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Why does the OAL matter and what can go wrong if its not right?

Discussion in 'Reloading' started by wrx04, Dec 8, 2011.

  1. wrx04

    wrx04

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    Ive loaded about 8000 trouble free rounds of 230gr ball ammo with my 550b to this point. Recently, ive decided to try a new bullet type for a change. I picked up a case of 200gr flatpoint fmj ammo from montana gold.

    Do i need to adjust my bullet seating die, or can i just run the new bullet type through it? The importance of the OAL is making sure the bullet contacts the rifling at the proper place, correct?

    When i line the new bullet (cartridge) up with a 200gr gold dot and a 230gr winchester ranger hp, they appear almost identical in length. The 230gr LRN ive been shooting is slightly longer than these three (obviously).

    I would measure the length, but my digital calipers just took a crap, and i dont have a spare battery. I cant 'F anything up too bad if the OAL isnt perfect, can I?
     
  2. F106 Fan

    F106 Fan

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    If you seat the bullet too deep, you will increase the pressure. That might be a problem.

    If you seat the bullet too long, it won't chamber - the bullet will run into the rifling. If it is just short of the rifling, that will solve the first problem but it might still be too long to run up the feed ramp.

    Finally, it might not fit in the magazine.

    So, yes, OAL is important and you should use whatever is specified in the loading manual of the bullet manufacturer. Often this data is available online.

    Sometimes you can get by using information from the powder manufacturers.

    What you can't do is just guess!

    Richard
     


  3. wrx04

    wrx04

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    So essentially, unless you set the bullet too deep and cause a spike in pressure, the only issue will be reliability. Thats what i wanted to know. Im positive its not set too deep, but i was concerned it may not be set deep enough.

    I have made some dummy rounds (no powder/primer) and they chamber/cycle just fine in all my guns. I will get accurate measurements before making any live rounds and reference lyman as well, but i think i should be gtg. Thanks.
     
  4. Three-Five-Seven

    Three-Five-Seven Señor Mombo Millennium Member

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    OAL is useless in any absolute sense.

    The problem is to get the rounds the proper dimension to run in the gun you want to use them in. Once you know where to seat the bullet to make the gun work, you can use the OAL of that round to make the rest of them.

    You can use a published OAL to make rounds only to find out that they don't work, or that they have serious over-pressure problems.

    Your gun, rather than published OALs, is your guide.
     
  5. F106 Fan

    F106 Fan

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    Let me put it another way. Personally, I won't load anything that I can't find in a loading manual. If it isn't printed, it doesn't exist.

    I want to be able to point at the page and say "See, it says so right there!".

    But that's just me. Then again, I use fast powders like Bullseye and, lately, Tite Group. There's no room for error and certainly no room for guesswork.

    Richard
     
  6. fredj338

    fredj338

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    While a nice thought, I couldn't reload if I didn't learn to extrapolate data. There is precious little lead bullet data & even less for plated. There are so many diff bullets, it's impossible to find published, vetted data for all. We won't even get into wildcat rounds where no data is available.
    Yep, OAL matters quite a bit when it comes to pressures & handguns. Read my little blog on vel testing w/ diff OAL. All things being equal, vel increases = pressure increases. Seating too long can also raise pressures if you are jambed into the lands, more a rilfe issue than handgun, but still it is there. So as noted, OAL is always gun & bullet specific, regardless of what printed data tells you.
     
    Last edited: Dec 8, 2011
  7. F106 Fan

    F106 Fan

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    The Speer manual shows an OAL of 1.200" for a 200 gr TMJ FN versus 1.260" for a 230 gr TMJ RN. Most of the difference is due to the fact that the FN isn't round. I would expect the distance between the base of the cartridge and the base of the bullet to be quite similar.

    The Hornady manual shows the 230 gr FMJ at 1.230" OAL.

    The Sierra manual shows the 200 gr FPJ at 1.155" and the 230 gr FMJ at 1.270"

    The right answer must be in there somewhere.

    Richard
     
  8. sourdough44

    sourdough44

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    I measure mine for each chamber, rifle loading. I don't want a bullet stuck in the rifling upon case removal without firing. It needs to fit the magazine. I usually am close to 'book' COL but vary as needed.
     
  9. leeward419

    leeward419

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    The ogive and shape of bullets are different. You need to ck and make certain the bullet isnt touching the lands/grooves. Too long and wont function in mag
    too short and also could have pressure issues. there is some wiggle room but you need to be careful. In my rifles I have bought a tool that measures the leade, in pistols I find bullet data that is as close as possible and start from there, I always ck to make certain that the bullet doesnt contact the rifling
     
    Last edited: Dec 9, 2011
  10. Jim Watson

    Jim Watson

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    That is a good approach. I would go one step farther by dropping a dummy into the chamber of the barrel, clean and out of the gun. It should go in freely to the same depth as a factory load or your previous lot of satisfactory reloads.
    The MG bullets are truncated cones similar to Hornady and cannot be treated like a roundnose.

    When Richard says "The right answer must be in there somewhere." he is probably right but it is up to you to find where in that wide range of bullet seating data you need to be for your bullets and your barrels.

    If you are going to load to recipe, you should pick a recipe before you buy the ingredients. A lot of people get terribly upset when they buy A and can find published data only for B.
     
  11. Gunnut 45/454

    Gunnut 45/454

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    All I'll add is the OP is loading 45 ACP which is one of the more forgiving calibers in pistol for OAL. Even with max charge wt's you have to cram the bullet very deep to get over pressure. Not that you can't but it is alot harder to do. And being an Semi auto he'll not be able to load to long as they will not chamber! OAL is more critical in Rifle rounds for all the reasons stated above. As it can cause a blow up!:supergrin:
     
  12. fredj338

    fredj338

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    Even the 45acp gets ugly quickly w/ uberfast powders running max & bullet setback, but certainly more forgiving than a 40 or 357sig. If every reloader keeps in their head that OAL is bullet & guns specific, they'll have few problems as long as they fit the bullet to the barrel/chamber, rifle or handgun. Overall length wasn't even mentioned in early reloading manuals. It was just assumed you fit the bullet to the barrel.:dunno:
     
    Last edited: Dec 9, 2011
  13. F106 Fan

    F106 Fan

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    And yet there are precision rifle shooters who want the bullet to not only contact the rifling but to significantly contact it. Actually, they want the bolt to push the case up on to the bullet.

    Then there are other shooters who want the bullet to jump to reach the rifling and for my 6.5x284 NORMA, I can't get within 0.060" of the rifling without the bullet falling out of the case. There's just no bullet to case neck engagement with a HPBT if the bullet is seated to touch the rifling.

    I'm pretty sure there are no constants in reloading. What there is is documentation. If you find a load that works, write it down! That's my great failing, I am always forgetting to document my loads. I'm working on it...

    Richard
     
    Last edited: Dec 14, 2011
  14. fredj338

    fredj338

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    And that is fine, as long as the load is adjusted for the huge increase in pressure that comes by wedging the bullet into the lands.:whistling:
     
  15. Colorado4Wheel

    Colorado4Wheel

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    For Pistol that is just a HORRIBLE idea. Make a dummy round that just touches the lands and back it off at least .010". You will find that will still normally be a pretty long round. If your loading LEAD you may not be able to back it off .010". You may need to settle on .005" as they sometimes load pretty short already.
     
    Last edited: Dec 14, 2011
  16. F106 Fan

    F106 Fan

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    I was pretty careful to state 'precision rifle shooters'. I agree that it is not a process for pistol shooters. Besides, I don't think rounds long enough to touch the rifling will even fit in a magazine.

    Most of my pistol reloading is .45 ACP and then only with 3 bullets: 200 gr LSWC, 230 gr LRN and 230 gr FMJ. These are pretty easy to load and data is all over the place. Of course, none of it agrees so I kind of pick a happy medium and don't load anywhere near max.

    In terms of RN and SWC, there is always the SAMMI spec to fall back on. In the document version I have there is data for RN on page 49 and for SWC on page 50. Still, the OAL has quite a range between min and max for OAL: 0.085" for RN and 0.105" for SWC.

    An OAL of 1.250" falls within spec for both bullet shapes and that is what I am using.

    Richard
     
  17. Colorado4Wheel

    Colorado4Wheel

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    It would be very easy to load lead rounds that touch the lands in a lot of barrels. I just wanted to be clear. I didn't read the entire thread.
     
  18. For more high pressure rounds like the .40, how much of a safe range is there? I am seeing OALs go from 1.123 to 1.130, with most coming in around 1.125. Is that ok? I measured a factory made round and it came in at 1.128.
     
  19. rpgman

    rpgman SCGLOCK

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    I load my 40's to 1.130 with a + or - of .005 so you should be fine.
     
  20. F106 Fan

    F106 Fan

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    Have you got any feeler gauges? If not, go to some auto supply and get a set. Take out a 0.003" gauge and look at it. Do you really think that such a small change in OAL could possibly matter? It's likely that the bullets vary by that much.

    Take a dozen bullets and measure their length. How much do they vary?

    Without the magic of statistics (which is really voodoo spelled the hard way), it isn't possible to tell exactly how your OAL is set but it looks like you are getting 1.1265", +-0.0035". Back to that 0.003" feeler gauge...

    What is important is when you compare your OAL to factory that they are the same bullet. You can't compare a FN to a RN or anything like that.

    Richard