Factory 6mm Norma BR chamber length?

[jinx-)]

Had anyone measured chamber length on factory barrel in 6mm Norma BR? I'm trying to determine brass trim length and I don't have chamber length gauge. Also, freebore length any ideas on that?

[Cover Dog]

I have a Savage F Class in 6mmBr and my chamber length is 1.581" using a Sinclair Chamber Length Gauge.

[jinx-)]

Thank you Cover Dog! I just got new brass and it measures 1.550", so it looks like I don't have to trim it fore a while.

[jinx-)]

Cover Dog, what's freebore in your chamber and if you ever loaded 105 gr A-max what's MAX OAL?
In my chamber using 1.550" brass and A-Max I get 1.8" to ogive or 2.325" oal.

[Cover Dog]

jinx.....Hornady 105gr A-Max OAL is 2.343 In bullet comparator it is 1.695 to ogive

Berger 105gr VLD OAL is 2.439 In bullet comparator it is 1.687 to ogive

Sierra 107gr MK OAL is 2.403 In comparator is it 1.687 to ogive. Both the Sierra and the Berger are the same to the ogive.

Using my chamber length of 1.581 freebore with both the SMK and the Berger would be .106" with the Hornady it would be .114"

[jinx-)]

Then I must have different chamber, but this is 6mm BR with 1:8 twist, I took more measurements and I consistently get 2.327" that's with 105 gr A-Max.

[Cover Dog]

Base to bullet tip in not a very accurate way of measuring, other then to see if a cartridge will fit in a magazine. Base to Ogive is what I always go by. What is your base to Ogive measurement?

[jinx-)]

good question, with virgin brass I measured 1.805" base to ogive, with once fired from my rifle and neck sized brass I can't get bolt to close and with once fired and FL sized I get 1.825" with 105 gr A-max, bits me why bolt wont close on neck sized brass... Headspace could be related...

[earl39]

jinx-) are you sure you are measuring correctly? Base to ogive should not change just because you are using neck sized brass unless your die is not locked down good. All rounds should measure the same (within a couple of thousants) no matter how your brass is sized.

Gary



with virgin brass I measured 1.805" base to ogive, with once fired from my rifle and neck sized brass I can't get bolt to close and with once fired and FL sized I get 1.825" with 105 gr A-max, bits me why bolt wont close on neck sized brass... Headspace could be related...

[jinx-)]

Gary, I know, that's why it beats me ??? As far as die locking its not always source. Buy box of bullets and sort them by ogive, you'll be surprised ;-) Also not sure why dies has to do with my chamber, are you suggesting that chamber is dynamic and something shifting? My steps are next I take bullet measure to have same ogive length as the one I used previously, then I have case with mouth expend so its tight but can be seated when operating bolt, so I seat bullet just a bit, measure ogive length then insert it in the chamber close bolt, open bolt measure ogive length again using hornady bullet comparator with insert for given caliber...

[Cover Dog]

jinx....somethings not right, as you know. Your OAL is .018" shorter then mine w/a 105 A-Max but your base to ogive measurement on a FL sized case is .13" longer.

You say your neck sized brass won't chamber. Sounds like the die needs to be adjusted to bump the shoulder back a little more. Are you using a shoulder bump gauge to set up you neck die?

And I agree with what earl39 said, your base to ogive measurement will not change no matter what method of sizing you use.

[earl39]

Jinx lets see if we can rule some problems out before we start looking for them. Virgin brass fits the chamber with no problem but neck sized once fired brass won't fit? (correct me any where i am wrong.)

Full length sized brass fits. Try once fired but not sized and see if it will go back in your chamber. The empty should fit with no more than a slight bit of pressure to close the bolt and may almost fall in.
We are trying to rule out a problem with the chamber here.

If that works take the rifle in both hands and try your best to unscrew the barrel with your bare hands. If you can't and you notice no movement we can say we have ruled the rifle out for most of the problem.

There is always the chance of a burr that is affecting measurments taken with a stoney tool but even that should be consistant. You and Cover Dog will need to compare bullet base to ogive and base to tip to rule out gross differences in your respective lots of bullets. Base to tip should be close but the ogive can be different due to different tools.

When everything is measured out and you are still getting different measurements on loaded shells check your seating die for any burrs or buildup. make sure your dies lock ring is not loose. You should be able to take your die out and put it back and have no more than .001 difference if all mating surfaces are clean and smooth. If your lock ring is not locked tight to your die you will always have to reset your die every time you use it.

If all else fails and you are still getting weird measurments try a different brand of bullets to rule out the bullets. I understand the differences in ogive measurment in a box of bullets.



good question, with virgin brass I measured 1.805" base to ogive, with once fired from my rifle and neck sized brass I can't get bolt to close and with once fired and FL sized I get 1.825" with 105 gr A-max, bits me why bolt wont close on neck sized brass... Headspace could be related...


This sounds more like a seating die problem at least from this quote. What brand dies are you using? If you are willing to maybe lose a piece of brass try necksizing a piece of once fired and then remove the guts from your FL die and ease the brass about 3/4 of the way in. Don't get it far enough to start neck sizing it. this should be enough to reduce any bulge formed by the neck sizing die.
I use Lee collet dies and they will bulge a case if they get a bit of trash in them and I have had a few cases ruined by them because i let them get dirty and not lubed up.

Give all that a try and let's see if we can't get you up and running.

Somewhere there is an answer to your problem and lots of times it seems to be something simple that we overlook.

Gary

[jinx-)]

Gary, well with neck sized I was able to close them by pushing really hard on the bolt, and they fired away with shotgun pattern, about 1 minute @ 300 yards. This bolt is stiff without brass in it, hard to open and close, same with FL sized brass also hard to cycle, but less force then neck sized. FL and Neck getting scratches in the shoulder and body towards the head. I'm using Forster benchrest dies. Take a look thats FL sized brass chambered few times:

http://img809.imageshack.us/img809/3905/6mmnorma3.jpg

http://img231.imageshack.us/img231/337/6mmnorma4.jpg

here is shotgun pattern @ 300 yards

http://img28.imageshack.us/img28/717/shotgunpat1.jpg

[Cover Dog]

If the bolt is hard to close without anything in the chamber, check the action screws. Front might be a little long and is rubbing on the bolt. Back off the front screw and see if that helps with the stiff bolt.

My bullets base to ogive is .570" Base to tip is 1.225"

Are you using a bump gauge to bump the shoulder on your neck sized brass?

[jinx-)]

front action screw has nothing to do with cycling my bolt so middle or rear action screw....
http://img651.imageshack.us/img651/4143/frntactsc.jpg

My bullets show base to ogive 0.706" and 1.230" long.
Bump gauge, I've heard about them, but never had need for one before.

[earl39]

OK now we are getting somewhere. There is .136 difference in what yall are measuring for ogive and only .005 for bullet lenght. that shows the difference in measuring tools i was talking about. the .005 can be nothing but the plastic tip. As for the brass the bottom picture looks like you are not getting the shoulder bumped back any. Notice the line on the neck where it changes shine made by the die. The lines on the shoulder shouldn't be there and can be causing some of your chambering problems but if it is hard to close the bolt on an empty chamber then something else is wrong. check the bolt face outer edges and see if you can see any rub marks. If you have to take candle and smut the edges on the bolt face then close the bolt and remove it. If it is rubbing it will remove the soot. If this happens your barrel is headspaced wrong and bolt is rubbing barrel which will cause a host of other problems and you could also have a bad chamber. This is all speculation on my part without looking at the gun but i would look there also. Vacation ends tonite but i will try to keep up with this thread and maybe we can get you up and running.
This could always be a Savage uh-oh that needs to be sent back to the factory but lets make sure before going that route.

Gary

[jinx-)]

My FL made by Redding its type S Bushing style, thats max I can do as far as sizing, it might be defective, since even with imperial wax I'm having hard time pulling brass out of it, but I didn't have problem with sizing virgin brass. About chamber, I did what you ask Gary and bolt did left carbon marks, also it looks like chamber is cut of center or just wrong angle when picture was taken...

http://img835.imageshack.us/img835/5607/6mmchamber1.jpg

[earl39]

well from the picture there are ridges that shouldn't be on the end of the barrel. It should have at most smooth machining marks. does the bolt head show scratches or galling on it? If so i would just stop there and send it back to savage. The off center chamber might be off center or it may just be the angle the camera was at. i will try to get a few pics and show you what it should all look like.

Gary

[jinx-)]

Send it back., this is what they send me back as replacement for my other rifle, just great... Its getting better and better...

[earl39]

send me an email and i will send you pics of barrel end and bolt head like i was trying to explain


lewisgaryl@aol.com

Gary