Reloading Question on COL

[NAPOTS]

ok, so I fired those 50 rounds I just loaded and wasn't completely thrilled with the results. my best 5 shot group was just under 1". I am using the load data from Hornady's website for the 69 gr Sierra Match King. 24-26 gr varget. I am using 25 gr. and a COL of 2.235". I have read elsewhere that people are getting good results with a COL of 2.260". The Hornady reloading book cautions against extending the COL to the point that the bullet contacts the lands of the rifling. There could be a dangerous pressure spike.

My question is between a COL of 2.235" and 2.260" is there much of an effect on the pressure and are the same powder charges still valid? I am a whole grain below the max charge for that powder. I.e., Can I load a 69 gr SMK to a COL of 2.260" with a 25 gr varget charge behind it? Brass trimmed to 1.750 if that makes a difference.

[O.S.O.K.]

Extending the COL will lower pressure - a little. Just be sure that the bullet isn't contacting the lands. Also, be sure that the rounds fit in and feed from the mags...

My usual method is to load the bullets .005" off of the lands - assuming they cycle at that length. Then, I test different loads - varying by .2 grains for the .223. Once the "favored" load is identified, I then vary the seating depth and see how the rifle responds to that. In other words, I seat them progressively deeper by small increments. There will be a "sweet spot" and it can surprise you. It's all about barrel harmonics.

Additionally, know that your rifle is going to "like" some bullets more than others and it has nothing to do with wether they are match bullets or not.

1" groups are very good for your first go at it. :)

[deth502]

yeah, i wouldnt be too upset with sub-moa groups. when you get down to that range, the shooter has as much to do with it as the load.

[Schuetzenman]

My best load for the 69 SMK is 25.5 to 25.7 grs. of Varget. Like I said, I load the bullet just as far as I can get it to feed reliably in the magazine. I think I leave about .010" between the tip and the inside of the mag. On the pressure pike, I doubt it will blow up your rifle on the first shot, but it will probably rupture the primers or cause the primer mateiral to flow back into the firing pin hole. You'll know it by a small ring around the firing pin strike. If the primers are flat at the outer edges but no primer flow into the firing pin hole IMO it's still ok on pressure.

The barrel on my match rifle is a Kreiger stainless match barrel with a 1 in 7.87 ich twist, just a little faster than 1 in 8. My Colt HBAR with factory 1 in 7 gets about 7/8ths inches with this load. The Kreiger does .400" or less.

[abpt1]

http://www.brownells.com/.aspx/pid=12634/psize=24/Product/OVERALL-LENGTH-GAUGE