300wsm...what twist rate do you recommend with 215 or 230 Hybrids?
- Thread starter Dutchie
- Start date
Matt is correct and I have used several 10" twist barrels that shot 230 Hybrids very well. But, Bryan Litz's latest research shows some B.C. improvement is possible by using a slightly faster twist. My current two barrels are 9.75" and the next ones will be 9.5". If you can only find a 10" twist, don't worry about it because it will work well. If you are ordering a custom barrel, consider the faster twist.
Steve Blair said:
Steve...ditto on the 9.5. What bullet-loaded neck diameter are you neck turning to with your reamer? Just about there.
Thanks,
Dan
[br]Outdoorsman said:
Berger's twist rate calculator takes bullet shape and optimal stabilization into account. It also has a decent bullet library. The recommendations include Bryan's latest research results. [br]
http://www.bergerbullets.com/twist-rate-calculator/
[br]dannyjbiggs said:
Dan, [br]
It's a Ø.337" chamber neck, brass is turned to .012" wall and loaded round neck is ~Ø.3325".
Steve Blair said:
Thanks Steve. Well, I came in at 0.3320! I plan to start "bruised shoulder" drills come Monday morning.
Dan
[br]dannyjbiggs said:
The recoil itself is not that bad. A hard grip is not necessary, but stay in firm shoulder contact when firing. Do not give it a running start at your shoulder.
H4350 is a little fast for 230's. I shoot H4831 SC with good effect. If you need to use H4350, start at 58.0 and shoot 3-shot groups .5 grain apart until you identify pressure bounds. This supposes that your COAL is in the 3.240"+ range. If you are seating deeper, reduce the charge and do the same testing.
I would start at 63.0 and do the same drill. My current charge is a little above the attached table but you can find it quickly with the recommended method. Look for a couple charges just below full pressure where the ES drops and velocity does not change much. Go back with 3-shot groups at .1 grain increments and define the bounds of that node. Load to node center, adjust seating depth in .003" increments for best accuracy, set the tuner (if you have one) and, you are good to go. [br]
Attached is a new chart and a target showing what these big 230's can do. That is 22 shots from prone, including two sighters, in 7.642" at 1k. Don't let anyone tell you that 230's cannot shoot.
Attached is a new chart and a target showing what these big 230's can do. That is 22 shots from prone, including two sighters, in 7.642" at 1k. Don't let anyone tell you that 230's cannot shoot.
Attachments
My current barrel and powder lot tuned at ~2850 fps from 34". I've shot barrels and lots that tuned as low as 2805 and up to 2865, all with H4831 SC. I can get a lot more velocity from IMR 7828 SSC, almost 3000 fps, but cannot manage it on the rest.
No, I usually use the mildest primer that will reliably ignite and produce low ES. That is not always true, but generally works. The first three .300 WSM barrels, I used Russian LR primers, first Wolf, later Tula. They are about the mildest primer available and comparable to CCI LR brisance. The latest barrel and powder lot just would not produce low ES with that combination. I tried Russian LRM (Wolf KVB-7M, lot 3-09), only slightly hotter, and obtained ES in the 5-8 fps range for five shots. My current lot of H4831 SC is a little slower, needing .7-.8 grains to produce the same velocity. My reasoning was that a slightly hotter primer might produce a good result. Russian LRM primers are not as hot as CCI 250. Federal 215 primers are very hot and not necessary for the short, fat WSM powder column.
The BR guys use mostly Federal 210 or 215. Most use a 210 because H4350 doesn't need a magnum to light mid 60 grain loads. Some guys say the Fed 215 works better. I think anything slower then H4350 might work better with the 215. If I was shooting in cold weather or hunting with it I would use the 215. Matt
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