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Posted: 10/18/2006 10:23:15 AM EDT
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Adjustable gas blocks performance range? I am looking at building a rifle and would go with a low mass BC group and am looking at the adjustable gas blocks (GB) but was wondering how narrowly tuned they are and when performance/reliability would degrade. I am looking at a 16” middy and would be shooting 69 gr match SHPBT’s hand loaded for accuracy, for beside the bed it would have IMI green tips (62 gr ?) and for 3 gun eat them up shooting I would use either WWB or the plastic cased cartridges in 55/62 grs. So I tune the GB for the 69 SHPBT’s and later shoot lighter bullets faster or slower, what effect would this have on the guns operation, what’s its reliability range for other cartridges. Better said, would be what would be the performance range of a GB tuned for the 69’s at near max FPS, to reliably work and when would that range be exceeded by either other bullets speeds or weights? Thanks in advance for any and all replies. |
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First, I recommend you go with a 17" barrel and rifle length gas system for 3 gun. Rifle gas system runs smoother. As for adjusting the gas system, just go try it. Way too many variables to determine by simply asking. Bullet weight and powder burn rate will have the most effect as it will effect the port pressure and therefore the adjustment point. 3 gun shooters typically pick a load, dedicate a Dillon 1050 to that load and shoot a BUNCH of it. Once the gas system is tuned, you won't need to fiddle with it anymore. |
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I would pass on the adjustable gas block and just tune the port to the load(s) you plan to shoot. The problem with the adjustable port is that you have to drill the port to the largest possible size that you ever plan to use, then restrict the flow from there. It may not make much difference, but I would rather not have my bullet running over a monster pot hole in the barrel if it doesn't need to. Tony |
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The JP Adjustable Gas Block is a great piece of equipment. It allows you to tune the cycle of your BCG just right. However, for a 16" middy, I'll say this. In talking with a lot of the top shooters/gunsmiths in 3-Gun, you don't really need to run a lightened BC (on the 16" rifles). It's not that big of a gain. However, it might be different with the mid-length gas system, so give it a whirl. Rich |
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