I'm trying to figure out what the difference is between jamming .020 or .025 or .010 into the rifling. I understand the benefit of jamming the rifling as a final "soft seating". What is the benefit of more jam? Seems like your just pushing the bullet into the case a little further. Can anyone help me out with this, maybe I'm just over thinking the whole thing and should go shoot.
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I know when I try to jam the rifling my bolt will not close on my rifle, so I have to stay out of the lands. This could be due to excessive force in the seating mode crimping the boolit harder. I am sure I don’t know and I have been loading for......... well since 1983............
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Some of the vld style bullets will actually shoot better jammed into the lands. Usually it is only .002-.003”. Jamming the bullet .020-.025” into the lands would just make it extremely difficult to close the bolt. I’ve only ever had one rifle that shot well with the bullet .002” into the lands. I’ve had several more that liked “kissing” the lands, but most like “just off” the lands. For a hunting rifle with standard bullets there is no need to jam the bullets.
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I was reading up on my bullet selection, nosler rdfs. Alot of guys are saying they shoot them with .020 jam. I was thinking what in the world is the difference between .010 jam and .020 jam. Seems like jammed in the rifling is jammed into the rifling. These would strictly be target loads not for hunting purposes.Originally Posted by JeffreyDeGraff
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I figure the bullet will push into the lands/rifling "x" far before the force overcomes neck tension or crimp. How far is "x"? Will depend from rifle to rifle. Saami spec should be way back from lands and the "x" will be way into the lands. Alllll those thousandths between are for experimentation. Some bullets may like to "jump" to lands, some may like to start in the lands. Then, some may want to be between. Am I missing what you're askin?
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Alright I get what your saying so the more jam is just becaus there is a greater amount of distance/force required to overcome the neck tension. Makes sense. I thought I was overthinking the whole process.
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There’s a few thing to keep in mind when dealing with COAL.
If you seat the bullet right on the lands, you may spike chamber pressure. So be careful there.
Every bullet is a little different in its preference, and a lot of it is dependent on Ogive design and chamber design. Some chambers have a really long throat making it near impossible to place the bullet on the lands, others have virtually no throat at all and even loading to SAAMI spec the round won’t chamber with specific bullet types.
SAAMI spec is set by the manufacturer that sponsors the round. They may set the COAL to a specific length so it works in the actions of rifle they intent to chamber the rifle for. Typically the magazine will be your limiting factor in how long you can seat the bullet out.
Seating the bullet closer to the lands in theory reduces bullet jump, which may help to ensure the bullet axis and the chamber axis stay aligned. If the bullet gets “cocked” even by a small amount it will self correct as it exits the barrel but this correction can introduce inaccuracy.
Oddly enough monolithic bullets do better when seated away from the lands. They typically recommend starting at least .050 thou off.
There’s a lot of room for experimentation here, and everyone’s rifle/bullet and cartridge combination will yield different results. Just be careful when “jamming” things into the lands, and back the load off a little, look for pressure signs, before working the load back up again.
Reloading...it’s like knitting for men.
Good stuff right there. Started building loads for my Bergara 6.5cm last weekend. My limiting factor is the feed ramp. My choices are notch the ramp, feed singles or be backed off the lands 20-60 thou depending on bullet.
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Yeah for mag fed 6.5’s I’ve starting using the misled RDF bullet. It’s a mimic of the Berger hybrid target bullet but it like a lot of jump. Anywhere from 40-80 thou and its happy, plus they are cheap compared to most all other bullets worth shooting
What is a RDF BOOLIT? I am interested cuz I am tired of spending .58/boolit.
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