New Production Norma 6mm Dasher Brass

[oldduc]

I received 200 of the new production Norma 6mm Dasher brass today (from Graf's), and decided to provide some info for the group regarding it.



I made some rough measurements as a comparison:

Cartridge-- LOA-- NECK LENGTH
Lapua 6mmBR-- 1.5555-- .3100
Lapua 6 Dasher Hydroformed-- 1.5375-- .2050
Lapua 6 Dasher Fireformed-- 1.5320-- .2250
Norma 6mm Dasher-- 1.5960-- .2900

The Norma shoulder is at the same length as the formed Lapua and the neck is .065 longer than my fire formed Lapua brass. As I have mentioned before, the Lapua neck is a lot shorter than the chamber in my current Dasher barrel. I tried chambering a piece of the new Norma brass. It chambers easily until the last portion of camming the bolt handle. The extracted brass appears to be belled inward about .025 along the neck indicating that it is longer than my chamber and is moving into the leade. It will require trimming before fireforming. The rims measure the same thickness as the Lapua. Haven’t had a chance to measure the case capacity yet, but it is probably not much different, except in the longer neck.

So far, the only downside appears to be that I will have to trim it to use it. All things considered, that is easier, faster, and cheaper than forming Dasher from 6BR. I will load some soon and see how it shoots.
~Gary

Edit: Does anyone know how to get an Excel table to work correctly here?

 

[FatBoy]

Gary ,

You know not the can of worms thou hath just opened.....


FWIW, I like the Norma Dasher brass, but I also have a reamer made for it and started with it from scratch.

Chris

 

[dmoran]

Myself am more concerned with base/webbing diameters then I am lengths, and how they compare to the actual chamber dimensions. The looser the fit, the less pressure endurance and case life; due to primer pocket expansion.

As I know it, the Shiraz/Norma 6Dasher cases are 1.5-thousandths smaller in base/web diameters then Lapua, which is a lot in terms of base/web expansion, when used in a Lapua brass spec'd chamber. Which is the reason I myself didn't switch to Shiraz/Norma 6Dasher brass, and would want my chamber specifications to be tighter for Shiraz/Norma 6Dasher cases.

 

[oldduc]

Myself am more concerned with base/webbing diameters then I am lengths, and how they compare to the actual chamber dimensions. The looser the fit, the less pressure endurance and case life; due to primer pocket expansion.

As I know it, the Shiraz/Norma 6Dasher cases are 1.5-thousandths smaller in base/web diameters then Lapua, which is a lot in terms of base/web expansion, when used in a Lapua brass spec'd chamber. Which is the reason I myself didn't switch to Shiraz/Norma 6Dasher brass, and would want my chamber specifications to be tighter for Shiraz/Norma 6Dasher cases.

I checked the base diameters and they are about .0005 different than the Lapua BR brass I have. That said, I have found different lots of Lapua varying by a thou, or so. I though I would just give it a try since I hate wasting time, powder, bullets, etc. fire forming from BR. By the time they are just right you're 25% through the case life anyway. My chamber is CIP spec, .272 neck, .110 FB, so I'll see what happens. Maybe it won't be $200 wasted.

 

[dmoran]

@oldduc
IME they will work, just may not be able to step on them to the same velocities/pressure that you could with Lapua made 6Dasher cases.
Being gentle on them there first firing or two, until there work hardened more, will greatly help as well.

 

[oldduc]

@oldduc
IME they will work, just may not be able to step on them to the same velocities/pressure that you could with Lapua made 6Dasher cases.
Being gentle on them there first firing or two, until there work hardened more, will greatly help as well.

Thanks for the tip. I have been shooting RL16 in the Dasher and was interested in the info from Tim Eicher at http://forum.accurateshooter.com/threads/6-dasher-norma-brass-reloader-16.3924787/. Where he was using info from you also. I was hoping the extra neck length would get me another tenth, or so, of a grain of powder as the "node" I found is semi-compressed. It's really just to try something different. I guess I'm easily bored.

 

[dmoran]

@oldduc
Bare in mind, they will gain capacity once they have been fire-formed, and will continue to gain capacity for a couple more firings. Which should play into your hand well with your use of RL16. Ones I kept track of started with case capacities around 39.8-gr when new, to around 40.6-gr capacity after fire-forming, to more then +41-gr capacity after a couple more firings.

 

[oldduc]

@oldduc
Bare in mind, they will gain capacity once they have been fire-formed, and will continue to gain capacity for a couple more firings. Which should play into your hand well with your use of RL16. Ones I kept track of started with case capacities around 39.8-gr when new, to around 40.6-gr capacity after fire-forming, to more then +41-gr capacity after a couple more firings.

That's good to know. As long as I don't use the extra space to go for the "high node" maybe they'll settle down and last for a while.

 

[dmoran]

@oldduc
Here is cycle data that I logged for 5-firings from a 31" Benchmark barrel (with 105-VLD's and CCI-450's):

 

[LRPV]

It's time to Dasherize the dasher and take full advantage of that long neck... LOL

 

[oldduc]

@oldduc
Here is cycle data that I logged for 5-firings from a 31" Benchmark barrel (with 105-VLD's and CCI-450's):

View attachment 1077366

I'll follow the bases and see what they do, expansion wise. I've never had a loose primer pocket so I guess I'm kind of a wuss in the load department. (Well at least in the last 30 years or so. Before that I did lots of stupid stuff)

The 31" barrel seems to make a significant difference in velocity. My current barrel is a Criterion 28" and I'm getting 2965fps from 34.6gr of RL16 (105-Hybs and 205Ms). It is a 7tw though so I guess that will slow it down also. Been shooting about 1/2 MOA at 600. I'd like to improve that....

By the way, how do you post a table like that? Is it a .jpg or something?

 

[oldduc]

It's time to Dasherize the dasher and take full advantage of that long neck... LOL

Yeah, if I had about a .250 freebore I could long seat the bullets and put about 40gr of Varget in there. be like a mini-6XC

 

[oldduc]

....Been shooting about 1/2 MOA at 600. I'd like to improve that....

Actually, I should clarify that, the 1/2 MOA was a 1 shot group with no wind. But really, shooting F-Open at 600 this gun will shoot 10 shots, or so, in about 1/2 minute. The second 10 shots seem to prefer a little different neighborhood. 199-14X is the best it's done. Would love to shoot clean...just once.....

 

[dmoran]

@oldduc
That is a "screen shot" image of an excel worksheet, cropped down to size.
Then attached to the my post, and set to be in "full view", instead of just an attachment.

Edited in later:
On a note to the velocity indifference: besides the differences in barrel length and twist, the bullets can make a difference as well. Fat bullets verses skinner bullets for one, bearing surface lengths, and over-all profile indifference (Hybrid verses VLD, etc...).

 

[oldduc]

@oldduc
That is a "screen shot" image of an excel worksheet, cropped down to size.
Then attached to the my post, and set to be in "full view", instead of just an attachment.

OK, got it! Thanks!

Also, I added a column showing the base diameter. I used my most accurate mic (.00005) and found the Norma base diameter to be .00135 smaller than unfired Lapua 6BR and .00190 smaller than 5X fired Dasher from the Lapua 6BR.

 

[oldduc]

I measured the actual length of the chamber in my gun at 1.582 and trimmed the new brass to 1.570. I loaded 25 rounds with 34.8gr of RL16, Berger 105 Hybrids, and Fed GMM205Ms. This morning I shot in a 600 yard "practice match". Mid 30s temp, light switching winds, foggy and damp. Used the Labrador to check the load and got 2970 average velocity. Slightly flattened primers. The brass grew in length to 1.572 and the base expanded to .4685. Shot 200/14X.
I'm happy with this brass and load, so far. Now I've got to get my to get my 6BRA shooting competitively .
Gary

 

[timeout]

I measured the actual length of the chamber in my gun at 1.582 and trimmed the new brass to 1.570. I loaded 25 rounds with 34.8gr of RL16, Berger 105 Hybrids, and Fed GMM205Ms. This morning I shot in a 600 yard "practice match". Mid 30s temp, light switching winds, foggy and damp. Used the Labrador to check the load and got 2970 average velocity. Slightly flattened primers. The brass grew in length to 1.572 and the base expanded to .4685. Shot 200/14X.
I'm happy with this brass and load, so far. Now I've got to get my to get my 6BRA shooting competitively .
Gary

I'm thinking I should have did a little more research prior to recently ordering 200 Norma Dasher brass. I didn't realize the base dimension was smaller than Lapua Dasher brass. I thought the only difference was the extra neck length (once the rim thickness difference was resolved). Probably would have been less expensive in the long run to use Lapua BR brass and fireform it, even though a few are lost to split shoulders. Anyway, too late now.

 

[oldduc]

I'm thinking I should have did a little more research prior to recently ordering 200 Norma Dasher brass. I didn't realize the base dimension was smaller than Lapua Dasher brass. I thought the only difference was the extra neck length (once the rim thickness difference was resolved). Probably would have been less expensive in the long run to use Lapua BR brass and fireform it, even though a few are lost to split shoulders. Anyway, too late now.

I don't think the .00125 difference is too important. The Dasher is not really a BR round and I really can't see the difference for F-class type shooting. When I change barrels, I'll make sure to use a "Norma chamber" sized reamer.

 

[timeout]

I don't think the .00125 difference is too important. The Dasher is not really a BR round and I really can't see the difference for F-class type shooting. When I change barrels, I'll make sure to use a "Norma chamber" sized reamer.

I'm not a competitor and correct me if I'm wrong, but I'm under the impression that the Dasher has been used a bunch for mid and long range BR. My concern is with expanding the brass too much at the .200" line, which can mean poor brass life or even brass failure. Makes no difference whether I am shooting BR or shooting a ton of informal target range and Prairie Dogs. Am I missing something or over thinking this?

 

[oldduc]

I'm not a competitor and correct me if I'm wrong, but I'm under the impression that the Dasher has been used a bunch for mid and long range BR. My concern is with expanding the brass too much at the .200" line, which can mean poor brass life or even brass failure. Makes no difference whether I am shooting BR or shooting a ton of informal target range and Prairie Dogs. Am I missing something or over thinking this?

Well, sure, the Dasher is competatively used for MR and LR rest shooting and is the most popular PRS/NRL round. When I said "not really BR", I was comparatively thinking of short range 6PPC type BR, where everything can be a problem. Using the Norma brass in my Dasher on a dead calm day it will shoot in the twos at 100 and I haven't seen any issues with the brass having any longevity issues. I pretty much don't pay attention to speculation about stuff. I shoot it and if it works, that's very cool. If it doesn't, I do something else. All it takes is time and money and those don't seem to be too important in this hobby.