7.7 brass from 30.06?

[Ranger Roberts]

Today I was walking around a local flea market with my wife and saw a beautiful Arisaka with the mum still intact! Turns out the seller was a veteran as well and he ended up giving me an incredible deal on the rifle.

On my way home I stopped at my LGS and got a box of 7.7 so I can go play in the backyard. Man that stuff is pricey! So when I got home I ordered 7.7 dies and started looking for brass. Even the brass is pricey! Then I vaguely remembered one of my uncles trimming down 30.06 to fit his Arisaka. I remember he would make us put marks on the brass so he wouldn't mix them up with 30.06 after he fired them.

So how would I go about trimming the 30.06 down to 7.7? Can I do it on my case trimmer? Also, does anyone have any recommendations for bullets? I'm just going to be plinking with it. Thanks in advance for lending me your knowledge guys!

 

[PapaG]

Can't recommend it. 7.7 brass is quite a few thousandths larger than 06 brass at the base ahead of the rim. Years ago, smiths made a few bucks converting 7.7s to 30-06, most of which produced bulged brass and more than a few split cases. Take care of the ones you have and they'll last you for quite a few loadings. I'm still using Norma brass I bought in the late 60s. Not a lot of loadings but I'm at least up to 6 times each.

 

[rcmodel]

I disagree.
People have been doing it since WWII.
The difference is so small it is meaningless.

30-06
Case at the head measures .470".
The rim measures .473".
Case length = 2.270".

7.7 Japanese
Case at the head measures .471".
Rim .470".
Case length = 2.494".

You can resize them in a 7.7 FL die to fit your rifles headspace.
Then trim as necessary in a standard case trimmer.

Hornady #4 has data for 150 SP, and 174 RN bullets.

rc

 

[fguffey]

I do not have a 7.7 Japanese forming die, I do have a 308 Winchester forming die, I use the 308 Winchester forming die to form 7.7 Japanese cases using 30/06 cases. The smallest batch I have formed at one time was 80, I sent the cases to a shooter west of Fort Worth, TX. 20 Were minimum length, 20 were go-gage length, 20 were no-go gage length and 20 were field reject gage length.

He loaded and fired the minimum length sized cases, he loaded and fired the go-gage length cases with light bolt closing, he had to size the no go-gage length cases and he had to size and trim the field reject gage length sized cases.

F. Guffey

 

[Ranger Roberts]

Thanks for the info guys. I am pretty psyched to put a few rounds down range with this rifle!

 

[Kp321]

I agree with rc. The difference is small and if the brass does not fail first firing you are good for several times. Not like you are repeatedly stressing the cases by bringing them back to 30-06 base dimension each time.
Back when I carried a 06 (ammunition manufacturing) license, I formed hundreds of 7.7 from 30-06 with no problems nor customer complaints.

 

[NCsmitty]

I've read that 8x57 Mauser can be fabricated into 7.7 brass and no trimming.

If it were mine, I would contact Graf & Sons to find out about the availability of Prvi-Partizan 7.7x58, as it's proper size and decent quality.

http://www.grafs.com/retail/catalog/product/productId/12653


NCsmitty

 

[Jim Watson]

30-06
Case at the head measures .470".
The rim measures .473".
Case length = 2.270".

7.7 Japanese
Case at the head measures .471".
Rim .470".
Case length = 2.494".

Uh, no.
Quite exactly bass ackward, in fact.
Don't get your reloading numbers off the internet.

I know that forming 7.7 out of .30-06 has been done for donkey's years but if it were a new project, I doubt it would have internet support.
Ken Waters said that actual over the counter .30-06 brass is usually smaller than spec and Arisaka chambers larger.
Y'all be careful, now, you hear?

 

[rcmodel]

Jim, Jim!

Uh?
I actually got my numbers out of the Hornady #4 Manual!!

Y'all be careful now too, you hear!

rc

 

[NCsmitty]

Here's the dimensions that I have.


NCsmitty

 

[Jim Watson]

Then Hornady has it backwards, rc.

The .30-06 is 2.494", not the .31 Jap.
At least that is what SAAMI and Lyman say. .

 

[rondog]

Go here and print these PDF's out.
http://surplusrifle.com/shooting2006/srtype99/index.asp
http://surplusrifle.com/reviews2006/srtype99part2/index.asp

 

[mstreddy]

RC,
For once there is an error - your source has reversed the length measurements on those two - 30-06 case length is 2.494"
7.7 case length is 2.270"

Now, let's all be careful out there!

 

[rcmodel]

You are all right.
I was all wrong.

In too much of a hurry today trying to look up case dimensions and type while my wife was 'Going Home' out the front door to see her mother, who died 15 years ago.

I'll stop trying to answer questions in the middle of the daily family crisis again.

My apologies to all!


Still, I stand by my post saying you can safely make 7.7 out of 30-06 brass without much to-do about a very minor case head diameter difference.

There is much more variation in manufacturing tolerances in cases & chambers then there is in case head size between the two.

rc

 

[Jim Watson]

I figured as much, and you have our sympathy.

But it reinforces my policy to double check numbers off the internet.

And I still think that if Arisakas were new on the US surplus market in this era of the Cautious Internet, without 50 years experience, that forming brass out of that much smaller brass would be unthinkable. Ken Waters saw a lot more difference in actual brass and chambers than the blueprints indicate and HE didn't like it in 1971.

 

[fguffey]

The shooter I formed the cases for was experiencing the same problem on the Internet, reminded me of a Jim Nabors response “You are going to hell for that”, anyhow, I contacted him off the internet, not easy to type with one hand and defend yourself with the other. The four group of cases had different head stamps, for easy tracking? He had other questions with the same results.

After he had fired all 80 cases he sent me the results. I then ask him if he had an interest in gun shows, the answer was yes, so I made arrangement for him to locate a few of the members on the forum that were trying to help him. My interest was to get him in contact with resource people. He brought with him a few projects, I gave him my opinion then took him to someone that knew noting about the answers he got. Same thing, not one of the four people he talked to would have destroyed one part to save another.

F. Guffey

 

[fguffey]

Surplus rifle has something wrong, they list the 7.7 Japanese as 7.7x58 as in millimeters. The 8mm Mauser is listed as 8mm57, bases on the 58mm and the 57mm I would think the 8mm57 would be a bad choice for forming 7.7 Japanese, if 1mm was close to .040" when doing fast math.

F. Guffey

 

[R.W.Dale]

I've done it from 8.x57 brass and 30/06 either works fine.

If undersized .473" case headed domestic 6.5x55brass doesn't rupture in a Swedish Mauser the nominal difference in 7.7x58 heads vs 30/06 is not going to cause an issue