Posted: 5/5/2003 8:33:14 PM EDT
I am interested on loading some 165gr Hornady SST rounds in my M21. Anyone have any good loads? The SST is too new and not in any of my manuals. Iuse LC brass and Winchester primers. I have Varget and 4350, would prefer to use Varget. Any one know the minimum and max loads for a M21? Thanks in advance.
While I have not loaded any rounds for the M21 and the 165 SST is as stated "new", (we have loaded plenty of the 129 SST 6.5mm rounds) I'm interested to try some of these 165s in my 30-06. I use the H4350 as my powder for my 30-06 Rem 700 custom barreled rifle, 56 grains in once fired Remmy brass w/ CCI 200 primers, top w/ Sierra's 175 MatchKing and for this rifle/round combination, believe you'll get better results using the 4350.
However if Varget's your choice, try starting w/ 43 expecting to go to 46(C)grains (which in a 24" 308 & a COL 2.800" using a 168 grn SMK moves at about 2730fps and creates pressures in the 50,600CUP range)
This data is available here: www.flintwood.co.uk/reloading/308win.htm and I have referred to this site (which has a link to Hodgdons) and his loads on several occasions for figuring out where to start and what my limits are. That is when my current gunsmith and friend does have a load already defined and worked out for what I'm wanting to shoot.
Be safe, start low and work up, yada yada yada....
For SSTs, try using the Nosler BT data. The SST has a "slightly" better BC than the Nosler - but it is close enough to put you in the ballpark.
An average load of Varget for M1A/M21-type semis average around 45gr for 165gr bullets - when using standard cases. For the LC cases, I'd start a work up around 43gr & cut it off around 44.5gr.
Thank you for the help MrWilson and Markwiz. I am new to loading rifles especially semi-autos. Now that my once massive (10,000 rounds of LC match ammo) is dwindleing I decided it is time to reload. All the brass I have is Mil-surp with 95% being LC and the the rest Winchester US military ball ammo cases. My only question is cut off all loads at 44.5 since it is all military or just the LC. I kind of understand the principle of LC brass creating more pressure due the thickness of the brass. If it is not a problem could any one give me a an easy explanation. Something simple enough a psychologist could understand. I aced biology and psychology but don't want to talk about physics and thermodynamics.
The case issue is simple Willie.
If you have 2 cases with the same external dimentions, yet they weigh significantly different amounts - there can only be two possible explanations:
1: They are made of different weight metals (not likely with brass cases) or
2: The heavier case has to have more metal in it - i.e., thicker walls.
Thicker walls mean there is less space inside the case (since both cases are sized the same externally) and if you put the same amount of powder into a smaller space, it will develop higher internal pressures.
With a simple chronograph, this extra pressure would show up as a higher muzzle velocity. And if you had the equipment to measure actual chamber pressures, so might be shocked at the difference. Chamber pressure is what makes or breaks a load or a GUN! - so you have to approach it carefully.
If you have a scale that you can weigh your cases with, measure the LCs & the Wins and if they are within about 5-10gr of each other - load them both the same way. I've found LC & IMI cases that weigh more than 30gr more than commercial Win nickel cases..............so the difference between commercial & military brass can be significant.
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