OAL question


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BAE984
March 3, 2010, 08:56 PM
Hey all..I'm a first time loader working up some 9mm. I've created a couple dummy rounds to test..they headspace perfectly and cycle fine. I'm using 147gr plated round nose bullets, but my manual (Lyman) lists flat nose lead, and FMJ loads. The FMJ load lists OAL at 1.115", while the flat nose lead is 1.089". I'm loading these with charges from the lead bullet column, but OAL at 1.115 because it's a round nose bullet...is this correct thinking? Want to load on the safe side.

Thanks!

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ranger335v
March 3, 2010, 09:09 PM
The primary issue with OAL is feeding and chambering. If it works, it's good.

Walkalong
March 3, 2010, 09:31 PM
The FMJ load lists OAL at 1.115", while the flat nose lead is 1.089". I'm loading these with charges from the lead bullet column, but OAL at 1.115 because it's a round nose bullet...is this correct thinking?

Yes, it is.

ranger335v is correct. The main issue with O.A.L. for autos is to feed well. Work up your loads at that O.A.L., whatever it may be.

thorn-
March 4, 2010, 12:22 AM
Another thing to consider: using a lower OAL than your book data can raise pressure in bad ways. Using a higher OAL will not make it unsafe, but as mentioned above can cause feeding issues. Point being: from a danger standpoint, a higher OAL is ok. Just don't go lower without considering that you're raising internal pressures.

thorn

BAE984
March 4, 2010, 05:32 AM
Great! Thanks

AzBuckfever
March 4, 2010, 06:25 PM
If just for plinking where precision accuracy isn't a concern, would it be a bad thing to just take a factory cartridge and measure the OAL; then go off that. Not meaning to highjack the thread here but every time I've shot factory ammo, I've never had an issue with FTF, Stovepipes, etc...

rfwobbly
March 4, 2010, 08:31 PM
BAE -
Sorry I didn't see this sooner...

There are particular issues with 147gr in 9x19 in that the bullet is sooooo long that there isn't much room left for the powder. Take your OAL and subtract the bullet length. That will tell you where the base of the bullet lies inside the case.

With some simple math you can calculate the base of the bullet below the case rim, so set your caliper's depth gauge to that distance and see if the depth gauge skims the powder once you've dumped that into the case.

I shoot A CZ which is one of the tighter chambers around. When I shoot Berry 147gr RN plated, I can load those all the way out to the SAAMI max length of 1.169". You may be able to do likewise if you are tight on powder space.

Hope this helps!

BAE984
March 4, 2010, 09:23 PM
Thanks RF...I'll check the measure. I gotta pick up a smaller powder disk tomorrow. I'm not throwing much powder, so I bet it own't be a problem.

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