Effect of trim length variance on non-crimped loads

Poodleshooter · February 11, 2002, 04:59 PM

Has anyone ever found a vast velocity or accuracy spread from non-crimped loads with wide variances in trim lengths???
I recently accidentally primed a bunch of .223 brass that I trimmed on my Lee trim kit. Over a batch of 300 rounds, the trim variance goes from 1.760" (max OAL)-1.740" (.010 under the trim length). I was going to trash this brass, but now that I've primed it, I'm trying to decide whether to write it off. I've sorted it into lots by trimmed length, so the box by box extreme length spread isn't more than .003".
I never crimp on my .223 loads due to the high powder density,so should I trash it, load it as blasting ammo, or load it up with decent bullets and not sweat it?

ryucasta · February 11, 2002, 09:47 PM

I would not sweat it the difference is negligible. My biggest concern would be are you using mixed head stamps. Since the different manufacturers of brass tend to have different case thickness and that will directly affect the performance of your rounds.

C.R.Sam · February 11, 2002, 10:29 PM

Yeah, different makers and lots probably make more difference than your case length variation.

Please report your results.

Sam

Poodleshooter · February 12, 2002, 01:45 PM

Cases are all the same lot of Malaysian soft 5.56 brass. It's crap brass that I cut and primed in a hurry for FMJ plinking loads (which I have subsequently given up on due to my HBAR barrel's propensity for destroying light 55gr bullets). The headstamps are barely readable, and there are extractor marks on the rim, but there are no interior rings or other imminent case failure signs. I've segregated them into batches with differences of .003", and loaded them with several test loads using WC846 (BallC2), AA2495 and 2520, CCI SR primers and Hornady 68gr BTHP match bullets loaded to 2.255 OAL. I'll report after firing them over the weekend. Powder weight data was from Hornady and Accurate Arms, but conflicts by nearly 10% with Sierra data for the same bullet weight, so I will refrain from posting it.

Fatelvis · February 12, 2002, 08:52 PM

As long as the longest case isnt over the max allowable, they`ll all be safe to fire. As far as accuracy, I think you`re wise for seperating them by headstamp, but the difference between the longer and shorter cases probably wont be detectable, especially in a stock rifle. Have fun shooting, and forget about the piddly details, that the gunwriters and benchresters worry themselves about!

Poodleshooter · February 22, 2002, 12:43 PM

Well, so much for that worry. I put 5 rounds into just under 1" at 100yds on a mildly windy day (and I have the flu!). Not a bad load!

C.R.Sam · February 22, 2002, 02:46 PM

What works
Does.

Thanx for the report.

Sam

February 11, 2002, 04:59 PM	#1
Poodleshooter Senior Member Join Date: August 7, 2000 Location: Floating down the James River in VA Posts: 2,599	Effect of trim length variance on non-crimped loads Has anyone ever found a vast velocity or accuracy spread from non-crimped loads with wide variances in trim lengths??? I recently accidentally primed a bunch of .223 brass that I trimmed on my Lee trim kit. Over a batch of 300 rounds, the trim variance goes from 1.760" (max OAL)-1.740" (.010 under the trim length). I was going to trash this brass, but now that I've primed it, I'm trying to decide whether to write it off. I've sorted it into lots by trimmed length, so the box by box extreme length spread isn't more than .003". I never crimp on my .223 loads due to the high powder density,so should I trash it, load it as blasting ammo, or load it up with decent bullets and not sweat it?

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February 11, 2002, 09:47 PM	#2
ryucasta Senior Member Join Date: February 4, 2002 Location: Los Angeles, CA Posts: 431	I would not sweat it the difference is negligible. My biggest concern would be are you using mixed head stamps. Since the different manufacturers of brass tend to have different case thickness and that will directly affect the performance of your rounds.

February 11, 2002, 10:29 PM	#3
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	Yeah, different makers and lots probably make more difference than your case length variation. Please report your results. Sam

February 12, 2002, 01:45 PM	#4
Poodleshooter Senior Member Join Date: August 7, 2000 Location: Floating down the James River in VA Posts: 2,599	Cases are all the same lot of Malaysian soft 5.56 brass. It's crap brass that I cut and primed in a hurry for FMJ plinking loads (which I have subsequently given up on due to my HBAR barrel's propensity for destroying light 55gr bullets). The headstamps are barely readable, and there are extractor marks on the rim, but there are no interior rings or other imminent case failure signs. I've segregated them into batches with differences of .003", and loaded them with several test loads using WC846 (BallC2), AA2495 and 2520, CCI SR primers and Hornady 68gr BTHP match bullets loaded to 2.255 OAL. I'll report after firing them over the weekend. Powder weight data was from Hornady and Accurate Arms, but conflicts by nearly 10% with Sierra data for the same bullet weight, so I will refrain from posting it.

February 12, 2002, 08:52 PM	#5
Fatelvis Senior Member Join Date: June 10, 2001 Location: Lockport, IL Posts: 490	As long as the longest case isnt over the max allowable, they`ll all be safe to fire. As far as accuracy, I think you`re wise for seperating them by headstamp, but the difference between the longer and shorter cases probably wont be detectable, especially in a stock rifle. Have fun shooting, and forget about the piddly details, that the gunwriters and benchresters worry themselves about!

February 22, 2002, 12:43 PM	#6
Poodleshooter Senior Member Join Date: August 7, 2000 Location: Floating down the James River in VA Posts: 2,599	Well, so much for that worry. I put 5 rounds into just under 1" at 100yds on a mildly windy day (and I have the flu!). Not a bad load!

February 22, 2002, 02:46 PM	#7
C.R.Sam Senior Member Join Date: October 29, 1999 Location: Dewey, AZ Posts: 12,858	What works Does. Thanx for the report. Sam