I have shot several 6.5 cals. Prc, gap, and a bunch of creedmoors. 9 twist creedmoors preferred 130s far more than 140s, one 8.25 twist shot 147s very well. 8 twist Gap, PRC, & creedmoors liked 147s very much so. I've got one 7.5 twist creedmoor and it shot 140s ok but seemed a little finicky with them. I didn't try 147s In it but I would bet the farm it would be less finicky with a 147. I'm going to say that your 7.75 twist would shine with 144-156gr bullets. I would think a 8.25-8.5 twist would cover 130-140gr bullets very well. Alot of folks say that you can't over twist a bullet. While I won't argue that idea, I believe it is very subjective. I do believe over twisting can sometimes make load development more finicky and to a point..... A balancing act.I have a 260 deer rifle that has a LW match barrel on it, light profile and 20". When they made the bbl. they asked me what weight bullets would be used and were told 130gr and 140gr only no heavier or lighter. They produced the bbl' with a 1-7.75" twist and I began to work up loads for it. With the light profile for weight reasons its only good for 3 shots and then a cooldown, load work is slowI have doubts about the fast twist with the 130's and have not gotten the accuracy I was hoping for. What say you? Would think it would be very much like the 6.5CM in ballistics and what works for twist rate.
What Twist For 6.5 Barrel?
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Savage 12BVSS
Well-Known Member
What you posted makes a lot of sense in my case, I'm trying to figure out if the twist is too fast for 130gr and is causing it to be so finicky or is it the extreme light profile of the barrel. Maybe both I don't know, they created the contour and its lighter than their lightest sporter profile is but I thought the twist would be more suited to heavier bullets than 130's as well. Guess if I wasn't so into accuracy I would simply live with a gun that averages shooting 3/4". Problem is every other gun I've put together has shot 1/4-3/8" groups so I'm not going to settle on this one. Your last sentence describes the situation perfectly.
Yes agree the gun should shoot tighter groups, not a barrel length issue its Profile or Twist issue or like noted above maybe both working against me. Powder choice simply needs to be something that don't fill the case like the 4350's do. Thats why I'm using 130's and won't change, short throat and mag length won't allow the longer bullets without heavy compressed loads. I'm close to done, if trying one more powder don't work it becomes a 7mm-08 because thats what barrel I have ready that I can put on. Got no problem getting my 7mm-08s to shoot three's with light hunting bullets (but they are 1-9").
Someone will get an awesome deal on a 260 match barrel with a ton of life in it, just hope they like heavier bullets. Dave
Your twist is not too fast for 130 grain bullets. My 6.5 CM has a 1:7 twist and shoots 130 Berger AR Hybrid under 1/2 moa at 500 yards using RL16.
pgmoa
Member
I have a a 260 with a pencil or light weight barrel and have numerous other guns with the lighter barrel. I have never been able to get more than my first 2 shots with accuracy. No matter what the outside temp. The barrel just heats up to fast.
Savage 12BVSS
Well-Known Member
No there's no threading or brake on barrel. Interesting video however for those using brake's with 5/8 threading. I'm going to try and get some shooting done at the range and will try the longer distances off lands however maybe before season kicks in and try that angle out before deciding to pull barrel and head down a different path. Colder weather will help with the barrel heating and pulling way back off lands will show if thats a possible issue. That way I'll know what to do.
Tripodmvr7
Well-Known Member
Your problem has intrigued me and I have run some simulations in Quick Load. With 130gr bullet try 38gr of Varget. Speed of 2640fps seems to be the number. Nobody promotes CFE223 for anything else than the 223. Give it a try with 41gr and a 130gr bullet. Speed of 2700fps or close to it. Both propellants give a fill of 90%.
Hugnot
Well-Known Member
Light weight? My skinny barrels also stop grouping well when they get hot. I usually shoot the first 2-3 then cool off the barrel with damp paper towels then resume shooting.
Measure your bullet lengths then go on-line to the Berger site and look up the twist/stability calculator and run it for your 7.5 twist barrel. I think the 7.5 twist is a real good twist rate for a 6.5 as it seems like 6.5 bullets are getting more pointy and longer and heavier. The 7.5 twist should also do well with 120's.
My 8 twist 6.5's do well with bullets weighing 100-140 grains but some of the longer 140's have marginal stability. Huge spin rates reveal any bullet imbalance but most bullets that are made today are very precise allowing shorter and lighter bullets to be accurate when used in fast twist barrels. My go to powder(s) for my .260 with 130's are H4350 or RL16 - use at 20* to over 90*.
Measure your bullet lengths then go on-line to the Berger site and look up the twist/stability calculator and run it for your 7.5 twist barrel. I think the 7.5 twist is a real good twist rate for a 6.5 as it seems like 6.5 bullets are getting more pointy and longer and heavier. The 7.5 twist should also do well with 120's.
My 8 twist 6.5's do well with bullets weighing 100-140 grains but some of the longer 140's have marginal stability. Huge spin rates reveal any bullet imbalance but most bullets that are made today are very precise allowing shorter and lighter bullets to be accurate when used in fast twist barrels. My go to powder(s) for my .260 with 130's are H4350 or RL16 - use at 20* to over 90*.
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Savage 12BVSS
Well-Known Member
Thats amazing as I'm not just sitting at the keyboard thru this thread but trying Varget load work right Now! I'm up to 38gr and climbing and its starting to shoot pretty well. Now I can move the bullets in more to try longer distance off lands as well. Still early but I'm thinking that 39-40gr will work pretty well, I'm also quite curious what a longer jump will do. Couple days and I should be able to post some real experience with this. May be hope for things...........Thanks for info its spot-on.
Tripodmvr7
Well-Known Member
Are you recording speed? Chrony at 5m and QL can give better inputs.
Seems you have been extremely thorough in your development efforts.
Pencil barrels heat up faster, and also cool faster. Shoot two "heaters" then wait a minute, and start your testing with one minute between shots.
Have you tried monometals?
Pencil barrels heat up faster, and also cool faster. Shoot two "heaters" then wait a minute, and start your testing with one minute between shots.
Have you tried monometals?
Counter intuitive, but have found same with some PSP pinker loads at ~.080.
If you do yank it, I have a Rem 721 in 6.5x55 that is shot out. Not sure what yours is coming off, maybe we can do a deal. Edit to add, saw "Rifle Basix" and it didn't click that its likely a Savage. ( User names don't apply either - i no longer own any HK's )anybody want a light profile 20" LW bbl in 260 with low miles give me a holler
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Savage 12BVSS
Well-Known Member
Left my chrony on loan at my gunsmiths and haven't got up to get it. Things are kinda hectic here as the season is upon us and I just got all my stands up and hunting stuff aired. Going straight out to see how much improvement is to be had from powder change and OAL tuning, before I'm sitting or stillhunting in the puckerbrush
Dave
