Bob Brushingham
Member
Do they shoot best in the rifling or jumping? I don't have many and would like to shorten my learning curve because I can't get any more in time for upcoming shoot.
Thanks Bob
Thanks Bob
BT bullets in cut rifled barrels
- Thread starter Bob Brushingham
- Start date
B
Big Al
Guest
It's because the base of a flat base bullet is easy to screw up in bullet making, a bad base on a bullet has been known to cause big problems for over a century. BT don't have the problem. I don't think I have to mention setting up the brass for pressure rings, do I?
Pete Wass
Well-known member
jackie schmidt
New member
It depends,
On the design of the bullet, (ogive), and what powder you use.
Since this is Benchrest.com, I will give you my experience with a very popular Boat Tail, the Bruno 00.
When using 133 and a cut rifled barrel such as a Krieger, the best agging capability seems to be when you jam the bejeebers out of them. I set mine up to where the marks on the bullet are twice as long as they are wide.
Sounds ridiculous, huh. But just about every shooter who has tried this says that it works.
Why it works seems to be a product of the way the part of the bullet that contacts the lands is quite shallow. What seems "tight" really isn't. It is like the lands just sort of slide along the bullet, rather than engraving it.
Now, from what I have heard, this does not work with other powders, particularilly 8208. A very light jam seems to be the ticket in that department.
As for the Boat Tails temselves, some of the more popular bullets being used are in fact Boat Tails. The Hosttentine, (sp), Barts, and Bruno all have a big following........jackie
On the design of the bullet, (ogive), and what powder you use.
Since this is Benchrest.com, I will give you my experience with a very popular Boat Tail, the Bruno 00.
When using 133 and a cut rifled barrel such as a Krieger, the best agging capability seems to be when you jam the bejeebers out of them. I set mine up to where the marks on the bullet are twice as long as they are wide.
Sounds ridiculous, huh. But just about every shooter who has tried this says that it works.
Why it works seems to be a product of the way the part of the bullet that contacts the lands is quite shallow. What seems "tight" really isn't. It is like the lands just sort of slide along the bullet, rather than engraving it.
Now, from what I have heard, this does not work with other powders, particularilly 8208. A very light jam seems to be the ticket in that department.
As for the Boat Tails temselves, some of the more popular bullets being used are in fact Boat Tails. The Hosttentine, (sp), Barts, and Bruno all have a big following........jackie
John Kielly
Shari's fan club
Was a time when we believed that a boattail would seat easier & likely straighter in the neck than a flat base......
goodgrouper
tryingtobeabettergrouper
Hmmmmm..... I've had my last two Kriegers like a little jump. This being with N133 and the 00 Bruno boattail. The closer I got them to the rifling, the worse they shot.
Exactly opposite of what Jackie has experienced.
One barrel that was well used, TOLERATED the bullets making just ever so slight of a mark on the riflings but it liked .005 jump much more.
Exactly opposite of what Jackie has experienced.One barrel that was well used, TOLERATED the bullets making just ever so slight of a mark on the riflings but it liked .005 jump much more.
C
caroby
Guest
Hmmmmm..... I've had my last two Kriegers like a little jump. This being with N133 and the 00 Bruno boattail. The closer I got them to the rifling, the worse they shot.
One barrel that was well used, TOLERATED the bullets making just ever so slight of a mark on the riflings but it liked .005 jump much more.
Yes, I have found this too..............................................
Bob, Jackie is right too. Ya just gotta experiment.
cale
6mmBR and Berger 105 BT
I shoot F-Class with three guns, two with Krieger barrels and one with a Shilen barrel. The Kriegers seem to like the bullet to jump .010" best when shooting the Bergers and like a .010" jam when shooting the Sierra 107 MatchKings. The Shilen barrel likes .010" jam with both bullets.
I shoot F-Class with three guns, two with Krieger barrels and one with a Shilen barrel. The Kriegers seem to like the bullet to jump .010" best when shooting the Bergers and like a .010" jam when shooting the Sierra 107 MatchKings. The Shilen barrel likes .010" jam with both bullets.
Kent Harshman
Member
BT's in the Short-Range Game...
...just spoke with Bill Niemi a couple of days ago about a couple of things. For those of you who may not know Bill...he has an outstanding reputation as an engineer and as a carbide bullet die maker. The biggest reason that he feels that BT's have become so much more popular and successful in recent years in the short-range game is because of how our jackets are coming through today. They are heavier in the base section, and while this does not make them "bad", it does present challenges in perfecting the base of FB bullets in the custom bullet making operation. As Bill described it, "Since the base of the bullet is made mechanically in the BT operation, it is easier to deal with the thicker base section of the jacket when making BT's. A custom bullet maker has far less control over the base when making FB bullets than when making BT bullets."
...just spoke with Bill Niemi a couple of days ago about a couple of things. For those of you who may not know Bill...he has an outstanding reputation as an engineer and as a carbide bullet die maker. The biggest reason that he feels that BT's have become so much more popular and successful in recent years in the short-range game is because of how our jackets are coming through today. They are heavier in the base section, and while this does not make them "bad", it does present challenges in perfecting the base of FB bullets in the custom bullet making operation. As Bill described it, "Since the base of the bullet is made mechanically in the BT operation, it is easier to deal with the thicker base section of the jacket when making BT's. A custom bullet maker has far less control over the base when making FB bullets than when making BT bullets."
Bob Brushingham
Member
Thanks to you all. My supply is limited and all the makers are back ordered big time. I will try big jam and .010 jump and experiment more when I have the luxury of 3 or 4 thousand sitting on my shelf. Thanks again.
Bob
Bob
Bob,
Start at jam and back off .005 at a time shooting only three shot groups. If the first two are real bad, seat the third deeper and load to more like it. That will save time and bullets. .005 will get you closer faster and then fine tune. With V133, 28.8grns seems to work very well when searching for bullet seating depth but use what you are comfortable with. If you like to run them hot...you might want to use a higher baseline of powder.
Hovis
Start at jam and back off .005 at a time shooting only three shot groups. If the first two are real bad, seat the third deeper and load to more like it. That will save time and bullets. .005 will get you closer faster and then fine tune. With V133, 28.8grns seems to work very well when searching for bullet seating depth but use what you are comfortable with. If you like to run them hot...you might want to use a higher baseline of powder.
Hovis
Jump or Jam
This is always the question for BT users. Unfortunately there is no direct answer > all barrels are not created equal. Somewhere between .040 Off and hard jam will be a sweet spot. VV-133 somewhere between 26.5 grains and 30+ grains will be a sweet spot. Be methodical, its not that hard or expensive to find a good spot for YOUR barrel.
It does, however, take some work. All ranges and enviroments are not created equal. Some tunes work better in the wind, some tunes work better at a trigger pull, there in is the dilemma. Find what works for you. Goodgrouper just kicked butt in Colorado, Jackie is one of the best shooter in the USA. Heed their advise and remember its all shooting and its all fun. Good Luck.
Marty
This is always the question for BT users. Unfortunately there is no direct answer > all barrels are not created equal. Somewhere between .040 Off and hard jam will be a sweet spot. VV-133 somewhere between 26.5 grains and 30+ grains will be a sweet spot. Be methodical, its not that hard or expensive to find a good spot for YOUR barrel.
It does, however, take some work. All ranges and enviroments are not created equal. Some tunes work better in the wind, some tunes work better at a trigger pull, there in is the dilemma. Find what works for you. Goodgrouper just kicked butt in Colorado, Jackie is one of the best shooter in the USA. Heed their advise and remember its all shooting and its all fun. Good Luck.
Marty
Being kind of new at this I have some stupid questions.
I know every gun is different. So if you can give a ball park figure.
How much can we expect to gain or lose from one jam or jump to another?
Say from the sweet spot then to what it doesn't like?
I spoke to Lester Bruno about his 00 f.b. he said to try a kiss at the lands then back off in steps, up to .035 max.
I guess I have the same question about primer's like Wolf, CCI, CCI 4,
Fed match - ETC
thanks Don
I know every gun is different. So if you can give a ball park figure.
How much can we expect to gain or lose from one jam or jump to another?
Say from the sweet spot then to what it doesn't like?
I spoke to Lester Bruno about his 00 f.b. he said to try a kiss at the lands then back off in steps, up to .035 max.
I guess I have the same question about primer's like Wolf, CCI, CCI 4,
Fed match - ETC
thanks Don
Last edited:
Pete Wass
Well-known member
What I am looking for
is a hole that measures around .030 from 3-.3085 bullets passing through it. I actually did that once with a 30-47 rifle I had briefly. It only did it the one time though. I think most of us here are looking to find a combination that will give us groups in the 1's or less, at least that is what I want to see.
is a hole that measures around .030 from 3-.3085 bullets passing through it. I actually did that once with a 30-47 rifle I had briefly. It only did it the one time though. I think most of us here are looking to find a combination that will give us groups in the 1's or less, at least that is what I want to see.
goodgrouper
tryingtobeabettergrouper
I can't speak for everyone but I can tell you my process and what I look for.
I use bullet seating depth as a fine tuning method ONLY after I have found a powder charge that is working for the day. I should also mention that I never fine tune in dead calm conditions. I prefer a little breeze around 2 to 5 mph and steady if possible because I've found some seating depths might work wonders in calm conditions but fall apart in "match conditions" if you know what I mean.
So, after I find my charge, I change the seating depth of the bullet by +.005" if my starting load was way off the lands or I will change it -.005" if the start load was jammed into the riflings. I suppose you could go in .002" increments or smaller but I have found that carbon residue and copper fouling can override this small of a change and give mixed results or tamper with the final data. You could clean the gun after every group but I like to see what the barrel will do when it's fouled because 99% of your shots are going to come from a barrel with at least a little bit of copper and carbon in it. And besides, I might need to find the best load quickly and .005" increments covers more ground in a small time.
Anyhow, I shoot three shot groups changing the seating depth incrementally until the group is putting three bullets at least 3/4 of the way into each other at 100 yards. When the tune is at it's farthest point away from optimum, three bullets might not even touch at 100 yards or they will form a triangular group with only the very slightest edge of each hole making contact with the other two shots. Of course, a hummer barrel might put them 1/2 the way into each other at it's most out of tune so it's hard to give you a concrete number. It's all dependent on the barrel itself. Some are not fussy with seating depth and will shoot anything you throw together and others need the "X" load and won't like much else.
Another thing I might throw in; you will usually have two places where the bullet shoots well. One off the lands and one in somewhat. So if you have the time, it might be worthwhile finding them both and comparing them against each other. This will, of course, require you to run the full ladder of increments from top to bottom to achieve it, but we're only talking three bullets times each .005" increment in a .040 to .050" measurement (.020" jam to .030" off).
The downside to the barrels that prefer lots of "jam" is that it makes it hard to extract a loaded round from the chamber if you can't clear by firing. The bullet is stuck and you'll have powder all over inside your receiver. That's why I have been liking the boat tail design. In my experience, they seem to prefer a little less jam than flat base bullets and a lighter load at that. But then again, every barrel is different.
Then once you start seeing good improvement in the group, shoot it a few times with five shot groups using sighters just like you would in a match. If it holds together for an aggregate, you have a tuned rifle ready to go.
As for primers, I believe a good load can be worked up around any primer so pick one and go for it. Just don't try to substitute one for another especially during a match! You will not like the results.
Last edited: