Home Forums Hunting & Shooting Ask The Gunwriters I have a hypothetical "determining pressure" type question

Good morning All,

I have a Savage 99 takedown that I would possibly like to add some barrels to, and in doing so, would like to use the same parent case (300 Savage) as my basis.

When increasing or decreasing caliber, how is pressure determined.?

Interesting idea. Having a couple of takedown 99's myself I'll be following this.

If everything else stays the same, a larger bore will lower the expansion ratio, and a smaller bore would raise it. I suppose one of those glue on strain gages could tell you what pressure you are getting, but I don't know how you would determine what is safe.

I would guess that the 300 case has been necked up and down over the years, but I don't recall ever seeing any data for them.

358wsm,

My pair of Gun Gack books contain some relatively simple formulas for calculating the effects of changes in caliber, powder capacity, etc.

In this instance, the effect of changing caliber of the same case results in about a 4-to-1 range in potential velocity, based on the bullet's cross-sectional area. A good example would be the the 7mm-08 and .308:

The area of a .308 diameter bullet's cross-section is .0745 of a square inch, and of a 7mm bullet's is .0633. Divide .0745 by .0633 and the result is 1.177, meaning the .308's bore area is .177 times larger. Divide .177 by 4, and the result is .0044. Thus the .308 is capable of about 4.4% more velocity than the 7mm-08, when loaded to the same pressure with the same bullet weight. (4% is close enough.)

Apply the same formula the other way, and the 7mm-08 is capable of about 96% of the velocity of the .308 with the same bullet weight..

Thank you John, I am picking up what you are laying down, and I DO have those Books by you.

I am not sure, but i believe it was you that said that the 300 Savage was approximately 90-some percent of the 308. I am NOT sure if this was in regard to capacity or pressure.

Would you be willing to expound upon that.?

If so, Thank You in advance.

Scott,

The .300 normally isn''t loaded as warmly as the .308 in 99s, though I never had any difficulties with either factory or handloads in my .308 99. As a result, velocities for the .300 do tend to end up at about 90% of .308 velocities--especially factory ammo.

Did use what was a fairly warm load in one of my .300 99's for several years, with no problems, 42 grains of Reloder 15 with the 165 Nosler Partition, which got 2600+.

John,

Thanks so much.
I do appreciate your sharing with me.

Sincerely

I see nothing but red flags here.....let me explain......or better yet ask the key question as I see it!

Is there any concrete knowledge that the savage 99 did or did not under go some metallurgical changes when the Savage company added the higher pressure rounds to the model 99?..... either in metallurgical composition or in the heat treating procedures and specifications.

I have no such knowledge of this but have always believed that they used a higher tensile steel when they added the .243, .284, .308 and .358 to the model 99. If it's the case that higher tensile steels were used at the time of chambering for higher pressure rounds then it might be something to consider when adding barrels to an older model 99 chambered to the .300 Savage.

Anyone with thoughts on this?

Ask the Savage guys.

Factory would only rebarrel in specific caliber in same ERA back in the early days, as I recall.

Vapodog,

That is a consideration, of course.
I'm thinking more along the lines of a hypothetical build, or I should say, "rebarrel."

My Savage 99 is rather early manufacture, 1926 era.
The pressure ceiling of the old 300 runs 52,939 psi.
Any 'cat barrel could be thusly stamped, i.e. "35- 300 Savage" (52,900 psi MAX)

Since my rotor feeds the 250-3000 like a greased stick of butter, I just may well, again hypothetically, run that as a companion barrel. I cannot imagine any work needing to be done with the old 99 that couldn't be accomplished with either cartridge .
That said, "if" the rotor will allow the thicker dims of a 35-300 Savage, things for ME could be a lot of fun.😁

The main draw, for me, would be a shorter, handier, rifle to tote in and through the thick stuff.
My current barrel, the 300, is 24" and I am NOT cutting it back, no way, no how.

A 20" or 21" barrel would would be sweet.
Even were it just another 300 barrel - kinda hard to beat the old 300 in a 99. 😉

There was a series of silhouette pistol cartridges based on the 300 Savage case the IHMSA if I got the acronym right. Many of these were shot in the contender pistols that had a slightly lower pressure rating. These were in the older Hogdon reloading manuals. And of course all the Creedmoor family is kin to the 250-3000. A 6 CM in a 99 would be interesting. They may not feed in the rotary magazine or not without modifications. Only go with the Hogdon loading information as silhouette shooters were fond of the "rocks & dynamite" loads to knock over the Rams.

I have frequently considered that Savage would have had to make such metallurgical changes. I also have wondered how to definitively find the facts as to whether such changes were made.

"Anyone with thoughts on this?"

John
Knowing if that 99 would have been an older model or one built to handle the 308 loads would be very helpful in informing this question?

It was an EG. Saw no reason to use it in one of my take-down .300 99s.

That said, have owned a bunch of 99s (and one 95), including several take-downs. Never did push any of them very hard; the 165 load listed above is, of course, well within the SAAMI standards for the 99. In fact, Alliant lists 44.0 grains of R15 as maximum with the 165-grain Speer Hot-Cor, at 2614 fps from a 24" barrel, which is what was on my 99.

Have found over the years that the Hot-Cors tend to produce just about exactly the same velocity as Partition of the same weight, indicating the pressure is very similar. This bullet-to-bullet comparison confirmed by some recent pressure tests from other companies.

Aside from velocity, I've found 99s will definitely tell you when pressures get a little high, with sticky levers.

The recievers are said to have been treated from the 1920 era onward. Have not heard of anything done to them with th late 1950's introduction of the 243/308/358 family. I have a 600,xxx serial number range rifle that pre-dates the 1950's 308 family intro date, chambered in 270-300 Savage, or 270 Titus. I've got 284's, a .17/22-250, 30/.284, and have had many other widlcats. No trouble with anything yet.

I would not put high pressure cartridges into a pre-1920 receiver.

Fireballs,

That's a very interesting little tid bit right there.

Thanks John - Deeply appreciated.