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View Full Version : 13.5 twist vs. 14 twist / boat tail vs flat base



scott mims
05-08-2015, 01:51 PM
It seem like the people I talk to uses a 13.5 twist barrel with boat tails...... Would that 13.5 twist shoot flat base bullets just as well? Also would a 14 twist shoot boattails just as well?
Let's say you have a couple thousand flat base bullets would you buy a 13.5 twist or a 14 twist barrel OR if you have a couple thousand boattails would you buy 13.5 twist or a 14 twist?
Do our 65-68 grain bullets (flat or boat) really show a difference between a 13.5 vs a 14 twist?

Didn't know how to ask my question so I put basically the same question in different ways 😃😃😃

GerryM
05-08-2015, 10:52 PM
FWIW i use a 13.5 twist because of data i received using JMB balistic's programs an it works.

Boat tail vs flat base I think that one is what a certain barrel likes

gabe ledesma
05-09-2015, 01:43 AM
Best thing to do is to buy a box of boat tails and a box of flat base bullets, Then see what works best on your guns barrel. Don't get lost on the 13.5 vs the 14 tw barrel thing, Both types have won records.

Wilbur
05-09-2015, 11:03 AM
Scott - there's no difference here. Yes, the barrel may prefer one over the other but the next one may be different. Any barrel might shoot both very well, one better than the other, or neither. It's the "neither" that often occurs - look at the match results from anywhere.

To answer your question further (and you know this) I'll ask that you ponder another question....How many barrels do the folks that win regularly go through looking for exactly what you're looking for? Folks with the kind of money you and I have need to first have a good rifle and then get lucky when buying a barrel.

goodgrouper
05-09-2015, 12:19 PM
Scott - there's no difference here. Yes, the barrel may prefer one over the other but the next one may be different. Any barrel might shoot both very well, one better than the other, or neither. It's the "neither" that often occurs - look at the match results from anywhere.

To answer your question further (and you know this) I'll ask that you ponder another question....How many barrels do the folks that win regularly go through looking for exactly what you're looking for? Folks with the kind of money you and I have need to first have a good rifle and then get lucky when buying a barrel.

Good points.;)

goodgrouper
05-09-2015, 12:25 PM
I had a chat with TB about twists once. He was playing with gain twists and Berger Column bullets at the time. I was shooting really short boat tails in 14" twists. He said that if he lived where I live (4500'), he'd never order anything but 15" twists. I thought he meant for the short little bullets I was using, but then he said 15's for everything. So if he recommends 15's for boat tails and flat base, I doubt the difference between a 13.5 and 14 will mean nothing. I've gotten both types of bullets to shoot in both of those twists, and in both cut and buttoned barrels. It's each barrel's preferences and you have to figure it out one at a time.

scott mims
05-09-2015, 03:43 PM
I understand barrel A might like so and so bullet while barrel B might like just the opposite. I just wondered if somewhere along the way someone found out/thought a 13.5 shot boattails better and did that mean they thought a 14 shot flat base better. Thanks again everybody.

Dave Coots
05-09-2015, 09:54 PM
Is the 13.5 really that, and the same with the 14?

Later
Dave

Wilbur
05-10-2015, 10:50 AM
I understand barrel A might like so and so bullet while barrel B might like just the opposite. I just wondered if somewhere along the way someone found out/thought a 13.5 shot boattails better and did that mean they thought a 14 shot flat base better. Thanks again everybody.

If they didn't do something like a lifetime test it would only be an opinion. Further, if it took a lifetime, it would be an opinion as well. Remember when the folks that full length sized their cases placed "mid pack"????

You're on your own on this one...as is everybody. I know you know this but just writing to be writing I suppose.

Boyd Allen
05-10-2015, 11:43 AM
I believe that the whole 13.5 thing took off after Lester Bruno found, and reported that combining one with his 00 BT bullets seemed to take him to a new level of accuracy. I think that his level of experience and place in the BR Hall of Fame are sufficient to merit consideration of the idea.

I am under the impression that for a given length bullet, that pointier BT bullets may require a bit more twist for optimal stabilization.

Also, I seem to remember (from the distant past) that Mike Walker had mentioned that he thought that 14" twist might be slightly less than optimal for .825 jacket bullets. I also note that Berger chose .790 jackets for their COLUMN bullets, perhaps in recognition of the fact that 14 twist barrels are probably the most common.

adamsgt
05-10-2015, 01:47 PM
I bought a couple of Kreiger LV 13.5 twist barrels from Bruno. 2-3 years ago I bought a bunch of Lester's 00 BT from Butch Fjoser. I even coated some with Danzac to make it even more interesting. Maybe I can marry them up now and see what happens.

GerryM
05-10-2015, 10:35 PM
If you check with jbm ballistics i'm sure you will get a few surprise,s

with the stability factors.