This is great info! I just have one question..."what is a small base die"? I have not heard of these before. Are they specific to a specific cartridge? Why is it that a full length die won't do what its namesake implies?
can't close bolt on round
- Thread starter Pinard
- Start date
A small base die is approximately .001 smaller in diameter at the base of the die and returns the case to minimum SAAMI dimensions.
I use the RCBS die set below when sizing the once fired Lake City 5.56 brass I buy.
https://www.midsouthshooterssupply.com/articles/rcbs_ar_dies.aspx
Just remember we live in a plus and minus manufacturing world and dies and chambers can and do vary in size
Example I have a "standard" Lee .223 full length die that sizes the base of the case more than my RCBS small base die does.
Also Federal brass is softer in the base and is noted for loose primer pockets after very few firings.
Meaning the base of the case can expand more when fired and cause problems like described.
Thanks for that.
There are two interesting things stated at that link. One is:
"Semi Auto, pump and lever action rifles tend to have tighter chambers than bolt action rifles, thus requiring the tighter small base sizer."
The other is:
"Most times a Full Length sizer would have done the job if the sizing die was set properly in the press to cam over. For some reason, handloaders back the sizing die up after contacting the shell holder, when they should be going a ¼ turn further down."
This seems to imply that if folks use their FL sizing dies properly, there would be no (or little) need for a small base die...not withstanding that your LEE die sizes smaller than your RCBS die.
- Location
- Victoria, BC (temporarily Toronto)
I have run into an issue and for me this was the problem. I wasn't sizing down enough on the sizing die. I seated the die a bit deeper in the press so the handle would cam over just a bit on the bottom press and sure enough, problem was cured.
Make sure you are screwing your die so that the handle is coming down then doing a little bit of a cam over at the bottom.
"Most times a Full Length sizer would have done the job if the sizing die was set properly in the press to cam over. For some reason, handloaders back the sizing die up after contacting the shell holder, when they should be going a ¼ turn further down."
This seems to imply that if folks use their FL sizing dies properly, there would be no (or little) need for a small base die...not withstanding that your LEE die sizes smaller than your RCBS die.
In most circumstances a standard Full Length die that is adjusted properly is all that is needed with brass fired in "your" rifle.
"BUT" brass spring back after sizing, the chamber diameter and die diameter can force you to use a small base die.
Read the link below, and look at the charts and you will see dies that vary over .004 in neck diameter.
Are Your Sizing Dies Overworking Your Rifle Brass?
http://www.massreloading.com/dies_overworking_brass.html
So again chambers and resizing dies vary in diameter and sometimes small base dies "are" needed.
Example, range pickup brass and buying once fired brass, and brass that is softer in the base.
How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests. (NOTE, Federal brass is softer than the brands listed below)
http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/
Pinard. Once you figure out your problem and you probably have already. Mark all your reformed/reloaded brass with a sharpie. After shooting these loads change over to a neck size die. Your brass after the first reloading and shooting will be fireformed to your chamber. You shouldn't need to full size your brass. The brass will fit exactly to your chamber. You just need to case trim for length. One reason you full size brass is to bring brass back to factory specs to fit ANY rifle with tolerance. If your reloading specifically for that rifle,try a neck size die. You get better accuracy,faster reloading,less work hardening of brass,brass lasts longer. Give it a try. Neck size die is inexpensive.
