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Posted: 5/30/2007 7:09:59 PM EDT
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Does anyone have a reliable recipe for reloading .308 subsonic rounds? I would prefer using VihtaVuori powders but am willing to look at all recipes. Thanks. |
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It's not really an exact science, so what works for one rifle may not work for another. Using a 180gr FBRN and 10g of TrailBoss was rediculously quiet (click, thump), but probably slower than I want. 10.5 was still very quiet. 11g gave me a little bit of sonic crack. I still need to load up some more around the 10.5g range and take them out with my chrono. Vipergts is working up some loads for his rifle as well, so maybe he'll chime in. We've been trading notes. |
That is exactly the case. I've developed subsonic loads for 3 rifles and have traded notes with several friends on how they go about doing it. Before I get into it-the 1:12 twist on the PSS will stabilize a 170 or 180grn subsonic bullet. Anything above that and you'll most likely run into problems. With that said, your options are very limited as far as factory loaded stuff. TTI Armory has closed its doors, so that's a no-go. Lapua's are too heavy for the 1:12 and I've yet to see Black Hills subsonic stuff readily available for sale. In addition to that, they are all expensive and you would be much better off loading your own. Subsonic rounds are good for impressing friends and for doing demo's to show how quiet the suppressor can be, but that's about it. They typically lack the same precision as full power loads (average about 1MOA), so making the same quality practice isn't very practical and I wouldn't hunt with one when I can do it more humanely with a full power round. They are kind of fun to play with though and component selection is critical. -Brass-Choose brass that has the lowest internal capacity. This means using Federal GMM, Lapua or MilSurp brass that you've sorted by weight to remain consistant. Brass from Winchester or Hornady has a relatively large capacity as far as .308 goes. The key is to be able to fill it up without much room to "slosh". -Bullets-Choose something with a round nose and a flat base. BoatTails don't seem to work very well at lower velocities and the different bullet provides instant visual identification as to what type of round it is. I like using the Remington 170grn .30-30 bullets seated to the cannelure. The extra seating depth eats into the powder reservoir further reducing the ability for the powder to "slosh". I've also used the Remington 180grn PSP's and Nosler 180grn Accubond's, getting the best results accuracy-wise with the Accubonds. -Primers-I used CCI large rifle primers just because I had a ton of them on hand. They worked well. -Powder-The only powder I've worked with has been Trailboss. It's worked so well and takes up enough space to minimize any sloshing that I haven't played with anything else. The key thing for picking powder is to pick something that will give you a fairly conisistant powder column. Having a chronograph available is critical for working up subsonic loads. The last thing you want on a precision rifle is a stuck barrel. If that happens you might as well get a new barrel because the obstructed barrel is toast. When working with factory rifles (Remington PSS/LTR, Savage 10/12's and FN SPR's) I would suggest starting at 11.5grns of Trailboss and reducing the loads in .3grn increments until you get into the 1035fps range. With custom rifles, start at 10.5grns and work down. I've only worked down loads for .308 subsonic loads on custom rifles and the results will vary from rifle to rifle. I've had friends that have been subsonic at 10.7grns on their factory Savage and Remington's and I've been down to 9grns of Trailboss on my custom with a Schneider barrel. The point is that whatever load you work on, keep it for that rifle only and don't use it in another rifle until you've had the chance to do proper load developement with it. |
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Gentlemen, Thank you for for assistance. I am going to be using this in a Savage 10FP with a 20" barrel and a 1/10 twist. I have a chronograph so I'll monitor speed. I have been told by a couple to use the 170gr. 30-30 RN bullet but also the 150gr flat based RN. I will probably have both loaded and work my way down with the powder charge. One thing I was concerned about was where the maximum reasonable load was to start down from- that looks to be in the 11.5 - 12.0 grns area which is where I'll start. Thank you all for your input. If you have additional information, I would appreciate hearing it. |
| Remember as you work your way down on powders you can hit a point in low case capacity that rather than a progressive burn on the powder you can get an all at one powder explosion with extremly high pressures, ususally when a rifle cartriged blows up an action it's due to too little powder not an overcharge. |
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