Some brass not bumping back

[KsKevin]

I've had rifles where I ended up measuring headspace using a different comparator die than the cartridge spec calls for as it gave the most consistent indication of chamber fit.

For example, a 280ai is headspace spec'd off the 0.375" datum line. Chambering all the new unfired brass before loading (ejector and firing pin removed) I sort all brass into chambers 'zero resitance', very slight resistance, slight resistance. I then measured all using both 0.375" and 0.400" comparators. What I've found is there were overlaps in headspace using 0.375" comparator as to how they chambered but when I looked at 0.400" comparator measurements it was much more consistent as to predicting which ones chambered easily vs slight resistance. Redid same exercise with the once fired brass and again found same outcome.

If the ones that you have with a bit longer headspace are chambering ok, perhaps try measuring all with a different comparator to see if they are more consistent and better predicts chamber fit.

 

[Rflshootr]

Hornady comparator and mititoyo calipers

I've tried it both ways, no change

i don't like cases that have resistance for hunting, and these do that, so I wanted to bump them.

Is all the brass from the same lot #?
Again, the shoulders aren't fully formed after 1 firing.
Shoot them again.

 

[bultinkle]

Is all the brass from the same lot?

Yes

 

[Csbc4fun]

My next purchase is a trimmer that makes me feel the same way I hope!

Henderson trimmer feels like cheating too!

 

[Pdvdh]

Are you absolutely positive it's the shoulder causing a tight chamber on those 6 pieces?
Did you measure all aspects of your brass prior to sizing and after sizing to see how well your die matches your chamber?

My bet is on the base of those 6 being a tight fit in the chamber and not the shoulder at all.

I ended up switching dies on a 300 WSM but before that I colored the case with a sharpie to find the problem spot. To verify I sanded just above the 0.2ish size line and suddenly they chambered without issue.
My father in law had a similar chambering issue but his was just below the shoulder.

This is a second real possibility.

The first step to solving the problem is determining where the cases interfere with the chamber.

It will typically be 1) the shoulder due to insufficient shoulder setback by the resizing die, or 2) case web diameter interference due to case web expansion ~0.2" - 0.3" forward of the case head, due to a resizing die that's too large in diameter. A chamber that's too large in diameter could also create the case web interference. But that's less likely.

We already identified the cure for cause #1, shoulder interference.

The cheapest cure for cause #2, case web area interference, will normally be a different resizing die with a smaller base diameter.

Firstly, confirm the location of interference, if you haven't already done so. I've used a black felt pen in the past. Close and open the bolt a few times and then examine the case for the interference location / removal of the black coating.

 

[2buffalo]

Press flex. Reinforce it and I would bet it bumps it back. I have had this issue before.

 

[victor3ranger]

Redding Competition Shellholders decrease the amount the shoulder is set back not increase it. This means they will make the situation worse not better.

Well crap
I guess the only thing I can do then is shave the top of a normal shell holder down a few thousands

 

[joelpend]

seems odd to me to need anneal that bad on once fired stuff

I'll set the aside and see about an annealeeze in the future

My experience with new Lapua is it is not fully annealed as one would think. Apparently they do some forming after the last anneal because it sure needs annealing before loading the first time. If you are loading for Precision then must anneal. Fortunately today there are inexpensive options for flame annealing. I love my AMP but they are not cheap. I lived for years torch annealing with a homemade setup.

 

[victor3ranger]

This is a second real possibility.

The first step to solving the problem is determining where the cases interfere with the chamber.

It will typically be 1) the shoulder due to insufficient shoulder setback by the resizing die, or 2) case web diameter interference due to case web expansion ~0.2" - 0.3" forward of the case head, due to a resizing die that's too large in diameter. A chamber that's too large in diameter could also create the case web interference. But that's less likely.

We already identified the cure for cause #1, shoulder interference.

The cheapest cure for cause #2, case web area interference, will normally be a different resizing die with a smaller base diameter.

Firstly, confirm the location of interference, if you haven't already done so. I've used a black felt pen in the past. Close and open the bolt a few times and then examine the case for the interference location / removal of the black coating.

Ding ding ding, we might have a winner here.
I know that when I process 556 brass that has been shot out of a SAW I have to use a regular 223 die first and after I will run it through my small base die.
I have to do the same thing with 308 brass that has been fired through a 240

 

[Rflshootr]

...

 

[pdog shooter]

Wow, lot of attention in a hurry.
anneal

Dead set to build inductance annealing apparatus.

Believe I have the necessary components (not all pictured). Have 2 power supplys 12 – 24VDC for a total of 960 watts. Some 50 amp relays. A pretty neat timer switch. ZVS board I believe is very capable. I can heat a medium screw driver cherry red in about 3.5 seconds. But thats ferrous metal...

www.longrangehunting.com

 

[emp1953]

are you using an RCBS press?
Just for fun, on the cases that are chambering with resistance, clean them thoroughly on the outside with alcohol or acetone, Cover the entire case with a black Sharpie and let it dry. Then chamber it, Lets see where the case is contacting the chamber.
Here are some things that I ran into. I use an RCBS single-stage press. I've had it since 1969. The bushing through which the ram runs had slightly worn. I couldn't detect any wear but it was evident after I used a friend's runout gauge. The cases themselves were no longer straight when they came out of the sizer. Straight going into the sizer, off-center coming out. I contacted RCBS and they had me ship the press back and they refurbished it. Now none of the sized cases fail my runout test.
Another issue arose with shell holders. Most rifle cases that I reload use the same shell holder, the bases are all the same dimension. The shell holder gets a lot of use. Gunk builds up in the groove where the shell base is captured, not allowing the case to center on top of the ram, thus the misalignment caused cases that failed runout. Again cases went in straight and came out off-center. I reloaded some pistol ammo and in the process lost my original rifle shell holder, so I ordered a set of Lee shell holders. Turns out they are not quite the same animal. Where the RCBS shell holder fits snugly in the slot at the top of the ram, the Lee holders had some up-and-down play. Not much but apparently enough. The die adjusted to touch the shell holder did not bump the shoulder far enough. I bought 3 of my favorite shell holders from RCBS and my shoulder bump issues went away. All rounds now fall into the chamber without any additional pressure.

 

[victor3ranger]

are you using an RCBS press?
Just for fun, on the cases that are chambering with resistance, clean them thoroughly on the outside with alcohol or acetone, Cover the entire case with a black Sharpie and let it dry. Then chamber it, Lets see where the case is contacting the chamber.
Here are some things that I ran into. I use an RCBS single-stage press. I've had it since 1969. The bushing through which the ram runs had slightly worn. I couldn't detect any wear but it was evident after I used a friend's runout gauge. The cases themselves were no longer straight when they came out of the sizer. Straight going into the sizer, off-center coming out. I contacted RCBS and they had me ship the press back and they refurbished it. Now none of the sized cases fail my runout test.
Another issue arose with shell holders. Most rifle cases that I reload use the same shell holder, the bases are all the same dimension. The shell holder gets a lot of use. Gunk builds up in the groove where the shell base is captured, not allowing the case to center on top of the ram, thus the misalignment caused cases that failed runout. Again cases went in straight and came out off-center. I reloaded some pistol ammo and in the process lost my original rifle shell holder, so I ordered a set of Lee shell holders. Turns out they are not quite the same animal. Where the RCBS shell holder fits snugly in the slot at the top of the ram, the Lee holders had some up-and-down play. Not much but apparently enough. The die adjusted to touch the shell holder did not bump the shoulder far enough. I bought 3 of my favorite shell holders from RCBS and my shoulder bump issues went away. All rounds now fall into the chamber without any additional pressure.

I am really glad you brought up point number 2.
I need to take a good look at my presses for wear

 

[Rich Coyle]

When I've experienced no further shoulder setback in spite of turning the die further in the press, the base of the resizing die was bottoming out on the shell holder.
I had to remove some material off the bottom of the resizing die. Or shave some material off the top of the shell holder.

Once the base of the die contacts the top face of the shell holder, you won't get any further shoulder setback when screwing the die down further in the press.

Otherwise, the shoulder should be set back further, by lowering the die in the press. No brass case shoulder is tough enough to not shove back, when rammed up into a hardened steel resizing die.

I did that with a couple of dies. It definitely solved the problem.