another noobie question...when to case trim?

[gordicans]

Should you trim your cases before or after you neck or full length resize? I'm guessing afterwards but thought I'd check. Thanks

[bladeracer]

Should you trim your cases before or after you neck or full length resize? I'm guessing afterwards but thought I'd check. Thanks

After sizing, sizing them makes them longer.

[SCJ429]

Fire them in your chamber first if possible. Then size and trim all the brass in your batch.

[Oldbloke]

Should you trim your cases before or after you neck or full length resize? I'm guessing afterwards but thought I'd check. Thanks

After sizing, sizing them makes them longer.

+1.
But i dont think its a big deal if you do them prior to sizing. You will catch them next time you trim.

[duncan61]

I found that once fired brass needs trimming after full length sizing then it will be fine for a few more reloads I trim every time however its rare that any material comes off after the first time.I use a reamer inside and out and that takes a small amount off

[gordicans]

thnx guys, the users of this forum are very helpful

[Roo farmer]

I've reloaded Remington 223 brass 20 times, without trimming any of them ever.

Explain to me why trimming is needed?

[SCJ429]

Some cases are more prone to grow than others, a 243 is a good example. Eventually the case will be too long to chamber and you need to trim it.

[duncan61]

To bring the fired brass back to the correct dimension.some people weigh brass and primers and stuff.

[Roo farmer]

Some cases are more prone to grow than others, a 243 is a good example. Eventually the case will be too long to chamber and you need to trim it.

Yes I understand the concept, I'm just surprised that no problems have shown up for me in 20 reloads (other than neck splits, which is not from lack of trimming), makes me wonder if it's quite as important as some people make out.

[duncan61]

Case makes a difference and also individual rifles.I have seen a case that got squished at the end it was a Hornet that had grown to the point it hit the lands on closing the bolt

[pomemax]

It sort of depends on the case too if its a 9MM not often it depends what you are asking about bottle necked or straight fire formed or not plus how they were loaded last time .
For my o mark,s i load for them hot 223 and 308 so I always check them after I full length resize but for hunting 223s and 308s i dont have to as much they are loaded no so hot .

[Stix]

Some cases are more prone to grow than others, a 243 is a good example. Eventually the case will be too long to chamber and you need to trim it.

Yes I understand the concept, I'm just surprised that no problems have shown up for me in 20 reloads (other than neck splits, which is not from lack of trimming), makes me wonder if it's quite as important as some people make out.

If the case gets too long it can hit the end of the chamber & if it is squashed it csn only go one way, & that could act like a crimp on the bullet increasing the pressure

[gordicans]

Some cases are more prone to grow than others, a 243 is a good example. Eventually the case will be too long to chamber and you need to trim it.

Yes I understand the concept, I'm just surprised that no problems have shown up for me in 20 reloads (other than neck splits, which is not from lack of trimming), makes me wonder if it's quite as important as some people make out.

Apart from anything else it gets to accuracy. If you're not worried about accuracy too much then probably doesn't matter provided you're not reloading hot. My (limited) understanding is that if you don't trim your cases then you'll have cases of different lengths which means you'll have bullets chambered with varying lengths away from the lands which results in reduced accuracy.

[duncan61]

The seating die sets the distance off lands.Case length will not affect this however neck tension will vary.To set the depth you can full size the case then gently file a bit out till the bullet is firm in the neck then chamber the round a few times on an empty case in different positions to give an overall length.I then set the press so the projectile is .8 mm off the lands I have been told that it allows for the expansion of the primer as the powder ignites it means the projectile is sitting on the lands when the powder burns so there is no jump.Bullet speed can vary a lot and the more that can be done to get consistent results will improve grouping

[gordicans]

actually, come to think of it if the cases vary in size the variability won't be in bullet distance from the lands in the chamber, the variability will be in the depth of seating in the case ... given that the bullet seating die will always seat from a fixed distance from the case holder

[duncan61]

what are you reloading for G

[gordicans]

222

[wanneroo]

Trimming is more a thing for semi and full auto guns. Bolt guns the pressure drops a bit before people unlock the bolt, but in semi and especially full auto guns, the case often has time to expand as it is getting stripped from the chamber and you will see this very much so in belt fed machine gun brass.

[Oldbloke]

From RCBS.

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