Lone_Gunman
Member
I was looking at some once fired Lake City 5.56 brass, and the site recommended using a small base die. I am not familiar with what that is exactly.
What is a small base die?
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ReloaderFred
Member
It's simply a sizing die that is somewhat smaller in diameter at the opening. It's used to bring brass that's been fired in automatic firearms back to original diameter near the base of the cartridge. This is due to most machine guns have generously proportioned chambers to facilitate feeding all kinds of ammunition and to be able to still function when the gun gets really hot.
You'll see them recommended for lever action rifles and semi-automatic rifles, but I've never needed to use one for any of my many lever guns and semi-auto rifles.
Hope this helps.
Fred
You'll see them recommended for lever action rifles and semi-automatic rifles, but I've never needed to use one for any of my many lever guns and semi-auto rifles.
Hope this helps.
Fred
JA
Member
From the RCBS website,
The Small Base Die set is intended for use for ammunition to be used in auto, semi-auto, and lever action rifles so that the loaded round chambers and extracts easily. The Small Base Sizer Die sizes the case from the shoulder to the head of the case a couple of thousandths smaller than a Full Length Sizer Die. In certain calibers it also sets the shoulder of the case back a thousandth or two more than the Full Length Sizer Die. The Full Length Die Set or Neck Die Set is not normally recommended for ammo to be used in auto, semi-auto, or lever action rifles.
I have had to use small base dies reloading for 3 rifles.
A Browning BAR 7mm magnum,Remington 7400 30-06,and a AR-15 with a match chambered barrel. All the rifles wouldn't chamber ammo reloaded with full length sizing dies even though the ammo worked fine in bolt action rifles or AR-15 rifles with mil spec. chambers.
The Small Base Die set is intended for use for ammunition to be used in auto, semi-auto, and lever action rifles so that the loaded round chambers and extracts easily. The Small Base Sizer Die sizes the case from the shoulder to the head of the case a couple of thousandths smaller than a Full Length Sizer Die. In certain calibers it also sets the shoulder of the case back a thousandth or two more than the Full Length Sizer Die. The Full Length Die Set or Neck Die Set is not normally recommended for ammo to be used in auto, semi-auto, or lever action rifles.
I have had to use small base dies reloading for 3 rifles.
A Browning BAR 7mm magnum,Remington 7400 30-06,and a AR-15 with a match chambered barrel. All the rifles wouldn't chamber ammo reloaded with full length sizing dies even though the ammo worked fine in bolt action rifles or AR-15 rifles with mil spec. chambers.
Lone_Gunman
Member
Does using a small base die affect chamber pressure since it sizes the case smaller?
Do you use the same recipe (ie, grains of powder) that you would use for regular dies?
Do you use the same recipe (ie, grains of powder) that you would use for regular dies?
Peter M. Eick
Member
Simple question for you?
Do your reloads have any trouble chambering or do you know you have a tight chamber?
If so get a small base die. I needed one for my SuperMatch because periodically I would have the round chamber but the bolt would not close. I got in the habit of checking the op rod position before I pulled the trigger. If not seated I would reach up and wop the op rod to close it. Small base dies took the problem away and I have never looked back!
Do your reloads have any trouble chambering or do you know you have a tight chamber?
If so get a small base die. I needed one for my SuperMatch because periodically I would have the round chamber but the bolt would not close. I got in the habit of checking the op rod position before I pulled the trigger. If not seated I would reach up and wop the op rod to close it. Small base dies took the problem away and I have never looked back!
In my opinion, small base dies are just a way for die manufactuers to get rid of dies that are the result of using the reamer tool long. Most of the time, they are billed for use in semi auto rifles which as I understand it, generally have chambers on the large side of SAAMI in order to facilitate more reliable feeding.
I'm not saying there isn't an occational firearm that needs to size brass a little tighter, but not outside of the smaller end of SAAMI. I think that a die manufacturer would make good on a standard set if they didn't do a good enough job and you sent them evidence of it.
I'm not saying there isn't an occational firearm that needs to size brass a little tighter, but not outside of the smaller end of SAAMI. I think that a die manufacturer would make good on a standard set if they didn't do a good enough job and you sent them evidence of it.
JA
Member
Chamber size in a semiauto rifle is not really a issue it is the limited amount of force the recoil spring provides to chamber a round. Also there is not the camimng action or ability to apply more force if needed like with a bolt action rifle.
1) No. Regardless of starting point the brass will swell up to fill the chamber. Then cartridge thickness and chamber internal dimensions affect pressure.
2) Yes. Absolutely no change.
Folks who claim small base dies are a gimmick just do not have the gages. I have chamber gages, cut by the reamers that cut my rifle chambers. I will drop sized cases into these gages, and with certain combinations of rifle, standard sizing die, I can observe an interference fit when a case is not sized sufficiently.
I would use small base dies for everything, if I could find them. I use a Redding T-7 press, it has plenty of leverage to small base die 30-06, 308, and .223. I small base these calibers because of the multiple target rifles in these calibers. It increases ammunition interchangeability.
The amount of force it takes to small base a 308 or a 30-06 is considerably more than if using a regular die. I have found proper choice of lubes makes a big difference, Imperial Sizing wax, or RCBS water soluble really helps. The .223 round takes very little force to resize whether standard sizing die or small base.
Since I have target rifles barreled quite frequently, it is always interesting to talk to the gunsmiths who rebarrel lots of rifles. One of the most frequent customer problems they encounter is the problem of reloads. Reloads fired in one rifle, then standard base sized, do not necessarily fit into another. They frequently get calls about gas guns jamming, failure to close bolt, failure to extract. The problem is always brass previously fired in some huge chamber. That brass is then standard base sized by the customer, who then finds out he did not size the brass sufficiently to enter the new rifle.
Regardless of die, use a cartridge headspace gage to set up your dies. If you are sizing for a gas gun, size all cartridges to gage minimum.
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