6mm build

If that's the case, then why are people shooting even heavier bullets with 10 gr. more powder with the 308 Palma brass? Doesn't make much sense that this brass would be popolar if that was the case.
 
Come to the FClass Western and Eastern Championships and observe successful results of top shooters using Lapua Palma brass. It works extremely well and the proof will be, again, shown in the results.

Regards,

Peter
Lapua in Canada
 
"If that's the case, then why are people shooting even heavier bullets with 10 gr. more powder with the 308 Palma brass? Doesn't make much sense that this brass would be popolar if that was the case."

Even the super mod. is correct on occasion!

Kindly,

Peter
 
I'm not saying it wont go bang and small primer 308 brass is not THAT popular. It's an exotic product used by relatively few competitive long range shooters.
I did mention about the powder burn rate. A 308 generally uses faster powder than a 6x47 with 115s, which might help a bit.
Even so, I have no reason to believe the small primer provides any advantage over the large primer for 308 for long range shooting.
Perhaps there is some specific exception like perhaps sub sonic rounds with trail boss powder or something along those lines, maybe other exceptions...
Hey if guys want to try it, they are welcome to try, maybe they will stumble upon something that could work, but I'm done chasing my tail.

If small primers were truly the way to go, there'd be a lot more people doing it.

I've been shooting in the ORA for a long time and know of people who use small primers, but the winner circle by no means a congregation of small primer fans.
 
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I don't think there is a significant advantage to the small primer. It certainly isn't my preference. If there was a cartridge that fit the bill, that had a large primer and brass was readily available, it would be a no brainer. Unfortunately, the only case that fits the bill and has been available through the shortage, is only available with a small primer. Forming from another case is fine when you're not losing a big chunk of your cases at each match. Doesn't work well if you are and don't have the time to form replacements.
 
If the discussion is Lapua Palma v. regular, you may wish to discuss with Chou Brothers and other top longrange shooters as the Palma brass can withstand higher pressures and many say produce lower SD. Those loading hot get more reloads from Palma brass.

The inducement for Lapua to produce the small primer brass was from the USA Palma Team.

Regards,

Peter
 
Already have. Talk to them regularly. Shot PR with them for years.

They have not used the Palma cases below 4 deg. C.
 
Since the topic was directly the 6x47 lapua, it seems that ALOT of shooters in the PRS matches are using it and getting very good success out of it with the CCI 450's. My barrel and action was chambered today, so hopefully in the coming weeks I will have some actual data to confirm, but with all the research I have done, the general consensus of shooters who are actually using the 6x476 are all using the 450's and H4350 with a fair bit of success.

Couldn't find any H4350 so I am going to go out on a limb and try the new IMR4451 since it is one up on the burn rate chart...
 
BadAsMo said:
Yes I did. After 200 rounds of unacceptable load development testing (using 115s) I finally discussed it at length with David Tubbs and he spoke with Obermyer about it.

The consensus was unanimous - You will not get consistent ignition when lighting 38+ grains of relatively slow burning powder for heavy bullets with small primers. You might get away with it on a warm day but from day to day your velocity will vary significantly.

Its a bad idea and a marketing stunt that draws people in thinking its a better mouse trap. Small primers may work well in certain specific situations - maybe light bullets and fast burning powder (like 100 yard bench rest) - but for heavy (long range) bullets and slow powder its just not even close to an improvement over large primers.

In my testing the CCI 450 magnum primers produced the best results - amoung small primers - but was not as good as larger Federal Gold Medal Match.
Click to expand...

I have two 6x47 lapuas that deliver absolutely world class accuracy. My findings are not in line with yours. I have had outstanding groups at long range in even cold weather. I use cci 450 primers and h4350 with berger 108s and 105s.One day last fall I shot back to back to back groups at 1000 yards which were 2.6, 3.2 and 4 inches. I would say those little primers are working pretty darn good in cool weather( and yes the conditions were very good obviously).....I obviously don't always shoot like that but it proves there is nothing wrong with the small primer in the 6x47 lapua case....Just make sure to use the magnum primers......
 
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From what I've heard/read, a lot of people who struggle with the 6x47L have chambers that have insufficient neck clearance for the neck thickness they are using (particularly those trying to run no-turn necks). Cases formed from 22-250 were likely neck turned and those may have shot better because they had the proper neck clearance, not because of the large primer. Even if the 6.5x47L brass was turned, it may not have been turned as thin.
 
"From what I've heard/read, a lot of people who struggle with the 6x47L have chambers that have insufficient neck clearance for the neck thickness they are using (particularly those trying to run no-turn necks). Cases formed from 22-250 were likely neck turned and those may have shot better because they had the proper neck clearance, not because of the large primer. Even if the 6.5x47L brass was turned, it may not have been turned as thin."

Dear readers, please pay attention to the above as this is a safety issue! Insufficient neck clearance can cause major pressure increases leading to catastrophe. Make sure you deal with competent builders who check neck clearance as standard procedure.

Regards,

Peter
 
A lot of times it's the burr that creates the issue. It's thicker than the neck and if it's getting pinched between the bullet and the chamber, it's going to give you small pressure spikes similar to donuts. All new brass has a burr around that case mouth. The burr is also created with stainless steel tumbling if you let it go for too long.

The chamber may be designed with enough clearance for the case wall itself, but may not have enough clearance for the burr.
 
The 6x47 I did my load development on had a tight neck chamber and all brass regardless of the parent case was precisely neck turned.
This was not a factor in my testing as all necks were identical.

There was a clear click... delay... bang - with all small primer loads, if you were perceptive enough to notice. That is not to say the rounds were not accurate, as they were - because I had an excellent barrel.

The real problem was the velocity. It changed significantly from day to day even with similar temps and always crappy SDs. Maybe what I call crappy is good by other peoples standards - I don't know. I just know it got a whole lot better (single digits) once I switched to large primers.

How some guys are getting "what they call good results" remains a mystery to me.


kombayotch said:
From what I've heard/read, a lot of people who struggle with the 6x47L have chambers that have insufficient neck clearance for the neck thickness they are using (particularly those trying to run no-turn necks). Cases formed from 22-250 were likely neck turned and those may have shot better because they had the proper neck clearance, not because of the large primer. Even if the 6.5x47L brass was turned, it may not have been turned as thin.
Click to expand...
 
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kombayotch said:
A lot of times it's the burr that creates the issue. It's thicker than the neck and if it's getting pinched between the bullet and the chamber, it's going to give you small pressure spikes similar to donuts. All new brass has a burr around that case mouth. The burr is also created with stainless steel tumbling if you let it go for too long.

The chamber may be designed with enough clearance for the case wall itself, but may not have enough clearance for the burr.
Click to expand...

What would one consider sufficient clearance on a neck?
 
Schecter 81 said:
What would one consider sufficient clearance on a neck?
Click to expand...

In theory, 0.001" is enough. In practice, you need more for case variance and carbon build up. 0.004" is common for LR chambers that are going to be running high pressure loads and firing lots of rounds. Benchresters can get away with less because they clean frequently. If you're running a no-turn neck, and you want to be able to fire factory ammo, use brass right out of the box or are using SS media, you should have more.

Let look at that in more detail. New cases and cases that have been tumbled in SS media have case mouths that are peened (mushroomed). You can see it looking at them.





The mouth has been beaten down. If you looked at a sectioned view of the case mouth, it would look similar to this (same effect):

hammer.jpg


If you run your finger nail along the edge of the case neck over the case mouth, you can feel the overhang of the mushroomed material. If you can feel the overhand, there is at least 0.001" of material on either side of the case mouth (inside and outside). Once you seat a bullet, the inside gets pushed to the outside, and you now have a 0.002" ring around the case mouth of material above and beyond the thickness of your neck. If your chamber was designed with 0.004" clearance over the neck wall thickness, you now have contact between the chamber wall and the mushroomed material. That mushroomed material is being pinched between the bullet and the chamber wall. Since the mushroomed material is not consistent, the tension this creates on the bullet will not be consistent and the loads will never shoot as well as they would if you had a clean bullet release.

Neck turning removes all traces of the mushroomed material from new cases. If you tumble with SS media, the mushroom will return. How much depends on how long you tumble for, but it will return to some degree. If it is not fully removed, it may create interference again as described above. Mic a loaded case neck below the case mouth and right on the case mouth and you will be able to tell very quickly if there is still anything left of the burr (mushroomed overhang).
 
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Great post K, I recently switched to SS tumbling and did not know this. Hasn't caused me any issues, but I trim and chamfer after every firing.
 
I used to use SS media. Have a Giraud trimmer. It would remove the burr nicely at first. But then the nice chamferred case mouth would get beaten down even further by the SS tumbling. After a few cycles, the cases were shorter than trim length and the Giraud would no longer remove the burr unless I trimmer the cases even shorter.
 
I only SS every 3rd firing. Only once the cases get really dirty. Regular tumble after each firing.
I just picked up a Giraud last week. Looks like a sweet piece of kit, going to speed up brass prep a lot.

Speaking of the 6x47L, what are you guys trimming your brass to? 1.845"?
 
If you are having poor results with small rifle primers it is due to faulty primers or insufficient strike. Lapua ammo with SRP are used in 300 M World Championship matches around the world and are in the winners circle in BR and FClass as well as other disciplines.

Thanks K for info on tumbler issue/clearance.

Regards,

Peter
 
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