COL with Sierra MatchKings

[paulo]

Wondering what you use for COL.
I am using Sierra MatchKing 80 grain BTHP moly in .223
Powder is Reloader 15, barrel twist is 1 in 7.7.
Thanks Paul

 

[1858rem]

mag length?

 

[HJ857]

I seat 69 grain SMK's to mag length, but for 75 grain AMax's I seat to .015 off the lands, so those are single load only.

I don't know the shape of the 80 SMK's but I'd be real hesitant to load a bullet of that weight to mag length.

 

[Canuck-IL]

In my WOA, per John Holliger's recommendation, 2.465 which is .01 off the lands. So, it depends on your chmber cut but definitely not mag length.
/Bryan

 

[ranger335v]

And a "WOA" is?

Any cartridge that fits the chamber and feeds from the magazine is correct. We arent't shooting a book so the book OAL numbers are just a place to start, not a law.

 

[paulo]

It would be single load only. Rifles are High Preformance Intl with Krieger barrels. Is this one of those deals where I need to find the sweet spot for each rifle and load accordingly? I do have the OAL guage.

 

[1858rem]

s this one of those deals where I need to find the sweet spot for each rifle and load accordingly?

it wouldnt hurt, you find a good powder charge yet? id find the sweet spot for the powder charge, THEN play with the col.

someone had mentioned using the optimal charge weight method you dont need to worry too much about col, just start around .010-015 off the lands using that method i think.

 

[Canuck-IL]

Any cartridge that fits the chamber and feeds from the magazine is correct

Not so ... as others above have noted, that bullet is designed for single loading - not to be crammed into mag length.

WOA is White Oak Armament one of the premier builders of service and match rifles.
/B

 

[45ACPUSER]

The best idea is to measure your chamber, and then you will have a foundatioon to build up loads with!

 

[HJ857]

I do have the OAL guage.

OK, just to be perfectly clear on this. The OAL gauge will tell you the OAL based on the distance where the bullet touches the rifling. This has nothing to do with the tip of the bullet. The tip is irrelevant, and will be well into the barrel before the bullet actually touches the rifling.

So, you're measurement is from the widest part of the bullet, not the overall length of the cartridge. To measure this accurately you should use a bullet comparator in conjunction with the OAL gauge.

http://www.midwayusa.com/viewproduct/?productnumber=231904

Each bullet type and weight will have a different shape profile, you need to use the OAL gauge with each bullet type, record the maximum length, subtract .010 to .015 which gives you the seating depth to the wider part of the bullet, measure that seating depth with the comparator and ignore where the bullet tip is.

This is much easier than it may sound. But if you're going to play the heavy bullet/seating just off the lands game, then you need to control the variables as much as possible.

 

[Coltdriver]

All chambers are different. One rifles col might be another rifles into the lands.

The ogive on one bullet will make your working col different from another bullet.

What anybody loads their col to is irrelevant to what you should be doing.

It is easy enough to determine what your particular chamber/bullet combo can be loaded to.

I would say your actual chamber/bullet combo is probably the single most important thing to know. And the truth is I did not figure this out until I had been reloading for over a year.

I have a ruger #1 that has a chamber that is so short that loading to book spec col put the bullet well in the lands. Fortunately I did not blow myself up and I was shooting some hot rounds. Ruined the brass. Then I got a stoney point comparator and figured out what I had done.