Small Base Dies Vs full length
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Small base VS full length
Actually the small base die is also a full length sizer die. The difference between a small base and regular full length sizer die is that the small base die sizes the base of the cartridge case more than the regular die. How much more depends on the cartridge for which the die is made. Yes, the small base die does work the brass more and can lead to shortened brass life. I would start with a regular full length sizer die and only use a small base sizer die if it is really necessary. I only own one small base die. That is for my match chambered .308 bolt gun. I have to use it on cases that are once fired in another chamber (i.e. Lake City Match or M118 brass). New brass does not require a small base die to fit and once the brass is fired in rifle I can use a neck sizer die from then on. But that is a bolt gun. A semi-auto would require a regular full length die. I don't use small base dies for my Garands (I have 9) or my ARs (I have a COLT HBAR and a RRA NM). I can use the brass fired in either AR by running it through my RCBS regular full length sizer die. I can do the same thing with my Garands. Two of my Garands have tighter commercial chambers while the others have USGI chambers.
Bill
Actually the small base die is also a full length sizer die. The difference between a small base and regular full length sizer die is that the small base die sizes the base of the cartridge case more than the regular die. How much more depends on the cartridge for which the die is made. Yes, the small base die does work the brass more and can lead to shortened brass life. I would start with a regular full length sizer die and only use a small base sizer die if it is really necessary. I only own one small base die. That is for my match chambered .308 bolt gun. I have to use it on cases that are once fired in another chamber (i.e. Lake City Match or M118 brass). New brass does not require a small base die to fit and once the brass is fired in rifle I can use a neck sizer die from then on. But that is a bolt gun. A semi-auto would require a regular full length die. I don't use small base dies for my Garands (I have 9) or my ARs (I have a COLT HBAR and a RRA NM). I can use the brass fired in either AR by running it through my RCBS regular full length sizer die. I can do the same thing with my Garands. Two of my Garands have tighter commercial chambers while the others have USGI chambers.
Bill
Bill
Thanks for the quick response. I've ordered RCBS small base dies that should be in this week for 6.8
Which full length RCBS dies do I need to order? There are several different types. I will be reloading for 6.8. and I'm glad you responded due to you use RCBS full length. I have a Hornady LNL. And have only used Hornady pistol dies thus far. Hornady 6.8 full lenght dies are not available.
Kip
Thanks for the quick response. I've ordered RCBS small base dies that should be in this week for 6.8
Which full length RCBS dies do I need to order? There are several different types. I will be reloading for 6.8. and I'm glad you responded due to you use RCBS full length. I have a Hornady LNL. And have only used Hornady pistol dies thus far. Hornady 6.8 full lenght dies are not available.
Kip
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818 Posts
Actually I the small base dies size the brass slightly smaller at the base then full length dies. Small base dies are to be used in semi autos for more reliable feeding and full length dies are more popular in bolt action as the brass is sized close to "spec".
ETA:
From Bucknrut
I have a quick question while we are on the topic. I don't know anyone that uses a SB die, so is there anyone who could tell me the difference between the FL and SB sets? Are the Small Base dies just more accurate/precise than the FL dies?
Response from Constructor
The base diameter is about .418 or .004 under chamber spec. a regular FL is apx .420 or .002 under chamber spec.
ETA:
From Bucknrut
I have a quick question while we are on the topic. I don't know anyone that uses a SB die, so is there anyone who could tell me the difference between the FL and SB sets? Are the Small Base dies just more accurate/precise than the FL dies?
Response from Constructor
The base diameter is about .418 or .004 under chamber spec. a regular FL is apx .420 or .002 under chamber spec.
In the SAMMI and SPC2 chambers you don't need small base dies, whats the point of sizing your brass smaller than it was when new.
Now the makers of the DMR chamber reccomend SB dies, must be the way they ream their chambers(probably just a way to get more pressure and still extract without issues) I'm not sure.
I do know I have a SAMMI 6.8 1/10 twist barrel and I use regular LEE (Hornady New Dem. dies on their way this week) FL dies and just make sure I'm properly sizing my brass with the correct head space and OAL to prevent overpressure which is what causes the case base to swell. After all the base of a cartridge being to larger to extract is clearly a sign of overpressure and these guys are just getting around the problem by undersizing their brass instead of realizing the real problem to begin with.
Load correctly and regular FL dies are all you need. JMO
Now the makers of the DMR chamber reccomend SB dies, must be the way they ream their chambers(probably just a way to get more pressure and still extract without issues) I'm not sure.
I do know I have a SAMMI 6.8 1/10 twist barrel and I use regular LEE (Hornady New Dem. dies on their way this week) FL dies and just make sure I'm properly sizing my brass with the correct head space and OAL to prevent overpressure which is what causes the case base to swell. After all the base of a cartridge being to larger to extract is clearly a sign of overpressure and these guys are just getting around the problem by undersizing their brass instead of realizing the real problem to begin with.
Load correctly and regular FL dies are all you need. JMO
It can be true but it really depends on your chamber.
Small base dies squeezes the walls of the case down to what the factory specs them to. But the area most all 6.8 cases fail at eventually is the case neck. It splits. Now if people were annealing their cases so that the necks were not the failure point it is possible it woudl be an issue. But even with that the main issue that causes case failures is how far you set the shoulder back from what it is after being fired. This is one of the things that causes that hologram looking line about a 1/4 of the way up from the bottom of the body. Given this info and the way the AR works the main thing effecting you case life as far as hand loading goes is how much you set the shoulder back. This is what givens you your headspace. You should keep this amount at about .003 for everyday rounds and if you are going for slow shooting top accuracy loads (not combat or your protection rounds) you can go down to .001. Even at 0 you are still technically sizing the shoulder as when the body is squeezed on the sides the brass has to flow somewhere and that is into making the case actually longer unless there is something pushing on the case shoulder which it then flows into the neck hence why you have to trim your necks every so often.
IMO I think the Hornady Head space tool kit is a mandatory item if you plan to be reloading. When used with a caliper another mandatory tool it will allow you to measure the distance fromthe case bottom to the datum line on the case shoulder. This will allow you to precisely set how much your die sets the shoulder back. As I said above most will do well with a .003 setback. This will give you top relaiblity with but still not make the case have to expand too much. The more you set the shoulder back the more the case has to stretch and then be sized back down. This back and forth motion work hardens the brass and causes it to fatigue and that leads to failures. If you keep your loads below the max (no swipes) and use no more than this amount of set back you should not see any reduced life in your cases by using SB dies. IN 90% of the cases your necks will split before anything else doing this.
Small base dies squeezes the walls of the case down to what the factory specs them to. But the area most all 6.8 cases fail at eventually is the case neck. It splits. Now if people were annealing their cases so that the necks were not the failure point it is possible it woudl be an issue. But even with that the main issue that causes case failures is how far you set the shoulder back from what it is after being fired. This is one of the things that causes that hologram looking line about a 1/4 of the way up from the bottom of the body. Given this info and the way the AR works the main thing effecting you case life as far as hand loading goes is how much you set the shoulder back. This is what givens you your headspace. You should keep this amount at about .003 for everyday rounds and if you are going for slow shooting top accuracy loads (not combat or your protection rounds) you can go down to .001. Even at 0 you are still technically sizing the shoulder as when the body is squeezed on the sides the brass has to flow somewhere and that is into making the case actually longer unless there is something pushing on the case shoulder which it then flows into the neck hence why you have to trim your necks every so often.
IMO I think the Hornady Head space tool kit is a mandatory item if you plan to be reloading. When used with a caliper another mandatory tool it will allow you to measure the distance fromthe case bottom to the datum line on the case shoulder. This will allow you to precisely set how much your die sets the shoulder back. As I said above most will do well with a .003 setback. This will give you top relaiblity with but still not make the case have to expand too much. The more you set the shoulder back the more the case has to stretch and then be sized back down. This back and forth motion work hardens the brass and causes it to fatigue and that leads to failures. If you keep your loads below the max (no swipes) and use no more than this amount of set back you should not see any reduced life in your cases by using SB dies. IN 90% of the cases your necks will split before anything else doing this.
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Small base dies do not size smaller than new brass. New SSA brass is .415 dia. , small base dies size to .418 and FL dies to .420 most of the time, some a little less some a little more.
The SAAMI and SPC II chamber is .422, semi autos really need .004 clearance to be reliable when hot and dirty so that means .418. The DMR-C chamber is .423 or .001 larger than the SAAMI or SPCII.
we did it to make sure the chamber is not small even after chrome even though the barrels are electro polished to remove the same amount that the chrome will replace.
Companies that are known to make benchrest dies like Redding and Forster usually make them larger for bolt action rifles to aid accuracy, those are the ones you need to be careful with as they may not resized the case enough. RCBS and Hornady usually size brass smaller.
What you need to remember is all machined parts have a tolerance of plus or minus .001. some as much as .005. If you use a company that designs the die to .420 and then goes large to .421 you may have issues. So we say for RELIABILITY it is best to go with small base dies, it is just like insurance that they will size the cases small enough to work when hot and dirty.
ETA Dude! We have to stop doing this
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OOPs you are correct, I will edit those. 12 hrs in the shop, 2 hrs on the phone it is 1am and I am a walking zombie
6 hrs and we do it all over again, what a life
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Still no excuse to not answer your phone when Im bored
My dies size the base of my SSA brass to .417", so it runs fine with regular FL dies.
Who has Hornady dies? RCBS emailed me today and said that their 6.8 dies, both full size and small base were on 2 to 4 weeks backorder. You know what that means, Maybe 2 months. How good are the Lee dies? And who has them, I'll cancel the order from RCBS and order those, if I have a good response from the forum. Also if they're available.
Kip
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241 Posts
I have both the Hornandy New Dimension 6.8 and RCBS Small Base dies. I've only reloaded 200 rnds thru the RCBS so far, but as far as sizing goes, I prefer the RCBS. The hornady seemed to not be as consistant as I'd like. They seemed to jump 0.002-3" up or down in a 50 round batch. It seemed like I was always adjusting them. The RCBS I just started using yesterday. I set them and I never had a case out of adjustment. I ordered mine last week thru MidwayUSA and had them in hand last saturday. YMMV. JMHO. I do perfer the Hornady Seater Die however.
ETA: Midway has the sizer die in stock, but not the two die set w/the seater die included:
http://www.midwayusa.com/viewProduct/?productNumber=222459
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7,772 Posts
CHeck midway they RCBS small base dies in stock a few weeks ago....
Actually the Lee dies are very good and are what I have been using so far and they are very consistent, the only reason I'm bought the Hornady dies was to try them out.
On my .223 the Lee dies really are more consistent and much easier to size with, I just like the seating die that comes with the Hornady set after the Micro-just is added to it to give you a comp. style guiding seating die for much less than some of the other companies and they work great.
On my .223 the Lee dies really are more consistent and much easier to size with, I just like the seating die that comes with the Hornady set after the Micro-just is added to it to give you a comp. style guiding seating die for much less than some of the other companies and they work great.
Midsouth
Thanks guys, I have a reminder set for Hornady full length dies, and ordered RCBS dies from Midsouth. Funny, the manufactuer (RCBS) has them on back order, so I cancelled those orders and Midsouth has them in stock now. You'd think it'd be the other way around.
Anyway, thanks a bunch,
Kip
Thanks guys, I have a reminder set for Hornady full length dies, and ordered RCBS dies from Midsouth. Funny, the manufactuer (RCBS) has them on back order, so I cancelled those orders and Midsouth has them in stock now. You'd think it'd be the other way around.
Anyway, thanks a bunch,
Kip
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I have the Hornady, RCBS Full length, and the RCBS small base. The RCBS small base are my favorite. The Hornady are the worse IMHO. For an autoloader, I switched to the small base for added peace of mind.
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