Why isn't my 6.5 Grendel brass "growing"?

[Lee Q. Loader]

I've been asking a few questions here now that I started a new to me cartridge.

I've loaded and full length sized some 6.5 Grendel brass 4 times now and not had to trim yet!

Is that strange? Does this just happen sometimes? Am I doing something wrong?

I measured the brand new Starline brass and most of it was around 1.509".

Trim length is either 1.515 or 1.520 depending on where you look.

After sizing 4 times most brass is about 1.512, so I guess it is growing a little bit.

Please let me know what you think about this, I'm happy to not have to trim, but I've never seen bottle-neck cases not grow much more.

 

[Bazoo]

The Normal thing that cause case growth are, long headspace, coupled with suitable pressure.

If you leave lube on the cases from sizing it will cause the brass to slip in the chamber and not grow.

Minimum headspace, or resizing the minimum amount helps reduce case stretch.

 

[AJC1]

If your shoulder doesn't move much your need to trim will be minimized. You may have gotten lucky and have a die that closely matches your chamber.

 

[Blue68f100]

I've been asking a few questions here now that I started a new to me cartridge.

I've loaded and full length sized some 6.5 Grendel brass 4 times now and not had to trim yet!

Is that strange? Does this just happen sometimes? Am I doing something wrong?

I measured the brand new Starline brass and most of it was around 1.509".

Trim length is either 1.515 or 1.520 depending on where you look.

After sizing 4 times most brass is about 1.512, so I guess it is growing a little bit.

Please let me know what you think about this, I'm happy to not have to trim, but I've never seen bottle-neck cases not grow much more.

Not unusual, happens from times to times. I have a 224V (AR-15) that has over 5 firings and has only grown 0.002"-0.003" from factory trim length. All it indicates that your load and chamber likes each other. This is the first gun I ever had do this in almost 50 yrs of hand loading.

 

[westernrover]

Grendel is a low-pressure cartridge. It's closer to a typical magnum handgun and lower in pressure than some. I load Grendel to maximum loads with H335. They're maximum in the published data but also because of the case capacity. I just can't get more powder in there. My Grendel brass (Starline) has never grown after many reloads. I don't track reloads on this brass, but I've fired about 1400 rounds with maybe 200 pieces of brass so it must be an average of 7 reloads on a case. It's all shorter than spec. Inquire at the 6.5 Grendel forum and I think you'll find other people that have never had to trim. I resize the body and bump the shoulder for consistent length in the appropriate Sinclair comparator (base to shoulder datum). I'll check the overall case length, but it's well under spec and since it is not headspacing on the mouth or crimping in a crimp-groove, I leave it rather than trimming it even shorter.

 

[JFrank]

What is the shoulder angle of the case ?

 

[Varminterror]

What is the shoulder angle of the case ?

30*

 

[jmorris]

…I've loaded and full length sized some 6.5 Grendel brass 4 times now and not had to trim yet!

Is that strange? Does this just happen sometimes? Am I doing something wrong?…

Please let me know what you think about this, I'm happy to not have to trim, but I've never seen bottle-neck cases not grow much more.

Having to trim comes from a chamber that allows the case to be blown outward and expand to fit the steel, then a size die that makes it smaller than that and the excess “growth” needs to be trimmed off the case. Case walls are getting thinner because there is no way to add back the brass you cut off to the other parts of the case.

Your cases are a good fit to the chamber, don’t “blow out” and subsequently you don’t move the brass much when sizing and there is nothing to trim off because of this.

What you are doing is not wrong and closer to ideal than having to trim every time by good margin.

 

[Lee Q. Loader]

Thanks everyone! I'm pretty happy to not trim brass. Honestly, it's the only thing in reloading that I don't enjoy.

 

[EricBu]

I've been asking a few questions here now that I started a new to me cartridge.

I've loaded and full length sized some 6.5 Grendel brass 4 times now and not had to trim yet!

Is that strange? Does this just happen sometimes? Am I doing something wrong?

I measured the brand new Starline brass and most of it was around 1.509".

Trim length is either 1.515 or 1.520 depending on where you look.

After sizing 4 times most brass is about 1.512, so I guess it is growing a little bit.

Please let me know what you think about this, I'm happy to not have to trim, but I've never seen bottle-neck cases not grow much more.

It's not growing because you aren't pushing it hard enough!

 

[Bartojc]

What you are doing is not wrong and closer to ideal than having to trim every time by good margin.

For sure. Sounds like OP has his FL dies set properly.

-Jeff

 

[Lee Q. Loader]

For sure. Sounds like OP has his FL dies set properly.

-Jeff

I just got lucky for sure!

 

[N555]

Must be nice. My 6.5creedmoor brass grows by 5 to 7 thousands per shot. I always trim that stuff after every resize.
My FL dies are set to give me 1 to 2 thousands of shoulder bump, if I 100% FL size them as far as the shell holder will allow the brass to go into the die I get 10 thousands or more growth per shot.

 

[JFrank]

Must be nice. My 6.5creedmoor brass grows by 5 to 7 thousands per shot. I always trim that stuff after every resize.
My FL dies are set to give me 1 to 2 thousands of shoulder bump, if I 100% FL size them as far as the shell holder will allow the brass to go into the die I get 10 thousands or more growth per shot.

That seems excessive.

 

[Blue68f100]

Should not get more than 0.003" per firing. I would confirm your only pushing the shoulder back 0.002". See of a as fired fits back into the chamber easily. Now if the body of the chamber is over sized you will have a lot of growth and premature brass failure. If a Simi-Auto you may need to cut back on the gas system.