Posted: 4/14/2017 7:08:45 PM EDT
Working on 223 development for a Savage 25 Walking Varminter.
GFL Brass, Nosler 69gr CC
Using the OAL gauge and the modified case, it was giving me a reading 2.025. Removing .02" to give me some jump landed me at an ogive of ~2.00. However, these ended up with very long OALs that wouldn't feed properly. I seated deeper to give me an ogive of 1.940, which ultimately gives me .08" jump. More than the 'ideal' numbers I've seen used. Problem is this is still giving me an OAL of ~2.31" (Average taking into account uneven meplats) which is over book recommendations. Seating deeper would only further increase my jump.
In a situation where I'm working towards accuracy, are these OK loaded long or should I dial them back to spec depths? I will be using H335 powder and working up from minimums in a ladder test
If you are working up carefully then put them where you want. Do you want to load to fit a magazine then load for the magazine. If you don't mind single feeding then work up from .020" off the lands or wherever.
Loading away from the lands does not mean you cannot get an accurate load. I have loads that are almost 1/2" off the lands and they shoot mid to upper .4s, about the same as my loads that are .010" off the lands.
How do we help this guy?
Don't rely too much on the SAAMI specs. In this instance, the SAAMI OAL spec ensures factory ammo fits all SAAMI spec chambers.
Three things to consider for OAL -
1. Do the rounds need to fit in the magazine? If so, the absolute max OAL is fixed. Measure the magazine length and go shorter than that.
2. Distance to the lands limits maximum OAL.
3. Compressing the powder limits the absolute minimum OAL.
If the rounds don't have to fit the magazine, the OAL is limited by the lands and the powder column in the case (items 2 and 3, above). Within those limits, the OAL is up to you, as long as you do not create excessive pressure.
Measurements to consider
#1 When working with loads to chase the lands the rule of thumb is to have at least one caliber width of bullet bearing surface in the case neck otherwise your risk a bullet being separated from the case.
#2 Measure you magazine length if that is a consideration that you need to run the ammo through the magazine, otherwise you are committing to having your rounds loaded one at a time!
#3 Key Measurements
COAL = Cartridge Overall Length Meplat tip to base brass case
OTB = Ogive to base length as measure with a comparator this of course will very bullet by bullet and as the throat erodes it will change
#4 If you are compressing loads.....use a drop tube and settle the powder manually
Thanks all I think you affirmed what I felt but wanted someone to back me up. I generally always single load anyway so long cartridges shouldn't be a problem