Inconsistent COAL because of case length?

[Djstorm100]

I loaded my first 32 rounds last night of Winchester Primer, 77 SMK, 8208XBR. Trying to load match ammo for my 18inch AR15 Powder is ranging from 22.0 to 23.4 (ladder test cartridge).

This is my first time loading rifle and I was told case length did not matter for COAL just as long the case length did not exceeded 1.760'

Brass was once first brass that ranged from 1.735 to 1.760. I ran these through a SB Full Sizer (RCBS). Set the bullet seating die to give COAL of 2.260 (magazine length . Load up another round and its 2.253, 2.240, 2.262. It's all over the place. I did not trim the brass since it was not over 1.760. I did measure the bullets thinking it was that but I was only seeing a change of 0.003-4. Not the 0.01 change I was seeing.

So I got on here and a search what Google hit on but guys were saying they are getting small changes to .005-9 not .01-2.

Thoughts?

Press is a Less single stage
RCBS SB full die and Bullet seating
Lyman Full sizer die and Bullet seating die


I did notice the Lyman's bullet seating guide (the part that actually touches the bullet) sat deeper on the bullet vs the RCBS being smaller (grabs at closer to the tip vs Lyman)

 

[JRM83]

Were the results the same for the RCBS and Lyman seater?

Did you chamfer the inside of the case mouth?

Were you being consistent on the amount of force you used to seat the bullets?

Did it feel like any of the bullets seated harder than others?

 

[Djstorm100]

Were the results the same for the RCBS and Lyman seater?

Did you chamfer the inside of the case mouth?

Were you being consistent on the amount of force you used to seat the bullets?

Did it feel like any of the bullets seated harder than others?

1) only used the RCBS, going to load some more tonight using the Lyman

2) Did not, was told I did not need to since it's boat tail

3) Yes, run the ram up until pressure it felt and add alittle more until the press cams over

4) I did not, at first I had too much crimp but I cure that by backing the die body out and then adjusting the bullet steam accordingly.

 

[wildfowler]

When I load ladders with increasing powder charges I find that I have to adjust my seater die between charges to compensate for the rising charge column of powder.

Also, when you get your load worked out consider a bullet comparator tool to measure OAL based of the bullet ogive not the tip. It will be more accurate. You will have to measure off the tip of a particular brand of bullet to keep within the confines of the magazine but then take a reading with the comparator and record that number in your load book.

That's all I got.

 

[wildfowler]

Also, I chamfer all new brass and then only after I trim when needed.

 

[Djstorm100]

When I load ladders with increasing powder charges I find that I have to adjust my seater die between charges to compensate for the rising charge column of powder.

Also, when you get your load worked out consider a bullet comparator tool to measure OAL based of the bullet ogive not the tip. It will be more accurate. You will have to measure off the tip of a particular brand of bullet to keep within the confines of the magazine but then take a reading with the comparator and record that number in your load book.

That's all I got.

The reason I kept my COAL to 2.260 was to take in account the rise in powder. I did measure some factory ammo and they are not open tipped but they measured considerably shorter (55 grain is why and so that it chambers in 99% of rifles)

 

[wildfowler]

Maybe I mis-understood? Are you seeing that much variation with bullets seated on top of the same powder charge or does it change in step with the powder charge increase?

 

[Djstorm100]

Maybe I mis-understood? Are you seeing that much variation with bullets seated on top of the same powder charge or does it change in step with the powder charge increase?

No matter what charge I have from 22.0-23.4 grains I'm getting a variation of COAL from 2.240-2.261

 

[wildfowler]

Sorry, I'm at a loss and will have to defer to the ogive comparator recommendation to rule out ogive to tip inconsistencies.

Seems excessive and I am probably not considering something else?

I can't get this info anytime soon, but I have several bins with sorted 220 grain SMK that probably vary by as much as you're reporting. But those were pull down and I don't know how much damage that process does to the bullet. May not be a similar comparison?

 

[BLDTYLRY]

There's always going to be variations in bullet Ogive which will effect your bullet seating depth and COAL. If your OCD requires a lower tolerance I recommend you sort your bullets by Ogive if you are concerned about COAL variations.

BTW - You mentioned Crimping, crimping can also effect your COAL depending how much crimp is applied. To see how much measure your COAL before and after crimping and report back.

 

[Djstorm100]

There's always going to be variations in bullet Ogive which will effect your bullet seating depth and COAL. If your OCD requires a lower tolerance I recommend you sort your bullets by Ogive if you are concerned about COAL variations.

BTW - You mentioned Crimping, crimping can also effect your COAL depending how much crimp is applied. To see how much measure your COAL before and after crimping and report back.

Thanks!

Is it good measure to get a case length is in the middle (say brass ranges from 1.740-1.760, so I would use 1.750) to use as the crimp? What I'm thinking is if I set the die up for a brass that is 1.740 and while reloading I use a 1.760 brass, that crimp will be too much. I place a very light crimp just enough so the bullet can not be push down.

 

[Twoboxer]

If you are seating and crimping in the same die/step, varying case lengths prolly explain your problem. Try applying NO crimp, seat a few, compare OALs . . . any differences should only result from varying bullets shapes plus the inherent =/-.001 or so.

Then either leave the rounds uncrimped, or perhaps use the Lee FCD to crimp. My understanding is that die can deal with varying case lengths..

 

[gstaylorg]

The case length variance should not have caused your seating depth variance...I'd look elsewhere. In addition, if you have a lot of bullets that varies by as much as .022" (max difference in seating depth you mentioned in OP) between where the seating die stem contacts the bullet and where your comparator contacts the bullet ogive, I'd also be looking to buy bullets from a different manufacturer. Is it possible that bullet variation in that region could be that high? Sure it is, but you will need to do some sorting before seating them if that is really the underlying cause. I'd be more inclined to believe that bullet variation is not your problem. From your description, I'm guessing it is something related to your seating die or resizing process. Whether that guess is correct or not, it's pretty easy for you to ascertain. Simply sort some bullets by OAL and seat a few of the same length. If your sorted bullet length varies by less than a couple thousandths, and the seating depth variance disappears, then you have your answer. If the length-sorted bullets still show large seating depth variance, then bullet variation was not the problem.

As mentioned above, you should always chamfer your brass. In addition, you may have an issue with neck tension, also as mentioned above. It should not be necessary to crimp, if that's really what you're referring to. I can't tell from the way you used "crimp" whether you're actually referring to neck tension or a true crimping process. If you want a little more neck tension, simply use a slightly smaller bushing when you resize. A .248" bushing will give you very close to .002" nk tension, .247" will be close to .003" nk tension, and so on. Even though factory ammo may have nk tension as high as .008"-.010", you probably don't need to go that far, even for a semi-auto.

 

[Djstorm100]

Inconsistent COAL because of case length?

I'm not using a bullet comparator. I use calipers from tip to base of brass. I've since learn you can not measure a OTM this way. I have a comparator coming today

Where can I get some of these bushing?

Using tapatalk

 

[InfScout1/69]

Unless you have a bushing die.. fL or Neck... You have no use for bushing.

 

[Djstorm100]

I got a rcbs SB FL, I don't know if you remember the pm I sent you Mark about the brass failing go/no go. With the ram all the way up screw the die down until it touches shell plate then lower ram and turn 1/8 addition turn in and lock it down. I use lanolin and 99% alcohol as lube in spray bottle. I shake the cases so most of them are point up and spray lube in most of the case necks and then shake and add spray or two then shake the container again. Die is setup to have decamping pin sitting .4 below the bottom of the die. I have not looked to see if I can remove the decap pin without removing the expander. But the cases are decamped in a stage on there own.

 

[STLSteve86]

If your seating die is locked in id say it's the bullets that are different lengths


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[Djstorm100]

Finally, got around to shooting some of my first loads. Did a ladder test with 8208 xbr 22.0 to 23.4. I did 4 8 shot strings while seasoning the new barrel. Last string all shots were under 1moa at 100 yards. I'll post pictures up later. I'm happy though.

Is 2650-2700 FPS ok or do I need to be closer to the 2600fps? 23.4gr gave me 2665 fps. brass show almost no signs of overpressure. 1 out of the 4 cases that I loaded with 23.4 have some marks where the rim meets the case but it is very little.

 

[PinesAndProjectiles]

Pictures?

 

[Djstorm100]

This is with a brand new barrel. First shot is 22.0 and following +0.2 grain. So 2nd 3rd and 4th are 22.2, 22.4 22.6 grains.

 

[BDA2]

For what it's worth, I don't crimp ANY of the loads I do for .223 and have never had a set back issue.

50gr and 55gr z/vmax hasn't been an issue in my AR with no crimp.

Maybe try not crimping at all. Then check a few to see if they set back during cycling.

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