.308x1.6125

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  • Last Post 30 September 2018
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Ross Smith posted this 20 September 2018

I bought the John Ardito rifle that was advertised here. I'm looking forward to a learning experience, probably a long one given my history.

The rifle came with several formed 308 brass, winchester, that are 1.61+ long so not standard 30 br????????? Searching this site it looks like 21-24 grn Rl-7 was his load????????/ and it was plenty hot. What might be a good starting point, 18 grn rl7, lyman #2 alloy, or harder? The rifle came with 2 Eagan molds,tapered bore rider style. One longer than the other 1.013" and 1.15" I think. The fired cases all chamber easily and if a bullet is finger seated in a case , it goes so far and stops. When that is chambered it has a slight resistance when closing the bolt. When extracting the case, the cast bullet will be seated a shade deeper and there is chamfering around the driving band. Did not see and rifling marks. The brass were all formed from trimmed and sized 308 brass.

Any advice is welcome on loads, brass forming, dies, good dogs , etc . post on the thread or pm me.

Thanks , Ross

 

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Ross Smith posted this 30 September 2018

OU: Thanks, after talking with Lee Wiggins, we think the exact one is the MX4 .30 ARD #2. That is the .311 version on the MX4 .30 ARD. It has a very slight 1degree taper just before the ogive. This rifle is getting more technical and challenging and interesting all the time. Just goes to show you can't just go buy a .5moa gun and go shoot .5moa just like that. There is a trove of info on this site if you know where to look.

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OU812 posted this 30 September 2018

Here is link to Donald V. Eagan catalog: You may need to download PDF

https://castbulletassoc.org/download/Eagan%20Catalog.pdf

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OU812 posted this 30 September 2018

I think your gun is chambered in the Donald V. Eagan line of .30MX cartridges called the .30x1.6mx.

I will try to find link to where I found one of his old 1990's catalog.

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RicinYakima posted this 26 September 2018

"A good idea doesn't care who has it or when."

This thread on short cased .30 caliber cartridges is an example. We are just twicking the 1960 Barnes .308 X 1.5", or the PPC ones.

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Ken Campbell Iowa posted this 26 September 2018

ric ... that was some 18 years ago, but then the 52d chamber was as good as the best ... heh. ...

 

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RicinYakima posted this 26 September 2018

Is there anything the beats the Winchester 52 D chamber spec's?

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Ken Campbell Iowa posted this 26 September 2018

speaking of throat configurations, i offer the following for interest:  using three match barrels ( 22 rimfire ) and 4 or 5 different chamber reamers with different throaters ... we found no accuracy difference between zero freebore and a freebore of nearly the length of the groove diameter of the bullet. ....

where cut,    freebore was snug fit on  bullet    taper was 1 and also 1/2 degree.

all three barrels and all combinations shot about 1/2 moa .

we felt there was a slight advantage to a chamber pretty tight at the front of the case.

***************

these were custom chambers, note that factory rifles error toward using any gritty loads you need to shoot at grizzlies and charging rabbits ...    but the above points to LBT type chambers might need a more serious try in a competition rig. ( long but tight freebore before rifling.  )   weatherby are long but not tight.

ain't this fun ??

ken

 

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OU812 posted this 25 September 2018

OU812: When you cut the inside shoulder in the case neck, I assume that you used an inside neck reamer? What was your setup for that? I need to do that to some of my cases, they have no shoulder. I do have 10 cases with shoulders but they are for a longer chamber and won't load in my rifle.The longer cases are 1.18 to the wide part of the shoulder and are trimmed to 1.618 but have a very (too) short neck. Anybody know what they are?

I misunderstood the question. My rifle is chambered in 308 Winchester and using factory Lapua 308 Winchester cases. No special neck turning or cutting inside neck for me.

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OU812 posted this 25 September 2018

My PTG neck reamer was guided using a snug slip fit pilot bushing fitted to bore. Then hand cut using their crude t handle. Reamer also has adjustable stop to cut free bore length. I know this is not the best way to guide reamer, but it did work.

Tom Gray mentioned he machines a hole at primer pocket to guide reamer along with snug slip fit pilot bushing.

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frnkeore posted this 25 September 2018

Best I can:

6mm br= 1.075 to the shoulder

mine 1.145"

--------------------------------------------------------------------

Ross, I was going by the above. With the new measurement, you would shorten it .389, plus a few thousands for spring back, say .395.

Frank

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Ross Smith posted this 25 September 2018

OU812: When you cut the inside shoulder in the case neck, I assume that you used an inside neck reamer? What was your setup for that? I need to do that to some of my cases, they have no shoulder. I do have 10 cases with shoulders but they are for a longer chamber and won't load in my rifle.The longer cases are 1.18 to the wide part of the shoulder and are trimmed to 1.618 but have a very (too) short neck. Anybody know what they are?

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Ross Smith posted this 25 September 2018

Frank,  The base to the wide part of the shoulder is 1.169, and to the top narrow part is 1.29 . About. The whole case is 1.62. Mine were trimmed short to 1.602 by the previous owner.

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OU812 posted this 25 September 2018

Lee, Thanks for posting the very interesting comments and pictures.

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frnkeore posted this 25 September 2018

Yes, your shoulder is 1.145, the Savage, 1.558. Difference = .413. I'd go .420 to allow for a little spring back.

You may also need to polish the base of the die a little but, be sure to radius and polish the die so, that it doesn't gouge the case.

Frank

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Ross Smith posted this 25 September 2018

Frank: What would I have to do, cut the die off short?

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frnkeore posted this 25 September 2018

Ross,

For case forming, since you have a 30 deg shoulder, you could use a set of 300 Savage dies.

Push the neck back, most of the way, then trim. Then push it back, until it will just chamber, expand with a M die and fire form.

Frank

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Lee Wiggins posted this 23 September 2018

Ross,

   Thanks for the info on your chamber cast. What you have is interesting because it is contrary to John Ardito's famous 1 degree throat. I'm scratching my head on this.

   By all means try the longer Eagan bullet and yes you can bump bullets that are even much harder than 80/20 or straight lino. But I question doing that assuming you want to tapered bullets for a cylinder throat. It is a bitch trying to get a perfect fit of a cylinder bullet in a cylinder hole (throat). Taper in taper is easy. I would just lube the long bullets and if you can chamber them , shoot them.

   Yes i've done this a few times . Threaded barrels chambered and throated with a throating reamer that i made. Have also cut a few bullet molds. I am lucky that I have a machine shop in my house. The wife isn't too happy with that when she steps on a sharp sliver in her bare feet that I tracked in.

                                                                                       Lee

 

                                    

 

e

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frnkeore posted this 23 September 2018

Ross,

Your case capacity is 2.58cc.

30 PPC = 2.20cc

30 BR = 2.44cc

30/30 = 2.88cc

.308 x 1.75 = 3.00cc / I found a listing for this, AKA .30 Doggie

308 Win = 3.47cc

Frank

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Ross Smith posted this 23 September 2018

My bore cast could be better but its .311 at mouth and .311 in front of rifling. could be .310 but I have too many pits at that exact point. And I get .504"  long straight throat.   .346 neck and .457 shoulder 

Holding my 2 different slugs that came with the rifle, The longer slug looks like it would fit better, infact I'm surprised I'm getting +- 1moa shooting the short slug. I need to try the longer Eagan slug. The bore ride section goes from .311 infront of the grease groove to .301 at the ogive and it will touch into the rifling. The short bullet won't. That's opposite the notes that came with the rifle. I also have another tapered breach seat type bullet and several bore riders to try. 

I'm not a machinist, I'd have to get some one else to make a bump die. Can you bump 80-20 mix? 

Sounds like you've done this before Lee. 

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Lee Wiggins posted this 23 September 2018

OOPS,

   Didn't think my post worked , should have seen Show more Post. I'll be more careful so I don't repeat myself

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