7mm Rem Mag Velocity Help

[Scurvydog]

I'm shooting a tikka t3 lite, 7mm rem mag with hand loads and a 24 3/8" barrel . My current recipe is:

168 berger hunting vld
Norma brass
Rem 91/2 primers
65.3g h4831sc
COL 3.282"

I have conducted OCW tests from 61g - 65.8g with no pressure signs. I found two decent nodes. One at 62.5 and the other at 65.2. I also conducted bullet seating tests with both nodes, however I am restricted due to the tikka magazine.

The rifle is a shooter. I have been able to shoot 1/2 moa 5 shoot groups out to 600yds and 1 to 3/4 moa out to 1000yds.

With all of that said I feel like something strange is happening concerning my muzzle velocity. I have been getting between 2600fps and 2700fps no matter the powder load from 62.5 to 65.2.

I think having to seat extremely deep to fit the tikka magazine is causing this, but I don't know for sure. I've been stuck with h4831sc because it's what I have.

Soooooo, I'm shooting well over book max and not even getting close to the book(berger manual) velocity of 2904fps. The book says they used a 26" test barrel.

Are the velocities I'm getting the best I can hope for considering my barrel length and seating depth? Or should I be looking at something else?

Sorry for the long post but I've been chasing this for almost a year now. Any help is appreciated.

 

[Powermac]

The first thing i'd try is to change powder. And possibly some fgmm 215 mag primers.
Norma brass is as good as it gtes. If your rifle is new it might also pick up speed after a lil while.
H-1000 and VV N560 would be my suggestion.
My 284 win with a 26 tube is faster then your RM so burning a whole lot of powder to do little, also your loads does seem a bit conservative.

 

[ChrisGarrett]

I'm shooting a tikka t3 lite, 7mm rem mag with hand loads and a 24 3/8" barrel . My current recipe is:

168 berger hunting vld
Norma brass
Rem 91/2 primers
65.3g h4831sc
COL 3.282"

I have conducted OCW tests from 61g - 65.8g with no pressure signs. I found two decent nodes. One at 62.5 and the other at 65.2. I also conducted bullet seating tests with both nodes, however I am restricted due to the tikka magazine.

The rifle is a shooter. I have been able to shoot 1/2 moa 5 shoot groups out to 600yds and 1 to 3/4 moa out to 1000yds.

With all of that said I feel like something strange is happening concerning my muzzle velocity. I have been getting between 2600fps and 2700fps no matter the powder load from 62.5 to 65.2.

I'm looking at my Sierra V manual and with their 168gr SMK, H-4831sc @ 64.7gr, OAL: 3.260" and Federal 215, they're showing 3000 fps out of a 26" Savage 116, so something is way off with your scale, or your chrono.

Sierra is a conservative manual, to boot.

Just as an aside, with my 26" Sendero v.1, using a 168gr SMK and 61.5gr of H-4831sc, I got 2708 fps with a SD of 21 for 10/10 shots fired.

On another occasion, I used 62.5gr of H-4831sc and the 168gr SMK and got 2752 fps for 10 shots logged in that group and a SD of 6.5.

Now, to be fair, the SMKs aren't Bergers, but something's up on your end? I don't expect you to be at 3000 fps, with ~65.0gr of H-4831sc and a 24.5" barrel, but you should be higher than where you are, IMO.

Chris

 

[Clark]

I have become a 7mmRemMag person.
I build one every year.
One year I built 3 of them.
I think it is the best long range cartridge for a rifle that needs to stay under 10 pounds with scope, sling, bipod, rear bag, and ammo.

The published 7mmRemMag loads are so wimpy, they can almost always be bested with 7x57mm Mauser rifles loaded to just under the threshold of long brass life.

I was headspacing at 0.215" because no brass was longer than that. Then in 2014 I got 250 pieces of WW that are 0.220", the SAAMI min headspace.

Larry Willis' Innovative Technology collet die is to shrink the brass right in front of the belt.

I have given up on that for hot loads. I now use the belted magnum brass only once, and run ~ 10 grains over max published loads. in 2013 I hunted with 11 gr over Hodgdon's max for 140 gr H4350. I am not getting any hard bolt lift or swipes on the case head. I just work up to loose primer pockets, back off 2 gr, load lots of ammo, and throw away the cases when done.

 

[No1]

I get 2925 fps, with
7MM RM
168g SMK
65.6g H4831
Rem 9 1/2M
3.315 OAL
26" barrel

I'd expect your 24" barrel to be less velocity, but not 200fps.

 

[JGorski]

I'm shooting a tikka t3 lite, 7mm rem mag with hand loads and a 24 3/8" barrel . My current recipe is:

168 berger hunting vld
Norma brass
Rem 91/2 primers
65.3g h4831sc
COL 3.282"

I have conducted OCW tests from 61g - 65.8g with no pressure signs. I found two decent nodes. One at 62.5 and the other at 65.2. I also conducted bullet seating tests with both nodes, however I am restricted due to the tikka magazine.

The rifle is a shooter. I have been able to shoot 1/2 moa 5 shoot groups out to 600yds and 1 to 3/4 moa out to 1000yds.

With all of that said I feel like something strange is happening concerning my muzzle velocity. I have been getting between 2600fps and 2700fps no matter the powder load from 62.5 to 65.2.

I think having to seat extremely deep to fit the tikka magazine is causing this, but I don't know for sure. I've been stuck with h4831sc because it's what I have.

Soooooo, I'm shooting well over book max and not even getting close to the book(berger manual) velocity of 2904fps. The book says they used a 26" test barrel.

Are the velocities I'm getting the best I can hope for considering my barrel length and seating depth? Or should I be looking at something else?

Sorry for the long post but I've been chasing this for almost a year now. Any help is appreciated.

You're lucky, when I loaded 63grs with 162 Hornadys my buddy got a pierced primer, had to lower the charge 1 grain and all was well. I now use RE22 & Retumbo for the 7 mag, the latter as of late.

 

[Scurvydog]

I'm still racking my brain about this. My first move is going to be changing powder. I'm not trying to get hot loads, it's just that I would like to get 7mm rem mag velocities out of my 7mm rem mag, otherwise I would have went with a 7mm-08.

 

[JGorski]

Aye matey, try a pound of Retumbo, should give you 2900 or so.
Take Aim at Rifle Reloading Data | Hodgdon Reloading

 

[former naval person]

Run a drop test with your most accurate node. Your chrony could be lying to you.

 

[Scurvydog]

I've plugged my chrono's velocity into "Ballistics" shot from 300 to 1000yds and entered the drop difference to get the corrected MV and it is withing 50fps of my chrono.

 

[goodgorilla]

I'm shooting a tikka t3 lite, 7mm rem mag with hand loads and a 24 3/8" barrel . Soooooo, I'm shooting well over book max and not even getting close to the book(berger manual) velocity of 2904fps. The book says they used a 26" test barrel.

Maybe your barrel isn't long enough to achieve maximum velocity.