I have a few questions I hope you guys can help me with? I am not new to reloading but new to reloading the 6mmbr. I wish I could post pictures to show you what is happening but seem to be having issues. I am using a 700 action with a firing pin upgrade and a 27 inch Krieger barrel, Lapua brass trimmed to 1.555, CCI 450 primers, and Burger 105 VLD bullets. I started my loads at 28.5g Varget with bullet .015 in the lands with a velocity of 2650 on the cronograph. I ran the loads as high as 30.0g of Varget taking it up to 2777 feet per second. On all of the loads tested the firing pin was leaving extruded divits and the primer was slightly pushed out, more so on the hotter of the loads. I have fired a total of 20 rounds through out the load tests so far and not once was the bolt showing any sign of sticking. Accuracy was good on all of the loads showing no sign of groups opening up, the 28.5 and the 30.0g loads showing the best results. I don't think I want to drop below 28.5g loads do I? On 6mmbr site they say 30.0g of Varget and a 105 bullet is a basic load but they don't state what primer they are using. The next think I am going to try in pulling the bullet out of the lands some. Please let me know what you guys think.
6mm br help
- Thread starter brad555
- Start date
I usually start at 30 or 30.5 grains of Varget with BR4 or 450 Primers and Berger 105 or Sierra 107's from touching the lands to .020 into the lands.
I have one barrel (I believe it's the chamber actually) that causes a fairly ugly looking crater on my primers. I say that it is the barrel (or chamber) that is causing this because when I rebarreled it the cratering went away and when I spun the barrel on again for the winiter, it started cratering the primers again.
Your primers backing out is a sign of low pressure (or loose primer pockets). The case usually gets slammed back against the boltface which pushes the primer back into the hole.
Optimal speed for a 6BR is around the 2920 mark with a 28" barrel. I would take a guess that 2850-2900 should be optimal for a 27" barrel but I would have to check with quickload and OBT. If I get a chance tonight I will see what they say for your barrel.
Try 30.5 up to 31.0 grains of Varget with your bullets Kissing the lands to start. Once you find a powder load that shoots well, then start messing with seating depth to fine tune it.
My 24.5" Barrel is shooting phenominally at 300M with a slow load at the moment (28.7g Varget running 2780 over the chrony) and it craters with that load as well.
I have one barrel (I believe it's the chamber actually) that causes a fairly ugly looking crater on my primers. I say that it is the barrel (or chamber) that is causing this because when I rebarreled it the cratering went away and when I spun the barrel on again for the winiter, it started cratering the primers again.
Your primers backing out is a sign of low pressure (or loose primer pockets). The case usually gets slammed back against the boltface which pushes the primer back into the hole.
Optimal speed for a 6BR is around the 2920 mark with a 28" barrel. I would take a guess that 2850-2900 should be optimal for a 27" barrel but I would have to check with quickload and OBT. If I get a chance tonight I will see what they say for your barrel.
Try 30.5 up to 31.0 grains of Varget with your bullets Kissing the lands to start. Once you find a powder load that shoots well, then start messing with seating depth to fine tune it.
My 24.5" Barrel is shooting phenominally at 300M with a slow load at the moment (28.7g Varget running 2780 over the chrony) and it craters with that load as well.
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OK... Here is what I would try, based on OBT and Quickload info.
30.8 Grains of Varget (Work up from 30.2 in .2grn increments though)
105g Berger VLD's just touching the lands (.001 in at most)
This should give you 2893 FPS in your 27" barrel.
If you have some Sierra 107's around try 30.7grns of Varget, and again, just kissing the lands.
If it groups well then play with seating depth (both into and away from the lands).
30.8 Grains of Varget (Work up from 30.2 in .2grn increments though)
105g Berger VLD's just touching the lands (.001 in at most)
This should give you 2893 FPS in your 27" barrel.
If you have some Sierra 107's around try 30.7grns of Varget, and again, just kissing the lands.
If it groups well then play with seating depth (both into and away from the lands).
If your primers are backing out you have too much head space. I have been playing with a used 22BR barrel. I had the head space set too long and the primers were backing out with the first light loads I tryed. This will not cause the primer cratering but will weeken the brass if is not set properly.
Stephen
Stephen
The cratering
of the primer can be stopped by having the firing pin hole bushed.
The 6br runs pretty high pressures. If you are using the CCi 450 primers they have the hardest cup of the primers.
If it is bothering you get it bushed. If not don't worry about it. Bushing the firing pin hole runs around 150.00.
My 6 BR is not bushed and I will get cratering. I use the stiffness of bolt lift to determine when I back off on my loads. It can be a bit of a pain when reloading as it will not fit in the shell holder but then I switch to my 30-30 lee shell holder to get the primer knocked out and replace with the proper shell holder.
of the primer can be stopped by having the firing pin hole bushed.
The 6br runs pretty high pressures. If you are using the CCi 450 primers they have the hardest cup of the primers.
If it is bothering you get it bushed. If not don't worry about it. Bushing the firing pin hole runs around 150.00.
My 6 BR is not bushed and I will get cratering. I use the stiffness of bolt lift to determine when I back off on my loads. It can be a bit of a pain when reloading as it will not fit in the shell holder but then I switch to my 30-30 lee shell holder to get the primer knocked out and replace with the proper shell holder.
superd222
CGN frequent flyer
Try some off the lands. Many F-class, TR, BR guys are getting better results with a 0.010" or greater "jump".
I never load my 6BR with the bullets anywhere near the lands and have had tremendous results.
Good Luck - SD
I never load my 6BR with the bullets anywhere near the lands and have had tremendous results.
Good Luck - SD
I wholeheartedly disagree. We have 7+ local shooters (myself included with 2 rifles chambered in 6BR), and I know many more, who all use Varget with the 105, 107 and 108 grn bullets. It happens to be THE best powder to use.
Re15 is also supposed to work well but is more temperature sensitive than Varget, both hit the Burn Rate Chart very close together.
Jerry doesn't shoot a 6BR
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I was curious about the head space issue and have a friend that just put together a Savage 6mmbr so I used his go and no go gauge in mine, with the no go gauge the bolt will not close and with the go gauge the bolt will close but definatly is tight when closing. So I don't have too much head space according to his gauges. When looking at the fired brass the bolt face is rubbing slightly on the one side of the brass. The action was not trued so please correct me if I am wrong but if the bolt face is not %100 true to the back of the brass when fired then this could allow the primer to slightly push back to hit the bolt face causing the results I am seeing. Due to not having the fire pin bushed it is causing the divit in the primer but also by not having the action trued it is allowing the primer to have movment to have to push back to the bolt face???? I had not fired the gun previous to the build so I have nothing to compair the results with.
If the Go Guage is tight then I would maybe have your gunsmith polish the chamber.
I know mine had a very tight chamber after cutting the barrel back, so tight in fact that I could not rechamber fired brass without a good amount of force. After my GS polished the chamber it is much better now.
I could tell where it was catching in the chamber by polishing a case with some metal polish and chambering it. The scratches stuck out like a sore thumb near the base of the case.
I know mine had a very tight chamber after cutting the barrel back, so tight in fact that I could not rechamber fired brass without a good amount of force. After my GS polished the chamber it is much better now.
I could tell where it was catching in the chamber by polishing a case with some metal polish and chambering it. The scratches stuck out like a sore thumb near the base of the case.
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Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Used to shoot the 6BR long before it was this popular
Your last thought about the bolt face is right on the money. if the bolt face is not square to the case head, it will allow the primer to pop out a bit. That bolt face must be way out of whack to cause that though.
Yes, the rubbing on one side is a sure sign things are not aligned.
If you keep firing this brass, the case heads will bend out of square leading to all sorts of fun at the loading bench and chambering. BAD idea.
Best solution is to get this rig to someone who knows how to true up a Rem and redo the rig.
I would not recommend bushing the firing pin hole. It is one of the best methods of monitoring your chamber pressure. The 6BR is nothing magical. running it at proof pressure loads will still stress the action steel even if the action functions with one finger ease.
Having the primers crater is a wonderful way to limit how hot you go. When the 450's get cratered, time to stop or backoff. If you want more speed, use a bigger case.
Polishing a chamber doesn't help this situation as that just makes the case even wider. Leading to possible bulging around the case web.
Best thing is to pull the barrel, square up the action, recut the threads and rechamber.
Keep in mind that all barrels have some variations in their bore diameter. If you have a barrel that is on the small side, you will see pressures much sooner then someone with a barrel that is fat. We are talking about differences of a few thou on either side of 243 but it makes a huge difference when loading to these elevated pressures.
Jerry
Your last thought about the bolt face is right on the money. if the bolt face is not square to the case head, it will allow the primer to pop out a bit. That bolt face must be way out of whack to cause that though.
Yes, the rubbing on one side is a sure sign things are not aligned.
If you keep firing this brass, the case heads will bend out of square leading to all sorts of fun at the loading bench and chambering. BAD idea.
Best solution is to get this rig to someone who knows how to true up a Rem and redo the rig.
I would not recommend bushing the firing pin hole. It is one of the best methods of monitoring your chamber pressure. The 6BR is nothing magical. running it at proof pressure loads will still stress the action steel even if the action functions with one finger ease.
Having the primers crater is a wonderful way to limit how hot you go. When the 450's get cratered, time to stop or backoff. If you want more speed, use a bigger case.
Polishing a chamber doesn't help this situation as that just makes the case even wider. Leading to possible bulging around the case web.
Best thing is to pull the barrel, square up the action, recut the threads and rechamber.
Keep in mind that all barrels have some variations in their bore diameter. If you have a barrel that is on the small side, you will see pressures much sooner then someone with a barrel that is fat. We are talking about differences of a few thou on either side of 243 but it makes a huge difference when loading to these elevated pressures.
Jerry
Take some fired cases and your rifle to your gunsmith and have him take a look at it.
I can only offer advice based on my recent experiences. Your situation may be completely different than I experienced.
If you are stating that a Go Guage is "tight when chambering" then that would suggest to me that the chamber is cut very tight and may need to be opened up a tiny bit.
I can only offer advice based on my recent experiences. Your situation may be completely different than I experienced.
If you are stating that a Go Guage is "tight when chambering" then that would suggest to me that the chamber is cut very tight and may need to be opened up a tiny bit.
The scuff marks I was refering too are very light and you have to look close to see them. My biggest concern was why the primer had deep distinct marks in them. In my .223 I had experienced this but I knew the loads were getting to max. In the case of the 6mmbr this started right off the get go and only 28.5g charge of Varget. I am going to back them off the lands and try them when I get time and see what the results are. Thanks for all of the great help guys, please feel free to keep it coming.
