Not enough neck to reach lands

[jcopas]

This may be a dumb question, but I have rifle that I have given me fits. The rifles (308 Win SPS Varmint) has a slow twist (1-12.375") and a LONG throat. 155gr bthp's I've tried clear the case mouth before reaching the lands, and 168's aren't much better. It has a tendency to put two bullets touching or in the same hole, and then the next one will be about an inch away. I'm trying to figure out something that will get them shooting more consistently.

I have a tang safety Ruger m77 in 7x57 with a measured twist rate at about 1-10". It has similar problems, and I found a work around on this one using 175gr RN bullets. But it's a 20" barrel that gets lugged around the woods. I don't want to resort to a heavy round nose for a bull barreled 308 though...

 

[Straightshooter1]

This may be a dumb question, but I have rifle that I have given me fits. The rifles (308 Win SPS Varmint) has a slow twist (1-12.375") and a LONG throat. 155gr bthp's I've tried clear the case mouth before reaching the lands, and 168's aren't much better. It has a tendency to put two bullets touching or in the same hole, and then the next one will be about an inch away. I'm trying to figure out something that will get them shooting more consistently.

I have a tang safety Ruger m77 in 7x57 with a measured twist rate at about 1-10". It has similar problems, and I found a work around on this one using 175gr RN bullets. But it's a 20" barrel that gets lugged around the woods. I don't want to resort to a heavy round nose for a bull barreled 308 though...

What case length are you trimming your cases to?

To get more neck contact for a loaded round, I'll trim cases to .005" short of maximum length for the chamber. I do this a lot to maximize case neck contact with the bullet's bearing surface and when trying to stay away from any contact with any donut. In some instances, it's takes a few firing along with sizing the necks where there's a lot of movement of the brass from the sizing process where I might gain .003 -004 in case length each time the brass is sized. Normally, I don't like to move the brass like that as that work hardens the neck, though the annealing that I do after each firing helps a lot with that.

You can always go with a longer bullet. Like going from a 168 SMK to a 169 SMK that's longer along with a longer bearing surface.

 

[Frankm]

Try a less aggressive pointed bullet. May not have as high a bc but if it groups good makes the rifle useful.

Maybe a Nosler BT or Sierra Pro Hunter. Good ole cup and core stuff. Those worked forever before all the hype on high BC ultra LR stuff …

Good Luck.

 

[jds holler]

Use one of the little chamber length gauges to see just how long your case can actually be. Many chambers are waayy longer than spec.

You didn't mention how much room your magazine allows, or your action port. jd

 

[jcopas]

What case length are you trimming your cases to?

To get more neck contact for a loaded round, I'll trim cases to .005" short of maximum length for the chamber. I do this a lot to maximize case neck contact with the bullet's bearing surface and when trying to stay away from any contact with any donut. In some instances, it's takes a few firing along with sizing the necks where there's a lot of movement of the brass from the sizing process where I might gain .003 -004 in case length each time the brass is sized. Normally, I don't like to move the brass like that as that work hardens the neck, though the annealing that I do after each firing helps a lot with that.

You can always go with a longer bullet. Like going from a 168 SMK to a 169 SMK that's longer along with a longer bearing surface.

I've been trimming by the book to about 2.005 if I remember correctly.

 

[DShortt]

In my opinion, a long throat in a 1 in 12 twist .308 was a poor choice by whomever chambered it.
You're kinda stuck with 'jump' now. Hopefully it's not a loose throat on top of being long, or I'd cut my losses before you spend enough on components to have the barrel replaced.
You're starting out with a far less than optimal situation which will only get worse as the round count increases.

 

[Bill Norris]

This may be a dumb question, but I have rifle that I have given me fits. The rifles (308 Win SPS Varmint) has a slow twist (1-12.375") and a LONG throat. 155gr bthp's I've tried clear the case mouth before reaching the lands, and 168's aren't much better. It has a tendency to put two bullets touching or in the same hole, and then the next one will be about an inch away. I'm trying to figure out something that will get them shooting more consistently.

I have a tang safety Ruger m77 in 7x57 with a measured twist rate at about 1-10". It has similar problems, and I found a work around on this one using 175gr RN bullets. But it's a 20" barrel that gets lugged around the woods. I don't want to resort to a heavy round nose for a bull barreled 308 though...

Remington always went crazy with long free bore in the .308. Almost impossible to reach the lands and have any bullet left in the case.

 

[jcopas]

Use one of the little chamber length gauges to see just how long your case can actually be. Many chambers are waayy longer than spec.

You didn't mention how much room your magazine allows, or your action port. jd

The last set of bullets were loaded to 2.90" far too long for the magazine. I can recheck the exact measurements later, but it was pretty long compared to my other 308 Win, something like 1/4" longer.

Try a less aggressive pointed bullet. May not have as high a bc but if it groups good makes the rifle useful.

Maybe a Nosler BT or Sierra Pro Hunter. Good ole cup and core stuff. Those worked forever before all the hype on high BC ultra LR stuff …

Good Luck.

I'd have recheck the loading bench again, but I don't think I have anything like that. I pretty well only messed with BTHP bullets as this rifle was originally bought just to punch paper.

 

[Straightshooter1]

I've been trimming by the book to about 2.005 if I remember correctly.

That's what I used to trim them to. These days, I'm trimming my .308 cases to 2.010" with ~.005 to spare. Since I trim after every sizing, I could go a little longer since it's the compression during sizing that'll make the case necks longer.

 

[jds holler]

I've seen chambers that are often 20 or even 30 thou longer than spec. You can make or buy a little doohickey to find out. You may be able to let your cases grow, but don't let anyone else shoot them. jd

 

[dellet]

You might take a look at Berger’s bullet reference chart. It has bullet dimensions and required twist. You might be surprised at the number of their bullets that a 1/13 is recommended.

You should be able to use the numbers to approximate what length they will hit the lands if you have figured your chamber. With base to ogive, less boat tail length, you can figure pretty close to how much bearing surface will be in the neck. If you know the touch length in your chamber

Bad news is that you might be shooting single shot more than you want.

Bullet Reference Charts

DESCRIPTION LEGEND FB: Flat Base High BC FB: High BC Flat Base BR Column: Bench Rest Flat Base BT: Boat Tail Long Range BT/Juggernaut: Long Range Boat Tail VLD: Very Low Drag Hybrid: Combination Secant and Tangent Ogive LR Hybrid: Long Range Hybrid AR Hybrid/Classic Hunter: Short Nose Hybrid...

bergerbullets.com

 

[jcopas]

You might take a look at Berger’s bullet reference chart. It has bullet dimensions and required twist. You might be surprised at the number of their bullets that a 1/13 is recommended.

You should be able to use the numbers to approximate what length they will hit the lands if you have figured your chamber. With base to ogive, less boat tail length, you can figure pretty close to how much bearing surface will be in the neck. If you know the touch length in your chamber

Bad news is that you might be shooting single shot more than you want.

Bullet Reference Charts

DESCRIPTION LEGEND FB: Flat Base High BC FB: High BC Flat Base BR Column: Bench Rest Flat Base BT: Boat Tail Long Range BT/Juggernaut: Long Range Boat Tail VLD: Very Low Drag Hybrid: Combination Secant and Tangent Ogive LR Hybrid: Long Range Hybrid AR Hybrid/Classic Hunter: Short Nose Hybrid...

bergerbullets.com

That's handy as the 155's I have now are the Berger full bore's.

 

[jcopas]

Try a less aggressive pointed bullet. May not have as high a bc but if it groups good makes the rifle useful.

Maybe a Nosler BT or Sierra Pro Hunter. Good ole cup and core stuff. Those worked forever before all the hype on high BC ultra LR stuff …

Good Luck.

Well, I pulled out a bunch of bullets and checked. Hornady 168 BTHP, Sierra 165 game changers 190 matchkings are all have just a little nub in the case once they hit the lands. The best fits I found were Swift 165 Scirocco II's and Barnes 168gr ttsx's. Both are pretty long, about 2.92 COAL at the lands. Too expensive for punching paper and maybe too long to stabilize. Base to Ogive measures out at 2.341", not a 1/4" longer than the other 308, closer to 1/10".

 

[JB10]

I have an extremely long throat rem 700 308. Does not like long jump from any bullet i tried. The best bullet i tried that i can get close to the throat and still be in the brass was berger 175 vld hunting bullets. Now the downfall, has to be single fed. Wont fit in mag. My gunsmith said he could set the barrel back and run a shorter throat remer in it. I have not shot it in about 5 years so i just leave it alone. Id change it over to some other cartridge but for some reason i want to keep a 308 around just in case i ever want one again.

 

[over_thetop]

does it have a mag filler?

 

[jcopas]

does it have a mag filler?

Not sure what you mean here. It's got the standard BDL bottom plate and short action box.

I have an extremely long throat rem 700 308. Does not like long jump from any bullet i tried. The best bullet i tried that i can get close to the throat and still be in the brass was berger 175 vld hunting bullets. Now the downfall, has to be single fed. Wont fit in mag. My gunsmith said he could set the barrel back and run a shorter throat remer in it. I have not shot it in about 5 years so i just leave it alone. Id change it over to some other cartridge but for some reason i want to keep a 308 around just in case i ever want one again.

I'm not too worried about single loading honestly, it's not something I would hunt with. My other 308 is shorter, lighter, and threaded for my suppressor, plus it shoots better to boot....

I'm tempted to just have a gunsmith rebarrel it instead of throwing powder, primers and bullets at this thing.

 

[over_thetop]

drop the follower and bottom plate and see if there's a rectangular box behind the follower or better yet pull the action out of the stock

 

[dellet]

I think a 175 SMK would be a good candidate.

 

[jcopas]

Bullet Reference Charts

DESCRIPTION LEGEND FB: Flat Base High BC FB: High BC Flat Base BR Column: Bench Rest Flat Base BT: Boat Tail Long Range BT/Juggernaut: Long Range Boat Tail VLD: Very Low Drag Hybrid: Combination Secant and Tangent Ogive LR Hybrid: Long Range Hybrid AR Hybrid/Classic Hunter: Short Nose Hybrid...

bergerbullets.com

Ok, so that list was pretty cool. It looks like the 185gr classic hunter has a short nose, long bearing surface, and relatively short OAL. That might be the last thing I throw at this thing before I give up on it.

drop the follower and bottom plate and see if there's a rectangular box behind the follower or better yet pull the action out of the stock

View attachment 1598758

That will have to wait to Friday, I'll be gone for work all day tomorrow.

 

[10XSHOOTER]

Have a gunsmith set the barrel back .050 - .100. not hard to do with a thicker recoil lug.