Building New Barrel Around 6.5 x 47 Lapua with 130 Berger VLD - What is Good for OAL?

[IndianaRem5r]

My plan is to have the 'smith chamber the barrel to put the 130 grain VLD on the lands out of the box then I can back it off a little. Any suggestions for a good OAL to start with for the dummy round? My first thought is an even 2.800" OAL. That puts the end of the bullet just past the neck to shoulder transition.

 

[Supersubes]

Do you have the components to make the dummy on hand now? Short case, with a long neck, in a big (relatively) magazine. You can set the bullet wherever you like without issue. I don’t have any 130 eld’s, but of the handful of dummies I have laying around from my reamer, none exceed 2.72”.

 

[padom]

Correct. 2.72-2.74 range...

 

[IndianaRem5r]

Yes, I have the components to load now. I have made one dummy at 2.800 OAL. The longer I seat the bullet, the more powder capacity, which is a factor in the 6.5 x 47 Lapua. I would like to avoid compressed loads.

 

[Supersubes]

You won’t be compressing powder with the 130. You also won’t see a marked increase in velocity by pushing the bullet out either imo, so don’t get too wrapped around the axle on that. I’d seat the bottom of the bearing surface .050-.075 above the neck/shoulder junction and call it a day.

Edit: just realized you wrote berger vld and I mistakenly read eld. No matter though, doesn’t change anything.

 

[5RWill]

What barrel length are you running? I'm running a pretty moderate free bore at .123 even with the long 130gr norma i never compressed loads and was managing 2800ish with a 23" barrel. Got to 2900 once i switched to berger Hybrids again without compressing loads. Varget should get you where you want to go depending on barrel length. I'd personally want the boat tail of the bullet at the datum line or a little below it so you can chase if/when the throat erodes.

 

[IndianaRem5r]

It will be a 26" barrel.

 

[Supersubes]

As 5RWill said, the shortcut to your answer is the freebore spec instead of messing around with COAL as a result of FB (extrapolating). My last 47L barrel was .155 IIRC and I lost enough neck right out of the gate using 130's that it reduced how much I could chase the lands. That FB was spec'd to balance 130's and 140's. I now use something like a .115 (have to check). I bet a .123 would be gtg for 130's as well.

I don’t think it's a shortcut to him, because he may not understand how to measure for it. I could be wrong. A dummy to the smith would be easy button stuff.

Agreed on the freebore. My reamer has .123fb. All I ever shot out of it was 130gr. I wouldn’t change a thing.

 

[Supersubes]

No better time than when building a dummy round to learn about FB

Cant argue with that!

 

[IndianaRem5r]

Thanks for all the great info, guys. I do know what the term "free bore" refers to, but I am obviously not the gunsmith that will be doing the chamber. I will look at the 0.123 dimension and verify.

 

[spife7980]

The throat of the chamber is the area after the brass but before you get to the full rifling in the barrel. The free bore is the section that has all of the lands removed (aka entirely groove), the leade is the section of the throat where the lands begin to taper up into the full rifling.

So basically it’s the space where the bullet jumps from the case but before being engraved by the lands.

The longer the freebore the longer your round will be to position a certain bullet at your desired position relative to the lands. The longer the bullet the less case capacity the case has so moving the bullet out further allows you to infringe upon that less and can fit in more powder.

The longer you go the further away your lands will erode and at a certain point you will be too far extended to position the bullet where you want relative to the lands while still maintaining enough grip/brass on bullet contact.

You could also infringe in your magazines internal capacities in that same scenario but a x47 shouldn’t really have that issue as the others have already gone over.

 

[5RWill]

I will say i prefer the aesthetics of more FB over less. My short 6.5x47 is .155 while my comp gun is .123. Of course .123 is more conducive to chasing the lands but i hate how stubby my rounds look lol. I seat 10 thou off the lands and even with a short bullet like the hybrid I’m slighlty below the shoulder. Though again not compressing loads. Not with varget or 4166 anyway. Something like H4350 or RL16 you probably would be. The hybrid is a relatively short 130 so it works very well. With the 26” tube though you shouldn’t have to push hard to hit 2800-2900 like i am.
Here are some pictures of .010 off the lands with the 130gr hybrid with .123FB. Then the .123gr Scenar with .155FB and the 123gr ELD-M with .155Fb Of course it's hard to get the bullets exact when making a picture like this but it gives you some idea. The 130gr Hybrid pic kind of sucks should've had the bullet to the right of the case. As said though you can make a dummy round and have the lands exactly where you want it.

 

[Hondo64d]

My plan is to have the 'smith chamber the barrel to put the 130 grain VLD on the lands out of the box then I can back it off a little. Any suggestions for a good OAL to start with for the dummy round? My first thought is an even 2.800" OAL. That puts the end of the bullet just past the neck to shoulder transition.

What is your magazine length? Make a dummy short of mag length that will feed well and allow you to chase the lands and base your freebore on that.

John

 

[IndianaRem5r]

My magazine is 2.86. I have tons of room.

 

[demolitionman]

2.105 to ogive with 130vlds here

 

[Hondo64d]

My magazine is 2.86. I have tons of room.

2.8 should be a good place to start then.

John

 

[bohem]

I have found that a .145 freebore is damn near optimal with the 130/135's and it still handles a 140

 

[Marksman10x]

 

[IndianaRem5r]

@IndianaRem5r is your gunsmith going to order a custom reamer from JGS or someplace for this barrel job?

Sorry, I cannot answer this as I have not inquired whether he has an appropriate reamer on hand or not.

 

[Supersubes]

I just watched the vid. Op, no need to go through all that. You can calculate the desired seating depth, and make your dummy. Bullet bearing surface length, plus case length, minus desired seating depth into the neck. The 6.5x47 has a a chamber neck of .320”, .015” short of that would be a trim length, so .305”. If you seated the bullet .255” into the neck, the bearing surface would be .050 above neck/shoulder junction.


I just did this for a 130 hybrid using a case that is exactly .015 short of my chamber length. 1.845 + .420 - .255= Base to ogive of 2.010”. Your numbers will vary of course because of your comparator. Chamber length for the x47 is 1.8606 according to my print. You can simply subtract your desired neck clearance from that (trim length).

Regarding the gunsmith. Some have a selection of reamers in a given cartridge, some have one or two, and some have a reamer with zero or very little freebore and use a throating reamer to cut the throat to any desired depth. If your guy is one of the first two, just get a freebore numbers from him and calculate if they’ll work for you. No need for the dummy unless you don’t feel comfortable solving for the required freebore. If he uses a throater, send the dummy, and they’ll do whatever you like. You can always order your own reamer. They’re about $160-200 bucks. Not a bad investment considering it will last a lifetime if treated properly. I rent mine to my friends occasionally, which offsets the cost as well.

 

[RFutch]

I was planning on ordering a Criterion 6.5x47L barrel and shooting the 130 RDF but after reading this thread I'm not so sure now. Their chamber has a .167 FB.

Any advice you guys might have? Do I need to pick a different barrel or bullet?

 

[Hondo64d]

Depends on your magazine length. I have no problems reaching the lands and feeding from a magpul magazine with my Criterion 6.5x47 barrel. The AICS mags have even more internal length.

As a side note, I highly recommend the Criterion Barrels. I have them in 6.5x47, 22-250, and .308. They are the best shooting barrels I have ever used and that includes some pretty notable competitors, Hart, Douglas, Krieger, and Brux.

John

 

[padom]

I was planning on ordering a Criterion 6.5x47L barrel and shooting the 130 RDF but after reading this thread I'm not so sure now. Their chamber has a .167 FB.

Any advice you guys might have? Do I need to pick a different barrel or bullet?

Pick a different bullet.. lolol. Just tested the 130 RDF in my 6.5x47L...no matter the searing depth accuracy was no where near as good as 8-10 other bullets I've tested in it. If you want to shoot 130's shoot AR Hybrids or 130 ELD-M

 

[RFutch]

Ok so I’m still learning here. Obviously a secant ogive gives you a higher BC. If you use a bullet with a tangent ogive, does that mean you won’t ever have to chase the lands to maintain accuracy over the life of the barrel?

Sorry I don’t mean to highjack this thread but my head is spinning with all these new bullet choices.

 

[Supersubes]

Ok so I’m still learning here. Obviously a secant ogive gives you a higher BC. If you use a bullet with a tangent ogive, does that mean you won’t ever have to chase the lands to maintain accuracy over the life of the barrel?

Sorry I don’t mean to highjack this thread but my head is spinning with all these new bullet choices.

Tangent ogive bullets don’t seem to care as much, as you noted, but you still have to address the rest of the load. Pressures tend to drop as the throat burns away. This could make it unhappy. Ultimately you’ll have to let your gun tell you.