I see that Small Base sizing dies are available for 308 Win, but I was wondering what they do that a full length die doesn't? Does anyone have any dimension diagrams to show the difference between them? I'm considering picking up some bulk 308, but they come with the disclaimer that they may need to be small base sized.
When is Full Length sizing not enough?
- Thread starter Marksman
- Start date
The small based sizing die typically will give you an additional .001 of sizing over a standard sizing die.
diagrams above are good to know, but you need to know what your chamber requires etc.
hunting with a semi auto and reloads is a good a reason to use a small base die
building a AR-10 with various components includes "tolerance stacking" and may benefit from a SB die
A lot of guys want a "snug" fit between their case and chamber even in their ARs, others not so much
But...that may be a disclaimer for the brass as they have no idea of what it will be used in
I have never needed a SB die but they make them for a reason, if a std. die doesn't do it then the Small base is the next option.
hope this helps
Larry W
hunting with a semi auto and reloads is a good a reason to use a small base die
building a AR-10 with various components includes "tolerance stacking" and may benefit from a SB die
A lot of guys want a "snug" fit between their case and chamber even in their ARs, others not so much
But...that may be a disclaimer for the brass as they have no idea of what it will be used in
I have never needed a SB die but they make them for a reason, if a std. die doesn't do it then the Small base is the next option.
hope this helps
Larry W
I never needed a Small Base die until I started reloading for a .308 AR. That rifle HAS to have that or it won’t chamber. Other semis I’ve had don’t seem to need it. Other folks have reported the same. So they have tighter chambers for whatever reason.
I’m giving some thought to using a pull through reamer and opening it up a thou or so on that rifle as it’s right at the bottom end of the headspace dimension. Or alternatively, I might even just ream it out to 7.62x51 NATO dimensions. The headspace dimensions are a bit longer on that, and really it’s probably more appropriate for this rifle anyway. Because for what it is(one of the retro AR10 builds from the parts Brownells had) it doesn’t need to be that tight.
I came up with an M80 equipment load for my 7.62 NATO military rifles(though I don’t have as many as I used to regrettably), basically to take the place of the surplus ammo I shot before it got outrageous in price. I find that a lot of the military brass I’m using, won’t just go into the SB die without problems. So I have to size in a regular full length die first. So I basically had to add another step in my reloading process just for that rifle, which I’m not exactly ecstatic about. But, I really like how it looks and handles, so I don’t want to get rid of it. So we’ll see.
I’m giving some thought to using a pull through reamer and opening it up a thou or so on that rifle as it’s right at the bottom end of the headspace dimension. Or alternatively, I might even just ream it out to 7.62x51 NATO dimensions. The headspace dimensions are a bit longer on that, and really it’s probably more appropriate for this rifle anyway. Because for what it is(one of the retro AR10 builds from the parts Brownells had) it doesn’t need to be that tight.
I came up with an M80 equipment load for my 7.62 NATO military rifles(though I don’t have as many as I used to regrettably), basically to take the place of the surplus ammo I shot before it got outrageous in price. I find that a lot of the military brass I’m using, won’t just go into the SB die without problems. So I have to size in a regular full length die first. So I basically had to add another step in my reloading process just for that rifle, which I’m not exactly ecstatic about. But, I really like how it looks and handles, so I don’t want to get rid of it. So we’ll see.
This is a picture of a ring die that we make and sell and a 30BR case with 50 firings on it. The die is a straight wall die that sizes the base only and can be made to fit your chamber. You can see where the die has been working the case. The problem with an FL die is that you can only size so much and then you start moving the shoulder back and introducing a new set of problems.
Attachments
The other issue is source of brass... 800# Gorilla is use of Range Brass / Bulk Brass. AR's are notorious for wide range of challenges (chamber dimension issues and lockup/release timing) that can cause problems for brass. There is also the potential issue with military brass (5.56 and 308) that gets fired full auto and belt fed. The end result is range brass has some known unknowns.
My caveman understanding is that metal has memory and to offset/remove the "expanded" metal memory from the case, you have to resize it (undersize it sufficiently) so that the "metal memory" is offset. As a result a SB Die may be only a temporarily fix for this issue. After firing, the case may still bounce back to the oversized dimensions. There have been some in-depth, technical threads on this topic that are worth viewing.
I only FL Size. If a case requires SB Die to fit then its a gamble that it will continue to be an ongoing issue. I toss that case in the recycle can. Brass is cheap compared to risk of a gun getting jammed.
My caveman understanding is that metal has memory and to offset/remove the "expanded" metal memory from the case, you have to resize it (undersize it sufficiently) so that the "metal memory" is offset. As a result a SB Die may be only a temporarily fix for this issue. After firing, the case may still bounce back to the oversized dimensions. There have been some in-depth, technical threads on this topic that are worth viewing.
I only FL Size. If a case requires SB Die to fit then its a gamble that it will continue to be an ongoing issue. I toss that case in the recycle can. Brass is cheap compared to risk of a gun getting jammed.
This is because some of the cases were likely fired in chambers larger than yours, and brass likes to go where it's been (what it has yielded to). It's not like you can anneal near webs back to baseline, and extreme downsizing is just going to break more grain structure, setting you up for cracking/failures.
Counter-sizing does not ever get you back to baseline brass character.
So Sandstorm is right. Use only new or properly functioning brass.
jackieschmidt
Gold $$ Contributor
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I got run through the wringer back in the late 90s when two friends of mine took turns owning an Accuracy International rifle in .308 Win. They discovered, as most have, that Federal Gold Medal Match performed the best including their hand loaded ammunition. So, seeing that they could just buy ammunition instead of developing new loads, they bought a bunch of the FGMM for competition.
No longer interested in reloading for this rifle, they kindly contributed that brass to my reloading career. Proceeding to resizing before loading, I promptly stuck both the first and second case in different sets of dies, learning much from these failures. I measured the once fired brass...
Significantly larger in the area above the head and soft, made this brass nearly useless for my or any other consumption. The chamber in their AI was significantly oversize and slightly ovoid. I let them know as carefully as I knew how that chamber was bad. We measured brass both new FGMM as well as the once fired brass from previous sessions. I cast the chamber. I suggested sending it back to AI requesting a new barrel. You'd thought I had suggested shooting their dogs!
No matter how awful this chamber was, the rifle was shooting and winning with spectacular regularity. Groups were tiny to say the least. The thought of replacing this barrel and taking the chance against lower performance was unthinkable! They chose to continue shooting it using new ammunition every time until they burned out the barrel.
Resizing the soft Federal brass was fruitless. I spent too much time trying to remove stuck cases from any of the commercial dies. No resizing was possible. I sent samples to both Federal and AI to inform them of these failures. Federal could have cared less, telling me what I already knew, the chamber was at fault. AI on the other hand, offered to pay to ship the rifle back to their US facility, rebarrel and pay to return the rifle. My friends vetoed that idea so I wrote to AI thanking them for their kind offer.
AR chambers are usually slightly oversize providing a little 'slop' to aid in chambering a cartridge. Resizing dies will usually handle the slight oversize of the brass. But sometimes you will find a need for SB sizing dies. Yes, there will always be those who claim to be the exception but in general, the SB can be very helpful.
Enjoy the process!
No longer interested in reloading for this rifle, they kindly contributed that brass to my reloading career. Proceeding to resizing before loading, I promptly stuck both the first and second case in different sets of dies, learning much from these failures. I measured the once fired brass...
Significantly larger in the area above the head and soft, made this brass nearly useless for my or any other consumption. The chamber in their AI was significantly oversize and slightly ovoid. I let them know as carefully as I knew how that chamber was bad. We measured brass both new FGMM as well as the once fired brass from previous sessions. I cast the chamber. I suggested sending it back to AI requesting a new barrel. You'd thought I had suggested shooting their dogs!
No matter how awful this chamber was, the rifle was shooting and winning with spectacular regularity. Groups were tiny to say the least. The thought of replacing this barrel and taking the chance against lower performance was unthinkable! They chose to continue shooting it using new ammunition every time until they burned out the barrel.
Resizing the soft Federal brass was fruitless. I spent too much time trying to remove stuck cases from any of the commercial dies. No resizing was possible. I sent samples to both Federal and AI to inform them of these failures. Federal could have cared less, telling me what I already knew, the chamber was at fault. AI on the other hand, offered to pay to ship the rifle back to their US facility, rebarrel and pay to return the rifle. My friends vetoed that idea so I wrote to AI thanking them for their kind offer.
AR chambers are usually slightly oversize providing a little 'slop' to aid in chambering a cartridge. Resizing dies will usually handle the slight oversize of the brass. But sometimes you will find a need for SB sizing dies. Yes, there will always be those who claim to be the exception but in general, the SB can be very helpful.
Enjoy the process!
When i first tried to reload in the late 70s, I never got any of my reloads to function very well in my Remington 742. I at that time didn't know a small base die existed. But that rifle wouldn't work reliably with factory federal ammo either. When i started loading again in the late 90s or 2000s, My mentor helped me with a DPMS varminter and he insisted on a small base die, and it works. Whether you buy bulk or buy new match brass try a few and see how it goes and if you need a small base die you will know soon enough. Many use a small base die with anything that is semi auto and i am not sure it is necessary.
I would never bother with brass fired in someone else's chamber.
But I could see potential in use of a ring die like Uthink pictured (for bolt actions).
I might use it once after a few fire formings, and once again after 3-4 more reload cycles, and never again.
Just to reasonably work harden the webs. That's all.
But I could see potential in use of a ring die like Uthink pictured (for bolt actions).
I might use it once after a few fire formings, and once again after 3-4 more reload cycles, and never again.
Just to reasonably work harden the webs. That's all.
I appreciate your perspective and for 99% of the time it holds water and works just fine. It that 1% or less of a chance that seems to always happens at the wrong time and ruins the fun.
There are enough threads and research that the only effective/repeatable annealing that re-aligns the metal alloy is with an induction anealer. For most of us annealing is performed utilizing a propane torch, and ultimately is just softening the brass to make it easier to resize and a bit more consistent with neck tension. However, if it is brass that has expanded beyond the point of its metal memory (we'll stick with caveman terminology) then this new dimension is it new steady state for this case. Regardless of resizing with a SBD, the case will always attempt to return to this dimension after firing. Typically, when you fire a rifle the case expands to match the chamber and then shrinks slightly before it gets extracted. It you have a case that has a steady state that is oversized then after firing it may not shrink adequately to release it from the chamber wall.
So...if you pick up a piece of range brass that required a SBD, there is a possibility that you will always need to use the SBD when resizing it. Not the worst thing, but if you have a tight chamber and that case is fighting to return to an oversized dimension it can create some unnecessary friction/binding. Aside from the safety concerns, having to "mortar" an AR15 to remove a stuck case is not terrible. However, having to hammer the bolt handle on a precision bolt rifle is altogether different.
I don't use range brass for my precision guns, but have been known to use it as donor brass when forming a wildcat cartridge. Range brass is abundant and cheap. I toss anything that I don't like without giving it a second thought.
butchlambert
Site $$ Sponsor
Hey fellers, you can buy a full length die off of EBay for little of nothing. Take the decapping pin out and drill through with a 29/64 drill, now cut about .050" off the base. You now have a small ring full length die. You will have to adjust it a little at a time to achieve your desired results.
wildcat3d
Silver $$ Contributor
Who is.... "we" Thank you as I don't know who you are referring to.
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