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Old 04-22-2010, 14:40   #1
cysoto
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Will OAL variance have a significant effect on accuracy (pistols)

When it comes to loading for pistols, will changing the OAL have a significant effect on accuracy?

I have noticed that changing the crimp does affect the spread of a group shot at 25yds; sometimes just a few thousands of a difference will produce marked results. But can the same be said of changing the OAL?

I am currently loading my 9mm rounds to 1.125" but I have noticed that a lot more people prefer 1.135". Is this something that is being done to improve feeding reliability or is there another reason why a longer OAL is preferred?
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Old 04-22-2010, 16:05   #2
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I haven't seen it. Bullet choice, powder choice, crimp, all affect accuracy to one degree or another. OAL just doesn't seem to come into play much. Look how much "freebore" there is in a 38sp revolver w/ WC ammo. Doesn't seem to hamper accuracy any.
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Old 04-23-2010, 12:07   #3
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Quote:
Originally Posted by cysoto View Post
When it comes to loading for pistols, will changing the OAL have a significant effect on accuracy?

I have noticed that changing the crimp does affect the spread of a group shot at 25yds; sometimes just a few thousands of a difference will produce marked results. But can the same be said of changing the OAL?

I am currently loading my 9mm rounds to 1.125" but I have noticed that a lot more people prefer 1.135". Is this something that is being done to improve feeding reliability or is there another reason why a longer OAL is preferred?
The COL can vary from bullet to bullet, Remingtons are shaped different than Winchester that are different from Hornady all in the same weight group. Some pistols like 'em short other like 'em long. My HP likes em short my 1911's like em long, sometimes!!

Shooter ability is more in play than COL in most handgun shooting. COL is much more important for reliability. Not that accuracy might not be affected but a few thousandths is probably not going to show for most of us. (that includes me BTW)

Greg
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Old 04-25-2010, 20:52   #4
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So, other than feeding issues, is there any other particular reason why people choose to load 9mm rounds to 1.135" over 1.125"?
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Old 04-26-2010, 02:03   #5
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So, other than feeding issues, is there any other particular reason why people choose to load 9mm rounds to 1.135" over 1.125"?
Again, bullet shapes vary. One 115gr FMJ is not identical to the next, some are more rounded, some more pointed. A diff of 0.01" is less than 1/64 of an inch! It really doesn't matter that much.
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Old 04-27-2010, 19:16   #6
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hah! i split the difference in that i am trying for 1.130". i have some that are a little shorter, and some that are a little longer, but nothing varies more than about 0.005" one way or another.

good enough for me.

-matt
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Old 04-27-2010, 19:53   #7
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Probably the only way to tell with an iron sight pistol or revolver would be to use something like a ransom rest, and then shoot alot of rounds.
I chalk my group sizes up to technique-or lack of it-in my shooting.
If you can hit a paper plate at 10 yards with your weapon it and your ammo are shooting decent groups.
just my 2 cents
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Old 04-27-2010, 20:22   #8
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Probably the only way to tell with an iron sight pistol or revolver would be to use something like a ransom rest, and then shoot alot of rounds.
I chalk my group sizes up to technique-or lack of it-in my shooting.
If you can hit a paper plate at 10 yards with your weapon it and your ammo are shooting decent groups.
just my 2 cents
If you can't hit a paper plate @ 10yds, then your ammo is not the issue.
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Old 04-27-2010, 20:45   #9
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If you can't hit a paper plate @ 10yds, then your ammo is not the issue.
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Old 04-27-2010, 21:09   #10
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If you can't hit a paper plate @ 10yds, then your ammo is not the issue.

I don't care what you say... it's the ammo I tell ya!

Jack
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Old 04-27-2010, 21:20   #11
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Varying OAL will change the velocity of the bullets. I observed this effect with 45ACP, trying to get Berry's 185gr RNHB bullets to work right. I don't reload 9mm, although I'd expect the same will hold true.
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Old 04-27-2010, 21:59   #12
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Varying OAL will change the velocity of the bullets. I observed this effect with 45ACP, trying to get Berry's 185gr RNHB bullets to work right. I don't reload 9mm, although I'd expect the same will hold true.
You are most certainly correct and I am sure this must be true of all calibers. If the OAL is shortened, then the pressure inside the case must be higher which therefore produces higher velocities.

One thing that I have found out though is that the higher velocity doesn't always produce better accuracy. I think there must be something like a "sweet spot" for bullet performance; they seem to be most accurate in a very particular (and sometimes small) range of velocities. With so many variables in any given caliber (bullet shape, weight, powder, etc) finding this "sweet spot" can be quite challenging.
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Old 04-27-2010, 22:03   #13
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Quote:
Originally Posted by norton View Post
Probably the only way to tell with an iron sight pistol or revolver would be to use something like a ransom rest, and then shoot alot of rounds.
I chalk my group sizes up to technique-or lack of it-in my shooting.
If you can hit a paper plate at 10 yards with your weapon it and your ammo are shooting decent groups.
just my 2 cents
I understand what you are telling me and I can assure you that I am not trying to put together a bullseye load. I am just loading for USPSA and IDPA. The "A-zone" on a USPSA target is roughly 11" x 6" and I have heard many say that, as long as I can hit that at 25yds, I really don't need any better accuracy. The problem is that sometimes you are not shooting a full "A-zone" but instead just a "head-shot" or a small plate. This means that I have to be pretty certain of where my POI is; and the more variance there is to accuracy, the better the chance of ending up with a hit on a lower scoring zone or even a miss.

I am happy with a load when I can consistently achieve an accuracy of 2.5" to 3.0" at 25yds from a bench rest. Then I hear others tell me about how they can shoot 1" groups at this same distance and it gets me thinking that I must be doing something wrong for not being able to get a tighter group.
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Old 04-27-2010, 22:09   #14
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I don't care what you say... it's the ammo I tell ya!

Jack
I am with you Jack!! When is comes to passing the buck for my poor performance I am always quick to blame my ammo, or the pistol, or the weather patterns in Kathmandu; but those two Mikes on that target... I shall not be blamed for those!!
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