Recent post on Twist rates got me thinking. My opinion on rates is from shooting reading and talking not from testing. Been using the same 32 & 38 twist for years never tried any others.

Mann’s “The Bullets Flight” has a lot to say about twist rates. Mann can be confusing at times, lot of detail some of it hard to follow.  I THINK he is saying faster twist will cause wider flyers if the bullet is unbalanced to start with.  If so it’s probably one of the sources of “don’t twist cast bullets fast” opinions. Leave it to you guys to interpret Dr Mann

More to the point and easy to understand is Charlie Dell in “The Modern Schuetzen Rifle”  Charles says three things affect stability.  Twist rate, Bullet length, and Velocity.  They are connected, move one it effects the others.  His recommendation is figure out what you want the bullet to do, consult the charts, then talk to other shooters find out what works for them.   

He goes on to say the 3 way relationship is forgiving, everything does not have to be perfect. His recommendation is stay in the middle of the parameters you won’t go wrong.  Not the fastest twist not the slowest. Same with bullets not real long or real short.

This makes sense to me. When I move from a 300 gr bullet in my 18 twist 38 barrel to 330 I increase the velocity to stabilize the bullet. Longer needs more spin, increased velocity makes it spin faster.

That’s all I know about it.

Boats

Dave

Charlie Dells has right much positive to say about Gain Twist too. Do you have his book ?

My main shooting partner and spotter uses a store bought 265 grain 38/55 bullet in his factory stock Browning High Wall.  beside my 300 grain bullet from a custom mold his drifts more than mine. Not a lot but enough to notice. Our scores are about identical except off days. Does little less drift make any difference in offhand scores ? No, paying attention I don't break a shot in adverse wind anyhow. Were less drift will help is if you get caught by a condition switch. 

If I went to a 365 38 bullet and fast twist barrel it would drift even less, at the expense of more recoil.  Light recoil is the reason I use a 38/55.  Trade off more drift  for less recoil. I don't shoot  equal offhand scores with my 40/65 CPA mostly because it kicks more.

This all for offhand matches. If the gun is rested a whole different game.

32 205 14 twist 1400 fps is a standard proven combination. You did  not make a big change to 235 & 11.5  Is that barrel a gain twist ? My guess is gain can stand more twist. Level of competition you fellows have up there few points can make a big difference match standing.

Boats

Boats:

I have not read Charlie Dell's book. I would like to but I am not sure where to find a copy. 
I met Charlie at ISSA shoots and it was one of his lube recipes that was the base for developing the Alberta Schuetzen Lube. 
We certainly respected his views and advice.

I had both a straight and a gain twist 14:1 .32 barrel and all my other RKS barrels are gain twist.
We believe gain twist improves the life of a barrel but does not significantly improve accuracy (from records kept by F-Class high power shooters).
However Ron Smith also chokes his barrels which really improve accuracy by reducing the potential of gas cutting around the side of a cast bullet.
Ron's barrel's are a continuous straight taper choke from precise machining (as opposed to those who step down the barrel diameter by intermittent lapping).

Harry Pope was always striving to improve the capabilities of his firearms and equipment. He never relied on only trying to improve only the shooter's capabilities (although that is also important as well).
I believe Ron Smith is following in Harry Pope's footsteps.

Dave

I believe Mann has clearly pointed out otherwise MB but as independent individuals we all have a tendency to hang onto to our own theories in lieu of relying on the already verified facts. The problem we all have as competitive cast bullet shooters / competitors is the inability to produce a truly balanced lead bullet by any of the means that are currently available. Thus the increased error with the faster twist rates as Mann pointed out still hold true to this very day. 

JLouis

Something you need to take into account, is that 16 was the standard twist for 32/40 for a hundred years and accuracy (accept for a very few exceptonal targets) and accuracy hadn't progressed much at all. 245's where about all that could be expected. then, two things happened and they came about fairly close together (Barry could give more accurate info on this, as he was one of the people that were involoved with it).

A lot of the top shooters went to 15 twist and also, spitzers entered the game. Somewhere in the 90's, I believe, the 14 twist, rared it's head. I know this one well, because Tommy Mason beat me by wide shot in, '94 with his RKS 14 twist, against my 30 cal Douglas 14 twist. He also beat me in the group match. But, in those years before '97 when I quit shooting, 247's became not so uncommon. Now I have to fast forward to 2010, when I started back shooting. I was amased at how many 250's that I saw had been shot in ASSRA & ISSA. It was really hard to believe but, it wasn't because everyone went back to flat nosed bullets and 16 twists and I was really impressed with that 236 gr PJ bullet that Dave gave me to take home from the Spokane match in 2011.

Frank

Schuetzendave wrote on Feb 26^th, 2015 at 1:27pm:


I just saw one sell on FleaBAy for about $110.00 a few days ago. 

Do you think he may be nose to nose soon? 

JLouis wrote on Feb 26^th, 2015 at 4:47pm:

If we would apply all whatever Mann found out, we'd all be shooting pure lead bullets too...  Are you?  And I'm not so sure that we cannot get a pretty good balanced bullet cast.  If it holds up at 1,000 yds, it would be pretty stable indeed.
BTW, do you really think spinning at 60,000 or 75,000 rpm will make that big of a difference?  if it's unbalanced, it will corksscrew - just the amplitude will be different.
FWIW, I have Mann's book, I have read it - and I wans't exactly overwhelmed.  While there is quite a bit of good information in there, I wouldn't call its contents as 'cut in stone'.   
I do believe current competition has shown that better results are possible using other methods than those advocated by F W Mann - if that's heresy, so be it.   Also, his work was done at 100 yds - change that parameter, and you have a different game.

110 for Charlies book is a lot, but worth it.  ASSRA had them for sale for 50+ some time ago, might check see if they have any left.

Boats