Did I screw up? Case length overlooked!

Pond, James Pond · May 15, 2015, 05:49 AM

So I've just primed 50 cases ready to do an OCW string at the range sometime soon.

Only once the hand-primer was put away did I remember that I had completely forgotten to trim the cases.

I've measured a few cases to see what length they are. One listed case length is 44.70mm (Lee), and another 44.50mm (Lapua).

Mine measure 44.65-44.75mm, where 0.05mm is about 0.002". So 2thousandths over the Lee max case length

Do I have to decap 50 cases and bin 50 perfectly good primers over this, or is it OK to proceed this once?

Either way, lesson learnt.

jwrowland77 · May 15, 2015, 05:56 AM

As long as you have a bench trimmer like the Hornady one, you can trim the cases without having to deprime...ask me how I know. Lol.

Since I have the Hornady, and I was in this situation, I would just go ahead and trim all the cases to the "Trim To" length.

steveno · May 15, 2015, 06:11 AM

I don't think I would get too excited about .002. dial up .002 on your caliper or micrometer and see how really small that is

mete · May 15, 2015, 06:47 AM

Properly you should form the cases to that particular chamber. If the case is too long you would probably have chambering problems !
Some cases I have never trimmed . The 45acp cases are below the length specs anyway in my experience .The 45acp chambers on the mouth of the case so too short can cause problems.
So expand , trim , crimp only enough to to function properly, not more .

Pond, James Pond · May 15, 2015, 06:50 AM

Quote:

As long as you have a bench trimmer like the Hornady one, you can trim the cases without having to deprime...ask me how I know. Lol.

I don't. I have the Lee case length.

I either decap and trim and recap or leave as is.

Quote:

Properly you should form the cases to that particular chamber. If the case is too long you would probably have chambering problems !

Well, I can look for my longest case and chamber it: see what happens.

What I don't want is a drastic effect on potential accuracy, particulary as this is a set of reloads looking for a pet load for my M400.

jwrowland77 · May 15, 2015, 06:50 AM

Leave as is and test first then.

steve4102 · May 15, 2015, 06:53 AM

44.70mm (Lee) is about 1.760 inches which is SAAMI max case length.

44.50mm (Lapua) is about 1.750 inches which is "trim to Length".

Both are correct.

Your 44.75 or 1.762 is over SAAMI Max case length, but I highly doubt it is "Max" length for your chamber.

Take a look at these diemnsions, note that all but one of these chambers are cut with a max case length of 1.77++.

http://ar15barrels.com/data/223-556.pdf

...and SAAMI list this chamber dimension as 1.772.

http://www.saami.org/pubresources/cc...0Remington.pdf

tobnpr · May 15, 2015, 07:13 AM

^^ This.

.002 could only (rarely) be a problem if you had a really short chamber and the case neck got jammed up before the shoulder made contact.

I've shot (not intentionally, just forgot to measure/trim brass) much longer out-of-spec than that without issues.

Pond, James Pond · May 15, 2015, 07:24 AM

Quote:

Leave as is and test first then.

If it is too long for the chamber, how evident will it be?

With a bolt gun, you'd find it hard to turn the bolt handle down into the locked position, but in an AR? Will the BCG be slightly out of battery?

As these are cases without bullets, if I let the BCG slam them into the chamber, the mouth may just squeeze into the lands under the inertia and the round will be chambered despite being too long, no?

Road_Clam · May 15, 2015, 07:35 AM

1.758 (44.75mm) IMO is of NO worries. My AR has chambered new ammo casings that ended up as long as 1.770 with zero issues. When I first started loading for my AR I was spending hours trimming to exacting tolerances of 1.750" +/- .0001

(well maybe this is a bit "over toleranced) . As I gained experience I realized for my recreational precision AR shooting there is NO need to be trimming to that tight of a tolerance as I notice NO difference in lost or gained precision. I now trim (or do not trim) to +/- .010 casing length and call it a day. I feel it's more beneficial to be spending more time behind my AR's trigger than spending time with trimming the casings. Now adversely, my precision bolt action rifles, I pay closer attention to trim lengths, I like to get those casings to +/- .003 for consistency.

Pond, James Pond · May 15, 2015, 07:48 AM

I've just measured all my newly-primed cases and there are cases from 44.70 all the way to 44.84mm!! That is still only 0.15mm so certainly no huge distance, but I still want to check them out in the chamber.

Starting with a 44.70mm case as a control. My plan is to put them in the mag, but with the mouth just over the edge of the mag.

Release the BCG but use the T-handle to ease it forward. When it stops, I'll see if I can push it forward any particular resistance until in battery.

I'll see how it feels with the control case, then go to the extreme end at 44.84mm and see if any difference is felt.

If yes, then I can start working my way back down the case length ladder...

Pond, James Pond · May 15, 2015, 02:04 PM

Well, I have loaded half my cases.

I had tried loading a few of the longest and they chambered fine. No marks of the mouth rim suggesting that they got rammed into the lands so I think it is all good in the chambering department.

I will say this though:

At 13.50 my time I posted with a worry and potential problem. Within 2 hours I knew where I stood and had learnt something new with a teacher-to-student ratio of 4:1!!

If that doesn't sum up TFL, I don't know what does!!

May 15, 2015, 05:49 AM	#1
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	Did I screw up? Case length overlooked! So I've just primed 50 cases ready to do an OCW string at the range sometime soon. Only once the hand-primer was put away did I remember that I had completely forgotten to trim the cases. I've measured a few cases to see what length they are. One listed case length is 44.70mm (Lee), and another 44.50mm (Lapua). Mine measure 44.65-44.75mm, where 0.05mm is about 0.002". So 2thousandths over the Lee max case length Do I have to decap 50 cases and bin 50 perfectly good primers over this, or is it OK to proceed this once? Either way, lesson learnt. __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.

May 15, 2015, 06:47 AM	#4
mete Senior Member Join Date: June 14, 2004 Location: NY State Posts: 6,575	Properly you should form the cases to that particular chamber. If the case is too long you would probably have chambering problems ! Some cases I have never trimmed . The 45acp cases are below the length specs anyway in my experience .The 45acp chambers on the mouth of the case so too short can cause problems. So expand , trim , crimp only enough to to function properly, not more . __________________ And Watson , bring your revolver !

May 15, 2015, 07:13 AM	#8
tobnpr Senior Member Join Date: August 1, 2010 Location: Tampa Bay Posts: 4,556	^^ This. .002 could only (rarely) be a problem if you had a really short chamber and the case neck got jammed up before the shoulder made contact. I've shot (not intentionally, just forgot to measure/trim brass) much longer out-of-spec than that without issues. __________________ Remington 700/Savage Rebarreling /Action Blueprinting 07 FFL /Mosin-Nagant Custom Shop/Bent Bolts Genuine Cerakote Applicator www.biggorillagunworks.com

May 15, 2015, 07:35 AM	#10
Road_Clam Senior Member Join Date: November 21, 2013 Location: New Hampshire Posts: 1,695	1.758 (44.75mm) IMO is of NO worries. My AR has chambered new ammo casings that ended up as long as 1.770 with zero issues. When I first started loading for my AR I was spending hours trimming to exacting tolerances of 1.750" +/- .0001 (well maybe this is a bit "over toleranced) . As I gained experience I realized for my recreational precision AR shooting there is NO need to be trimming to that tight of a tolerance as I notice NO difference in lost or gained precision. I now trim (or do not trim) to +/- .010 casing length and call it a day. I feel it's more beneficial to be spending more time behind my AR's trigger than spending time with trimming the casings. Now adversely, my precision bolt action rifles, I pay closer attention to trim lengths, I like to get those casings to +/- .003 for consistency. __________________ "To be old an wise you must have been young and stupid"

May 15, 2015, 07:48 AM	#11
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	I've just measured all my newly-primed cases and there are cases from 44.70 all the way to 44.84mm!! That is still only 0.15mm so certainly no huge distance, but I still want to check them out in the chamber. Starting with a 44.70mm case as a control. My plan is to put them in the mag, but with the mouth just over the edge of the mag. Release the BCG but use the T-handle to ease it forward. When it stops, I'll see if I can push it forward any particular resistance until in battery. I'll see how it feels with the control case, then go to the extreme end at 44.84mm and see if any difference is felt. If yes, then I can start working my way back down the case length ladder... __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.

May 15, 2015, 05:56 AM	#2
jwrowland77 Senior Member Join Date: March 23, 2012 Location: Conway, Arkansas Posts: 1,398	As long as you have a bench trimmer like the Hornady one, you can trim the cases without having to deprime...ask me how I know. Lol. Since I have the Hornady, and I was in this situation, I would just go ahead and trim all the cases to the "Trim To" length.

May 15, 2015, 06:11 AM	#3
steveno Senior Member Join Date: June 18, 2004 Location: Minden , Nebraska Posts: 1,407	I don't think I would get too excited about .002. dial up .002 on your caliper or micrometer and see how really small that is

May 15, 2015, 06:50 AM	#6
jwrowland77 Senior Member Join Date: March 23, 2012 Location: Conway, Arkansas Posts: 1,398	Leave as is and test first then.

May 15, 2015, 06:53 AM	#7
steve4102 Senior Member Join Date: December 23, 2005 Location: Minnesota Posts: 2,955	44.70mm (Lee) is about 1.760 inches which is SAAMI max case length. 44.50mm (Lapua) is about 1.750 inches which is "trim to Length". Both are correct. Your 44.75 or 1.762 is over SAAMI Max case length, but I highly doubt it is "Max" length for your chamber. Take a look at these diemnsions, note that all but one of these chambers are cut with a max case length of 1.77++. http://ar15barrels.com/data/223-556.pdf ...and SAAMI list this chamber dimension as 1.772. http://www.saami.org/pubresources/cc...0Remington.pdf

May 15, 2015, 02:04 PM	#12
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	Well, I have loaded half my cases. I had tried loading a few of the longest and they chambered fine. No marks of the mouth rim suggesting that they got rammed into the lands so I think it is all good in the chambering department. I will say this though: At 13.50 my time I posted with a worry and potential problem. Within 2 hours I knew where I stood and had learnt something new with a teacher-to-student ratio of 4:1!! If that doesn't sum up TFL, I don't know what does!! __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.