7 rum

[Deleted member 25294]

I bought this rifle used with a rather beat up bore and still got around 400 rounds from it before she started tossing two groups. My first 7rum went about 1,000 rounds at full throttle before she gave up the ghost and she was a bdl.. Depends on how hard you flog the rifle, but 1,200-1,400 rounds before a re-barrel or setback should be doable if you don't get crazy.

1000 rounds is optimistic with a 28 Nos let alone the 7 RUM.
Guys are burning out 300 RUMs in 700-1000 rounds.

 

[HARPERC]

......1000 rounds is optimistic with a 28 Nos let alone the 7 RUM Guys are burning out 300 RUMs in 700-1000 rounds.

While I have no doubt some are harsher on barrels than others, I'm not aware of a "standard" for "burnout".

Is it measurable barrel wear in your mind, or functional, the point where it no longer performs as intended.

 

[Deleted member 25294]

While I have no doubt some are harsher on barrels than others, I'm not aware of a "standard" for "burnout".

Is it measurable barrel wear in your mind, or functional, the point where it no longer performs as intended.

Loss of accuracy, big drop in velocity, and damage to the jacket causing flyers are pretty standard indicators.
Those should be popping up well under 1000 rounds with a chambering as overbore as the 7 Rum

 

[26Reload]

What about all the bore additives to make things not only supposedly slicker but improve heat dissipation in barrels...ie..nitrite(?) for barrels.....do these product not really work and are a waste of monies....

 

[Deleted member 25294]

What about all the bore additives to make things not only supposedly slicker but improve heat dissipation in barrels...ie..nitrite(?) for barrels.....do these product not really work and are a waste of monies....

That's a great question.
I'm putting a 6mm Creed together for match shooting and will be using 115 Boron Nitride coated Dtac bullets.

It'll be awhile before I can report on whether or not it extends barrel life..

 

[HARPERC]

......Loss of accuracy, big drop in velocity, and damage to the jacket causing flyers are pretty standard indicators......Those should be popping up well under 1000 rounds with a chambering as overbore as the 7 Rum.....

No disagreement.

I do think for some purposes, the 7 RUM, (and others) can be useful, longer than the same amount of barrel decay needed to sideline others.

 

[Lefty7mmstw]

1000 rounds is optimistic with a 28 Nos let alone the 7 RUM.
Guys are burning out 300 RUMs in 700-1000 rounds.

Not really talking about 28nos here; it's pretty dead to me as most people who run the 28 are running it hard to justify the stupidity of not just using the 7stw or 7rum... My 'smith had to whack 2 inches off this barrel to get rid of the damage caused by a couple hundred rounds of 28nos...
I do usually just count boxes of bullets run through a rifle so I can be a few shots off; the subject is really academic though. I've re-barreled two different 7mm's in the last couple of years as I wore them out. Barrels are no more permanent than tires to me any more; while it shoots it's a go and when it dies it's time to ponder what the heck to do with the action. I have a lh bdl in 300rum that's got rather good fire cracking but still shoots. I also have a lh Browning ab2 in 300win that will need a new pipe. thinking 7x300win on the browning...

 

[meatyrem]

What about all the bore additives to make things not only supposedly slicker but improve heat dissipation in barrels...ie..nitrite(?) for barrels.....do these product not really work and are a waste of monies....

Powder selection is another key point because some run cooler than others which is why I have selected US-869 for use in my RUM.

 

[tbrice23]

Powder selection is another key point because some run cooler than others which is why I have selected US-869 for use in my RUM.

Do you mind sharing your load info?
Do you find 869 dirty?

 

[meatyrem]

Do you mind sharing your load info?
Do you find 869 dirty?

I just used hodgdons manual
It had listed a max of around 103gr US-869 with a 160.
Stock 700 bdl ss Rp cases book length I believe 3.65" 160 accubond fed 215
And where I stopped was 101.5gr which gave me .48" groups at 3248fps. It was around 2gr under max and you'll have to check that manual again as I think those change from year to year. I did not push it because I want to take it easy on this particular one and IMO any 7mm over 3200 with a 160 is really good in my book.
With that particular rifle I would not shoot more than one shot in at least five minutes as to never let that barrel even get warmed up. This is while ladder testing. Just set it aside and shoot something else, set that aside fire another round and so on. Now if I were to be out in the field waiting between shots is not something I would practice but only at the range where I had the time.

 

[meatyrem]

Do you mind sharing your load info?
Do you find 869 dirty?

I didn't really notice it being dirty and I imagine primer type and hotter loads would change that too if it were dirty.
US-869 is good with heavy for caliber loads and it shines with the heavy 7mm that's I have seen. Usually pulling away the heavier you go too. Thinking of going with something around the 180gr mark too to draw out more of its potential.

 

[Lefty7mmstw]

Well, the rifle extracts fine with the new extractor... However, I'm running at start charges for 180's with retumbo and still showing high pressure when the rifle warms up... I shot 1 round with a 175 Hornady in it and blew the dang primer... I cleaned the bore and looked down it; the throat is 1/2 what I'd expect with a 7rum. I suspect my 'smith was sent a short throat reamer. He doesn't work for the shop he was at any longer; I suppose my only options are to drop the powder charges further or have someone else ream the throat.

 

[Lefty7mmstw]

https://www.longrangehunting.com/threads/7mm-rum-coal-problem.46588/#post-320965
well, I found my issues in a post from ten years back... directional ignition... retumbo is too fast of a powder for my 7rum as it sits...

 

[gunaddict]

I use 50 BMG out of my 7 Rum. 180 VLDH. 3300 fps out of a 29 inch barrel.