Is this HUGE jump to the lands in my R700 normal?

P

punkwood2k

Sergeant
Full Member
Minuteman
Nov 19, 2013
152
1
Green Valley Ranch, CO
#1
In another post, I was told that the AICS magazine length is 2.875", which would also be the max cartridge length obviously.. The length to the lands in my new .308 R700 is 2.372 (ogive measured), or 2.957" to bullet tip. Skipping all the math and ogive to tip conversions, this means that my MAX length cartridge (fitted to magazine) would have a HUGE jump to the lands of 0.102" . ONE TENTH of an inch! When we are talking 0.005 to 0.010 jumps making significant differences in accuracy, what in the heck is 10x's that going to do?

Has anyone else noticed this with their R700's? Or is mine just out of spec or something?

For reference, its an R700 ADL .308WIN, 26" varmint barrel
 
#2
You won't know until you try it. I run my 140 VLDS at mag length in my 260. It shoots half moa groups(+/-) with a .095 jump

Sent from my XT1080 using Tapatalk
 
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#3
I'm not a 700 guy but with factory barrels I seem to recall most people not being able to hit the lands in a magazine. My advice would be to use a bullet that is more tolerant to being jumped. I just purchased an AI and with the factory barrel I can't hit the lands with a Berger HVLD so I am going to shoot Matchkings instead. What bullet were your planning on using?
 
#4
That doesn't mean it won't shoot. A lot of guys jump the smk175's .050" or more and have good luck with them. Alpha mags will get you a little more length. Best to shoot it and see.
 
#6
HonkeyMcGee88 said:
I'm not a 700 guy but with factory barrels I seem to recall most people not being able to hit the lands in a magazine. My advice would be to use a bullet that is more tolerant to being jumped. I just purchased an AI and with the factory barrel I can't hit the lands with a Berger HVLD so I am going to shoot Matchkings instead. What bullet were your planning on using?
Click to expand...

I shoot 175gr Nosler CusComps.
 
#7
Like the other guys have said go try it out, chances are it will work fine. The Bergers I shot weren't hitting the lands but the still shot just fine, I just decided to change to a matchking because I could closer to the lands with it.
 
#9
Yep its normal for the factory 0.308 varmint barrel. When I bought mine it had something like 3 feet of freebore but I still found a good load that shot 0.5in at 100 and 1in at 200. It was a pretty good barrel and if remington didn't have to lawyer proof/american idiot proof the chamber it'd be even better. Just use the SMK/Nosler CC and you shouldn't need to worry about jump in that thing.

As for the more blunt less slender bullet question the answer is yes but you won't be getting world record groups with it any way but should still get 1/2 MOA with the right hand load.
 
#11
It can be fixed to your specs you desire. Talk to a local smith. Let him know what bullet you want to run, measurements, all that good stuff. It can be re-chambered easily. I burned the throat out of my 204 recently. A local smith will cut off 1", re-chamber for a little under $200.

Now for JUMP??? I bought my son a cheap Rossi 3 barrel single shot kit a few years ago. The 20ga and 22LR barrels are great! The 243...sucks! 3/8" jump. Thats why I could never get it to group.lol. I read many forums and blogs. Most said this was due to gun manufactures lawyers recommending long jumps for safety. Basically, factory rifles could in no way engage the lands from hand loads, which reduces overpressuring issues totally. Have a smith cut it for you, you'll be happy.
 
#12
If you want true numbers for any bullet jump you need to get a bullet comparator set, and a OAL gauge. Whatever bullet you decide to run is also what you'll put in your OAL gauge to check the throat of the rifle with. That'll give you a more true number as to the jump. Different bullets have the ogive in different location with regard to the meplat of the bullet. Yes a smith can whack an inch or so off and use a reamer closely matching your cartridge set up and rechamber it....I say if you go that far, spend a couple hundred extra and go aftermarket barrel so your not upset when you put it back together and find a rough factory bore the hard way. Just my .03
 
#13
I posted a similar thread about a month ago and yes. Mine measures 3.08" (yes, ironic). My 223 16.5" tactical has way too short of a freebore area and I have it with Keith at PCR right now getting it recut, but you can't really do much about too big of a freebore.
 
#16
168 gr amax seems to work fine in my 700 with a factory tube also - very similar throat to yours. Huge jump for magazine fed, but the Amax seems to like it just fine. Berger 185 VLD - not so much. Nosler 155gr custom comps were also not very happy with the large leap, but the Lapua 155s didn't seem to mind.
 
#19
Hello,
Since I am new could someone explain in a bit more detail what a 'jump' is?
Are we talking about the rifling lands and grooves?
Is it the distance from the magazine to headspace depth? The overall headspace tolerances?
I am not a noobie to firearms, but am just not familiar with all of this new long range shooing terminology.
Thanks!
 
#20
AyKay said:
Hello,
Since I am new could someone explain in a bit more detail what a 'jump' is?
Are we talking about the rifling lands and grooves?
Is it the distance from the magazine to headspace depth? The overall headspace tolerances?
I am not a noobie to firearms, but am just not familiar with all of this new long range shooing terminology.
Thanks!
Click to expand...

It's referring to a gap between where shoulder ends and the rifling begins. If you want to run bullets from a magazine they can only be so long and the space between the tip of the bullet and the point in the barrel before the rifling begins is the distance the bullet has to "jump" before engaging the rifling. A lot of guys with custom chambers load rounds so the tip of the bullet is touching the rifling. The theory being that the bullet cannot come out of alignment in the space it needs to travel before entering the rifling. If everything is concentric and the bullet lines up perfectly with the rifling a jump shouldn't be a problem, but often factory rifles are not completely concentric.

Conversely if the bullet is too far into the rifling when it is loaded, it may not be able to taken out of the chamber if it is not going to be fired and the bullet gets stuck int eh barrel while the brass is pulled out, spilling the powder in the chamber and causing a huge dangerous mess that needs to be fixed before another round can be fired.
 
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#21
punkwood2k said:
In another post, I was told that the AICS magazine length is 2.875", which would also be the max cartridge length obviously.. The length to the lands in my new .308 R700 is 2.372 (ogive measured), or 2.957" to bullet tip. Skipping all the math and ogive to tip conversions, this means that my MAX length cartridge (fitted to magazine) would have a HUGE jump to the lands of 0.102" . ONE TENTH of an inch! When we are talking 0.005 to 0.010 jumps making significant differences in accuracy, what in the heck is 10x's that going to do?

Has anyone else noticed this with their R700's? Or is mine just out of spec or something?

For reference, its an R700 ADL .308WIN, 26" varmint barrel
Click to expand...

2.970 in my AAC-SD. I'm about to attempt load development at loading to 2.820 factory bottom metal length and hope it's not a waste of time. Load will be using Lapua brass, BR2 primers, 175 SMKs and Varget.
 
#22
Thank you for clearing up what jump is for me! Is this a phenomenon or more of a proven fact? Seems like a CHF Remy barrel should be straight..?
Although, if the bullet is touching the rifling, I could see where that would be beneficial.
 
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