Small Base vs Standard Die
- Thread starter C.E.Smith043
- Start date
Yep, and to baffle it even more...if a shoulder cannot be "bumped" at all why does one need so many of these devices????
GSPV
A failure to plan is a plan for failure.
Look. *In the normal case*, you can have two resize issues: bolt lift and bolt click.
Tight bolt at the bottom is related to shoulder bump.
Bolt click at the top is related to sizing the base of the case.
The two sometimes conflict. I.e., you can’t get both of them like you want them at the same die setting.
That’s why custom dies and such exist.
YMMV.
Tight bolt at the bottom is related to shoulder bump.
Bolt click at the top is related to sizing the base of the case.
The two sometimes conflict. I.e., you can’t get both of them like you want them at the same die setting.
That’s why custom dies and such exist.
YMMV.
NV_Dmax
Gold $$ Contributor
I have bad bolt click with my BRX and I can't size enough with the Whidden die I have. I have a sizing die on order with Neil Jones. He says it'll probably be around the first of the year before he can even think about getting to it. So in the mean time I will use a small base 308 die to eliminate the click.
I used a standard RCBS full length die for my Remington 760 pump and also never had a problem. And Barlow raises a good point about chamber diameter and even a standard die might be a "small base die". Meaning how much the die reduces the case diameter.
I had someone I hunted with that also had a Remington 760 pump, "BUT" someone told him he needed a small base die for reloading it and he was having case head separations. This was in the early 1970s and both of us were following the RCBS dies instructions. Meaning with the die making hard contact with the shell holder. And I never had a case head seperation in my 760 pump. I'm not sure if it was the amount of shoulder bump or the dies diameter that caused my hunting friends case head separations.
So again chambers and dies vary in size, and all you need to do is measure a fired case and a resized case. To know if you are reducing the case diameter enough for the type rifle you have.
Example below for the .223 and 5.56 AR15 chambers, the base diameter of the AR15 chamber is .002 larger. And in a semi-auto the resized case should be .003 to .005 smaller diameter than its fired diameter. This allows the case to spring back from the chamber walls and extract reliably. Meaning in a bolt action rifle with a smaller diameter chamber the case has more time to cool and spring back from the chamber walls. (as long as your not the Flash or Superman and faster than a speeding bullet)
NOTE, no magic feeler gauges or shell holder were used in the making of the posting.
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The small base die didn't cause the case head seperation. Bumping the shoulder too much did. Thats not what a small base die is for. MattI used a standard RCBS full length die for my Remington 760 pump and also never had a problem. And Barlow raises a good point about chamber diameter and even a standard die might be a "small base die". Meaning how much the die reduces the case diameter.
I had someone I hunted with that also had a Remington 760 pump, "BUT" someone told him he needed a small base die for reloading it and he was having case head separations. This was in the early 1970s and both of us were following the RCBS dies instructions. Meaning with the die making hard contact with the shell holder. And I never had a case head seperation in my 760 pump. I'm not sure if it was the amount of shoulder bump or the dies diameter that caused my hunting friends case head separations.
So again chambers and dies vary in size, and all you need to do is measure a fired case and a resized case. To know if you are reducing the case diameter enough for the type rifle you have.
Example below for the .223 and 5.56 AR15 chambers, the base diameter of the AR15 chamber is .002 larger. And in a semi-auto the resized case should be .003 to .005 smaller diameter than its fired diameter. This allows the case to spring back from the chamber walls and extract reliably. Meaning in a bolt action rifle with a smaller diameter chamber the case has more time to cool and spring back from the chamber walls. (as long as your not the Flash or Superman and faster than a speeding bullet)
NOTE, no magic feeler gauges or shell holder were used in the making of the posting.
GSPV
A failure to plan is a plan for failure.
As I posted earlier in the thread, it’s all about how your chamber and your sizing die match.
Sometimes you can’t get enough bump and can shave the bottom of the die or the top of the shell holder.
Sometimes you have the bump right but have bolt click. When that happens, you have two choices, get a smaller die, or open up the rear of the chamber. Both work. When you choose to go the smaller die route, you can get a custom die, shop around for a regular die hoping one will fit a bit tighter, or you can get a small base die that at least advertises that it’ll size the base more.
All this is why I like custom dies.
Sometimes you can’t get enough bump and can shave the bottom of the die or the top of the shell holder.
Sometimes you have the bump right but have bolt click. When that happens, you have two choices, get a smaller die, or open up the rear of the chamber. Both work. When you choose to go the smaller die route, you can get a custom die, shop around for a regular die hoping one will fit a bit tighter, or you can get a small base die that at least advertises that it’ll size the base more.
All this is why I like custom dies.
A skinny case fired in a fat chamber has to stretch to outward contact the chamber walls and stretch to meet the bolt face. Meaning the case can stretch in two directions at once. And the 760 pump has a larger diameter chamber just like a semi-auto than most bolt actions have.
And if you use a small base die on the HXP case below it will cause a case head separation even with the correct amount of shoulder bump. And both cases below were fired in the same chamber.
The factory loaded case below stretched and thinned .009 on the first firing and the rifle was below the SAAMI NO-GO gauge. But the military chamber it was fired in was very large in diameter. So never say never, it is chamber size vs die size.
That Greek case doesn't come in a 760 or any other Remington. I have had lots of 760's and the chambers were like the 700. That thinning of .009 didn't cause the separation on the 760. Bumping too much there after did. MattA skinny case fired in a fat chamber has to stretch to outward contact the chamber walls and stretch to meet the bolt face. Meaning the case can stretch in two directions at once. And the 760 pump has a larger diameter chamber just like a semi-auto than most bolt actions have.
And if you use a small base die on the HXP case below it will cause a case head separation even with the correct amount of shoulder bump. And both cases below were fired in the same chamber.
The factory loaded case below stretched and thinned .009 on the first firing and the rifle was below the SAAMI NO-GO gauge. But the military chamber it was fired in was very large in diameter. So never say never, it is chamber size vs die size.
I freaking love this place!!!! You just can't get these kind of debates on your normal run-of-the-mill forums. So much info to gather from this.
muleman69
USMC -1st marine Div. RVN
I was just thinking the same thing before I read your post
Then we will agree to disagree and you are missing my point. The case also has to expand to reach the chamber walls. And a small base die adds to the amount of case stretch to the chamber walls. Again the case stretches in two directions when fired so it depends on the chamber diameter and the dies diameter how much the case stretches to the chamber walls.
Also the 760 pump does not have the primary extraction force of a bolt action. Meaning the 760 chamber diameter is not the same size as a bolt action. Trust me I tried to load my 760 with a Lee loader and they would not extract until the cases cooled off. Meaning you can forget being cheap and trying to neck size a 760 pump with a $9.00 Lee loader
RCBS Dies FAQ
http://rcbs.com/Help/FAQ-s.aspx
- Q: I see a Small Base Die Set listed for my caliber. Do I need these or should I buy a Full Length Die Set or Neck Die Set? How does each set differ?
A: 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. The Full Length Die set is recommended for ammunition used in bolt action rifles, particularly for ammunition to be used for hunting. The Neck Die Set can also be used to produce ammunition for use in bolt action rifles. The Neck Sizer Die sizes only the neck of the case so it will hold the bullet firmly. It does not size the body of the case nor does it set the shoulder back. Neck sized cases will usually chamber for three or more firings, depending on the powder charge and chamber dimensions. However, over a period of time, a slight drag will be noticed when the bolt is locked. At this point, cases will need to be full length sized and the shoulder set back so they will chamber and extract easily.
Your 100% correct, but then again I heard Chesty Puller was a Navy cook and we could debate this for hours.
Sorry I couldn't resist, Aim High Air Force, MAC 69-73
Sent TDY twice to Iwakuni MCAS and the Gunny wanted to give me a hair cut both times.
Dusty Stevens
Shiner
Some chambers need a small base die. Yet another example of how neck sizing is useless. If youre using a 760 youre probably leaving the cases in the leaves next to the stand.
I no longer have a 760 Gamemaster AKA Amish Machine Gun.
I have greatly matured and now use a bolt action .308.
A skinny case fired in a fat chamber has to stretch to outward contact the chamber walls and stretch to meet the bolt face. Meaning the case can stretch in two directions at once. And the 760 pump has a larger diameter chamber just like a semi-auto than most bolt actions have.
And if you use a small base die on the HXP case below it will cause a case head separation even with the correct amount of shoulder bump. And both cases below were fired in the same chamber.
The factory loaded case below stretched and thinned .009 on the first firing and the rifle was below the SAAMI NO-GO gauge. But the military chamber it was fired in was very large in diameter. So never say never, it is chamber size vs die size.
This is very good,however the cases shown are .303 British,the HXP are smaller at the base than the Privi Partisan,which most likely made to the correct dimensions.What you are saying is correct in that some chambers have length as well as diameter measurements that need correcting at the same time.A skinny case fired in a fat chamber has to stretch to outward contact the chamber walls and stretch to meet the bolt face. Meaning the case can stretch in two directions at once. And the 760 pump has a larger diameter chamber just like a semi-auto than most bolt actions have.
And if you use a small base die on the HXP case below it will cause a case head separation even with the correct amount of shoulder bump. And both cases below were fired in the same chamber.
The factory loaded case below stretched and thinned .009 on the first firing and the rifle was below the SAAMI NO-GO gauge. But the military chamber it was fired in was very large in diameter. So never say never, it is chamber size vs die size.
muleman69
USMC -1st marine Div. RVN
Thats funny ,never heard that before. I'm a proud Marine for sure but I always thought if I had to do it over I would go Air Force......lol
Now that's Flippin funny...........I'll be using that term in my neck of the woods.
Mark
After reading this, I have a question. I shoot a palma 308 rifle chambered with a palma 95 reamer. Started loading with new brass that worked perfectly at first but after 4 firings I have a very bad click when raising my bolt. So bad I have to take the rifle out of my shoulder and muscle in open. I shoot a mild load 45g of Varget with 155's only. Been resizing with a Forster national match die bumping the shoulder back 1-2 thousands. Just purchased an RCBS small base die to try, haven't done it yet just came in yesterday. On midway's website RCBS says "not for bolt gun use" in bold type, but at this point I have no other option. I have no idea what caused this?
Doug Beach
Silver $$ Contributor
Get the small base die, it will likely solve your problem. One possible cause of your problem is a chamber that is smaller than your current dies can accommodate.
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