7MM RUM freebore problem

[Greg Nolan]

I picked up a 7 RUM in a Savage 110 and after some initial load work I thought I had a sub MOA 2 shot group with NABLR 168gr bullets. WRONG! 5 shots 5" at 100yds.
I checked the freebore and was astounded to see the 168gr at 4.05" OAL to the lands. The 160gr at 3.865". The magazine is 3.60" max.
So now what. Should I look for some 175 gr roundnose bullets or make the rifle a single shot at seat to an OAL of 4 inches. :? Help!!

 

[Ridgerunner665]

You don't need to be on the lands to have accuracy....

I've been shooting long range for over 30 years and in all that time only 1 rifle, of many, really liked bullets loaded to the lands.

My standard practice is to load a round to a length that will comfortably and reliably feed through the magazine... I've always been able to find a good load at that length.

Freebore length isn't necessarily a bad thing...

 

[Greg Nolan]

I've had freebore issues before, most recently with a Kimber and I ended up going with a blunter bullet but based on your findings I'll keep working on loads. Have you any special hints on the loads you've found. Over all length, velocity or bullet type? I've also only had one rifle I couldn't get to shoot and I ended up re-barreling.
Thanks for the help Lynn.

 

[Ridgerunner665]

I always start at, or very near, SAAMI length.

And have also always used boat tail bullets... Mostly Ballistic Tips.

Berger VLD's and Elite Hunters are another monster.... Good bullets, even great bullets, just not usually at SAAMI length.

ABLR's should shoot at SAAMI length.

 

[Greg Nolan]

I'm maxed out at SAAMI 3.6" and I've tried 160 gr. Accubonds but haven't tried but one load. The frustration here is that I have a 7 RUM Rem 700 and it loves every load and the 168 ABLR especially. I had plans to sell it, use this Savage, and finish modifying a 280 to Ackley Improved.

 

[Ridgerunner665]

I'm confused...

You're selling a good shooting rifle and replacing it with a fussy one?

Why sell the 700 if you want a 7mm RUM?

Everybody should have a 280 Ackley!

 

[Greg Nolan]

It is confusing I admit. I decided to get out of the 7 RUM to generate some Christmas cash and I still had all the brass, dies etc. I saw the Savage at half the Rem's price so I could get the cash I needed for Christmas and the 280 re chamber and still have a 7 RUM. Sometimes being retired requires some money juggling that would have made no sense when I was working. :?

 

[skidmark]

The freebore in my Weatherby 340 is like an interstate Hwy.

 

[JD338]

Greg,

Retumbo shot really well for me in the 7mm RUM.
What powders have you tried in the Savage?

JD338

 

[Greg Nolan]

I started off with RL25 and went to Retumbo and I'm using IMR 7828 Now. I've used Fed 215 and CCI 250 primers. I've tried 168 NABLR 160 NAB 140 NAB and Hornady 139 BTSP in every configuration. The accuracy went to a steady 1.5" If I lengthened the NABLR 168 gr. OAL to 3.8" It won't fit the magazine though. Since I'm dealing with an oversized chamber and the resulting stretch I cant full length resize to get neck tension so I'm waiting for a neck sizing die to arrive. Meanwhile I prepped the brass and trimmed, but they still have to fireform to the chamber size. I tried some 140 gr bullets at Nosler max load with about .20 of the neck resized and the neck tension were too lose and allowed blow by and put pressure flutes down the sides of the brass. They look like military dummy rounds. This is going to be quite a process. I may have to have to do some barrel modifications.

 

[kraky1]

when weatherby moved their production from Japan to the United States I bought one of the first 300 Weatherby ultra lights. The thing drove me crazy with terrible accuracy no matter what bullets and what powder I tried and yes it had free bore. The bottom line was eventually after much experimenting I started seating the bullets very deep so I had even more jump. and,guess what happened.... that turned it from being a 2-3 MOA gun to a sub MOA gun and now I have total confidence in it but I just can't hang those bullets out and make sexy looking ammo.... I just get sexy looking targets now.

 

[Richracer1]

Greg, here's my 7 RUM recipes:

Bullet Powder & charge Primer COL Brass & Trim
150ET Retumbo 91 GM215M 3.655 Rem 2.83
160AB Retumbo 91 GM215M 3.635 Rem 2.83

Regardless of magazine length, there's no way I can get the above two bullets even close to the lands on my Rem 700 SPS rifle.

 

[Greg Nolan]

As soon as my neck sizer arrives I'll try both those ideas and loads. Thank You for your help!

 

[Whitesheep]

Yeah, Weatherby Mag's have a lot of free bore. When working up loads for my .340 I measured a box of factory rounds and matched the average. I did this because the bullet fell out of the Hornady modified case before touching any lands when I tried measuring the chamber. It was surprising, however, how great the spread was in length of the factory stuff (0.019"). The factory shoots MOA as do my reloads, so I guess a 0.020" variance in base to ogive is OK. At least for the .340 WBY.