??New Brass- Trim first then size, or Size first then trim?

[txsendero]

On new brass, if length trimming is needed, is it best to trim first before sizing, or size first before trimming?

 

[Laelkhunter]

I have never had new (Virgin) brass that needed trimming. It should be good to go. At most you might have to true the mouth of the case if it is isn't perfectly round. I do that by just running the mouth of the case over the expander button. I don't resize the case. If you do choose to size the case however, check the OAL, and trim if is too long.


I guess to answer your original question, trim AFTER sizing, but again, sizing nor trimming should be needed for virgin brass.

 

[Mikecr]

size first

 

[Grumulkin]

I have never trimmed or resized new cases except for a 460 S&W Magnum where the cases had to be resized to hold the bullet securely. It is a waste of time but of course, it's your time.

As for case mouths not being perfectly round; that happens but I rarely even have to do anything about that as seating the bullet straightens it out. New cases should be inspected though as rarely you'll find one with a flash hole WAY off center, etc.

 

[Waynzee]

Inspect, size, trim and inspect again all your new brass. I just bought some Winchester brass for my 7x57 Mauser and one piece had a dent in the side of the case with a pin hole clean through.

 

[jaeger19]

Size . Then trim to make uniform.

 

[Rich Coyle]

On new brass, if length trimming is needed, is it best to trim first before sizing, or size first before trimming?

Shoot first, size then trim.

 

[Frank in the Laurels]

Use a mild load, way under max, some junk bullets not your good pricey hunting bullets and shoot first, let em stretch to fill your chamber cut and then trim if needed, as long as your not shooting it to the max all the time it's sometimes surprising how little they really grow..

 

[J E Custom]

If the brass doesn't need trimming to safely fire it, wait until you fire it the first time and then trim all brass to a uniform length.

I do recommend however that all new brass be turned true (Just enough to clean it up and make the neck thickness uniform before firing it and risking off setting the neck.

After turning the necks and firing the first time your cases should be very consistent dimensionally
except for the case length and this is a good time to true everything up.

I used to totally prep my brass before I fired it the first time. but after checking it after firing,
I found differences in length especially in wildcats, so I now trim after the first firing to get the best results and prevent excessive trimming.

PS: After firing the first time and trimming the case to consistent lengths, It is a good time to weight sort if you want to.

J E CUSTOM

 

[txsendero]

Thanks for all of the replies guys. The lengths are somewhat consistent on the new brass I have (Rem 270WSM). Most are where they should be, some are .002" - .004" over the rest. I'll probably wait until they are fired then size then trim to get them consistent.

 

[engineer40]

I've had bullets not want to go into the case mouths before with brand new cases, so I got into the habit of resizing before shooting... but I realize that I probably don't need to for all new brass.

I also will usually uniform primer pocket holes if it's not Lapua brass.

One time also with brand new brass I had to inside chamfer the case mouths. If I didn't the bullets weren't seating properly.

I have yet run into needing to trim brand new brass though. I could see needing to if the case lengths were all over the place I suppose.

 

[Gene]

I always expand necks and champfer the mouths of new brass before loading. Trim after first firing.

 

[Predator 22]

If the brass doesn't need trimming to safely fire it, wait until you fire it the first time and then trim all brass to a uniform length.

I do recommend however that all new brass be turned true (Just enough to clean it up and make the neck thickness uniform before firing it and risking off setting the neck.

After turning the necks and firing the first time your cases should be very consistent dimensionally
except for the case length and this is a good time to true everything up.

I used to totally prep my brass before I fired it the first time. but after checking it after firing,
I found differences in length especially in wildcats, so I now trim after the first firing to get the best results and prevent excessive trimming.

PS: After firing the first time and trimming the case to consistent lengths, It is a good time to weight sort if you want to.

J E CUSTOM

Quick question JE, you said to turn necks before the first time firing. How do you know the brass is perfectly round from the factory? Couldn't the neck be slightly out of round and when you turn you are taking more off the high out of round spot than the rest of the case? I'm going to be turning 6.5 SS brass and don't want to screw up the nice norma brass. If you could share some more of your knowledge on turning brass I would appreciate it.

 

[J E Custom]

Quick question JE, you said to turn necks before the first time firing. How do you know the brass is perfectly round from the factory? Couldn't the neck be slightly out of round and when you turn you are taking more off the high out of round spot than the rest of the case? I'm going to be turning 6.5 SS brass and don't want to screw up the nice norma brass. If you could share some more of your knowledge on turning brass I would appreciate it.

Most new brass is out of round in the beginning. that's why I like to use a neck turning tool that first uses a sizing mandrel to true up the neck and pre fits the turning mandrel for a perfect turning of the neck and a perfect fit.

I do this to make sure that the neck gets formed perfectly centered. The chamber will/should do the same to the case body.

This is one of the tools available for this process.

http://www.sinclairintl.com/reloadi...clair-premium-neck-turning-kit-prod35271.aspx

And these are the expander mandrels and the turning mandrels.

http://www.sinclairintl.com/reloadi.../sinclair-neck-turning-mandrel-prod33136.aspx

There are other tools that are less expensive, but I just like the complete kit with all the mandrels
I need.

Note; When ordering mandrels be sure and ask for both the sizing and turning mandrels for that caliber.

J E CUSTOM