Savage11006 Posted February 26, 2022 Report Share Posted February 26, 2022 I know this is a .308 forum but I've decided to build mine in 6.5 creed. The parts i have so far are: Aero m5 upper and lower Toolcraft bcg Wilson combat super sniper 22" I decided to go ahead and check the gas port diameter and came up with it being the same size as a 5/64 drill bit which my el cheapo calipers that only go back 2 digits reads as .07 . I believe that's too small from what I've read. So my question is what should it be? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 26, 2022 Report Share Posted February 26, 2022 I have a match in the morning, but I'll get back to this. I'll run the math on your gas port, compared to my .260 Rem 20" gun. 20" rifle gas .260 Rem with a gas block journal size of 0.750" needs to be 0.080" to run right, with the proper recoil system in it. <<< that part is key, right there. Proper recoil system. I'll get back to this. Quote Link to comment Share on other sites More sharing options...
shooterrex Posted February 26, 2022 Report Share Posted February 26, 2022 The gas port on my Wilson creedmoor barrel is good. Gun runs and shoots great. Rifle recoil system. My barrel is only 16". Quote Link to comment Share on other sites More sharing options...
Savage11006 Posted February 26, 2022 Author Report Share Posted February 26, 2022 (edited) 8 hours ago, 98Z5V said: I have a match in the morning, but I'll get back to this. I'll run the math on your gas port, compared to my .260 Rem 20" gun. 20" rifle gas .260 Rem with a gas block journal size of 0.750" needs to be 0.080" to run right, with the proper recoil system in it. <<< that part is key, right there. Proper recoil system. I'll get back to this. Thanks man. And my journal size .875 and it's rifle length gas. I plan on running the rifle length buffer system and know the buffer should be around 5 inches and weigh 5.4oz or so if i remember correct with the spring being a certain number of coils as well. I know I've seen a lot mention spring co as good options so that's probably the route I'll take. Edited February 26, 2022 by Savage11006 Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted February 26, 2022 Report Share Posted February 26, 2022 1 hour ago, Savage11006 said: journal size .875 The thicker barrel will make a difference in the size of the hole needed. @98Z5V is the one who can calculate what difference that is. Don't drill until he can get back to it. Quote Link to comment Share on other sites More sharing options...
Savage11006 Posted February 26, 2022 Author Report Share Posted February 26, 2022 Definitely not drilling anything until i know for sure lol Quote Link to comment Share on other sites More sharing options...
98Z5V Posted February 27, 2022 Report Share Posted February 27, 2022 So, we're comparing the exact same hole in the barrel, as the .260 Rem and 6.5 Creedmoor both shoot .264" diameter projectiles. On my .260 Rem, 20" rifle gas, 0.750" journal diameter, the first barrel shipped with a 0.070" gas port diameter. It was too small, and had to be at 0.080" to run correctly. I found that out and fixed it. The second .260 barrel I got from them, identical dimensions, shipped with a 0.075"ish port. I drilled it to 0.080" before I put that upper together. So, on yours, two things changed, that affect proper gas port sizing, over what I have. Both are shooting .264" projectiles, but you're have a 0.875" journal, and a 22" barrel. When you go up in journal size, you go down in port diameter. It's almost 0.005" per journal change (there are 4 common sizes, 0.625", 0.750", 0.875" and 0.936"). The change here, from known, is up to 0.875" from 0.750" Take that 0.080" that works on mine, and drop 0.005" from it to make it work with your journal diameter. Somewhere around 0.075" solves that part. Next, dwell time. You and I have the same gas system, rifle gas. I have a 20" barrel, you have a 22" barrel. You have increased dwell time over what I have, because there's more barrel after the gas port, to affect dwell time. Every 2" of barrel, when dwell time goes up, gas port comes down. If dwell time went DOWN, gas port would go up. It's in 0.005" increments (roughly). Example - if I was moving to an identical barrel on my .260, but got rid of the 20" and went with an 18" instead - all other details remaining the same - I'd have to have a gas port up from the original 0.080", and need something around 0.085". So, on your barrel, we already know it needs to be around 0.075" just for the change in gas block journal size. It needs to go down another 0.005" for the 2" increase in dwell time. Bottom line: You will need a gas port diameter around 0.070" for that barrel config to run properly... Which is about what you have right now... Quote Link to comment Share on other sites More sharing options...
Savage11006 Posted February 27, 2022 Author Report Share Posted February 27, 2022 3 hours ago, 98Z5V said: Bottom line: You will need a gas port diameter around 0.070" for that barrel config to run properly... Which is about what you have right now... That's awesome! Thanks, this was really appreciated! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted March 1, 2022 Report Share Posted March 1, 2022 On 2/27/2022 at 4:50 PM, Savage11006 said: That's awesome! Thanks, this was really appreciated! I'll be happy when you shoot it and it works. Until then, my math is a mystery. You shooting it and it works - tells me my math works... Quote Link to comment Share on other sites More sharing options...
Savage11006 Posted March 2, 2022 Author Report Share Posted March 2, 2022 20 hours ago, 98Z5V said: I'll be happy when you shoot it and it works. Until then, my math is a mystery. You shooting it and it works - tells me my math works... May be a while. Trying to catch parts on sale to save some money. But will definitely let you know what it does. 👍🏻 Quote Link to comment Share on other sites More sharing options...
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