COAL not consistent - why?

[dickttx]

Beyond fitting in a magazine COL is completely irrelevant to me.

I use a Forster nut style comparator that measures from the full bore ogive terminus on the bullet. I base all my records off this measurement which is far far more consistent AND can carry over to different projectiles.

I use the simple magic marker dented case mouth technique to determine where the rifle's "comparator to casehead" point is.

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Explain.

 

[blarby]

Quote:
OAL variance does not matter.

Well, that truth is in the eye of the beholder, with some certainty.

With that said, even nutzo gents like me realize there are tolerances in any machining/ assembly process.

To me, just helps to separate "perfect" from "good enough"

In reality, the difference is unlikely to effect you significantly assuming that your seater die is engaging the ogive, not the point.

 

[gamestalker]

The most consistent olgive I've seen was with .277" Speer Hot Core PSP BT back in the early 1980's. It was a long time ago, but I remember how amazed I was that they were within .003" of being the same to the lands from the olgive.
In an attempt to hang on to my last thread of sanity, I just seat up as close to the lands as possible, provided they chamber without problems.

 

[A-FIXER]

I just seat up as close to the lands as possible, provided they chamber without problems.

gamestalker states it correctly but do be aware of pressure on the shot if you extend into the lands and may want to move down a 1 grain or 2 to avoid overpressure and yes you will lose some fsp but should give you greater accuracy.

 

[USSR]

The problem is, a bullet seated so it's a couple thou into the lands will normally chamber just fine. For competitive shooting, I was seating mine so that they were .020" into the lands, and they chambered without any resistance. Of course, I had to reduce the charge weight by about 1 grain to match the velocity with the bullet seated off the lands.

Don

 

[AussieInUtah]

OK, guys. You've convinced me. I ordered a Hornady OAL gauge and bullet comparator today.

I'm still going through the process of finding the best powder charge. (Firing rounds loaded at 0.5 gr increments with Varget from 42 gr to 45 gr behind a 175 gr HPBT, I got my best groups around 42.5 gr to 43.5 gr.) I'll go back to the range with 0.1 gr incremental loads soon...

Question: Once I've measured the chamber, etc how do I go about finding the best distance off the lands to load my bullet? I'm asking here about the actual process of experimentation - i.e. do I load 5 rounds with my favorite powder charge and seat to 0.01" off the lands, then 5 rounds 0.015" off the lands, then 0.02" etc?

BTW, all indications so far are that this Savage 10LE .308 is a very accurate rifle, before I've even finished tweaking the handloads. Can't believe I bought it used for $650 with a Leupold VX-II scope on it! Thanks for your helpful advice.

Regards

Dave

 

[A-FIXER]

Aussie,
Now you will just have to make that find yourself and the rifle in question for example you have 3 different powder load and you shoot them and if your grouping is good and then you take the 1 best group and try different COL measurement and find which of the distances your rifle works well then you are doing the process of designing a load for that rifle and that particular round (bullet) to make things repeatable you should trim your cases every time so all the bullets are exactly the same each and everytime, don't mix different type of cases what you strive for is REPEATABILITY......
once again you will have to do this ALL OVER AGAIN for each different type of powder/bullet/case it is called reloading and again how technical you want to be is just to get the best out of you and your rifle.

 

[twofifty]

split the difference

Since your best groups were with the 42.5 and 43.5 loadings, I'd cut to the chase and load up a bunch at 43 grains, but with different seating depths.

Reason for splitting the difference is that a 43 grain load should in theory still perform well and safely if your over or under charge a round. It should also still perform well and safely if hunting/match air temps are above/below your development temperatures. Why? Because that your rifle did well at 42.5 and 43.5.

For seating, I'd start .040" off the lands, then move in closer to .030", .020", .010", then almost touching. Say .020" gives you the best and most consistent groups, then you could fuss over it more by loading some to .025", .020" and .015". Taking it that far is splitting hairs, esp. if you'll end up shooting these SMKs at 200yds or less. Joey won't be able to tell the difference.