What am I doing wrong now? OAL question.

[RavenVT100]

I generated my very first loads for .223 tonight. 69 grain Sierra Match King bullets, with a minimum load of Varget (23.5 grains).

I was trying for an OAL of 2.260". When I set my seater die, I am getting anywhere between 2.263" and 2.257" OAL, with one that actually ended up being 2.252". I am using a caliper to measure. I think the reason this is happening is because the tips of the match kings are not uniform.

Is there any other way to accurately measure OAL? How dangerous is being 0.008" lower than recommended OAL in the manual?

 

[taliv]

it's not, don't sweat it. your seater works on the ogive of the bullet, not the meplat (i hope)

look at sinclairintl.com for some tools that let you measure oal from the ogive

edit: they also have a meplat trimmer if it's really bothering you

 

[waffentomas]

taliv is correct.

Don't sweat that small amount. I've seen factory stuff (fail safes) come in under minimum OAL and shoot great. It's all about the ogive.

Tom

 

[RavenVT100]

I'm using an RCBS X-Die (small base) since these will be for an AR. I have the seater die cranked up so that it doesn't crimp. I notice a little ring around where the seater hits the ogive--you guys are right, the meplats vary in length quite a bit. I'll just average out about 10 or 20 to establish true OAL. Right now it's around 2.259 with a couple of outliers.

I am using a Dillon taper crimp die to apply some light crimp. This doesn't seem to alter the length at all.

 

[ocabj]

Don't trim the meplat just to get the COL to be the same. You trim the meplats to make the meplats consistent so that the BC is consistent. Trying to get the COL to be a specific length by trimming the meplat is counterproductive.

FYI: Trimming meplats to get the BC consistent also lowers the overall BC. I have the Sinclair meplat uniformer for 22cal, but I have yet to even test it to compare the benefits between non-uniformed and uniformed meplats. Assuming it works, I would use it mainly for the short line and only trim/uniform a meplat on the long line bullets if the meplat on a specific bullet were malformed. And even then, I would probably cull out that bullet depending on how malformed the meplat is.

When I seat 77gr bullets for the short lines, I find a setting on my Redding micrometer die that gives me a COL from base to tip that consistently stays between 2.250 and 2.260. Even 2.270 will fit into most of my 20 round Colt mags. The meplats on Noslers and Sierras are always going to be slightly different from bullet to bullet.

 

[RavenVT100]

ocabj:

Speaking of gauges I have this little headspace/cartridge gauge from Wilson that is essentially a tiny chamber with ridges. If the bottom of the case is over the top ridge, there's negative headspace. If it's under the bottom, there's too much. Is this sufficient or should I be looking into getting a case micrometer?

 

[Bullet]

I use this to set the headspace in my AR –

http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=477756

 

[ocabj]

Speaking of gauges I have this little headspace/cartridge gauge from Wilson that is essentially a tiny chamber with ridges. If the bottom of the case is over the top ridge, there's negative headspace. If it's under the bottom, there's too much. Is this sufficient or should I be looking into getting a case micrometer?

I have one of those for .223 that I use just to spot check loaded rounds.

Personally, I don't take much pains to make sure I'm keeping my FL sizing to a minimum for a specific rifle. The only time I actually set the die to bump shoulders back just enough is in the bolt guns.

But if you want to try it, that RCBS mic that was just mentioned will work.