup in the case, decreasing the case volume and there by increasing the pressures with the same powder charge.

Not saying that this is the problem, just a thought that hadn't been brought up. Retumbo is a fairly clean burning powder, but all powders will leave a buildup in the case over time. With 3 fireings is not likely, but maybe so....

I've actually seen this in .30-06 Cases and .270 cases using IMR or Reloader powders.

Without seeing the brass and mic-ing the cases, it's hard to see what the problem could be. I am seeing a little of this, with my friends .300RUM that I load for, but not nearly to this extent.

Just a thought?

Dan