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COL Longer is better?


xracer

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Is this a true statement or not? The longer the COL the better as long as it doesn't engage the rifling when chambered and feeds properly(fits in the magazine). I recently heard of someone loading to 1.09" and thought "thats a little short" Looking at it from an accuracy standpoint.

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"Better" is to simple a concept.

More case volume means less pressure in a given load, that's the main reason to load long when using heavy bullets and fast powders as so many of us like to although if overpressure is not a concern with your particular combination of powder and bullet, I don't see any problem with loading shorter than SAAMI specs.

As for accuracy: I don't know... I'm not yet to the stage of my load development where I'm tuning OAL for accuracy, but I have heard some people swear by the accuracy of shorter loads.

I started reloading primarily to shoot 9 major, so my first priority has always been to make major and not blow up the gun, then to cycle reliability, then to produce as much gas as possible to work the comp, then accuracy. I haven't made it that far yet :)

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I've loaded 9mm major to 1.145" out to 1.170", and found no difference

in accuracy.

By 9mm minor is slightly more accurate with a slightly shorter OAL,

but doesn't feed as well, so I load a little longer and lose a little

accuracy.

If you enjoy tweaking the most out of your handloads, start with

the longest OAL your mag/chamber will take, and then experiment

with shorter OAL's also, to see which is "best" for YOU. :cheers:

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With my Glock 34, I did one test at max length to get to power factor. So I loaded at 1.155 and bumped the powder until I got to a little over 125 power factor. Then I loaded 10 each OALs from 1.085" to 1.155" in .01" increments. Then I shot these all for groups. I found in my gun, with my load, 1.125" shot the most accurately, had no feeding problems, and made about 130 PF. I shot from 1.155" down, checking velocity and for pressure signs at each step. Even at 1.085", I think I was only at 134 PF. So, after establishing that 1.125" shot the most accurately and made PF, I loaded up 200 of them and shot them in a local match (I don't have anywhere I can currently shoot that allows me to simulate match conditions. Probably a better idea to try this in practica). They functioned flawlessly, and now I have my load. That's my process, hope it will help you.

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The thing is you cannot just make a blanket rule. different guns behave differently. even guns of the same model but different actual guns behave differently.

All I can say is, don't just accept that longer is better. do something like johnsons1480 did.

Basically what I do is pick the bullet I'm going to use, the powder and the primers (for 9mm I use a mix of brass, if you want to get scientific use same headstamp and trim to length too - too hard for me).

once ive got a load at a nominal OAL (say 1.100) that makes the PF I want (usually around 130 for minor) then I load up a bunch with different OALs.

In my CZ I went as short as 1.070 and up to whatever was the longest I could load (from memory around 1.130, something like that). In my particular CZ (in fact in 2 of them) I found group size closed up quite a bit as I got shorter. I settled on 1.080 as the best compromise between reliable length and accuracy.

but again, that's with a particular bullet (135GN RN CMJ - frontier brand), powder and primer combo.

many others find in their gun, with their bullet longer works better.

so my advice? experiment a little with your own gun and your own load.

it actually doesn't take as long as you think. you have to review the results with a grain of salt as there's a human factor in there (unless you mount the gun in a ransom rest). I usually shoot the groups supported with some kind of rest at 15 yards.

when I've got say the 3 best I then shoot a few more off hand the way I normally shoot to see how they 'feel' to shoot too.

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Unfortunately, I was using Chrono Log to document the velocities (terrific app btw), and I had to wipe my phone recently and lost all of the velocity data except for the load I ended up with. I can show you the group sizes at 25 yards and the screenshot of the one load I have though.

I used Bayou Bullets 135 gr RN, Federal Cases, Federal Match SPP

10 Shot Group Sizes

1.085 OAL = 6.694"

1.095 OAL = 5.462"

1.105 OAL = 6.353"

1.115 OAL = 6.058"

1.125 OAL = 3.163"

1.135 OAL = 8.303"

1.145 OAL = 9.407"

1.155 OAL = 9.088"

Velocity Stats for 1.125" OAL

BayouBullets_9mm_135_VVN320_3.6gr_1.125O

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J1480, are you finding that The Magic OAl (1.125") has decreased your

group sizes from 6-9" down to 3"?

I've never seen or heard of that magnitude of change before.

I would expect 4" down to 3", but not such a large change. :cheers:

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J1480, are you finding that The Magic OAl (1.125") has decreased your

group sizes from 6-9" down to 3"?

I've never seen or heard of that magnitude of change before.

I would expect 4" down to 3", but not such a large change. :cheers:

I did a similar test with Montana Gold about two years ago and didn't see such extreme variations. It was surprising to me how badly they shot at certain OALs, but they weren't random flyers. These were "groups" more or less, evenly distributed around the large box that became the max spread. The only way to take out the human in the equation is to repeat the test with a ransom rest. I don't have one of those, so I supported my forearms with sand bags and was able to hold very steady through the shot. I would be more than happy to repeat the test with a ransom rest if anyone is willing to loan one out :cheers:

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One thing to bear in mind is that the case wall gets thicker as you get closer to the base. So if you load to 1.100" or shorter, you'll have more rounds not pass case gage/plunk test. With a long bullet, like the Bayou 147g 9mm, 1.130" is enough to start to see a significant increase in the number that fail.

I have a CZ-75, so I have to load most bullets pretty short to not engage the rifling. The only exceptions I've found, so far, are the Berry's RN, Extreme RN, Golden Saber JHP, and the Bayou 124g RN. With those, I can load to 1.155" easily, and can load 1000 with maybe one or two failing the case gage. With something that requires me to load to 1.100" or shorter (Berry's FP, Bayou 135g, every other hollowpoint I've tried, every Blue Bullet, etc.), I'll have 3 or 4 fail out of every hundred.

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I have seen dramatic changes in group size like that but it was with rifle loads. Did you try 1.120 and 1.130 to see if the data followed any trend line? That would be interesting to see.

One thing appears clear, that barrel really did not like anything 1.135 or longer.

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I have seen dramatic changes in group size like that but it was with rifle loads. Did you try 1.120 and 1.130 to see if the data followed any trend line? That would be interesting to see.

One thing appears clear, that barrel really did not like anything 1.135 or longer.

I did not. I decided that it wasn't worth my time to chase any additional accuracy gains. Also, I don't have a micrometer seater, so quite a few rounds were dumped into the practice bucket while trying to get the OAL right for this test.

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Thanks for the reply on the data request

I was hoping to see how performance was effected by oal

always been told best accuracy is around 130-135 pf for 9mm

I'm working on a steel challenge load and have noticed a significantly pronounced sweet spot but nothing like you got.

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Thanks for the reply on the data request

I was hoping to see how performance was effected by oal

always been told best accuracy is around 130-135 pf for 9mm

I'm working on a steel challenge load and have noticed a significantly pronounced sweet spot but nothing like you got.

If that's the case, that would explain the very bad groups from 1.135-1.155. They averaged between 125-130 PF. Everything 1.125" and shorter averaged between 130 and 135 PF.

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Unfortunately, I was using Chrono Log to document the velocities (terrific app btw), and I had to wipe my phone recently and lost all of the velocity data except for the load I ended up with. I can show you the group sizes at 25 yards and the screenshot of the one load I have though.

I used Bayou Bullets 135 gr RN, Federal Cases, Federal Match SPP

10 Shot Group Sizes

1.085 OAL = 6.694"

1.095 OAL = 5.462"

1.105 OAL = 6.353"

1.115 OAL = 6.058"

1.125 OAL = 3.163"

1.135 OAL = 8.303"

1.145 OAL = 9.407"

1.155 OAL = 9.088"

wow.

I never would have guessed it would be this crazy, from 3" to 9", that is insane....

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Like I said, 'noticed a significantly pronounced sweet spot but nothing like you got'

I went maybe 3/4" better groups at 25 yds, not 6" to 3". And that was confirmed with averaging 4-5 ten round groups

pf, bullet jump are all elements but my interest was just oal variations and pressure.

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Unfortunately, I was using Chrono Log to document the velocities (terrific app btw), and I had to wipe my phone recently and lost all of the velocity data except for the load I ended up with. I can show you the group sizes at 25 yards and the screenshot of the one load I have though.

I used Bayou Bullets 135 gr RN, Federal Cases, Federal Match SPP

10 Shot Group Sizes

1.085 OAL = 6.694"

1.095 OAL = 5.462"

1.105 OAL = 6.353"

1.115 OAL = 6.058"

1.125 OAL = 3.163"

1.135 OAL = 8.303"

1.145 OAL = 9.407"

1.155 OAL = 9.088"

Velocity Stats for 1.125" OAL

BayouBullets_9mm_135_VVN320_3.6gr_1.125O

Curious if varying the bullet weight given the exact load and OAL schedule would result in the same results. My thought is there is an optimal OAL for a given bullet weight given an identical load.

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Curious if varying the bullet weight given the exact load and OAL schedule would result in the same results. My thought is there is an optimal OAL for a given bullet weight given an identical load.

I'm not sure I'm following, can you restate that?

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Curious regarding OAL,

Typically is it true that if all other factors are equal the longer the oal the higher the power factor?

Lower the PF. Longer OAL means more volume, less pressure, less velocity. That being said, powders do funny things once you just them out of their useful range...

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