Since all of my shooting/hunting takes place in the frozen North (with a fondness for heavy lead added in), I'll add my vote for the 14 twist.
Best,
John
Since all of my shooting/hunting takes place in the frozen North (with a fondness for heavy lead added in), I'll add my vote for the 14 twist.
Best,
John
That's really impressive Larry!
I'm about to order a heavy 26 inch SS barrel for my scoped M98 30-06, for long 190gn cast bullets for 500m competition, do I order 12 or 14T? 2600fps is plenty fast enough for our required power factor also.
Looking at your results I think 14T but I really value your genuine opinion thanks!!
Last edited by MaxJon; 12-29-2017 at 01:13 AM. Reason: missing info
THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!
FWIW:
I was wondering the same thing awhile back and asked about bbl's. Was looking at a 308w bbl for a old puma rifle & wasn't sure about the twist. I posted the bbl would have a .340" match chamber & a 1 in 14 to be used be mainly for cast bullets. The answers I got?
runfiverun posted Where are you going to find brass with .340" necks?
Larry posted That would be an excellent choice!
I had to post telling runfiverun about this thing called surplus brass and more specifically lc (nato) brass that is thicker than commercial commercial brass.
The bbl mfg I was ordering the bbl from offered 2 different match chambers. A .332" for neck turned commercial cases and .308" bullets. I opted for the .340 chamber for the thicker nato cases and .310/.311 bullets.
At the end of the day:
Years ago I shot a little high power, had a 40x/300mag combo that I used on a 1500yd range. Used cast bullets for pistols out to 200yds and 100yd/30a3 (30-06) on reduced targets/service rifle. I've acquired several 30cal molds over the decades (30+) and tinkered with then in several different 30cal firearms. Fast forward:
A couple of years ago I was at a gunshow and saw a cil 950T (puma rifle) on a rack at a give away price. It reminded me of the 40x I used to own, heavy stock/handstop rail/setup for irons & scope/etc. It had the older savage action (great/easy bbl swaps) and a good 3-way adjustable trigger in it so I bought it.
1st thing I did was rebuild the bolt ensuring consistent ignition. Then I bought a 20" 1 in 10 twist deep grooved bull bbl for it & started testing. It was nothing more than a cheap bbl from ebco. I tested that 1 in 10 with 16/17 different cast bullets along with 3 different bump die profiles along with swaging bullets. Learned a little about alloys, gc's, bullet sizing/fit, static fit. One of the bump died I made was for a static fit in that ebco bbl. Took a 230gr blackout cast bullet (lee) and bumped it to fit the 308 case/chamber/throat. The now gc'd bullet (boattail before) has the gc of the bullet sitting so the gc is centered in the bottom of the neck of the case & the arrow points to where the freebore ends and the throat taper begins as the nose turns int a bore rider with a short unsupported nose (a slump thing).
[IMG][/IMG]
The last thing I did to that ebco bbl was to take a 3/4* throat reamer and re-cut the throat. Wanted to do testing for future use of the 3/4* reamer, along with reuse the bbl and cut a match 30-06 chamber. Want to cut a 30-06 match chamber with no freebore, just chamber and a 3/4* throat. Anyway a bullet from the standard 308w throat (top) next to a bumped bullet (same bullet, 3/4* bump die), bottom. You can see where the top bullet has rifling marks on it and the bottom bullet has full length rifling marks. The wiper groove was compressed and that's where the rifling ends in that chamber. The space from the end of the case to the start of the rifling is the ball throat/freebore I want to take out when I re-cut the chamber in that bbl. Hence easier to bump/static fit any cast bullet in the long tapered throat.
[IMG][/IMG]
Then I bought a 1 in 11 twist bbl with shallow grooves 308/301 and a custom chamber, 25" long, varmint contour from apache gunworks. I is cut/designed to shoot 175gr smk bullets. It was a good bbl to experiment with & the shallow riflings were extremely sensitive to small changes with cast bullets. This bbl was a good test bed for alloys/lubes/amount of lube. It got put thru the paces with different bullets/lubes/sizes/bumped profiles/etc. It's going to end up on another 308w project, a nib rifle I bought 2 years ago.
After testing cast bullets in those 2 bbl's for 2 year I was ready to buy a bbl specifically for cast bullets and posted what I was thinking. Namely a 308w varmint tapered bbl with a match chamber/.340 neck and 1 in 14 twist. I trusted Larry's advice and ended up buying a:
1 in 14 twist, varmint contour, 30", .340" match chamber with recessed target crown from shilen.
I looked at it this way:
I did do a little testing with different bbl lengths, profiles, chambers, grooves, groove depths, bullet diameters of .308/.309/.310/.311/.312, 3 different bump dies and a bunch of different lubes/alloys/molds. It wouldn't of mattered if I ordered a 1 in 10,1 in 11,1 in 12,etc. It all costs the same. So I took the slow twist path, installed the new bbl and partially bedded the receiver and took it to the range to test for function. It only took 14 shots to get a lube star on the end of the muzzle, note the high point/clearance of the bbl in relationship to the stock (excellent cooling & no bind with slings).
[IMG][/IMG]
Went back finished bedding the bbl'd receiver and did some initial test loads. Wanted to test the bedding, test the receiver screw lengths (3 different sets) & set the torques on the action screw. Used mixed range pick-up brass (both nato and commercial), plinking bullets (bullets cast and only culled for major flaws like wrinkles), h335 powder that most people don't recommend for cast bullets and 20+ year old magnum primers (probably older/$.50 label on them). Anyway, 30* winter weather, light 7mph winds and blammo ammo.
[IMG][/IMG]
While nothing to write home about by any means that 2679fps 10-shot group at 100yds got my attention. That 1 in 10 twist generic bbl never did that at anywhere near those velocities. The custom 1 in 11 bbl never did that at those velocities either . The 1 in 14 did it without even trying. Shot the same loads same bullet, this time the bullets were traditionally lubed. The lube gave up at the 35gr load.
[IMG][/IMG]
The bullet used, the pc'd bullet just started coming in at 36gr/2650+fps, plan on testing that pc'd bullet at 37gr/38gr/39gr with some cases from the same lot. I also put another coat of 45/45/10 on the traditionally lubed bullets. The only had a little bit of lbt blue from a lyman 450 sizer and 1 coat of 45/45/10. Going to retest the 35gr/36gr loads with good brass also. The bullets used, I'm really looking forward to the re-lubed bullet tests. I'd love to see this bullet in the 2700+fps range with both lubes and pc'd coatings seeeing how I have a 6-cavity mold that rains bullets.
[IMG][/IMG]
If I were you I'd measure your necks of the brass your using on some loaded rounds and have your chamber cut accordingly. Mine measures .3385 with a .310 bullet so I had a .340 neck cut. I would also go with a longer bbl. I could of got a 26" bbl for $100 less but it's money well spent to get the longer bbl. Less pressure per load for more velocity. In another post a forum member is using 24" bbl'd 308w same bullet and 39gr of h335 to get the same velocities I'm getting with that 34gr load out of that 30" bbl. I'd also look at bullet profiles/weights and try to figure out what velocities you need to carry the bullet accurately to 500m.
Snow hit hard 20+''s so I haven't been back out yet with the new bbl. Been casting/sizing/lubing/coating for when the range opens back up.
Sorry for being so long winded. Was asking the same questions awhile ago. Larry gave me excellent advice. I put my $$$ where my mouth is and pony'd up for a 1 in 14 twist.
Just another opinion
Kinda quiet of this thread.
Go figure.
Bought the 12 twist!!!
THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!
"Don't worry what they think. In the end it is not between them and you, it is between you and God."
Je suis Charlie!
"You won't know until you Actually try it"
"The impossible just takes longer."
"Don't let them beat you down with their inexperience."
"You'll never accomplish what you don't try. " - Moldmaker
I have a 1-12 twist on a model 1917 30-06. I really like it. It may not be perfect for anything but it's pretty darn good at a lot of things. Maybe the 1-12 is the "jack of all trades and master of none".
I went with the 12T because I think it will love my 190gr cast beauties, but if it ends up not liking them, I still have a jword rifle that will shoot all weights south of 180gr which I will be happy with also.
THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!
Any idea what chamber/throat angle you'll be using????
Actually a 30-06 with 12' twist will shoot all jacketed bullets south of and including the 220 RN. The only exceptions will be the really long VLD types of 180 gr and heavier. The heavier and longer "bore riding" noses of cast bullets make them harder to get consistent accuracy with the faster we spin them. Your 190 gr cast beauties would have done quite well in the 14" twist, actually better than they will in the 12" twist. If you want to push the higher velocity envelope with a cast bullet in your soon to have 12" twist 06 you might consider a design more capable such as the NOE 310-165-FN XCB. If accuracy alone is the name of the game your 190s should do well in the 1700 - 2000+ fps range.
Last edited by Larry Gibson; 01-10-2018 at 10:22 AM.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!
bullbarrel033
Sounds like it will be a nice rifle, looking forward to pictures when you get it up and running?
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |