300 RUM or 300 Jarrett

[jwp475]

No point in going with a 300 Jarret over a 300 RUM. No case can give more velocity with less powder unless you run higher pressures. No way around that and add to the fact that a Jarret case has to be formed and it is a no go for me.

 

[Derek M.]

I don't have a biased opinion on this, just trying to look at the facts, as I presently know them, realistically and make an informed choice on caliber.

This is sort of like comparing a 30.06 in a 23" barrel to a .308 in a 24" barrel. They are so close, you just need to pick the one that gives YOU the warm and fuzzy feeling for owning it, i.e., which one gives you the "wow" factor.

I went through this decision making process a few years ago with the same 2 calibers. I am lazy. I chose the RUM and have no regrets whatsoever.

I personally do not give a hoot about "efficiency," or a few fps more or less, yada yada yada. If we really cared about "efficiency" we'd ditch the trucks and buy Toyota Prius cars, right? I buy rifles in calibers b/c I WANT it and take the good with the bad. If I have to fireform cases, I knew that going into the project.

There are pros and cons to both of your choices. Just pick the one you think you have your heart set on, get it built and have a ton of fun with it. You won't be dissappointed either way.

 

[Bravo 4]

Well the facts and opinions have been laid out for ya and everybody that answered your post, from what I gathered, chose the 300RUM over the Jarret. You seem to be wanting somebody to chose the Jarret and tell you it's better...well it isn't. But, if it'll help you decide... I say go with the wildcat round and have the added coolness of having such.
Would I chose it? Nope...

 

[J E Custom]

No point in going with a 300 Jarret over a 300 RUM. No case can give more velocity with less powder unless you run higher pressures. No way around that and add to the fact that a Jarret case has to be formed and it is a no go for me.

Jwp said it best !!!! There is no free lunch. Case design can give you a better/
more consistant burn rate (better Standard devations) making it more accurate
but pressure and time gives you velocity.

Before It was called a Jarret the smiths that were messing with the 8 mm case
called it a super 30.

I looked in to it and found that a 300 Weatherby was its balistic twin so I went
with the 7mm/8mm (Now called the 7 STW) sizing and fire forming was not a
problem but there was no advantage over the factory 300 Weatherby mag.

The Jarret/30 super is not more efficient Just smaller in case capicity (About 10
to12grs meaning you must use faster burning powder (More pressure)to get the
same velocity,s This also shortens case life.

With lighter bullets (130 to 150) its not far behind the RUM but with heavy bullets
180 to 240gr there is no contest. If you intend to use the 200 or 210 gr bullets
this is right up the 300 RUM,s alley.

I have the 7 STW and the 7 RUM and the Rum has 12 % more velocity and energy
than the 7 STW but I still like shooting it and hunting with it.

I use the 140gr bullets with the STW and 160gr bullets with the 7 RUM at almost
the same velocity.

And as far as belted cases the only negative thing is that they use up case capicity
for the same size case body(.532" belt on Jarret and .546 case body on the RUM.

Your question was a good one and I think everyone answered them very well.

"BUT" if you want a Jarret you should build it and enjoy because thats what custom
rifles are all about.(Build what you want not what,s popular.

J E CUSTOM

 

[trueblue]

Thanks to everyone for taking the time to respond. Since I will be shooting the heavier bullets out of this rifle I will be looking at the 300RUM, as JE CUSTOM recomended. I also liked the comments made concerning the 300 Jarrett having to operate at higher pressures with less powder to get the same velocities as the 300 RUM. Something I didn't know. Very good info from all, and well appreciated. One question though concerning the comment made by JE CUSTOM on case design.
How does case design give you more consistant burn rate and does the angle of the shoulder come into play ? Maybe should ask this question on a new thread, but ....

 

[Eaglet]

How does case design give you more consistant burn rate and does the angle of the shoulder come into play ? Maybe should ask this question on a new thread, but ....

That's a good question. I'm glad to know there's a bunch of knowledgeable people that would help with this one.

 

[silvertip-co]

Nobody sells 300 Jarret ammo so unless you just wanna be 'special' I'd go with the 300RUM. Even the Chinamart sells 300RUM ammo. My friend in PA has a RH 300RUM for sale, I told him to advertise it here for sale. He's a turkey hunter so he'll probably post it there.

 

[Varminator 911]

I have a 300 Jarrett that I inherited. But Kenny in all his wisdom found it best to build it as a 12 twist, 25.5 inch barrel. So I've only shot it with light bullets. When I can figure out what is the best way to go, I'm planning on having it rebarreled in a fast twist 300 RUM or 338 Edge. I'd never consider the 300 Jarrett even though it came with brass and dies.

If I were to do it now I'd go an 8 twist for the 220 Henson in 300 RUM or whatever is needed for a long 338 bullet. But the Henson bullets aren't proven yet so I'm waiting on further bullet development. If the Berger 338s are good, I may go that way. Bergers 308 bullets aren't high enough bc to get me excited.

 

[J E Custom]

Thanks to everyone for taking the time to respond. Since I will be shooting the heavier bullets out of this rifle I will be looking at the 300RUM, as JE CUSTOM recomended. I also liked the comments made concerning the 300 Jarrett having to operate at higher pressures with less powder to get the same velocities as the 300 RUM. Something I didn't know. Very good info from all, and well appreciated. One question though concerning the comment made by JE CUSTOM on case design.
How does case design give you more consistant burn rate and does the angle of the shoulder come into play ? Maybe should ask this question on a new thread, but ....

Trueblue

I will try to explain it the best I can .

The case design can have an effect on burn rate and pressure curve consistency buy
directing pressure waves back towards the geographic center of the case causing a
more uniform burn of all the powder.

A strait sided case tends to blow all of the powder forward, A steep shouldered case
like the 6mm ppc and the ackley improved cartriges tend to redirect the pressure and
flame front back producing a more complete burn before exiting.

This is the reason for the short fat cases with 40o or more of sholder.

The benchrest guy's can probably explain it better than I have but thats the jest of
it.

J E CUSTOM

 

[JPRITT]

Love my Rum.

27'' lilja #5

210 bergers at 3115 fps. with 91.5 grs of H1000.

I would think this would be very simular to your set up if you chose the Rum.

Good luck

 

[trueblue]

JPRITT,
What is the barrel twist on that Lilja that you are shooting 210's out of ?
I am using H-1000 in my 338 and getting very low velocity spreads, so I like the idea of doing the same in the 300RUM.

 

[JPRITT]

the Lilja is a 1-10 5 groove stainless

H1000 seems to be the ticket for this rifle. I started out with retumbo but had podwer fowling problems after about 12 rounds. H1000 I can shoot more then my shoulder will take and no fowling or accuracy issues. I'm sure it would be awesome in a 338 also.

 

[Shumba]

First let me say I have been creeping around this site very occasionally for a year or so now. There is some great info on here so I registered today and this is my first post, so hello to everyone.

I have had 3 Jarretts and currently still have one. I do not think that you could realisticlly hope to get 3000 FPS with 210's out of the jarrett. You could always have the chance of a fast tube but 3K with a 26" barrel would be pushing it. 2950 with 200's is about the norm and that is pushing it to max. This was typical in all the rifles I have had and all of them had 26" barrels. I love the Jarrett and there are good sources of fireformed brass that run @ 2.25 a peice. You would not need to fireform brass yourself if you did go with the Jarrett.

That being said, if I did not already have the dies and brass..etc.......and was making a new long range rifle in 30 cal I would probably go with the RUM myself. I think you will get a little more out of it with the heavy bullets, probably not so much with the lighter ones.

I do not have any experience with the 300 RUM as far as accuracy goes but I do have an extremely accurate 338 RUM and I cannot see why the 300 woud not be just as accurate. one thing to think about is that the 300 RUM is a very long cartridge. Especially if you are going to have the rifle made to shoot the long 210's I would make sure to build it on an action that can accomodate the length of this long cartridge/bullet combo and still get to the lands.

Hope this info helps you some

 

[trueblue]

Shumba,

I would probably buy a donor rifle in 300Rum for the action. I assume I would need a Wyatt mag box with the Berger210's.