Problems with .223 OAL - Driving Me Nuts.

[bayou06]

BLUF: I am having inconsistencies in my .223 OAL while loading some 55 FMJBT and it’s driving me nuts.

First, some background, I am new to rifle and precision reloading (I’ve reloaded pistol for many years). After a lot of research and study, I started reloading for my little AR-15 carbine. Currently the loading is just for plinking.

I am using Lee Pacesetter dies on a 3 Turret Lee press.

Here are the components:

Brass: Batches of PPU, Winchester & RP, all once fired.
Powder: RL7 @ 21.5 grains
Primer: CCI 41
Bullet: 55 FMJBT w/ Cannalure – Bulk no-name
OAL: 2.40

Now the problem: While reloading the PPU I kept getting some wide discrepancies in OAL. Ranging from 2.20 to 2.50. Most fell into the 2.30 to 2.45 range. Even when the OAL was relatively consistent, the cannalure would vary where it met the case mouth. I suspect that the problem lies in the bullet manufacture or possibly my die & press set up. The Winchester and RP varied between 2.30 to 2.45. The fell into this range more consistently, but still varied.

My questions:

1. Do bulk bullets really vary that much in shape and OAL? I would assume there would be some minor differences, but this much? I earlier reloaded a few 55 grain Sierra Spitzers that seemed only to vary a very small degree.

2. Does the placement of the cannalure vary on bulk bullets as well?

3. Could movement/misalignment in the bullet mandrel in the seating die cause this? I kept an eye on my dies during this batch and the die and depth adjustment knob didn't budge.

I recently purchased 500 52 grain Sierra HPBT Match King bullets and sure hope I don’t run into this with these bullets, especially for the price I paid for them.

I appreciate your input on this.

Bayou06

 

[bigwheeler]

Re: Problems with .223 OAL - Driving Me Nuts.

First you need a comparator to put over the bullet to measure from the ogive.
Next take the seater out of your die and see if it is shaped correctly and seating the
bullet off, or close to the ogive not some other random place. Lastly bullets do very
a lot, So cheaper bullets may vary well be worse.

 

[MitchAlsup]

Re: Problems with .223 OAL - Driving Me Nuts.

Line up 10-30 bullets against a corner and shoot a picture of the them. This will let you see the BOAL variation, and the cannelure variation. By looking really close you migth be able to see some minor variation in the shape of the ogive.

I suspect that the bullet seater is pushing near the middle of the ogive, where it is least consistent. Competition bullet seaters push at the ogive-to-shank transition. This still results in a OAL variation, but the critical parameter is the ogive to lands which is kept small and in close tollrance.