How much does OAL matter?

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PeasantWithPitchfork
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How much does OAL matter?

Post by PeasantWithPitchfork »

I have just started reloading. I'm doing 9mm and I have the dies set up and working. I am using the Berry's 115gr plated RN with Winchester primers and 4.0 gr of Titegroup. The loading manual specified 1.130 OAL When I use Federal brass, the OAL is 1.130. PMC is 1.137, blazer is 1.140, and I forget what the Herter's comes out to. All without fiddling with the dies - the OAL is different depending on the brass. [WWB brass is something completely different, I have to change setting on the dies for it.] Does OAL matter that much? I can see that if the COAL was < 1.130 I might run into pressure problems, but I am thinking that longer but still staying under max should be OK? Do I need to test-fit unprimed & unpowdered rounds in the barrels I will be firing the reloads from?
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JustaShooter
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Re: How much does OAL matter?

Post by JustaShooter »

That very issue is why I sort even handgun brass by headstamp - I know it doesn't really matter in the accuracy department or prevent safety issues but it makes me feel better...

Anyway, 1/100" over published OAL is unlikely to matter at all, especially with 9mm which headspaces off of the case mouth. If anything, as you said you will get very slightly lower pressures with longer OAL. If you were loading revolver rounds with longer bullets and were already at the end of the cylinder, that could cause an issue with locking up the cylinder. Or if you were loading rifle rounds where you are out near the lands and the 1/100" might put you touching the lands which could generate pressure issues.
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tbram88
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Re: How much does OAL matter?

Post by tbram88 »

It sounds like you might be using a crimp/seating die (like Lee) if you set it up with federal brass and then used a longer piece (PMC) the case would start to crimp before the bullet was fully seated and you would get a longer COL.

If you set the die up from the longest brand of brass with no crimp your COL will all be the same no matter how long the brass is.
I use a FCD so I don't want any crimp on the seating die.

If you want to roll crimp with the seating/ crimp die then you will need to adjust the die for each different kind of brass to keep the same COL.

Hope this helps, Bob.
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Re: How much does OAL matter?

Post by WY_Not »

Could always set up the die twice. Once to seat and then go back and crimp.
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Re: How much does OAL matter?

Post by Javelin Man »

My P11 would choke on WWB but no other brand. After holding them up to other cartridges, it was visibly obvious that WWB was much longer than anything else and my gun choked on it. When I reload my 9mm, I keep that in mind and make it a little short. I'm away from my reloading journal right now so I don't know the OAL I reload and it's been too long to remember offhand.
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Re: How much does OAL matter?

Post by mreising »

tbram88 wrote:It sounds like you might be using a crimp/seating die (like Lee) if you set it up with federal brass and then used a longer piece (PMC) the case would start to crimp before the bullet was fully seated and you would get a longer COL.

If you set the die up from the longest brand of brass with no crimp your COL will all be the same no matter how long the brass is.
I use a FCD so I don't want any crimp on the seating die.

If you want to roll crimp with the seating/ crimp die then you will need to adjust the die for each different kind of brass to keep the same COL.

Hope this helps, Bob.
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JustaShooter
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Re: How much does OAL matter?

Post by JustaShooter »

mreising wrote:
tbram88 wrote:It sounds like you might be using a crimp/seating die (like Lee) if you set it up with federal brass and then used a longer piece (PMC) the case would start to crimp before the bullet was fully seated and you would get a longer COL.

If you set the die up from the longest brand of brass with no crimp your COL will all be the same no matter how long the brass is.
I use a FCD so I don't want any crimp on the seating die.

If you want to roll crimp with the seating/ crimp die then you will need to adjust the die for each different kind of brass to keep the same COL.

Hope this helps, Bob.
One does not typically roll crimp rounds that headspace on the cartridge mouth.
This. ^^^

But it certainly applies to rimmed rounds like the .38 special / .357 magnum and .44 special / .44 magnum families.
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Re: How much does OAL matter?

Post by Rockcat »

I'm loading 9 mm 147gr Berry's with 3.2 gr of titegroup. I strive to achieve a 1.140 OAL but am comfortably happy with a 1.135-1.145 OAL as long as they drop in and out of the case gauge. As a side note, as long as they all drop in and out of the case gauge, I have found they shoot just fine if they are in the 1.130 - 1.150 OAL range.
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Re: How much does OAL matter?

Post by BobK »

If you sample 10 rounds of ordinary commercial ammo, like Winchester white box, you'll see a 0.010" variation in length.
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Re: How much does OAL matter?

Post by PeasantWithPitchfork »

I think I have it figured out now. I increased the belling 1/8th of a turn, and cranked down the lock rings on the seat and crimp die. I am now getting 1.130 to 1.132 on most of the FC stamped cases. I am definitely sorting by headstamp now. Of course, I am out of 115 gr and am moving on to 124 gr bullets, so I have to start over.
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evan price
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Re: How much does OAL matter?

Post by evan price »

I load 9mm 1.125" OAL with 4.4 of Titegroup, because 4.0 was just too light to cycle the action properly on a couple of guns. In my experience Titegroup burns cleaner at the upper charge levels. If it helps I've worked up loads that are in excess of that using 124 & 125 grain bullets so while 4.4 is listed max load by Hodgdon, it's not a hard ceiling. As long as your chosen OAL is not below published data and not too long to fit the magazine you will be fine, you can adjust your charge and OAL to match the performance you want.
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