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Old April 12, 2012, 10:42 PM   #1
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Newbie OAL Issue

Ok here is what I was loading.

Manual: Sierra
Bullet: Winchester 9mm 115 FMJ-RN
Case: Win
Primer: CCI 500
Powder: Unique
Powder Work Up: 5.0, 5.2, 5.4, 5.6, 5.9, 6.1.

I made a dummy bullet last night prior to charging tonight and set to OAL at 1.165. I did fine on my powder weights because I trickled all of them to make sure I had precise weights.

Issue: when I loaded the bullets into the cases tonight, I checked the OALs and it ranged from 1.158-1.164. What am I doing wrong? I do know that none of the bullets I worked up are over 1.165.

Last night while setting the dummy bullet first, I got the OAL I wanted. I backed the seating pin out and adjusted my crimp to where I wanted. With the lever in the down position and bullet up in the die, I put the bullet seater back to where it was touching the top of the bullet.

Any help would be much appreciated. Thanks.

Last edited by jwrowland77; April 13, 2012 at 07:12 AM.
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Old April 13, 2012, 12:01 AM   #2
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Most pistol seating dies don't push on the tip of the bullet. Instead, they are typically cup shaped (to spread the load and reduce deforming a round-nose bullet) or flat (to push uniformly on a flat-nosed or hollow-point bullet).

If you have the seating die set up for flat bullets, it is possible you are deforming the lead bullet, even though it is jacketed.

If this is not happening, it is possible you are not using a taper crimp die but are trying to use a combination seater/crimp die. These are typically designed to do a roll crimp.

With really careful adjustments, it is possible to make them work for cartridges that do not work with a roll crimp (like 9mm and .45ACP), but it is much easier to use a separate taper crimp die and just use the seater/crimp die for seating.

As the degree of that "just right" taper crimp is a function of case length, the cases have to be all the same length for combination seater/crimp die to work well. When you use a separate taper crimp die, it is just removing the bell with a gradual change in diameter. IMO, these are far less critical of case length.

Finally, it is possible that some of all of the 0.006" difference is actually just manufacturing tolerances.

So, there are three guesses. Without more complete information, that's about all I can come up with...
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Old April 13, 2012, 02:30 AM   #3
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Measure your projectiles to see if there are variances there. You didn't say what kind you are using, most will vary to some degree. Depends on the press too, if it is a center-post turret or progressive it is not uncommon to get OAL differences.
Consistant pulls on the press makes a difference too, make sure you are getting the full stroke when you are seating and crimping.

Seat/crimp dies have the correct type of crimp for the round. If you have a 9mm set the seat/crimp die will taper crimp, I guarantee it. Most do like to crimp separately, though.
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Old April 13, 2012, 03:24 AM   #4
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A variance if +/- .005 is pretty common and nothing to worry about unless you are working at or near max loads.

The causes of the variance are pretty well covered by the posts above.

I determine a target crimp for any round by adding .020 to the bullet diameter. The crimp will vary due to thickness of the cases since I use mixed brass for pistol reloading.
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Old April 13, 2012, 05:03 AM   #5
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I am using a single stage press Hornady LNL. I am using a combo seater/crimp die. I did have to pull some of the dummy rounds I did and the things I noticed were there was a slight line on the bullet near where it was being crimped. Is this ok? I am using just enough crimp to just take the belling out I am using Winchester bullets. I'm pretty sure the seater/crimp is setup for a RN. I do not know if I bought the taper one or not. I bought it from a local store since they actually had them in.
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Old April 13, 2012, 05:31 AM   #6
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Let me add too, that I did not trim any of the cases. I did a lot of reading on here and couldn't get a real read on whether I needed to trim or not. It seemed like some people did and other didn't. If I need to trim then I will.
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Old April 13, 2012, 06:48 AM   #7
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What make or brand of bullet? Is it a real jacket or is it a plated bullet? As noted that variation is normal. If you want you can also crimp as a separate operation. screw the seater dies our 2 turns so that it does not crimp and then seat the bullets to your COL then remove the seater plunger readjust your seater die down to do the crimp.
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Old April 13, 2012, 07:06 AM   #8
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Pa-joe, they are Winchester and they are jacketed.
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Old April 13, 2012, 07:32 AM   #9
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I agree with dmazur especially concerning Winchester bullets.
I load quite a lot of 9mm with various types/brands of bullets and have noticed considerable variation in nose shape/ogive length. While it is important to match the OAL especially on small case, high pressure rounds like 9mm, consider the length to base of bullet as much as OAL.
This dimension determines actual interior combustion area volume(my terminology) more precisely than OAL but OAL is an easier dimension to measure and is usually close enough.
Remember to check fit in your magazine before loading a big lot of ammo.
BTW I never bother "trickling" except on top end mag loads. Just check your measure occasionally-I check every 25 rounds +/-.
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Old April 13, 2012, 08:56 AM   #10
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I load a fair amount of range ammo. Most of mine are mid range loads. For range ammo varying .005" isn't a big deal on OAL in mild to mid range loads. I do suggest loading a full magazine to make sure the OAL is not too long.

I do use a progressive press and when checking the powder drop at the start of a run I first make 5 or 6 drops before I start checking the weight. If I'm using 5 grains of powder I will put the first charge in the pan and if it is 5 grains I add the next one to see if it will then measure 10 grains. I do this for 4 times. I expect to see 20 grains at that time. If it is off I make my adjustment and do it again. My scale is supposed to be accurate plus or minus .1 grains of powder. Using this method I figure I should be close to plus or minus .025 grain. Once I'm satified, I start loading. When I add another 100 primers to the tube I check the powder again the same way. So far using ball type powder that my measure likes I have not had to adjust the powder drop during a run. It still makes me feel better to check it like I do. My ammo seems to be quite consistant using this method. I'm fairly certain it should work for other powder measures too.
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