Home Forums Reloading Big Game Rifles RCBS dies, very tight chambering

After close to 25 yrs using a RCBS Reloader Jr. press, I bought a new Rock Chucker. I am having a problem with some once fired 257 WBY brass, some will chamber very tight and some won't chamber at all. My older batch works fine, it's just these newer ones giving trouble. I had to reset my old sizing dies with the new Rock Chucker, just like the instructions say, shell holder touching dies and 1/8 to 1/4 turn in, slightly cams over center, with decapping pin 3/16" just enough to knock old primer out. I would appreciate any help. Thanks
31 bertram

Were all the once fired cases fired in your gun?

stubblejumper,I think the ones giving trouble were fired from my old 257.

That is actually quite common.It sounds like your old 257 had a sloppy chamber compared to your new 257.

Thanks stubblejumper, I had forgot about shooting those rounds in the older gun, I think that's where the problem is. This is a relatively new Mark V. Thanks again.

Just turn the die down a bit at a time, up to maybe another eighth or quarter turn more and size the cases down just a tad more until they chamber to your liking.

I had the same problem with my belgium browning 7mm rem mag when I had a new shilen barrel installed. even with my rcbs dies down tight my old brass would not go in to the new chamber and I thought I had a bad chamber job, as soon as I used new W-W brass the problem was solved. I still have 5 boxes of Browning 7mm rem mag brass in the fancy gold and black boxes sitting on my shelves ( this was 25 years ago) that I can not use. It was great Brass. As a side note it comes to me now after all these years there use to be a note from rcbs that some brass( norma and browning? ) took a # ( 26 or 28?) shell holder instead of the #4 and that is what I used for this brass so it must have been slightly different dimensions.

Gentlemen,

Once I had to take .010" off the bottom of a die to make it work. Been using it for a couple decades now.

I have been loading for a 264 WM I have been reading about all the problems from belted mags, the case expanding foward of the belt. What I understand is that standard full length dies do not resize the brass forward of the belt, often times not enough. There is a size die made just for resizeing the case forward of the belt. It is expensive about $90 I haven't bought one yet but sounds like it will solve all issues regarding expansion forward of the belt. I'll look up the link and post so you can be as confused as I am.


Inovative technoglies larrywillis.com

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That is a very common problem with brass shot out of different rifles. If you are bottomed out with your sizing die screwed down touching the shell holder, just grind a few thousands off the top of the shell holder. It is easy to do on the side of an electric grinder. Shell holders are cheaper than dies. Then turn the die down to size the brass a little more and push the shoulder back some. Do this in stages so you don't over work your brass. Not all chambers are created equal. Daryl.

You can find the Belted Magnum Collet Die at this link. However it is quite expensive, and it's probably cheaper just to buy new brass.

Belted Mag Die

Before modifying your dies or shellholder, Remove the expander ball assembly and size a case. Sometimes it is the expander ball moving the shoulder forward that is the cause.Rick.

I had the same problem with the 6.5x 47 Lapua.
I cut .010 off the top of the shell holder and adj the die to bump the shoulder back.
You can use the side of a grinding wheel,be sure to hold it tight.
Put the shellholder in a vise and use a flat file, be sure to cut it straight.
Easy to do on a flat wheel used to sharpen planner blades.

Coach

I have used old mechanics feeler gauges between the shell-holder and the case to bump the case up tight to the rim of the shell-holder. The nice thing about it is that you can find a blade thickness on most sets that will work just right based on the case rims thickness. I've picked up used sets of mechanics feeler gauges at garage sales, pawn shops etc. usually for a couple of bucks a set.
I ran into this again with a friends custom 280AI that had a very tight chamber and new Nosler 280AI brass that wouldn't chamber. I used the above method until he eventually had the chamber lengthened a few thousandths and this solution worked without surface grinding a shell-holder or having a die cut down at a machine shop or returned to the die maker.