General case length and trimming questions - Page 3

Metal god · October 11, 2018, 10:33 AM

I have this target showing that .010 increments in seating depth matter in accuracy .

This target/load was done using the OCW method and this was my final seating depth fine tuning of that load and process .

The final result was this load . That's a 1" orange sticker in the center and was shot at 300yds

So at least for me and this load .010 difference in seating depth shows on paper . The question would seem to be does .005 ? If so getting the distance from datum to bullet ogive consistent would seem to be pretty important ???

hounddawg · October 11, 2018, 11:09 AM

Quote:

The question would seem to be does .005 ? If so getting the distance from datum to bullet ogive consistent would seem to be pretty important ???

According to the big boys in LR benchrest .003 matters. I figure for someone like me that difference would get lost in the noise so when I get to .5 MOA I call it good enough.

Good shooting BTW, I'd take that last load to a 300 yard match with a smile on my face and a song in my heart.

**44 AMP** · October 11, 2018, 11:31 AM

For all those discussing measuring to ogive, datum point, shoulder set back, distance to the lands from some magical mystery point and how to measure it, I have a couple questions, #1, how does that answer this...?

Quote:

I'm still new to reloading and looking to refine my case trimming technique. I'm reloading 30-06 for my M1 Garand and was hoping someone could help with answering some general questions.

1) Can I prolong the life of the case by trimming less, and trim to the MAX case length of 2.494" rather than the Trim-To Length of 2.484"?

2) Can I get more accuracy by trimming to the MAX case length of 2.494" so the ogive of the bullet sits 0.010 further into the free bore?

3) I use a Tri Way trimmer to trim my brass and the case length varies with each case a little to a lot depending on the starting length of a given case. To what decimal place do I need to match my cases in case length to produce the best groups?

The OP asks about case trimming, NOT how to measure distance from ogive to lands, or so it seems to me.

Next question, can you tell us if ammo loaded to ".xxx" off the lands, (set that way with whatever system you use to measure) can you tell us that ammo WILL work in the OP's M1 Garand?? Can you tell us that it will give improved accuracy? Will you claim it will make a difference in an M1 Garand??

Metal god · October 11, 2018, 11:45 AM

Quote:

The OP asks about case trimming, NOT how to measure distance from ogive to lands,

With all do respect ( and I mean that ) It's called the natural progression of a conversation . The OP mentioned his trimmer indexes off the shoulder and that brought up a few more interesting points that go directly to using that type of trimmer . I might be wrong because I don't remember in detail everything the OP has said in this thread but I think he talked about seating depth as well , maybe not ?

If the OP is satisfied with the narrowed scope of his question I'm more then happy to stop . He may not know this but there are some very experienced reloaders talking about things that at some point he will have questions about . We may be overloading him because he's new to this and that was/is never my intention .

**Unclenick** · October 11, 2018, 02:10 PM

Yes, it did seem to wander into this progression, but at this point it has probably run its course.

To review the answers to Riley's original questions:

Case life cannot be improved by improving trimming precision. Learning to resize to make the head-to-shoulder measurement only about 0.002" shorter than the brass is after firing in your chamber should enable it to feed the Garand and that practice will extend case life if your gun's chamber isn't at dead minimum, in which case, that would be about what you are getting out of the sizing die now.

Accuracy is not affected by trim length within the normal SAAMI case length range, which is 2.474" to 2.494" for 30-06. Don't exceed the high end, but going a little below the low end won't normally hurt anything as long as bullets are seated with adequate depth and you are not crimping.

Case length variation when trimming with the Tri-Way is due to variation in the head-to-shoulder datum measurement after the brass has been resized. That variation will be reflected as variation in bullet jump, but using standard COL's as given by the bullet makers, it should not be so snug that this error source matters a lot in the Garand.

I have owned and rebuilt and loaded for several Garands and can say the most important things about loading for them are to be sure the primers are seat hard and at least 0.003" below flush with the case head. I think the CCI #34 primers are a worthwhile added safety precaution in this application. Use powders that are not too fast for the gun or get an adjustable gas cylinder plug. The old rule of thumb is that any powder that has a maximum charge weight listing of over 53 grains for a 150-grain bullet is too slow for the Garand and will raise muzzle pressure to a point that it can hurt the operating rod. Avoid trying to exceed government ammunition velocities with it. The 150, for example, should not exceed 2740 fps at 26 yards (about 2800 fps at the muzzle). If you are driving it faster, you are probably overworking the op rod.

cw308 · October 11, 2018, 03:29 PM

44AMP
You did the same thing with your last question . It Happens .

F. Guffey · October 12, 2018, 07:59 AM

Quote:

. The OP mentioned his trimmer indexes off the shoulder

There are a lot of reloaders that can not keep up. I am not one of 'one those' reloaders. I am one of the third kind of reloader. I am the fan of the L.E. Wilson case gage reloaders. I understand you guys

have a dislike for the datum that is not my problem. From 1938 the Wilson case gage has been a datum based tool. The Wilson case gage measures in two directions, it measures from the datum back to the end of the case head and it measures from the datum forward to the opening of the neck. The length of the Wilson case gage from the top to the bottom is the same length as the case length according to reloading manuals.

A reloader should be able to determine how much the case should be trimmed. A reloader should be able to determine the length of the chamber from the shoulder to the case head. The part that is too complicated for reloaders is the mindless trimming of cases that is not necessary because they do not understand the datum based tool was designed for the reloader to read the instructions.

The instructions suggest the reloader use a straight edge, for me? Not a problem. I use the straight edge and I added the feeler gage and I made a tool with a dial indicator to determine case protrusion in thousandths. Most reloaders use their thumb nail.

SO? The Wilson case gage was designed to be used with trimmers that set up on the shoulder, Do reloaders just go through the motions of reloading to without understanding what they are going?

I know, this stuff I do is over your head; I have one chamber that is .016" longer from the shoulder of the chamber to the bolt face than a minimum length/full length case. When I trim cases for that chamber I add the .016" to the length of the case . If I am trimming cases with a trimmer that sets on the shoulder of the case I do not have to worry about it. 'WHY! ?'

F. Guffey

RC20 · October 12, 2018, 02:22 PM

Yep, way over my head. So far over my head I am at the bottom of the Marianna's trench in comparison. I just am not sure how I will struggle on with life.

Shock, I still manage to shoot 1/2 inch groups and have not gone to heck for my being over my head.

So yes, I will bumble along in my plebeian way and I know its shocking, but enjoying myself as I do so.

F. Guffey · October 13, 2018, 09:06 AM

I understand all of that, the one thing I see no humor in is the 'laughing at' I had rather laugh with.

F. Guffey

October 11, 2018, 10:33 AM	#51
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	I have this target showing that .010 increments in seating depth matter in accuracy . This target/load was done using the OCW method and this was my final seating depth fine tuning of that load and process . The final result was this load . That's a 1" orange sticker in the center and was shot at 300yds So at least for me and this load .010 difference in seating depth shows on paper . The question would seem to be does .005 ? If so getting the distance from datum to bullet ogive consistent would seem to be pretty important ??? __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

October 11, 2018, 02:10 PM	#55
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Yes, it did seem to wander into this progression, but at this point it has probably run its course. To review the answers to Riley's original questions: Case life cannot be improved by improving trimming precision. Learning to resize to make the head-to-shoulder measurement only about 0.002" shorter than the brass is after firing in your chamber should enable it to feed the Garand and that practice will extend case life if your gun's chamber isn't at dead minimum, in which case, that would be about what you are getting out of the sizing die now. Accuracy is not affected by trim length within the normal SAAMI case length range, which is 2.474" to 2.494" for 30-06. Don't exceed the high end, but going a little below the low end won't normally hurt anything as long as bullets are seated with adequate depth and you are not crimping. Case length variation when trimming with the Tri-Way is due to variation in the head-to-shoulder datum measurement after the brass has been resized. That variation will be reflected as variation in bullet jump, but using standard COL's as given by the bullet makers, it should not be so snug that this error source matters a lot in the Garand. I have owned and rebuilt and loaded for several Garands and can say the most important things about loading for them are to be sure the primers are seat hard and at least 0.003" below flush with the case head. I think the CCI #34 primers are a worthwhile added safety precaution in this application. Use powders that are not too fast for the gun or get an adjustable gas cylinder plug. The old rule of thumb is that any powder that has a maximum charge weight listing of over 53 grains for a 150-grain bullet is too slow for the Garand and will raise muzzle pressure to a point that it can hurt the operating rod. Avoid trying to exceed government ammunition velocities with it. The 150, for example, should not exceed 2740 fps at 26 yards (about 2800 fps at the muzzle). If you are driving it faster, you are probably overworking the op rod. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

October 12, 2018, 02:22 PM	#58
RC20 Senior Member Join Date: April 10, 2008 Location: Alaska Posts: 7,014	Yep, way over my head. So far over my head I am at the bottom of the Marianna's trench in comparison. I just am not sure how I will struggle on with life. Shock, I still manage to shoot 1/2 inch groups and have not gone to heck for my being over my head. So yes, I will bumble along in my plebeian way and I know its shocking, but enjoying myself as I do so. __________________ Science and Facts are True whether you believe it or not

October 13, 2018, 09:06 AM	#59
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	Laughing at or with? I understand all of that, the one thing I see no humor in is the 'laughing at' I had rather laugh with. F. Guffey Last edited by F. Guffey; October 13, 2018 at 09:09 AM. Reason: add the no and add h to rather.

October 11, 2018, 03:29 PM	#56
cw308 Senior Member Join Date: September 2, 2010 Location: Plainview , Long Island NY Posts: 3,863	44AMP You did the same thing with your last question . It Happens .