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Old May 3, 2013, 10:33 AM   #1
ops
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Nobody pays attention to COAL on straight-walled pistol cartridges?

I have definitive proof that cartridge OAL on a 45ACP is paramount to group size-that is-paramount to top accuracy. Why does no bullet manufacturer's ballistician or any old-timer that can shoot reputable back-woods bullseye groups that I have spoken with agree with or consider this seating depth factor? Any comments, anybody?
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Old May 3, 2013, 10:46 AM   #2
45_auto
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Maybe because everyone but you has "definitive proof" that it's not critical? Maybe if you shared your definitive proof you would get some useful feedback on why others don't find it applicable.

Group size at 25 yards with any of my .45's is identical regardless of the cartridge OAL.

Of course, it's always possible that everyone in the world is wrong except you.
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Old May 3, 2013, 11:08 AM   #3
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Quote:
Originally Posted by ops
Nobody pays attention to COAL on straight-walled pistol cartridges?
Not sure where you got that idea? If you read through threads on loading .45 Auto or any other pistol round on this forum you will find lots of folks pay close attention to cartridge overall length (COL or COAL if you hyphenate overall to over-all, as was done before 1950) in handgun loads.

Quote:
Originally Posted by ops
I have definitive proof that cartridge OAL on a 45ACP is paramount to group size-that is-paramount to top accuracy.
It can make a big difference with cast bullets. I've had the illustration below on this board for years. Seating cast bullets to headspace by bullet contact with the throat rather than the case mouth (third from left) has cut group size as much as 40% for me, and reduces leading.



With jacketed bullets, on the other hand, it does not seem to matter nearly as much. The 25 yard group below was shot with Hornady 200 grain JSWC's seated with the shoulder of the bearing surface at about 0.020" in front of the case mouth, as is typical of commercial loads. It was not near the throat.



Quote:
Originally Posted by ops
Why does no bullet manufacturer's ballistician or any old-timer that can shoot reputable back-woods bullseye groups that I have spoken with agree with or consider this seating depth factor?
Be careful here. Seating depth and COL are not the same thing. You control seating depth (how far the bullet goes into the case) by adjusting COL (Cartridge Overall Length), but unless your cases are exactly the same length, the same COL for all will not yield the same seating depth for all.

Seating Depth = Case Length + Bullet Length - COL

COL = Case Length + Bullet Length - Seating Depth
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Old May 3, 2013, 11:17 AM   #4
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Quote:
Nobody pays attention to COAL on straight-walled pistol cartridges?
Not true. I pay close attention to COAL on my handloaded pistol rounds. I load to fit the chamber when possible (the magazine may limit the length). I vary the amount of “jump” depending on bullet type and material; example, I’ll set lead bullets closer to the lands than jacketed.
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Old May 3, 2013, 11:21 AM   #5
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I don't get that accuracy focused in pistol. If OAL affects rifle accuracy about 1/2" at 100 yds, that would be about .1" at 25....=doesn't matter to me!

What does matter to me is the plunk test and feeding. I load ammo as long as I can that will do both of those. I get decent accuracy too.

So what is your proof?
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Old May 3, 2013, 11:22 AM   #6
ops
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OK you said "Group size at 25 yards with any of my[your] .45's is identical regardless of the cartridge OAL." That would have been good enough. I get most of my groups from the range, and most of my sermons from Baptist preachers.
I find that 0.010" change in seating depth with 5.0gr Win.231 and a Berry's 230RN in a Kimber Stainless Target at 18 feet from a sandbag puts 10 rounds in 7/10". Any seating depth other than that specific COAL value throws them all over a 12x12 paper. I wonder if anyone ELSE sees this type behavior.

And the thing is, when I ask a ballistician they say it shouldn't make a difference. OK! And the guys that got me into the ACP shooting can ding a quarter at 25 yards and they say they've never even thought about seating depth, as long as they get proper feed and function!
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Old May 3, 2013, 11:36 AM   #7
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I worry far more about feed and function in my ACP's than I do anything else. I also rarely shoot past 10 yards for anything other than fun (never really got the point of shooting 25 yards with a pistol).

I also readily admit that I just about always view a pistol as a purely defensive weapon and want to make sure that at ranges I'm most likely to be using said pistol that it functions, feeds, extracts and I can put rounds where I need them to go.
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Old May 3, 2013, 11:51 AM   #8
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If my groups went from .7 to "all over the paper" from a .010" change in OAL, I certainly would look for another cause. I would think that a lot of experienced reloaders of the .45 ACP here pay a lot of attention to cartridge OAL, I do. I shoot my 1911 out to 25 yards regularly and occasionally try for 50 yard hits (not a lot to brag about there!) so I like my ammo to be as accurate as I can, within reason (I don't swage/form primer pockets, I don't weigh each powder charge, but do weigh a lot of them, I don't weigh each bullet or case. But I do take care to get each cartridge fairly close; all bullets seated to within .003", uniform "crimps", etc.).

Could you share your "definitive proof?"
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Old May 3, 2013, 11:56 AM   #9
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I just wanted to say thanks to unclenick and serf 'rett for their informative posts, as I am learning about reloading for semi-auto guns.
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Old May 3, 2013, 12:36 PM   #10
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Quote:
Originally Posted by ops
OK you said "Group size at 25 yards with any of my[your] .45's is identical regardless of the cartridge OAL."
I never said any such thing, so the quote marks are not appropriate. That group was intended as an example of a load which was not tuned to the gun in any particular way. The gun is, however, a tightly match accurized gun and not typical.


Quote:
That would have been good enough. I get most of my groups from the range, and most of my sermons from Baptist preachers.
I was not giving you a sermon. I simply pointed out your blanket statement that nobody pays attention to seating depth is a false assertion. And also, you will confuse readers if you try to use cartridge length and seating depth interchangeably. Since we have many dozens more readers of each thread than ever log in to read or participate in them directly, defining terms to keep communication clear for them is a normal moderating role.

Quote:
I find that 0.010" change in seating depth with 5.0gr Win.231 and a Berry's 230RN in a Kimber Stainless Target at 18 feet from a sandbag puts 10 rounds in 7/10". Any seating depth other than that specific COAL value throws them all over a 12x12 paper. I wonder if anyone ELSE sees this type behavior.

And the thing is, when I ask a ballistician they say it shouldn't make a difference. OK! And the guys that got me into the ACP shooting can ding a quarter at 25 yards and they say they've never even thought about seating depth, as long as they get proper feed and function!
OK. Now I understand what you are asking.

The most likely cause of that much group spread is the action not locking up consistently completely. It can be consistent enough to fire and function, but not enough to get the barrel into the exact same position relative to the sights each time. That can happen if the rounds don't chamber smoothly enough and some guns can be very, very picky about the exact cartridge length when it comes to feeding a particular bullet. I suspect that's what is happening here.

When you have some of your ammo that goes all over the map, try loading just one round into the magazine at a time and dropping the slide manually to chamber each round. Then push on the back end of the slide to ensure it is all the way in battery. See if a group fired with these singly-loaded rounds is tighter. If so, then you have the answer; it's a feed problem with the other cartridge lengths. In that case, having a reputable gunsmith do reliability work that includes feed ramp and barrel alignment and timing on the gun will likely remove much of that sensitivity.
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Last edited by Unclenick; May 3, 2013 at 12:42 PM.
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Old May 3, 2013, 01:04 PM   #11
ops
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Unclenick. I apologize for misdirection. I have put you on alert and need to apologize because of someone else's attempt to insult. My sermon comments were for the first responder at the very top of the page, the one who waits for new users to come online and has no data himself to share.
Thanks immensely for your data and tested results. I asked my friend at the range "how long before I can shoot like you do"? He said "how many rounds have you fired"? I said 2,000. He said "you'll be ready in about another 6,000 rounds"! Ha! Now when be outshoots me I can say (because he doesn't look at COAL for accuracy) "well you just got lucky"! Thanks again very much.
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Old May 3, 2013, 06:43 PM   #12
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Quote:
Unclenick. I apologize for misdirection. I have put you on alert and need to apologize because of someone else's attempt to insult. My sermon comments were for the first responder at the very top of the page, the one who waits for new users to come online and has no data himself to share.
Even in an apology you're insulting. Your first comment was pretty strong and way outta left field. You say you're the only one with "definitive proof" and even ammo manufacturers don't know as much as you do. 45_auto was merely the first to tell you that you don't know what you're talking about...
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Old May 3, 2013, 06:56 PM   #13
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I would like to make an interjection here--after 35,000 rounds in the last four years thru my pistols and doing the "Plunk" test as I always do, i still don't know what I am doing.
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Old May 3, 2013, 07:06 PM   #14
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My basic accuracy standard for service autos is 4" at 50 yards, for five shots from a rest. I expect a good centerfire revolver to shoot better but to tell the truth, I have a hard time holding any closer than that.

For better than 40 years, I've been able to meet that standard with untrimmed pistol brass in both autos and revolvers. If I were shooting for money or trophies, I'd take every precaution to insure the consistency necessary for 10 shots in 2" at 50.

Nick raises a good point about getting your seating depth just right with 45 SWC's. Assuming a close copy of the H&G #68, I have run them at 1.250" for decades with good accuracy in a number of guns- and boring reliability.
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Old May 3, 2013, 08:04 PM   #15
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Quote:
18 feet from a sandbag
Carry on.
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Old May 4, 2013, 05:20 AM   #16
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Plated bullets, based on load process, can show drastic accuracy changes.
Suggest examining your process, and experimenting with other bullets of different material and manufacture.
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Old May 4, 2013, 06:06 AM   #17
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On revolvers ya gotta pay attenion to the amount of bullet going into the case !!!

Makin the boiler smaller makes pressures spik faster!!
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Old May 4, 2013, 01:07 PM   #18
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I would try what Uncle Nick has suggested, I have used his advice since I started reloading and have made my reloads better and my shooting has improved. (I am still going to tell anyone else that inquires that I am just a natural! )

Also, try adjusting powder charges and seating depths. Like others, I have not had to worry to much about jacketed bullets, but lead, for me, seems to have to be set a little closer to the lands for the "WOW! Did you see that shot?" effect.
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Old May 4, 2013, 03:33 PM   #19
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Thanks for the support.

On re-read, I think the OP just didn't express what he meant clearly until his second post. By "definitive proof" I believe he meant he had proved that in his gun with his ammo component combination he'd shot enough test rounds at different COL's to demonstrate the described effect wasn't shooter error and wasn't a figment of his imagination. He just didn't understand why others weren't reporting the same issue. Hopefully, we're on the way to an answer.

The single shot test will make the magazine follower pressure the same on each round, so the clip stripping forces are the same each time, so the slide closing momentum is the same each time. That and the manual push on the slide should get him into battery the same way each time. Watching the back of the slide to see how close it comes to flush with the back end of the frame after each shot is another good indicator of feed consistency. The exact amount of overlap there isn't critical as long as the gun functions, but that overlap does need to be the same each time for accuracy.

All sides of the discussion should keep in mind that few of us on the forum are professional writers and few of us have the literary skill to accurately convey the subtleties of a grin, a sneer, or a shrug, or to control innuendo precisely. There's no body language to read for backup, so it's easy to read some unintended offense into a post. Unless it's spam, the default mode should be to give the apparent offender the benefit of the doubt. I got the wrong idea here initially, too.
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