Small base for precision 308 gasser?
- Thread starter Winny94
- Start date
It depends on the size of the chamber. Do you have a .470” chamber or .475” or something in between. How much does your sizing die reduce the diameter of the case? What is the diameter of the case? It’s not all the same. You need .003-.005” clearance for reliable function. Gasser chambers get dirty fast and you also have to account for outside sources of dirt.
....if cost is a concern, just go SB/FL to avoid any potential chambering issues. It has "been" recommended over the years that for auto-loading platforms to use SB/FL, or at least FL sizing dies due the variations in manufacturing processes. Todays technology/tooling has mitigated some of that variance.
...if cost isn't a concern, go with what you feel.
...one consideration regardless if FL, SB or SB/FL is shoulder bump and how much control you will have over that if you are looking for "precision" oriented loading.
...if cost isn't a concern, go with what you feel.
...one consideration regardless if FL, SB or SB/FL is shoulder bump and how much control you will have over that if you are looking for "precision" oriented loading.
Large frame ars esp with no forward assist can be a pita if your die does not get down all the way. Also depends on how hot your loads are over the life of the brass....
If you want to guarantee the highest chance that your reload will chamber and go bang when your rifle is dirty I would use a SB die for gas gun reloads.
If you want to guarantee the highest chance that your reload will chamber and go bang when your rifle is dirty I would use a SB die for gas gun reloads.
I SB size all my L.C .308 cases for my M1A. I came across quite a stock pile of L.C .308 cases and in order to chamber them, I needed to SB size them. Works every time and shoots a minute, if I do my part. Why not SB size them for an auto loader? 
Unless the brass was previously fired out of a machine gun I haven’t seen the need. I use the Redding FL bushing die with the carbide expander ball and haven’t had any issues. My SCAR has a pretty tight chamber and fired brass comes out about .003” over saami min on my comparator so I just set it back .003”. Rounds will drop right in the chamber and run out is basically non existent.
RCBS small base dies are the tightest, at least .001” tighter than Redding SB. They will take your brass down to .467”
I will only use an SB Die if experiences with hard chambering and/or extraction has dictated such a need.
I also see no accuracy issues that demand an SB Die, only feeding/extraction issues.
I see it as a specific tool to resolve a specific problem, and pass it up unless that problem is undeniably present.
There can be drawbacks, such as hardening of the brass at the base when it's used unnecessarily. That can impair brass life. I prefer to only work the brass as much as is clearly necessary.
Greg
I also see no accuracy issues that demand an SB Die, only feeding/extraction issues.
I see it as a specific tool to resolve a specific problem, and pass it up unless that problem is undeniably present.
There can be drawbacks, such as hardening of the brass at the base when it's used unnecessarily. That can impair brass life. I prefer to only work the brass as much as is clearly necessary.
Greg
I have a small base die because it was needed to get ammo chambered in my 308 gasser. Its possible that the Lapua brass was oversized for the chamber but I doubt it.. I think it was a BHW barrel, not the best - but not the worst - could have been undersized. After running through SBD, it chambered fine. I've loaded for another 308 gasser where a SBD wasn't needed. I guess the answer is, it depends.
If the brass you shoot in this rifle is dedicated to this rifle only (from first firing) then you probably don't need a small base die.
If you load ammunition using brass fired in other rifles you might need to small base, depending on whether it feeds and functions properly.
A small-base die is just another tool. If you need one, get one. It'll size cases closer to virgin dimensions. I find it a rare fella who doesn't like shooting virgin factory ammo, but there's always someone in the group who prefers fire-formed from that chamber.
If you load ammunition using brass fired in other rifles you might need to small base, depending on whether it feeds and functions properly.
A small-base die is just another tool. If you need one, get one. It'll size cases closer to virgin dimensions. I find it a rare fella who doesn't like shooting virgin factory ammo, but there's always someone in the group who prefers fire-formed from that chamber.
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