Savage Factory 6BR Neck Dimension? How tight are they?

[RonAKA]

For those that have the Savage chambered in 6BR have you measured your fired brass neck OD to see how big they are? OD" that you measured?

Also, for those that have the 1 in 12" twist, do you feel Savage has shortened the throat appropriately to allow the shorter bullets this twist is designed for to still jam the lands?

 

[Nomo4me]

On my 12" twist LRPV 12" I can't come close to reaching the throat with a 70gr boattail, but can jamb with an 80 gr Berger flat base and somewhere around 3/16" seated into the neck.

1x fired lapua cases measure .2715" at the neck out of this gun.

HTH

Mike

 

[Steve Blair]

My 12F has a .272 chamber.

 

[RonAKA]

Thanks for the feedback. I like those neck dimensions. Better than I expected.

Not so sure I like the sound of the throat length. 80 grain flat base is about the limit for 1 in 12" twist. It sounds like you can't go much lighter than that and still be able to jam? I guess the problem with the 70 grain is the boat tail? Not enough of the full body length to still seat the bullet? How light of a flat base do you think you can still get out to the lands? It is sounding like 60 grains may be out of the question.

 

[camac]

I agree with the above posts - 272 neck but after spring back mine measure in the low 271's. Throat length is optimised for the 80 gr flat based bullets and the 12 twist shoots these amazingly well. I must say though I have also had great accuracy (better than 1/4moa) out of nosler 55 and 70 gr and sierra 55 and 70 gr, jump or extended right out with only 0.100 inch seated (although this doesn't sound ideal - it was the most accurate but I seat deeper for my hunting rounds.)

 

[1972]

I just got a Savage LRPV in 6mmBR Norma with the 1:12 twist. I've ordered some Lapua brass for it and have been trying to figure out which bullet it would be most accurate with.

From what you gentlemen are saying it sounds as if the "most accurate" bullet for this caliber and twist is going to be something between 70 grains and 80 grains.

Is there any consensus on which bullet (exactly) is the most accurate for this rifle combination? The 80 grain Berger flat base?

Great thread for me as a "Newbie". This is exactly what I've been trying to figure out.

So I"m thinking Lapua brass, CCI450 primer, Varget powder, and maybe the 80 grain Berger?

 

[RonAKA]

So I"m thinking Lapua brass, CCI450 primer, Varget powder, and maybe the 80 grain Berger?

That is similar to what I am thinking, although I may go with the Hodgdon H322 Powder.

 

[1972]

From the information being supplied it’s obvious you gentlemen know a lot more about this than I do. As I said, I’m a “Newbie” and trying to figure out what I need to do here.

I’ve got a new Savage LRPV in 6mmBR Norma on the way. I should have it in a week or so. It’s got the 1:12 twist.

I’ve ordered Lapua brass for it so that’s taken care of. I’m not sure about bullets, but I’ll likely start with something in the 70 to 80 grain range. From the tone of this thread, it sounds as if the rifle should like the 80 grain flat base Berger. So that’s likely a good starting point.

I intend to order some Redding dies for it but as you know these are the “bushing” type dies. So I have to know what size bushings to order. Is this something I can pre-determine based on the information in this thread? For example, it seems that those who have these rifles are saying that the neck size of a 1X fired Lapua brass in this rifle is .272. Is that close enough for me to order bushings for the dies?

Or should I wait until I get the rifle, fire a couple of rounds of factory ammunition, measure the neck on those fired cases, and then use that figure to determine which bushings I’ll need? I’m assuming this would be more accurate because it would be the size of this particular chamber.

And how do I determine what size of bushing to order after I know what the neck size of a fired cartridge is? How much do I need to size the neck down with the bushing? I understand that the neck will “spring back” a bit after it is sized, so that will have to be taken into consideration as well. Is there a “ball park” figure for this? For example, if a 1X fired case indicated that your chamber was .272 then how much would you size that down (what bushing would you use) to prepare for re-loading?

I’ve also read that the Lapua brass is slightly oversize, so does this mean that I’m probably going to have to turn the necks on this brass so it will chamber without being too tight? The finished diameter of the loaded cartridge will be the neck wall thickness (X2) plus the bullet diameter. Then there has to be a certain amount of clearance between the case neck and the chamber walls to allow for easy chambering. I’m not sure how much that should be. I guess once I know that then the necks will have to be turned down to allow for that.

Any tips or advice would be appreciated.

 

[RonAKA]

My view is that the size of the fired brass is not a critical dimension. Because it is a factory barrel, Savage pretty much has to make it large enough for the brass that is out there -- which seems to be almost all Lapua.

What is important in selecting your sizing bushing diameter is the size of the neck in a loaded round. As you have said that is bullet diameter plus two times the thickness of the brass. If you are not going to be using custom bullets which may vary from 0.2430", then you already know the bullet size. The only real variable is the brass thickness, and that will depend on your batch of brass. While you never really will know until you get your brass and load it, it seems Lapua quality control is quite good, and you should expect 0.2685" to 0.269" for a loaded round diameter. And if the chamber is 0.272 as has been reported in this thread, then all is good. 0.003" clearance is not bad for a factory chamber.

If these assumptions are all correct, then my thoughts are that a .267 bushing for sizing is ideal. It will give a .268" neck after springback and 0.001" tension when a .2430" bullet is seated, to bring you back to a 0.269" loaded diameter.

If the brass turns out to be thicker and you have more than .269", you have a couple of choices, and both are pretty good. Leave it there, and take a tighter fit in the chamber, but you probably should then get a larger bushing so you maintain the neck tension, or just allow 0.002" tension instead. If you have followed the other thread on neck tension, you will see there is no clear answer, other than it has to be repeatable. You are now getting into a near custom chamber fit (loaded round 0.271" for a 0.001" clearance to a 0.272" chamber) which is not bad for a factory barrel.

The other option which has some advantages too is to turn the brass down so it gives 0.269 loaded. This will remove any variation in thickness of the neck.

If the loaded round is undersize, then you will need a smaller bushing. I understand that sooner or later the brass will thin out and you will need smaller anyway.

 

[jonbearman]

Just try some flat base bullets,I like the 68 grain flat base and use h 322 powder,29.6 grains works in my gun but work up slow.Varget seems a little temperature sensitive. Seat it out and see what you get.If you want I will send you some test bullets for 10.00 shipped via priority ,small box to your door. Just pm me and let me know.

 

[heath]

I have a Savage F-class 6BR 1 in 8 twist that loves 68 Bergers with 30.0 grains of H322. I have won several matches at 100 and 200 yards. I have shot some scores better than some of the custom rigs in the VFS class. This gun has also shot several groups at 500 yards that are less than 1/2". I wish I could do it more often.

 

[tome]

i have the same savage.. 80 gr berger hpbt W/ 31.8 gr of varget,rem 71/2 primer & lapua brass..have won club varmint gun matches @ 100m...107 gr sierra hpbt match w/ 28.1 gr of varget & rem 71/2 primer..lapua brass are my 300m load

 

[fieldratsniper]

I think it's awesome that so many accurate shooters are using factory savages and having such great results. I love my LRPV. 1-9 twist 223. I've had it for about 4 years and it's an amazing shooter! And that ugly barrel nut is great for those guys who wish to swap their own barrels.

 

[Nomo4me]

My Savage 12 LRPV DBM is a 12" twist. The 80 grain berger seats about .150" deep when jumped .015" or so.

Using Lapua Brass, .267" neck bushing, 30.5 grains Benchmark and a 450 primer it yields 1" groups at 200 yards in my gun on a still day.

I tried a 269 bushing on virgin brass but didn't get enough neck tension to hold the bullets in place.

 

[RonAKA]

Just as an update I measured some cases that had max Nosler recommended load -- 29 grains of H322 behind the Berger 80 grain Varmint Match. The average neck OD of fired cases was 0.2702". So it looks like the Savage LRPV 6BR that I got has a neck just around 0.2712. I'm happy with that.

On bullet depth to reach lands I got similar results to Nomo4me. This 80 grain reaches the lands with the base almost to the base of the neck. A Berger 69 grain Varmint High BC, is just into the neck when touching the lands. At 0.100 into the neck there is a 0.020" jump to the lands. Kind of wish they cut a shorter freebore, but for flat base non high BC bullets it should be OK.

 

[deadlyswift]

I still can't figure out why Savage would use such a long throat in a 1in12 twist. It's got to be something that Savage isn't aware of that some employes are actually doing on their production lines. Surely Savage knows with a 1in12 or 1in14 twist their customer's are wanting to shoot lighter bullets. So with that said. Those barrels should be cut with a reamer that has a shorter throat. To have the right amount of the lighter bullets seated into the neck. Surely they know that this is a big deal when speaking of barrel or should I say throat life. Surely Savage is smart enough to understand that Throat length is probably one of the most important deminsions of the chamber. My question is should this be something that savage should be made aware of? Don't get me wrong I'm not knocking Savage. They make great rifles, but that would be a major problem if I spent money on a rifle that wasn't throated for the bullet type that I wanted to shoot. Are they using the same reamer to cut chambers for the 1in12 that they are using to cut chamber for the 1in8? My reamer that I have from PT&G with a 95gr berger vld seated .050 above the shoulder/neck junction has only a freebore of .021 Thats alot shorter than what is being discribed here. Again not trying to put anyones rifle down nor Savage! Just trying to understand What am I missing?
Mark

 

[RonAKA]

I still can't figure out why Savage would use such a long throat in a 1in12 twist. It's got to be something that Savage isn't aware of that some employes are actually doing on their production lines. Surely Savage knows with a 1in12 or 1in14 twist their customer's are wanting to shoot lighter bullets. So with that said. Those barrels should be cut with a reamer that has a shorter throat. To have the right amount of the lighter bullets seated into the neck. Surely they know that this is a big deal when speaking of barrel or should I say throat life. Surely Savage is smart enough to understand that Throat length is probably one of the most important deminsions of the chamber. My question is should this be something that savage should be made aware of? Don't get me wrong I'm not knocking Savage. They make great rifles, but that would be a major problem if I spent money on a rifle that wasn't throated for the bullet type that I wanted to shoot. Are they using the same reamer to cut chambers for the 1in12 that they are using to cut chamber for the 1in8? My reamer that I have from PT&G with a 95gr berger vld seated .050 above the shoulder/neck junction has only a freebore of .021 Thats alot shorter than what is being discribed here. Again not trying to put anyones rifle down nor Savage! Just trying to understand What am I missing?
Mark

I think it comes down to what you suspect. Do they have a different reamer for the 12 twist and the 8 twist? At just over $100 or so for a reamer, surely Savage could afford two.

 

[deadlyswift]

I still can't figure out why Savage would use such a long throat in a 1in12 twist. It's got to be something that Savage isn't aware of that some employes are actually doing on their production lines. Surely Savage knows with a 1in12 or 1in14 twist their customer's are wanting to shoot lighter bullets. So with that said. Those barrels should be cut with a reamer that has a shorter throat. To have the right amount of the lighter bullets seated into the neck. Surely they know that this is a big deal when speaking of barrel or should I say throat life. Surely Savage is smart enough to understand that Throat length is probably one of the most important deminsions of the chamber. My question is should this be something that savage should be made aware of? Don't get me wrong I'm not knocking Savage. They make great rifles, but that would be a major problem if I spent money on a rifle that wasn't throated for the bullet type that I wanted to shoot. Are they using the same reamer to cut chambers for the 1in12 that they are using to cut chamber for the 1in8? My reamer that I have from PT&G with a 95gr berger vld seated .050 above the shoulder/neck junction has only a freebore of .021 Thats alot shorter than what is being discribed here. Again not trying to put anyones rifle down nor Savage! Just trying to understand What am I missing?
Mark

I think it comes down to what you suspect. Do they have a different reamer for the 12 twist and the 8 twist? At just over $100 or so for a reamer, surely Savage could afford two.

RonAKA,
Your probably right as to it coming down to what one expect's. As well I could be expecting a somewhat custom feature out of a factory rifle. I have 3 Savages. One is the 10fcp with a 1in10 twist. With the 175gr berger long range BT match bullets at a .010 jam, my OAL is 2.923. So it seems there is a long throat. However with a 1in10 twist in .308 cal I would expect a long throat. The 208amax and 210 vld berger can be shot out of a 1in10. The other is a rim fire so throat isn't even thought of in that rifle. The other is a Target action that I have put a broughton 5c barrel on and is in a Shehane MBR Tooley stock Chambered in 6br with a PT&G reamer. Like I said above I'm not really knocking Savage. The two present Savage rifles that I am shooting are really nice rifles and shoot very well. The 10FCP really does surprise me how well it does shoot.

I think My concern and point that I'm getting at is Barrel life. I would think with Savage as they do build awesome out of the box rifles. They have got to understand If one buy's a 1in14 or 1in12 6br rifle, that the customer is going to shoot the lighter bullets. So yes I would say they have different reamers with different free bores. If not they should IMO. I'm wondering if Savage as well other gun manufactures are trying to keep up with demands? So that leading to putting a lot of pressure on their empolyees to meet demands, and the empolyees not taking the time to change out reamers so that the free bore is set to a particular barrel twist? weather it's 1in14, 1in12, or 1in8, etc.
Mark

 

[fdshuster]

I'm betting it's a "lawyer" thing. They (Savage) know the vast majority of ammo used will be handloads, and there will be some who will be operating at or above "red line", so to keep pressures down they provide a generous throat length. Another reason for a custom cut chambering reamer. Spending the big bucks, I'll be the one to decide what chamber neck diameter, throat length and chamber oal I want. I will also not give up future barrel life based on excess throat length. Start out with .104" of freebore and it's no different than having fired well over a thousand rounds down the barrel. I spec my chambering reamers to the shortest throat length possible, based on the bullet I intend to use as the main one in that chambering. Works for me!

 

[deadlyswift]

I'm betting it's a "lawyer" thing. They (Savage) know the vast majority of ammo used will be handloads, and there will be some who will be operating at or above "red line", so to keep pressures down they provide a generous throat length. Another reason for a custom cut chambering reamer. Spending the big bucks, I'll be the one to decide what chamber neck diameter, throat length and chamber oal I want. I will also not give up future barrel life based on excess throat length. Start out with .104" of freebore and it's no different than having fired well over a thousand rounds down the barrel. I spec my chambering reamers to the shortest throat length possible, based on the bullet I intend to use as the main one in that chambering. Works for me!

And...... Most likely where my questions are coming from! ;D Understanding throat length. That the throat is basicly the life of a barrel! Even if setting a barrel back again the free bore is what will determine the life of your barrel for shooting a particular bullet.
Mark