25 PRC

[cbuck516]

Needing some help.

Finally was able to spin the barrel on and I'm having some headspace issues.

Would anyone have a 6.5 PRC go gauge to lend for me to verify headspace?

Also, if anyone would like to share what their base to datum measurement is to have as a reference, that would be great as well.

I was able to get a piece of necked down ADG brass to cycle but only after I trimmed off the neck and set the shoulder back a good amount.

I've bottomed out my Forster bushing die to bump the shoulder.

I believe it's a headspace issue.

Are you saying that you were unable to get an unloaded piece of brass to cycle? Not a dummy round or loaded round?
When you were able to get something to successfully chamber, what was your cartridge base to datum measurement? The one 25 PRC print I quickly found in a Google search showed datum measurement as 1.6486" minimum but doesn't show a maximum. This is very close to the value from the 6.5PRC saami print which is "1.6517 - .007". I am guessing you haven't fired the rifle yet where you could simply measure the formed brass?

I built a 25-06AI last year and myself thought I had a headspace problem, but it turned out I needed to turn the neck down a little bit as the brass thickness in the neck was too thick after going from 30 cal down to 25 cal. I was curious if you may possibly be experiencing something similar with the neck thickness of 0.016" that you previously mentioned. I guess it kind of depends on how the neck in your chamber is sized.
I also had the resizing die bottoming out, but I wasn't getting any bump at all so I ended up having to take 0.010" off the top of my shell holder to allow me to control shoulder bump. I set the headspace in my rifle with a GO and NOGO gauge though so I had a decent ammount of confidence that I should be in the realm of correct headspace.

 

[Far North Hunter]

My 25PRC required a neck thickness of .0138/.0140. The fired BTD on the fired rounds is 1.651.
if this helps.

 

[LiveToHunt7]

Could not get an unloaded piece of brass to chamber.

This was after necking it down using a .285 bushing.

My notes from the barrel says it has a .291 neck so I assumed my neck tolerance was fine.

The only piece of brass I was able to chamber was a piece of brass that I had taken the neck completely off and trimmed some of the base of the case. That base to datum measurement is 1.621".

One of the pieces of brass that I sized and necked down measures 1.637" and didn't chamber.

 

[cbuck516]

Could not get an unloaded piece of brass to chamber.

This was after necking it down using a .285 bushing.

My notes from the barrel says it has a .291 neck so I assumed my neck tolerance was fine.

The only piece of brass I was able to chamber was a piece of brass that I had taken the neck completely off and trimmed some of the base of the case. That base to datum measurement is 1.621".

One of the pieces of brass that I sized and necked down measures 1.637" and didn't chamber.

I still suspect neck thickness being a factor here based on what you said about needing to take the neck completely off, but I'm confused why you also are having to trim the base. What exactly do you mean by trimming the base? I can't say I have ever done that. Could you describe what exactly you did there?
Do you have any smaller bushings to see if adjusting neck diameter has any impact? Even something in the 6mm range would help isolate some variables here. If the neck is indeed too thick, it will only get worse after you seat a bullet in there. I learned the hard way.
If your brass that measures 1.637" CBTD still doesn't chamber after oversizing the neck to well below 0.291" (or just cutting the neck off, your call) then my guts says you probably do have a headspace issue.
Just out of curiosity, after using your 0.285" bushing what is the neck diameter?
Did you chamfer and debur the case mouth prior to checking chamber fit? Just spitballing here...

 

[LiveToHunt7]

I own a lathe and faced off the base of the brass .010". That's what I did when I say I trimmed the base.

When I get home, I'll verify the OD of the neck.

Yes, chamfered and deburred.

I'll be doing some tests when I get home and report back.

 

[wasskeet]

I own a lathe and faced off the base of the brass .010". That's what I did when I say I trimmed the base.

When I get home, I'll verify the OD of the neck.

Yes, chamfered and deburred.

I'll be doing some tests when I get home and report back.

If you took a piece of new brass, cut the neck completely off and cut .010" off the headstamp BEFORE it would chamber - I would say you definitely have a headspace issue. In my thinking, if the neck diameter was the issue it wouldn't even come close to chambering.

 

[LiveToHunt7]

Curious, anyone know where to rent a "Dave Manson – Live Pilot – 0.131″ Freebore – 0.291″ Neck" reamer?

 

[cbuck516]

If you took a piece of new brass, cut the neck completely off and cut .010" off the headstamp BEFORE it would chamber - I would say you definitely have a headspace issue. In my thinking, if the neck diameter was the issue it wouldn't even come close to chambering.

Right, it just helps to identify how many root causes might be stacked up by isolating them one by one.

 

[cbuck516]

Curious, anyone know where to rent a "Dave Manson – Live Pilot – 0.131″ Freebore – 0.291″ Neck" reamer?

If it were me I would try to more precisely identify exactly what the problem is before trying to rent specialty equipment to solve an unknown issue.

If your headspace is totally wrong a throat reamer won't help with that.

Did you trim 0.010" off the base of the case because the resizing die was bottoming out on the shell holder? If the answer is yes, then I think you need to take some material off the top of your shell holder. I literally had to do this myself a few days ago.

What is the CBTD on your unfired brass? Is it correct to assume that you have not tried to chamber a piece of unfired brass that only has the neck removed?

Also, is this a shoulder fit barrel or an adjustable shoulder, barrel-nut type barrel? Sorry for the 20 questions, just trying to help diagnose as I feel your pain.

 

[LiveToHunt7]

So to make sure it wasn't a neck issue, I took a piece of brass and removed the neck.

My CBTD was 1.641". The brass did not chamber.

 

[LiveToHunt7]

Well, for some closure, I went ahead and necked down a piece of brass.

I then went ahead and faced off the headstamp to 1.621" that did chamber.

 

[cbuck516]

Well, for some closure, I went ahead and necked down a piece of brass.

I then went ahead and faced off the headstamp to 1.621" that did chamber.

Where did this barrel come from and does it have a barrel nut? If no barrel nut, is it possible this was intended to be a short cut chamber so a smith could finish setting the headspace?

 

[LiveToHunt7]

No barrel but. A barrel manufacturer that does prefits. They already are going to take care of me and set the headspace correctly for me.

 

[LiveToHunt7]

Anyone have any data on the 110 ELDxs?

My COAL is 2.826 on a short action. Wondering if I should've went long action now. Bullet seating depth is pretty deep.