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

 

[K22]

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.

My RCBS dies, in the neck area were "scratched" by the accumulation of brass debris shaved off virgin cases before I began chamfering before sizing. At least this was RCBS's diagnoses when I sent the dies back to be refurbished which they did at no cost to me.

However, you may be correct, I do not know, but something causes the neck area of the die to leave vertical lines in the neck area. Since I adopted RCBS's recommendation, I have not had a recurrence of this condition after the dies were refurbished.

 

[old_heli_logger]

Never say, "never" and never say, "always"
Oh crap, nevermind.

I learned one thing at Intel...the proper engineering answer is, "it depends"
If nothing else, that gives you some time to think it through, haha

 

[ebb]

Every set of calipers I've ever touched had a lock nut to lock the jaws at a dimension that you chose. Pick a number, max length, measure your chamber and allow some clearance, whatever. Pick a number that works for your chamber and your liking then lock the calipers and check every piece of brass with the "gage" you have created. If you need to trim some you will know, they won't fit between the jaws. My mentor would cut them a little short to make them all the same. That thinking says if all the necks are the same length then they will all release the same. I have done that for years, I don't have proof that it works but I trust him.

 

[Liven The Dream]

Good Post.
I just received two different orders of Alpha GT Brass. I found necks out of round and outside neck burrs.
I did a complete prep on the complete 400.
I also needed to trim OAL.

Time spent Know, hopefully will show up on the Target ?

 

[kenhwind]

IMO most factory brass seems to be on the short side of oal. But it seems to me that the best time to trim your brass is after it has been fired and resized.

Correct on the case neck being dinged up and out of round. Here you can neck size or just run the brass into a Lyman "M" Die.

When I load virgin pistol brass, I back up my sizing die to just size for bullet depth, using the Dillon 550.

 

[dellet]

I have had a few batches of Norma brass over the years that were slightly over SAAMI max for base to shoulder and longer than I normally sized to. When sized, overall length was max +/- a couple thousands. Kind of nice actually when you think about it. That was the only brass I ever bought that fully formed on the first firing.