Hopefully this is the right forum. I am thinking about reloading for an ar-10 but not really sure how i can get more neck tension for a gas gun. I emailed redding since those are the dies I usually use. They said not to do bushing dies and use the regular dies. If anyone can point me in the right direction i would be grateful. Been reloading for my bolt guns but have not reloaded for a gas gun yet.
- Thread starter BigBlastin300win
- Start date
I use a std. full length resize die with the decapper/resize stem removed and size the neck id with a Sinclair expander mandrel. Two seperate operations on a RCBS Rockchucker single stage press. The mandrel will determine the id of the necks. There will be a small amount of springback with fired cases. Mandrels can be reduced in size by spinning in a drill and emery cloth. Be sure to lube the inside of case necks. You may or may not need a small base die. Your chamber will determine that. If a clean dry resized case will not drop in and fall out on its own in a clean dry chamber, a small base die will be needed. Better to have ample chamber clearance than not enough in the gas gun. I like to set the shoulders back at least .003 in the gas guns and .005 is not too much.
I am running into this issue on my ar10 6.5cm. Brand new riffle. Seems the chamber is super tight and I’m going to need a small base size die. Problem is there is not much to choose from that are in stock for those dies (rcbs is what you will find mostly).
The issue I’m having is factory ammo is even being pushed into the bolt face and getting marks on it and the brass is getting scratched on the neck and base
Seems that I can make is somewhat better with resizing using bushing comp dies and century mandrel die, but finding the chamber is just very tight
I’m gonna try the short body rcbs die set for AR. It’s cheap enough to try
Can anyone explain why this seems to be an issue with gas gun chambers that are supposed to be saami reamers ?
I’m gonna go back to the smith that made mine but I am still trying to confirm all this on my own.
The issue I’m having is factory ammo is even being pushed into the bolt face and getting marks on it and the brass is getting scratched on the neck and base
Seems that I can make is somewhat better with resizing using bushing comp dies and century mandrel die, but finding the chamber is just very tight
I’m gonna try the short body rcbs die set for AR. It’s cheap enough to try
Can anyone explain why this seems to be an issue with gas gun chambers that are supposed to be saami reamers ?
I’m gonna go back to the smith that made mine but I am still trying to confirm all this on my own.
I use redding (non bushing) dies on my AR-10 and it works like a champ. It is Redding Premium Die Set 66155
I don't see why you cant use a bushing die and just get a smaller diameter neck bushing to give you more neck tension? I stay around 3-4 thou for gas guns
You might like watching these by one of the users here: https://www.snipershide.com/shootin...or-6-5-grendel-9mm-308-and-223-enjoy.6947785/
I second this^
I would not look overlook the possibility of needing a small bass die. I small base on everything I run through ARs chambered in 308. If full length is used in my experience, the ones I have loaded for do not run reliably. I tried full length sizing which is basically .003 bigger on the periphery of the case body and had jams and cycling issue.
I personally use a RCBS small bass die with the expander ball/decapper installed. Which I believe gives around .002 of neck tension.
My concern if you try for more neck tension is deformation of the tip of the bullet during seating, which can cause inconsistent seating deaths and a deformed bullet. Consider crimping instead of increasing neck tension if you’re concerned with the bullet moving around during chambering.
How much are you bumping the headspace back from fire formed?
I don’t have it all figured out yet but I’m getting close. I got an RCBS AR series short base die set (just to try).
Today, I used my digital caliper and SAC headspace gauge to measure a fired lapua case…a virgin one…and, my 65CM GO gauge
The virgin case was 2.5820
GO gauge was 2.5850
Fired was 2.5880
So, I figure .003 thousands is what I should bump for this gun
My SAMMI chamber shuts with the go gauge and does not shut with nogo (I checked all that)
I then setup my rcbs short base fl die with proper shellholder
Took the 2.5880 fired case and ran it through SB die
It measured 2.5900. I annealed it before doing so. WTF. I figured it would come back form .5880 to .5850 or .5860. But it came to .5900
It fits in the chamber and falls out but I guess I just don’t get it
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Virgin is 3 thousand less than GO gauge
GO is 3 thousand less then fired
After sizing it grew 5 thousandths from what the fired case was
I didn’t zero my caliper after putting the headspace gauge on.
Not sure what you mean. I am using shellholder systems not turning my die up or down.
I’m guessing that a short base die also changes how the shellholder set does its thing.
At the same time I am just not sure if I’m doing something wrong using the caliper and sac headspace gauge
The virgin case was 2.820
GO gauge was 2.850
Fired was 2.880
Fired Minus Virgin = .060
GO gauge was 2.850
Fired was 2.880
Fired Minus Virgin = .060
And yea your right. I mistyped my numbers. I edited the post above with correct ones. Legist is still same
The measurement increased because when you resized the case, the brass moved to the area of least resistance. Sounds like you did not have the sizing die far enough down and the die body was not yet contacting the shoulder. Slowly screw the dye down a little bit further until the desired measurements is achieved.
Edit-Case overall length will likely increase too. Might require a trim. Be sure to check that. One of the negative aspects of small base. At least from what I have seen.
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Which "system"? If you meant Redding competition set, then they ADD to the length.
Yea the Redding set. I started with #10 and set the die to that with some cam over. The #10 is supposed to be the smallest…then you go to 8,6,4,2.
Once I ran the fired case into the #10 it made the case headspace measure go from 2.5880 to 2.5900
I then ran the case into al the others all the way down to #2. Got the same measure of 2.5900. Never changed
Guess I just don’t know how to make the bump work. Either that or the small base fl die just made it to the point of not being able to be smaller
Ughhh. I need a person loca to come and help
I suggest starting over with a standard shell holder. Figure each 1/16th of a turn on your die is worth ~ .001" adjustments. You will be more successful.
Yeah I get what your saying. I have the RCBS SB size die down to hit the ram with the Redding #10 shellholder in it (touching). Then I filed a 1/4 inch more.
It has cam over. I can surely try more cam over but I got a good Amit of cam over now
I also know about cases grow some when you FL size. But, case was annealed and check for length of 1.9110 (I trimmed it slightly to get it .911).
When I started the fired case was may 1.9125
Lapua brass is pretty much damn near to 6.5CM trim length anyway
I did take the expander ball off of the rcbs small base die decap pin. The ball on it seem to be way big but I know your supposed to use it with a crimp seater that comes with the set
REMEMBER: I also have Redding comp bushing dies that I was using first with a separate mandrel die before I bought the small base die
My main issue is that it’s harder to find bump for headspace on an AR10 (for me at least). PLUS, my brand new gun was leaving marks on factory ammo case heads and necks were scratched.
I reloaded those fired factories with the Redding bushing dies and mandrel die and got better results but still had marks on base (I also used 1 fresh lapua when I did that)
I pulled one of the great grouping factory rounds to measure the powder weight (h4350)
So, that’s why I’m trying small base at this point PLUS truly trying to get me bump correct to a close to sammi measurement
I agree
No reason to complicate reloading for a gasgun.
Dont use a Small base die unless you have to, a case fired from your chamber should only
need a standard full length sizing die.
When using a bushing die a small section on the neck right before the
shoulder does not get resized, this may cause issues with some chambers.
Bump the shoulder back .002 - .003, more is really not necessary.
When taking measurements of your fired cases to determine shoulder bump
remove any raised burs from the case head as this will skew your measurements.
Dont use a Small base die unless you have to, a case fired from your chamber should only
need a standard full length sizing die.
When using a bushing die a small section on the neck right before the
shoulder does not get resized, this may cause issues with some chambers.
Bump the shoulder back .002 - .003, more is really not necessary.
When taking measurements of your fired cases to determine shoulder bump
remove any raised burs from the case head as this will skew your measurements.
