Printable View
Hi all, I have a spare Omark 44 action, (.308W bolt face) which i am considering building a dedicated .30cal castboolit varminter on. I am thinking of portability also, so was thinking of a 20" bullbarrel, and i want to be able to shoot a variety of castboolits thru it out to about 200M. What i am not sure of is cartridge .308 or .30/06 and the best twist rate. I do like the longer neck of the 30/06. Suggestions??? Larry Gibson hello???
I have the lyman 314299, and the lee C312:-155 moulds so i was thinking of the 30 06 with 1/10 T maybe. But i do like the 6.5X55 too! But that's another story Haha.
Since Varmints is the name of the game I'm going to suggest several things;
1st is a minimum of 26" heavy sporter barrel with 28 - 30 being even better. A shorter barrel means nothing except less velocity and/or you have to push to higher psi with sharper time/pressure curve to achieve same. All of which interprets into more structural stress the bullet goes through during accelleration which increases imbalances which destroys varmint accuracy. You want optimal barrel length to use the slower burning powders like RL19, AA4350, H4831SC or RL22 efficiently. Those will give the gentlest push to the bullet yet achieve the desired high velocity for better trajectory for varmint shooting.
I'm going to suggest a Palma 14" twist for the barrel. This will stabilize .30 cal cast bullets upwards of 170 gr. I use the 311466 in my own Palma .308W with 14" twist 27 1/2" barrel. I push them at 2600+ fps and they are deadly on varmints to at least 300 yards. My next barrel will have a 16" twist for use with 160 and lighter cast bullets at even higher velocity. I'm not recommending that right now though as I've not been there yet and can't say for sure how high a velocity a regular cast bullet can be pushed with excellent accuracy while keeping the RPM in check, probably best to let me go there 1st unless you are truely adventurous.
I'm going to suggest the 30-06 cartridge with a match spec chamber with tight neck. With that case you can match prep and turn the necks to fit the chamber for maximum concentricity with minimal neck expansion on firing. The longer '06 neck will also support the 311466 Lovern bullet or the LBT 150 (my recommended bullets) so the GC stays in the case neck with the front driving band or ogive just touching the leade. The 30-06 case also has optimal case capacity for the slow burning powders mentioned for velocities of 2600+ fps in the longer 26 - 30" barrels, a 20" barrel does not.
Larry Gibson
Thanks Larry ! As usual very good informative reply from you. That's awesome. I didn't really want that kind of barrel length but sounds like it's needed for cast bullet stability .
Sometimes if we want a top perfomance cast bullet rifle (and your "varmint rifle" parameters certainly demand top performance) and we are building it........what we "want" isn't necessarily what "works". There are a plethora of factory 10" & 12" twist .308Ws and 10" twist '06s out there with 18 - 24" barrels. When we load cast for those we are held to what they are. If were are building the rifle no sense limiting it to the restrictions we know are already there with ready made rifles. That is an Omark 44 action no? Would you put retreads on a Farari?
Larry Gibson
The most accurate .30 cal. for cast bullets including use at 200yds. is the .30 BR. and it uses the same bolt head, I have one and it is awesome. Check the CBA benchrest accuracy records/results!!!