Fireforming and resizing

[C-130 Dude]

We know that fireforming works for getting the best performance out of your cases.

But if you full length resize, you end up putting the case back to saami spec.

Doesn't that mess up the desired effect of fireforming?

I personally do a full length with neck resize every time. But that's just me. It's all good.

 

[Huntnful]

You don't take it back to Saami spec though. You only bump the shoulder .002, and your chamber, especially a factory chamber, may have blown the shoulder forward upwards of .009 possibly with the first firing. And the case body also grows, and the sizing die doesn't squeeze the case body back to the original dimensions either.

 

[Bang4theBuck]

You don't take it back to Saami spec though. You only bump the shoulder .002, and your chamber, especially a factory chamber, may have blown the shoulder forward upwards of .009 possibly with the first firing. And the case body also grows, and the sizing die doesn't squeeze the case body back to the original dimensions either.

Agree with Huntnful, woth.one clarification. If you follow the instructions that come woth the dies, they will typically result in a fully resized case. You need to follow a different process than what is provided by the die manufacturer to leave the case only .002' short of fire-formed dimension.

 

[C-130 Dude]

You don't take it back to Saami spec though. You only bump the shoulder .002, and your chamber, especially a factory chamber, may have blown the shoulder forward upwards of .009 possibly with the first firing. And the case body also grows, and the sizing die doesn't squeeze the case body back to the original dimensions either.

But it does put the case body back to saami spec. That's the point. My case prep always starts and ends up the same way. Clean, resize, and trim. .002 bump. Always.

 

[Coyote Shadow Tracker]

What Huntfnul & bang4the Buck said. It's not taking it back to SAAMI, but Bumping it .002 back will help getting the cartridge into the chamber when reloaded. You can just neck size, and you case will be fireformed to your chamber, but after a few reloads you might have a hard time chambering your reload. If you Full Size every time and bump back .002 your accuracy will stay the same. There has to be allowance for the Brass to SPRING Back.

 

[lancetkenyon]

But it does put the case body back to saami spec. That's the point. My case prep always starts and ends up the same way. Clean, resize, and trim. .002 bump. Always.

SAAMI spec? Or virgin case size?
You can set your FL sizing die to resize your case to better fit your chamber than minimum.

Now, a Small Base FL die brings a case down even more, close to virgin brass size. Used mostly for semi-auto rifles.

FL dies can vary. I have two different 7RM FL dies, both RCBS. And they size very differently, even while bumping the shoulders back to the exact same measurement.

 

[C-130 Dude]

What Huntfnul & bang4the Buck said. It's not taking it back to SAAMI, but Bumping it .002 back will help getting the cartridge into the chamber when reloaded. You can just neck size, and you case will be fireformed to your chamber, but after a few reloads you might have a hard time chambering your reload. If you Full Size every time and bump back .002 your accuracy will stay the same. There has to be allowance for the Brass to SPRING Back.

I currently use a RCBS Match Master full length with neck sizing die. I have it setup to bump the sholder back .002. Let me get this straight: So your saying that (using fireformed cases) I should just neck size and trim (a/r) until I run into chambering issues? Doing this will get me better performance out of my cases? Once I experience chambering issues, then do a full length resize?

 

[C-130 Dude]

SAAMI spec? Or virgin case size?
You can set your FL sizing die to resize your case to better fit your chamber than minimum.

Now, a Small Base FL die brings a case down even more, close to virgin brass size. Used mostly for semi-auto rifles.

FL dies can vary. I have two different 7RM FL dies, both RCBS. And they size very differently, even while bumping the shoulders back to the exact same measurement.

I use a sb fl die for my AR rifles only.

 

[lancetkenyon]

I use a sb fl die for my AR rifles only.

Exactly what they are for. l, too, use an SB FL for my .223 Wylde brass.

 

[Coyote Shadow Tracker]

I currently use a RCBS Match Master full length with neck sizing die. I have it setup to bump the sholder back .002. Let me get this straight: So your saying that (using fireformed cases) I should just neck size and trim (a/r) until I run into chambering issues? Doing this will get me better performance out of my cases? Once I experience chambering issues, then do a full length resize?

You can do it that way, but doing the FL, Neck Size and bump back every time gives you consistency. every reload will be the same.

 

[C-130 Dude]

It's the consistency that I am looking for. Therefore, I will continue to FL, Neck Size, Bump .002, and trim every time. No matter if the cases I am using are new or fireformed.

 

[dfanonymous]

It's the consistency that I am looking for. Therefore, I will continue to FL, Neck Size, Bump .002, and trim every time. No matter if the cases I am using are new or fireformed.

I mean, there's limits to what is defining of consistency in hand-loading and depending what you theories you subscribe to, can be quite tedious. Sometimes for not much gain.

You were kind of right in assuming that a FL resizing is SAAMI. This is because most chambers are SAAMI, and you're fireforming to the chamber. So yes, but because SAAMI is fairly loose tolerances (relative) and because of variations in machine tools and manufacturing, you're setting your FL die to bump back the shoulder just enough to close the bolt reliably while keeping it as close to its fire formed size. That's what most people mean who know anything about this mean by .002 bump.

The neck sizing however is meh. If you use a mandrel die, maybe a bushing die you can add setting neck tension into the same step. I don't have all day to mess around loading ammo, so I try to get in and out. A lot of guys here are retired and have no problem doing extra steps. The Lee collet dies can work good too.

Even then, if it's your second firing…the case will continue to change…that's when annealing comes in…
So it would be more like:
-FL resize virgin brass
-Fire form
-FL resize/bump
-Neck tension

Go shoot

-Anneal
-FL/bump
-Neck

 

[ButterBean]

You can do it that way, but doing the FL, Neck Size and bump back every time gives you consistency. every reload will be the same.

******************************THIS***********************************

 

[C-130 Dude]

I mean, there's limits to what is defining of consistency in hand-loading and depending what you theories you subscribe to, can be quite tedious. Sometimes for not much gain.

You were kind of right in assuming that a FL resizing is SAAMI. This is because most chambers are SAAMI, and you're fireforming to the chamber. So yes, but because SAAMI is fairly loose tolerances (relative) and because of variations in machine tools and manufacturing, you're setting your FL die to bump back the shoulder just enough to close the bolt reliably while keeping it as close to its fire formed size. That's what most people mean who know anything about this mean by .002 bump.

The neck sizing however is meh. If you use a mandrel die, maybe a bushing die you can add setting neck tension into the same step. I don't have all day to mess around loading ammo, so I try to get in and out. A lot of guys here are retired and have no problem doing extra steps. The Lee collet dies can work good too.

Even then, if it's your second firing…the case will continue to change…that's when annealing comes in…
So it would be more like:
-FL resize virgin brass
-Fire form
-FL resize/bump
-Neck tension

Go shoot

-Anneal
-FL/bump
-Neck

I've actually been reloading since 1971. Started on shotshells. Started and stopped reloading 3 times due to my moving so much. Active military can do that to you. 98% of my reloading has been for hunting purposes. But since I got hurt just before I retired from the AF, I stopped hunting. My back can't put up with it any more. I was away from all shooting for 15 years. My wife said I needed to get out and find a hobby. And that was that. Since I like to shoot, I considered taking up target shooting. Now my focus is to "pip the ace". I have always been a pretty good shot and now I want to see just how fine tuned I can get. Even with these old eyes. Reloading for hunting and target shooting is similar, but not entirely the same. My process has worked well for a long time. And because I tend to be very task focused, I don't mind taking the time to do it right. I'm trying to weed out the finer points of ammo prep for target shooting specifically. I really enjoy doing this and find it relaxing. Thanks for all the input. You can bet I will consider everything carefully!