barrel recommendations for a 7 RUM

[jlvandersnick]

rebarreling a 7 RUM. looking the shoot the berger 195s and thinking 28 inch, 8 twist. This will be something that I can hopefully reach out to 1500 yds
specifically looking for length recommendations. Thinking about Rem Sendero contour. This will not be a carry rifle ! !

So for those of you that will question my choice....,I already have a 28 nos with a long freebore. I know a 338 Lau Imp is an awesome choice, but don't have any components and sold the 8 pounder of R33 that I had. I do have 100 pieces of new Norma 7mm RUM brass.

Also interested in chamber ideas. Are you using a chamber with free bore? how long

Also interested in your pet loads. Would love to hear some velocities. Quickload is WAY low on velocities.

I have a lot of retumbo, H1000 and n570. I also have a lot of berger Hunting VLD 180s and EOL 195s. would prefer to go with an 8 twist and use the 195s.

Thanks for your help.

 

[LVLAaron]

I'm no doctor but 7.5 or 8 looks like the ticket.

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[PA Jeep]

I run a 30" 7.8 twist Bartlein and shoot Berger195's a few FPS over 3200 accurately. Great hunting caliber.

 

[CJ6]

Why such a light bbl profile ?? Put a 1.350 straight on it. You're not gonna carry it anyway.

 

[FrankG]

Depending on rate of fire and what your using it for….gonna be a barrel burner! Better get two if you plan on shooting it a lot.

5R rifling!

Later, Frank
Bartlein Barrels

 

[PA Jeep]

Depending on rate of fire and what your using it for….gonna be a barrel burner! Better get two if you plan on shooting it a lot.

5R rifling!

Later, Frank
Bartlein Barrels

Spoken like a happy barrel maker.

 

[std7mag]

Shouldn't have got rid of the RL33.
It's what i'm planning on using for my 7mm WBY Magnum with 175gr ABLRs.

Going to try it in my 7mm Rem Mag with the same bullet.

 

[Murray Brook]

I tried it in my 7mm Weatherby mag with the 175 gr Hornady. Started at 79 grs and went up to 83grs. Could only get 2920 ft/sec. I felt it just a tad to slow of a powder for the 7mm W. Using the same components with Norma MRP I could get to 3156 ft/sec. JME

 

[Edd]

rebarreling a 7 RUM. looking the shoot the berger 195s and thinking 28 inch, 8 twist. This will be something that I can hopefully reach out to 1500 yds
specifically looking for length recommendations. Thinking about Rem Sendero contour. This will not be a carry rifle ! !

So for those of you that will question my choice....,I already have a 28 nos with a long freebore. I know a 338 Lau Imp is an awesome choice, but don't have any components and sold the 8 pounder of R33 that I had. I do have 100 pieces of new Norma 7mm RUM brass.

Also interested in chamber ideas. Are you using a chamber with free bore? how long

Also interested in your pet loads. Would love to hear some velocities. Quickload is WAY low on velocities.

I have a lot of retumbo, H1000 and n570. I also have a lot of berger Hunting VLD 180s and EOL 195s. would prefer to go with an 8 twist and use the 195s.

Thanks for your help.

What action are you going to use?

 

[46and2]

rebarreling a 7 RUM. looking the shoot the berger 195s and thinking 28 inch, 8 twist. This will be something that I can hopefully reach out to 1500 yds
specifically looking for length recommendations. Thinking about Rem Sendero contour. This will not be a carry rifle ! !

So for those of you that will question my choice....,I already have a 28 nos with a long freebore. I know a 338 Lau Imp is an awesome choice, but don't have any components and sold the 8 pounder of R33 that I had. I do have 100 pieces of new Norma 7mm RUM brass.

Also interested in chamber ideas. Are you using a chamber with free bore? how long

Also interested in your pet loads. Would love to hear some velocities. Quickload is WAY low on velocities.

I have a lot of retumbo, H1000 and n570. I also have a lot of berger Hunting VLD 180s and EOL 195s. would prefer to go with an 8 twist and use the 195s.

Thanks for your help.

195 gr for 7rum... I would try H50BMG or RL50.
Those powders make a 26 Nosler shine with 147gr. These two combinations have a similar bullet weight to case capacity ratio.

 

[Sandstorm]

Id use a strait taper barrel (1.25 all the way)

This..^^^^

 

[jlvandersnick]

Pierce action

 

[Yote Hunter]

96.5 gr H 50 BMG powder in my my 7mm RUM. 175 gr SMK. 3382 fps ES 16 for 3 shots 0.560” @ 543 yards. 33” 1.350 Straight Krieger 4 groove 9 twist. Much faster and the bullet jackets fail. 180 gr Berger hybrids, 180 gr SMK and especially the 180 gr ELDM’s will not hold up. Honestly the 28 Nosler can achieve the same useable speeds with a lot less powder. The RUM will go faster but most of the bullets won’t make it to the target

 

[B23]

Do you think your barrel being a 4 groove, combined with high velocities, had anything to do with the bullet failure/s?

I've read where 3 and 4 groove barrels along with high velocities and thin or thinner jacket heavy for caliber bullets can cause bullet failure. Wonder if you had a 6 groove or 5R rifling barrel if there would still be bullet failure.

 

[FrankG]

Spoken like a happy barrel maker.

Hey it's funny #$%^

I once told a gunmaker/ammo company years ago! You guys keep coming out with these barrel burner calibers...it'll keep us busy! Guy was really quiet on the phone.

On a serious note....the trade off for high velocity as the saying goes....you want to go fast...it's gonna cost you to go fast $$$ on way or another. Either in the equipment you need or in the life of the equipment.

 

[FrankG]

Do you think your barrel being a 4 groove, combined with high velocities, had anything to do with the bullet failure/s?

I've read where 3 and 4 groove barrels along with high velocities and thin or thinner jacket heavy for caliber bullets can cause bullet failure. Wonder if you had a 6 groove or 5R rifling barrel if there would still be bullet failure.

3 groove or 4 groove or 6 groove conventional rifling bullet failure is more of a problem. Obermeyer always maintained that the 5R rifling helped fight bullet failure and was better for accuracy.

In my opinion on one hand the style or number of grooves until recently didn't effect accuracy but I have maintained now for years that the 5R does help fight bullet failure because the odd number of lands and grooves (the lands don't directly oppose one another distorts and upsets the bullet jacket less). You don't get this with a 3 groove barrel even though it's odd number of grooves/lands. Why? All of the 3 groove barrels I've seen the lands/grooves are so wide that you still end up with a portion of one land opposing another to some extent. So you don't get the full benefit.

Also not to long ago I am starting to believe more and more...the 5R rifling will help the flight of the bullet which can help the accuracy of the bullet as well at long range. This was proven by a ammo/bullet maker and in a separate unknown test by the Army. Both got the same data results.

One exception I make to this rule is for the 6ppc bench guys who want guns to shoot in the low .2xx's and .1xx's etc..Those short jacket 6mm bullets and it's worse with the boat tail bullets...you want conventional rifling. I don't care if it's a 4 groove or conventional 5 groove etc...those short bullets don't have a lot of bearing surface area for the rifling to bite the bullet and drive them properly. I'll tell you with a 5R rifled barrel and the short jacket 6ppc bullets....upper .2xx's to a flat .3xx is the best you will get out of them.

Later, Frank

 

[B23]

3 groove or 4 groove or 6 groove conventional rifling bullet failure is more of a problem. Obermeyer always maintained that the 5R rifling helped fight bullet failure and was better for accuracy.

In my opinion on one hand the style or number of grooves until recently didn't effect accuracy but I have maintained now for years that the 5R does help fight bullet failure because the odd number of lands and grooves (the lands don't directly oppose one another distorts and upsets the bullet jacket less). You don't get this with a 3 groove barrel even though it's odd number of grooves/lands. Why? All of the 3 groove barrels I've seen the lands/grooves are so wide that you still end up with a portion of one land opposing another to some extent. So you don't get the full benefit.

Also not to long ago I am starting to believe more and more...the 5R rifling will help the flight of the bullet which can help the accuracy of the bullet as well at long range. This was proven by a ammo/bullet maker and in a separate unknown test by the Army. Both got the same data results.

One exception I make to this rule is for the 6ppc bench guys who want guns to shoot in the low .2xx's and .1xx's etc..Those short jacket 6mm bullets and it's worse with the boat tail bullets...you want conventional rifling. I don't care if it's a 4 groove or conventional 5 groove etc...those short bullets don't have a lot of bearing surface area for the rifling to bite the bullet and drive them properly. I'll tell you with a 5R rifled barrel and the short jacket 6ppc bullets....upper .2xx's to a flat .3xx is the best you will get out of them.

Later, Frank

Frank, I was really hoping you'd see this and respond.

So for an overbore hot rod 7mm build what barrel would you recommend, a Bartlein 5R and what length? I tend to be of the mindset, the more overbore something is the more beneficial a 28-30 inch tube is but does a bullet spending more time in the barrel, due to it being longer, have more of a negative affect on bullet failure, compared to say a 26in barrel?

 

[Edd]

I have a Bartlein 7mm barrel I bought 7 years ago. It is a custom Palma contour. It has a 1.0" neck diameter, an .820" muzzle diameter at 28", eight .075" deep flutes, a .315" chamber end diameter, and an 8" twist.

If anyone ever builds an action that I like with a 1.125" tenon thread, I'm going to build a big 7mm.

 

[jlvandersnick]

What action are you going to use?

Pierce action

 

[FrankG]

Frank, I was really hoping you'd see this and respond.

So for an overbore hot rod 7mm build what barrel would you recommend, a Bartlein 5R and what length? I tend to be of the mindset, the more overbore something is the more beneficial a 28-30 inch tube is but does a bullet spending more time in the barrel, due to it being longer, have more of a negative affect on bullet failure, compared to say a 26in barrel?

If you have a lot of case capacity a longer barrel helps burn the powder and hence forth to an extent gives you more velocity. A 6BR for example burns like 98% of the powder in a 28" long barrel. The gain per inch after 28 on average is only like 6fps. So a waste of time in my opinion running a 30" barrel on a 6BR case.

Now a 7mm chambered in some version of a 7mag....I'd say 30" no problem. 32"...maybe it will help you but your probably getting to a point of diminishing returns on a 32" or 34" long barrel unless your really stepping on it!

The longer the time period the bullet is in the barrel...the more the bullet heats up. I cannot put numbers on it....but it can effect bullets and bullet failure. I do know and again I cannot put numbers on it....but a really long barrel if the barrel is fouling this seems common. When you fire a round and yes everything happens in milliseconds. When the bullet jumps into the rifling copper gets shaved off the jacket and instantly goes from a powder form/metal shavings and gets turned into a molten liquid...this copper liquid is held in suspension and will follow the bullet down the barrel. When the copper liquid gets to a point where it cools enough...it will transform back to a solid and that's when the copper from the bullet will stick to the bore. Usually but not always it's about the mid point range of the barrel and towards the muzzle it will be the heaviest.

If the throat from chambering is really rough....or as the barrel is starting to get burned out the throat will get really rough as well....and the fouling can start all the way back at the chamber.

Also type of bullets even from lot to lot from the bullet maker and or shooting solids can cause fouling situations as well.

My 300PRC on my f class gun. Is a 32" barrel and is a laser beam but I'm not getting the extra velocity out of it I thought I would. So the next barrel is just going to be a 30" finish length. At 32" I'm pushing 225/230gr bullets an honest 2900fps. I thought with a 32" I'd be in the mid 2900's but didn't get it. Gun will hold 1/3moa at a 1k yards!

Later, Frank