6BR Go gauge question

[K9TXS]

I going to have a REMAGE barrel made up soon and was looking for a Go gauge in 6 BR "Norma". I found quite a few 6 BR Remington, but no Norma. I know there is a difference in the cases as shown below, but would it be safe to use a Remington Go gauge to set the barrel? I've looked at the specifications on different websites for each caliber and it seems most of them are always just a little bit different, not by much, but a little.

 

[WSnyder]

According to your drawings I see no reason why a HS gauge would be different between the two. Other than base of neck radius all neck/shoulder dimensions are the same so I assume the datum would be as well. Mby someone with experience with the Norma will have a reason to say different.

 

[shoot4fun]

Contact either JGS or Manson Reamers to get the correct answer to your questions.
I have Redding Competition Dies stamped 6BR Remington. I spoke to Redding about using them for 6BR Norma (they didn't have dies marked 6BR Norma) and was told their dies work for either one.

 

[K9TXS]

Contact either JGS or Manson Reamers to get the correct answer to your questions.
I have Redding Competition Dies stamped 6BR Remington. I spoke to Redding about using them for 6BR Norma (they didn't have dies marked 6BR Norma) and was told their dies work for either one.

Thanks for the information. I looked up Manson Reamers and on page 28 of their catalog, they show a list a "Headspace Gauge Interchangeability Chart". Very helpful chart.

 

[RussellJ]

I going to have a REMAGE barrel made up soon and was looking for a Go gauge in 6 BR "Norma". I found quite a few 6 BR Remington, but no Norma. I know there is a difference in the cases as shown below, but would it be safe to use a Remington Go gauge to set the barrel? I've looked at the specifications on different websites for each caliber and it seems most of them are always just a little bit different, not by much, but a little.

View attachment 1327868

Attached will answer your question. It is from the Precision Shooting Magazine. It's my favorite bedtime story.

 

[WSnyder]

From the article: "there are three versions of what is commonly called the 6mm BR; the original and slightly shorter 6mm BR, the 6mm Bench Rest Remington, and the 6mm Norma BR. The case dimensions for all three cartridges are the same except for one dimension… the neck length of the original 6mm BR is .040" shorter than the other two cartridges."

This would indicate the HS gauge would still be the same and his drawings are for the two modern versions and not the original. Does anyone still chamber for the original 6mm BR?

 

[K9TXS]

Attached will answer your question. It is from the Precision Shooting Magazine.

Thanks for posting this. Very interesting read

 

[RegionRat]

The traditional type Go-No-Go gages are only used to set the shoulder datum length dimension.

As you can see on your two drawings, the vertices and diameters of the shoulders are identical.

The confusion comes from the differences in the lengths beyond the shoulder, but the shoulder dimensions being the same means you really only have the same Go-No-Go gages between them.

Brass, case lengths, bullet lengths, dies, and reamers, must still be coordinated according to your intentions.

 

[Murray Brook]

@RussellJ
Great read
TKS

 

[Ackman]

According to your drawings I see no reason why a HS gauge would be different between the two. Other than base of neck radius all neck/shoulder dimensions are the same so I assume the datum would be as well. Mby someone with experience with the Norma will have a reason to say different.

With a remage barrel you set the headspace. Set headspace to your brass and don’t mess with no steenkin’ gauge.

 

[Rat Rifle]

With a remage barrel you set the headspace. Set headspace to your brass and don’t mess with no steenkin’ gauge.

So true. Your not going to shoot a Go Gauge.

 

[DJSBRS]

If you set the headspace with new brass and set it up too tight, a regular non custom die may not be able to size all the way down on the case when full length resize.

DJ

 

[divingin]

Does anyone still chamber for the original 6mm BR?

I don't think anyone chambers for anything except Norma, anymore. At least, I've never seen anything else.

 

[DickE]

So, I think originally the 6mm BR Remington had more differences than what is now considered "the same dimensions. I have several old boxes of factory Remington loaded ammunition of "6mm BR Remington, 100 grain Core-lokt pointed soft PT." in the yellow and green box.
Clearly marked on the end "NOTICE: This 6mm Rem. Cartridge will not fit in 6mm BR chambers."
Although the case length is the same, and I believe the datum is the same, the .200" line on the head is not.
An un-fired Lapua brass measures .468" and the Remington brass measures .463". at the .200" line.
So, if your reamer is for the "6mm BR Remington", the Lapua brass will not fit.
But what I am seeing now is a lot of people in the reamer, die, loading manual business using measurements as one and the same.












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[NorCalMikie]

My guess is you'll probably NOT be going to use factory loaded ammo??
So with that in mind, set your head space with new or full length sized brass.
Skip the SAAMI specs. Most are way too loose. Set yours snug and you won't be moving brass too much.

 

[DickE]

So, I can't even find the "6mm BR Remington" SAAMI spec. Did this get deleted? Is that why they are presumed the same now?

 

[NorCalMikie]

If you were to get a 6 BR "Remington" chamber by mistake, you would know in short order that they ARE NOT the same. 6BR Remington brass will chamber in a 6BR Lapua chamber, NOT the other way around.
If you were to start off with the "Remington" chamber , you wouldn't know the difference till it came time to buy and fit brass.

 

[RegionRat]

So, I can't even find the "6mm BR Remington" SAAMI spec. Did this get deleted? Is that why they are presumed the same now?

No, but the issue began with a question on the shoulder datum length between the two, and those two have always been identical.

That is not to say there are no differences in the throats, small differences in the rims, etc., but it is saying that there are no differences in what the OP needed to shop for in terms of Go-No-Go gages. Those two use the same gages. While the older ammo prior to 1996 might not meet even the previous 1989 standard, it isn't because the two have a different shoulder datum length.

When Remington sold their first factory Remington 6mm Bench Rest case in the 70's, it was a thin walled 308 based case but it was small rifle primer and meant to be finished by the loader. Their market was BR competitors who expected to have to dimension their reamers for the bullets they used and the trend in the early times was lighter bullets than what we would recognize later on. It was a while before Remington standardized their design in 1989, but they had been selling a 40X production rifle for a while.

Later on and far away... Norma standardized on a competition round that was very close, but used a different weight range for the bullets so the biggest differences began with the throat. In 1996, the Norma 6mm BR had minor differences in the case but it used the identical Go-No-Go gages. The throats were cut to accommodate higher BC bullets used in 300 meter competition, and their pressure went up to 58740 PSI from the Rem version which was 52000 PSI.

Both the Sierra manual and the Berger manual have write-ups on the history. The Berger manual still treats them separately but the Sierra manual combines them.

In 2022, the user must focus more on the throat and neck for the brass and bullet they plan to run, but the label on the Go-No-Go gage doesn't matter since they are both the same standard length.

If you go back a few posts and read the story that RusselJ linked in post #5, it pretty well covers the history of both as well as the ammo.