PSA for reloading newbs- FL sizing brass from other rifles

[jjohnsonElknewbie]

For the reloading newbs out there like myself, I want to post a tip to help you avoid the same issue I ran into recently.

When FL sizing fired brass from a different rifle, make sure you chamber a few after sizing. Because different guns chambered for the same cartridge have different chambers, the shoulders are often different. As a result, you may have issues closing the bolt on this brass.

I recently FL sized around 150 rounds of Federal Premium .308 brass, fired from a few different rifles, for my 7-08. The neck down was simple and was executed with little effort. I followed the Hornady instructions and set the sizer die to SAAMI standard (screwing down the sizer die until it touched the shell holder) and called it good. I measured several cases at random, and they were all 2.025 +/- which is roughly SAAMI trim length for the 7-08.

I loaded up some rounds for pressure testing, and while some took a little effort to chamber, I was excited for load development and didn't think much of it. After pressure testing I loaded up several rounds to check groups and again had some rounds that were difficult to chamber (some were VERY difficult) even though OAL of the sized cases was within trim spec. This was a pain in the a$$ and made feeding unpleasant to say the least, but firing and ejection were normal.

Well my OCD kicked in over the weekend, and I started researching to see what other guys have done in this situation. After reading several articles and threads from other forums, the consensus was that when FL sizing brass from other rifles and they don't chamber normally, even though the OAL is correct, sometimes you have to screw your sizer die past SAAMI standard to push the case shoulder back further. Folks also said that this exercise should only have to be done once, as after shooting in your rifle's chamber they're fire formed to your exact chamber spec.

To test this, first I grabbed some of the fired brass from my rifle that had been hard to chamber. Sure enough, these cases now chambered normally in the gun.

Next I randomly tested brass that had already been FL sized as mentioned above, and wouldn't you know, most of them took extra effort and then some to chamber.

As a final test, I reset my FL sizer die to SAAMI standard, and then lowered the ram and screwed the die 1/8 turn further down. I lubed up 20 previously sized cases and ran them through the die again. When complete, I took the entire lot over to the rifle and tested chambering. Every one of the cases now fed normally without any extra effort.

Buying brand new brass would almost certianly prevent this issue. However, for those of you that are saving some money buying fired brass, I hope that this note helps avoid the same issue I experienced.

 

[N2TRKYS]

How much were you bumping your shoulders back? You adjust your die based off of that measurement. Otherwise, you have no idea what you’re doing.

 

[jjohnsonElknewbie]

How much were you bumping your shoulders back? You adjust your die based off of that measurement. Otherwise, you have no idea what you’re doing.

I didn't measure exactly how much bump I needed. However, from what I read, 1/8 turn of the die should be around .009, although this varies by the die. Some guys recommended a quarter to a half turn, and I wanted to be conservative. This much bump solved my problem, and after firing this brass in my chamber, the shoulders will be reset.

In retrospect, I could have measured the fireformed brass from my rifle and determined how much bump was needed. This would certainly have been more precise to your point, and if I had a micrometer sizing die, I could've dialed it in more closely.

 

[N2TRKYS]

I didn't measure exactly how much bump I needed. However, from what I read, 1/8 turn of the die should be around .009, although this varies by the die. Some guys recommended a quarter to a half turn, and I wanted to be conservative. This much bump solved my problem, and after firing this brass in my chamber, the shoulders will be reset.

In retrospect, I could have measured the fireformed brass from my rifle and determined how much bump was needed. This would certainly have been more precise to your point, and if I had a micrometer sizing die, I could've dialed it in more closely.

Yeah, don’t base it off what the instructions say. Base it off the actual measurements. You’ll get it right and have alot less head scratching No need for a micrometer sizing die, either. The head space kit is inexpensive.

 

[jjohnsonElknewbie]

Yeah, don’t base it off what the instructions say. Base it off the actual measurements. You’ll get it right and have alot less head scratching No need for a micrometer sizing die, either. The head space kit is inexpensive.

Thank you for this and quick question. Now that these cases chamber normally, if I plan to FL size (standard approach) after firing these rounds, are these measurments still necessary or just an added step? I know there are those that simply neck size after firing so long as OAL is still in spec., but I like to keep things as simple as possible (FL size after firings).

 

[Harvey_NW]

Well my OCD kicked in over the weekend, and I started researching to see what other guys have done in this situation. After reading several articles and threads from other forums, the consensus was that when FL sizing brass from other rifles and they don't chamber normally, even though the OAL is correct, sometimes you have to screw your sizer die past SAAMI standard to push the case shoulder back further. Folks also said that this exercise should only have to be done once, as after shooting in your rifle's chamber they're fire formed to your exact chamber spec.

Be careful with this, because more often than not it's the lower portion of the body/base that's not getting sized, as opposed to shoulders contacting. I would color a tight case completely and chamber it a couple times to see where contact is, because .009" shoulder bump on a 308 sounds excessive. My guess would be that you're smashing the shoulders that far back to get the lower portion of the die to size the base area enough to chamber easily. I believe this can be solved with a small base body die, size the body until it chambers easily and then screw the FL die in until you're getting a .002" shoulder bump. Very common for brass not to size properly and intermix in different chambers.

 

[Axlrod]

The most accurate way to measure bump and know how much to bump, is using your chamber to measure. Need to remove your firing pin and plunger ejector (if present), then keep adjusting your resize die down, until your bolt will close without effort. Then your die will be perfectly adjusted for your chamber.

Picking an arbitrary number to push shoulders back, is like cutting 6" off a piece of rope you want to be 4 feet long, without measuring the starting length of the rope.

 

[N2TRKYS]

Thank you for this and quick question. Now that these cases chamber normally, if I plan to FL size (standard approach) after firing these rounds, are these measurments still necessary or just an added step? I know there are those that simply neck size after firing so long as OAL is still in spec., but I like to keep things as simple as possible (FL size after firings).

I only FL size. After I get my die setting my shoulders back .002”, I set the lock ring. In theory, it should be good from now on. However, I check it every time I set it up after that. Just to make sure I’m getting what I want and nothing has moved.

 

[Harvey_NW]

The most accurate way to measure bump and know how much to bump, is using your chamber to measure. Need to remove your firing pin and plunger ejector (if present), then keep adjusting your resize die down, until your bolt will close without effort. Then your die will be perfectly adjusted for your chamber.

Picking an arbitrary number to push shoulders back, is like cutting 6" off a piece of rope you want to be 4 feet long, without measuring the starting length of the rope.

I like to use measurements based on how the rifle and components are in the state they're going to fire, or have been fired in. I don't think a case that won't chamber, or chambers tightly, is an arbitrary measurement if you can bump the shoulders a measurable .002" and then have them chamber smoothly. My personal preference anyway.

 

[jjohnsonElknewbie]

Be careful with this, because more often than not it's the lower portion of the body/base that's not getting sized, as opposed to shoulders contacting. I would color a tight case completely and chamber it a couple times to see where contact is, because .009" shoulder bump on a 308 sounds excessive. My guess would be that you're smashing the shoulders that far back to get the lower portion of the die to size the base area enough to chamber easily. I believe this can be solved with a small base body die, size the body until it chambers easily and then screw the FL die in until you're getting a .002" shoulder bump. Very common for brass not to size properly and intermix in different chambers.

Great information and thank you! Unfortunately, I already ran all the brass back through the FL die. The rounds I already fired for pressure testing chamber easily now.

I will make a note and remember this for any future purchases of used brass. However, at this point, I'm probably going to stick with new moving forward.

 

[Pharmseller]

Separate your brass by rifle and neck size only.





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