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Discussion Starter · #1 ·
I've been pretty content with my 9MM loads for a while now. I load Xtreme 115g RN bullets with 6.0g of Ramshot Silhouette to an OAL of 1.157. I decided to play with OALs to see if there would be any increase in accuracy. I started at 1.110 and worked my way up to the max OAL of 1.169 in groups of 5. The ones that grouped the best were the 1.169 loads.

Anyone load their ammo at this OAL?
 

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I sorta doubt it's the OAL that increases your accuracy.


When you keep the same powder charge and increase OAL,
you decrease pressure and decrease apparent burn rate.
That slows down the bullet, obviously. Which affects recoil but also
allows the gun to rotate more as the bullet travels down the bore.

My suspicion is that your gun shoots better under those conditions.
Not because the OAL varies, but because the powder burn and
internal bullet travel have slowed down.

One way or the other, if it works for you then keep it up!



Note:
Longer OAL is common when trying to achieve max velocity with
tons of very slow powder in a 1911. It is common in 1911 pistols
because you can use 38 Super magazines for the longer cartridge length.
In fact, you can go beyond 1.169" especially with heavy bullets like
130, 135 and 147 grain. But caution: Guys who do that are generally
well above SAAMI pressure levels to gain Major Power Factor in special guns.
This isn't something you want to do unless you want to damage
your gun or shorten its useful life. This is a competition thing with
Open class guns made for the purpose.
 

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But caution: Guys who do that are generally
well above SAAMI pressure levels to gain Major Power Factor in special guns.
This isn't something you want to do unless you want to damage
your gun or shorten its useful life. This is a competition thing with
Open class guns made for the purpose.
Other than a ramped barrel(which most 9mm 1911s are) there isn't anything different in an open gun barrel and a regular 1911 barrel that makes it more suitable for 9mm Major ammo. Yes it will burn the barrel out faster (guys claim 70-80k rounds) but its not a different barrel.
 

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Congratulations; YOU are a handloader.

I normally run my 'generic' 9x19 ammo at 1.010 out to 1.155" (based on specific bullet), and rarely exceed that.
 

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I sorta doubt it's the OAL that increases your accuracy.


When you keep the same powder charge and increase OAL,
you decrease pressure and decrease apparent burn rate.
That slows down the bullet, obviously. Which affects recoil but also
allows the gun to rotate more as the bullet travels down the bore.

My suspicion is that your gun shoots better under those conditions.
Not because the OAL varies, but because the powder burn and
internal bullet travel have slowed down.

One way or the other, if it works for you then keep it up!
???

So in other words, it is OAL.
 

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load it as long as your gun and magazine will take. the only issue you might have is that you won't be able to use those rounds in another gun because of the length.
 

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My standard "minor" load is at 1.160". Longer than that and you will have problems with some magizines.

I have some "major 9" loads that use OAL's too long to fit in most 9mm magizines but with with the pistols I use them in, the mags have enough room to hold 38 super.
 

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???

So in other words, it is OAL.
No, did you notice that he uses the same powder charge at all cartridge lengths?
He's changing pressure when he changes OAL. The OAL by itself isn't the critical factor.

My suggestion is that he achieves the same result in his gun with shorter OAL and less powder.

I'm hoping our good OP takes the challenge to set up a series of tests by varying powder charge
to see if he also achieves accuracy at other powder/OAL combinations. That would be cool.

Got it? :)
 

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My guess is the longer OAL allows the bullet to enter the bore more concentrically, AND center itself sooner in its travel.

But it's just a guess.
 

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No, did you notice that he uses the same powder charge at all cartridge lengths?
He's changing pressure when he changes OAL. The OAL by itself isn't the critical factor.

My suggestion is that he achieves the same result in his gun with shorter OAL and less powder.

I'm hoping our good OP takes the challenge to set up a series of tests by varying powder charge
to see if he also achieves accuracy at other powder/OAL combinations. That would be cool.

Got it? :)

Same powder charge for all lengths. The only change is OAL. Therefore OAL is the variable that makes the difference.

Yes, pressure changes with OAL with the same powder charge. But all you're done is identify one effect of changing the OAL. There are other things that change with OAL, as weshoot2 has noted.
 

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It does not surprise that the greatest OAL gave the best accuracy with the powder charge being equal. That is the standard practice in rifle cartridge loading and MAY be applicable here. This is due to the bullet engaging the rifle lands sooner rather than later. There are specific tools to measure headspace in rifles, maybe even for pistols. I have only used the rifle tools
 

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No, did you notice that he uses the same powder charge at all cartridge lengths?
He's changing pressure when he changes OAL. )
Yes, as you lengthen the OAL you can drop pressure until a point then once you touch the rifling and eliminate any free bore, your pressures will go up again.
 

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Bless you guys!

I'm trying to challenge Mr. Thomas to set up tests to see if his achievement is OAL,
or perhaps attributable to other variables.

I hope your good posts don't discourage him into thinking one answer always works.
If he thinks he lengthened his OAL for better accuracy and that's all he needs to do every time,
he will surely miss out on discovering a lot of reloading knowledge and skill on his own.


Truly, I don't think it's his OAL. I think he simply lowered his velocity.
But that doesn't matter, the only way he will find out for sure is to test, test, test.
Ultimately, you and I can't tell him for sure. The gun will tell him.
 

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I'm trying to challenge Mr. Thomas to set up tests to see if his achievement is OAL,
or perhaps attributable to other variables.
Ahh yes, the only way to know everything is to try everything.
 

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Discussion Starter · #16 ·
I'll do some testing once I get my chrony.
 

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I have some (actual and 'official') NATO 9mm on my shelf that measures 1.169"........
 
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