I was wondering if having a custom barrel makes bullet jump the the lands less important? I guess my thought is that if a guy has a better quality barrel than factory, it should be less picky. So if a guy throated a custom barrel with a long throat could he get more fps that a throat that he can reach the lands in? Or does the gain in fps come from being able to seat the bullet longer and get more powder in the case?
Barrel throating ?
- Thread starter jmad_81
- Start date
good questions..... and I like your thought process. Others will know more than I, but I'll give you my take.
Deep throats can really effect pressures, the extra case cappacity could end up useless.
You can gain extra velocity by adding length to the barrel. Custom barrel makers can finish the barrel any length you want (they typically charge more for over 28").
Personally, I'd throat the chamber according to what the barrel maker suggests with the type of bullet I want to shoot as well as magazine depth.
Deep throats can really effect pressures, the extra case cappacity could end up useless.
You can gain extra velocity by adding length to the barrel. Custom barrel makers can finish the barrel any length you want (they typically charge more for over 28").
Personally, I'd throat the chamber according to what the barrel maker suggests with the type of bullet I want to shoot as well as magazine depth.
- Nov 4, 2004
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Jake,
Ask the barrel maker what they suggest. My 280 AI is throated long BUT I also have the magazine length. I am actually seating bullets .015-.020" off the lands. If I followed SAAMI spec, there would be a lot of jump.
JD338
Ask the barrel maker what they suggest. My 280 AI is throated long BUT I also have the magazine length. I am actually seating bullets .015-.020" off the lands. If I followed SAAMI spec, there would be a lot of jump.
JD338
Ridge_Runner
Handloader
- Sep 29, 2006
- 1,394
- 760
jmad_81":2b4xtju4 said:
both, bullet jump increases mv, and increases case capacity. so ya get a double dose of more fps with a long throat. a bullet in the lands takes more pressure to get in started into the rifleing than a bullet thats moving when it hits the rifleing, an example
my 6.5 gibbs loaded on the lands with a 140 berger and 61 gr of re22 runs 3240 fps and loses the pocket upon firing, give it .030" jump and runs 3340 fps and the cases last 4 firings.
a long throat does limit your ability to chase the lands as the throat erodes however.
RR
Ridge_Runner
Handloader
- Sep 29, 2006
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thats with a hot lot of re22 scotty, the next lot I tried .030" off ran 3120, sure I could add powder and get the velocity back, but would the next lot be fast or slow? that and the temp sensativity combined turned me against re-22 for my long range rigs.
RR
RR
Ridge_Runner
Handloader
- Sep 29, 2006
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have no idea scotty, for at least a year I heard rumours about lot to lot varience in re22, then about a year ago on my 4th pound of it, my trajectory went to pot, some work with the chrony told the story.
RR
RR
- Thread starter
- #9
Thanks RR. SO if I'm understanding this right, if I can't go any longer in the mag, but get a longer throat, I can get more fps, and not have as big of a psi issue? I believe that the weatherbys have a lot of free bore to help them get more fps, is this right?
Desert Fox
Handloader
- Aug 14, 2006
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The reason for Weatherby freebore is to maximized case capacity by having the bullet seat farther out. In doing so they're able increase powder capacity. This is how Weatherby cartridge achieved higher velocity. Barrel throating is not the same as free bore although the concept is quite similar. Barrel throating applies to the shape of the bullet ogive. What I mean with it is that, your barrel chamber can be throated to the type of bullet you're going to use. A good example is throating your barrel to shoot VLD bullets.
