Does factory new brass ever need to be trimmed prior to its first use ?

[Hammer]

Know a brand new unfired case needs its mouth deburred and chamfered, but does the case length ever need to be trimmed before its first loading ?

 

[alf]

I've been known to do it, but I prefer to shoot them once to fireform to the chamber, & full length size before detailing.

 

[47WillysGuy]

Measuring the length and compare that number to SAAMI. Otherwise no.

But before deburrimg and chamfering, the necks need to be round,

 

[NorCalMikie]

Something else to consider. Chambers are cut about .020 "over" SAAMI max trim length. Might be a good idea to know "your" chamber length before you consider trimming.

 

[K22]

As long as it is not over the max chamber length, no it does not need to be trimmed.

However, I trim, chamfer, and F/L size (zero bump) for uniformity purposes. Often, I find virgin cases with out of round case mouths. Therefore, I like to make sure the neck is aligned with the body of the case thus the reason I like to F/L size.

Also, I never size virgin cases with first chamfering the necks because I've often found the necks to contain rough edges especially on the OD which can peel of brass and scratch the die if not chamfered first.

 

[JFrank]

does the case length ever need to be trimmed before its first loading ?

I’ve never trimmed virgin brass.

 

[JLT]

As long as it is not over the max chamber length, no it does not need to be trimmed.

However, I trim, chamfer, and F/L size (zero bump) for uniformity purposes. Often, I find virgin cases with out of round case mouths. Therefore, I like to make sure the neck is aligned with the body of the case thus the reason I like to F/L size.

Also, I never size virgin cases with first chamfering the necks because I've often found the necks to contain rough edges especially on the OD which can peel of brass and scratch the die if not chamfered first.

Dies are hardened steel. Brass won't scratch it, but it will stick to it. That gives the appearance of scratches on subsequent pieces of brass.

 

[shoot4fun]

I can't say "never" to trimming unfired virgin brass. I usually will run a fresh box of brass through the intended rifle to make sure it is "to spec" and, yes, I have had occasion where NIB brass would not chamber. A simple pass through the sizing die always fixes that one (after I inspect for some other issues).
One time, with Alpha BRA brass, the "run through" brass all chambered but just didn't feel right. I did some measurements and found it was, as Bob Ueker would say, "just a bit outside". I ran that all through an expander mandrel and then trimmed very slightly and all was good then. It's the only time I have ever encountered such.

 

[Dufas]

Can't hurt anything to MEASURE it. Trim any that need it.

 

[bozo699]

I’ve never seen new brass that’s longer than my chambers. With that being said I do measure new brass and if it was to long I would trim it of course. With something like a Dasher, BRX , BRA etc fireformed from 6br brass I’ve never seen any of it to be perfectly uniform in oal so I like to shoot it several times , 2 or 3 at least. After that because I’m ocd about keeping everything the same to take out any variations I measure every piece, I don’t usually trim to the shortest piece, I separate into groups the shortest ones I mark and don’t trim I use them for fowlers and getting centered up on target and uniform all the rest. For groundhog and plinking ammo I usually don’t trim them until they need it to safely chamber. In my humble opinion in a perfect world I like my brass to almost touch but not quite as I don’t see carbon build up as bad as when it’s multiple thousands off as it usually is with new brass but that’s just me.
Wayne

 

[D Coots]

Obviously works for you.

I've heard a SR HOF shooter say that if the case mouth is too close to the bbl, it will hit upon the explosion and change the impact of the bullet. I see your point and his also?????

Haven't been inside a chamber lately....

 

[Straightshooter1]

Know a brand new unfired case needs its mouth deburred and chamfered, but does the case length ever need to be trimmed before its first loading ?

You'd have to have a chamber outside of SAAMI specs to be concerned about having to trim them, as brass manufacturers tend to produce brass that's within SAAMI specs. The biggest issue I have with virgin brass is making sure the necks are round and chamfered.

 

[SD guy]

Ever need to be? Never say never. Though I expect this depends on your chamber, If by chance you have a short chamber then I think you can fill in the rest. A cast of your chamber & a few measurement should help understand the application to a given chamber. There is a chance that the next chamber just may fall outside the expected parameters.

 

[bozo699]

Obviously works for you.

I've heard a SR HOF shooter say that if the case mouth is too close to the bbl, it will hit upon the explosion and change the impact of the bullet. I see your point and his also?????

Haven't been inside a chamber lately....

I actually read an article years ago about just what you mentioned. I’ve checked but don’t think I’m hitting , I don’t run that tight however it’s something to ponder. Thanks for sharing that.
Wayne