The PRC die "problem"

Back when it first came out in 2008 I had clickers with the 338 RCM. Tried RCBS dies. Talked to the now retired Lonnie at Hornady about the issue. My reamer specs were exactly the same as their reamer specs. I got a Hornady die set. Still had issues. Sent in several fired cases to Whidden for their die set which didn't solve the issue either. With three die sets I figured I had nothing to lose. Took the RCBS FL die and chucked it up in my lathe cut off the top and bottom of the RCBS die with a carbide tool bit. then sanded and polished. It worked! Looks the same as phorwath's die.

Made another for the 300 RUM and solved its clicker issue too.

To date both short dies have not cracked but I am aware that they could. In a similar thread on Long Range Only the 6.5 PRC issue was discussed. There is a chance in using a short base sizer die that the case could separate just above where the die sizes. I have not encountered it but another poster did.

Agree that Alex's suggestion that the reamer specs should be larger. Either make the reamer larger. Or try to make a small base die which may not endure the pressure or sand the hell out of the rear portion of the chamber which is not precise.

Has me thinking....what if there was a way to correct an existing tight chamber base by precisely grinding off some metal in a lathe?
 
AZShooter said:
Back when it first came out in 2008 I had clickers with the 338 RCM. Tried RCBS dies. Talked to the now retired Lonnie at Hornady about the issue. My reamer specs were exactly the same as their reamer specs. I got a Hornady die set. Still had issues. Sent in several fired cases to Whidden for their die set which didn't solve the issue either. With three die sets I figured I had nothing to lose. Took the RCBS FL die and chucked it up in my lathe cut off the top and bottom of the RCBS die with a carbide tool bit. then sanded and polished. It worked! Looks the same as phorwath's die.

Made another for the 300 RUM and solved its clicker issue too.

To date both short dies have not cracked but I am aware that they could. In a similar thread on Long Range Only the 6.5 PRC issue was discussed. There is a chance in using a short base sizer die that the case could separate just above where the die sizes. I have not encountered it but another poster did.

Agree that Alex's suggestion that the reamer specs should be larger. Either make the reamer larger. Or try to make a small base die which may not endure the pressure or sand the hell out of the rear portion of the chamber which is not precise.

Has me thinking....what if there was a way to correct an existing tight chamber base by precisely grinding off some metal in a lathe?
Click to expand...
You will never convince a die maker to go smaller than a virgin case head on a sizing die, so that leaves us with .003" sizing on this case at the base, not going to work. What you have made is similar to what BR shooters call a ring die. There used to be one on the market with interchangeable rings so you could size the base differently. A very cool idea. If your process is working then no need to change. I do think that for most thats not going to be enough becaause if the case head grows a little which they do on top end loads your never going to get it to size enough. Picture the solid web expanding, it pulls the brass above it outward with it which is why it gets harder and harder to size that brass, and its why you cant fix brass once it gets to that point usually.
To fix an existing chamber all a smith has to do is polish out .002" in the back of the chamber in the lathe. Quick and accurate.
 
AZShooter said:
Back when it first came out in 2008 I had clickers with the 338 RCM. Tried RCBS dies. Talked to the now retired Lonnie at Hornady about the issue. My reamer specs were exactly the same as their reamer specs. I got a Hornady die set. Still had issues. Sent in several fired cases to Whidden for their die set which didn't solve the issue either. With three die sets I figured I had nothing to lose. Took the RCBS FL die and chucked it up in my lathe cut off the top and bottom of the RCBS die with a carbide tool bit. then sanded and polished. It worked! Looks the same as phorwath's die.

Made another for the 300 RUM and solved its clicker issue too.

To date both short dies have not cracked but I am aware that they could. In a similar thread on Long Range Only the 6.5 PRC issue was discussed. There is a chance in using a short base sizer die that the case could separate just above where the die sizes. I have not encountered it but another poster did.

Agree that Alex's suggestion that the reamer specs should be larger. Either make the reamer larger. Or try to make a small base die which may not endure the pressure or sand the hell out of the rear portion of the chamber which is not precise.

Has me thinking....what if there was a way to correct an existing tight chamber base by precisely grinding off some metal in a lathe?
Click to expand...
Good to know!!

Wonder if someone can make something similar to a throating reamer but just for the body of the case that will only go so far that uses the shoulder of the chamber as a stop at? Could this work? Make some sort of pilot to keep it squared to the bore. Wish I had axis to machining equipment!! I can do some damage!
 
If you spin the barrel in the lathe and hold emery cloth to polish the chamber or a new reamer it will remain concentric. If you turn a tool into a stationary chamber it may remain concentric or it may cut more on one side. The best bet is to do it in the lathe.
 
Alex Wheeler said:
If you spin the barrel in the lathe and hold emery cloth to polish the chamber or a new reamer it will remain concentric. If you turn a tool into a stationary chamber it may remain concentric or it may cut more on one side. The best bet is to do it in the lathe.
Click to expand...
Got ya. I need to call Clayton and see if he has ran into this issue or is aware of it and see if he can help me out or something.
 
Alex Wheeler said:
There are a number of people experiencing sizing issues with the PRC case. When designing a chamber, brass, and resize die there is no one size fits all. We want good hard case brass, but its harder to size. We dont want sloppy chambers either. I have experience with designing reamers with hard brass and in my opinion the PRC base diameter is just too small to work. The die specs are not the main problem. You cant make a die much smaller than the solid web without it cracking. And once a case head expands a little no die can fix the clickers that you will get.

Looking at the 300 PRC and ADG brass there is only .003-.0035" difference between a virgin case head and the chamber. Thats not enough for this type of brass in a magnum case head. And will lead to long term problems.

I already have reamers spec'd out for myself with other changes, but I have spec'd new ones and will post the prints here with the only change being to the base size. That in my opinion should have been the Saami spec to begin with. They should solve most all of your sizing issues. The dies still needs to measure .5295"-.530" at the base though. Many are polished out.
Click to expand...
Smart Move! I wish I was as well versed in reloading but I'm fairly new in the game.
Thanks you.
 
I am in process of getting ready to order either a 300 PRC - OR - a 30SM barrel ... Forgive me for a few stupid questions here as I am trying wrap my mind around this ...

1. What are 'clickers'?
2. @elkaholic - Does the 30SM have risk of this same issue or does the 30SM reamer already add a couple thou at the base to reduce/eliminate this issue?
3. Is this the sort of thing belts on 'traditional' magnum cases was intended to eliminate?

Thanks in advance ...
Tim
 
nkyshooter said:
I am in process of getting ready to order either a 300 PRC - OR - a 30SM barrel ... Forgive me for a few stupid questions here as I am trying wrap my mind around this ...

1. What are 'clickers'?
2. @elkaholic - Does the 30SM have risk of this same issue or does the 30SM reamer already add a couple thou at the base to reduce/eliminate this issue?
3. Is this the sort of thing belts on 'traditional' magnum cases was intended to eliminate?

Thanks in advance ...
Tim
Click to expand...
1.
3. No, belted mags can have the same problem. Usually worse do to the dies not sizing far enough down on belted cases.
 
Alex Wheeler said:
Yes, once a harder case expands its harder to size. 7 saum is a good example, ADG is small on the case head, so plenty of difference between the chamber and web but standard dies struggle to size it.
Click to expand...

Alex, thanks for this info. I'm having a 7 SAUM built now and have ADG brass to use in it. Do Redding FL Type S dies struggle to size the brass?
 

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