Too much jump?

[FireFlyFishing]

Well, I don't think it will damage your rifle if that's what you're asking. I agree with @FEENIX about choice #2 though.

 

[FEENIX]

as mentioned you need to change your way of measuring. flat based bullets like you pictured are not jump sensitive and can be jumped .100 or more pretty easily, have done it many times. remember Weatherby uses huge amounts of free bore and shoot accurately.

Yep!

With 145 Black Hole, I can touch the lands on my .257 WBY (SAAMI). The current load is .015" off the lands.

 

[FEENIX]

Guys, im well aware of cbto and coal
This is a hypothetical question
I'm not looking for a how to,
I just wanna know if its possible and if someone has tried it and what their results were.

Please show the CBTO measurements to satisfy our curiosity.

 

[Marksman LLC]

Please show the CBTO measurements to satisfy our curiosity.

I'll try, its gunna be hard to do with a modified case but ill see if I can.
My dummy rounds are still with the Smith and I'm not curious enough to seat a bullet.

I was just guessing that it would be a half inch jump but we'll see how close that guess was.

 

[FireFlyFishing]

Sorry, this came to mind when you said 0.5".

 

[FEENIX]

Sorry, this came to mind when you said 0.5".

View attachment 544134

You behave!

 

[Marksman LLC]

You behave!

Okay first is 133 berger at Jam

Second is a 75gr Hot-cor flat nose with base at shoulder/neck junction and right under cannelure

Third is sierra 100gr gameking Spitzer with boattail at neck/shoulder junction

 

[Marksman LLC]

So closer to a quarter inch than half inch
About .230 jump for those 75 grain

 

[Buttermilk]

I had a 300 Blackout Remington 700 SA rifle that had a throat a mile long. I was jumping ~1/2" or so and getting 1/2 MOA groups from my hand loads.

Bullet used was a Nosler 125 BT and shot in a 1:7" twist barrel.

 

[FEENIX]

I'll try, its gunna be hard to do with a modified case but ill see if I can.
My dummy rounds are still with the Smith and I'm not curious enough to seat a bullet.

I was just guessing that it would be a half inch jump but we'll see how close that guess was.

The difference between COAL and CBTO can be huge depending on bullet design (ogive). Below is an example. .300 WSM with 215 Berger.

2.961 - 2.197 = .764

 

[QuietTexan]

My question is has anyone else done this and what was the results?

Very common issue with varmint bullets even in some SAAMI spec designs, so don't sweat it. I've shot bullets so short I can't even measure BTO touching the lands because the bullet comes out of the neck trying to use the comparator.

My 243AI is set up for heavies, 100+gn in a 7 twist, but will jump light monos no problem. 223AI in an 8 twist will jump 55gn Nosler Varmint BTs (that's not quite as agressive as a 243AI/7 twist) and they hold together fine at those velocities.

~80gn from a 25 Creedmoor, to heck with it, send them.

 

[Reelamin]

Is there such a thing?

Let's say for instance I have a 25 creedmoor chamber that's throated for really long high bc bullets, but have some 80 grain Varmint bullets that are jumping a half inch into the lands....

If it doesn't shoot then it's too much. If it shoots great then it's just right.

 

[Mathews Diehard]

I believe Barnes states, or used to, that their bullets may like up to a quarter inch jump. Or maybe I'm remembering wrong lol

 

[243winxb]

A long jump needs rounds centered in chamber.

Size only 1/2 of neck with bushing. Unsized part fully expands to chanber, soon or later.