Thread: 7mm Rem Mag advice

Hi team

I need to make a decision on a load out of these three here. I changed batches of 2217 and there is quite a difference. My old load was 72.5 grains but I had quite a sticky bolt using the same load with this new batch.

So I came back down a couple and got these groups today. All at 100 yards off a bipod with rear bag.

First one is 70.5 grains with three shots.
Velocities went: 2936, 2982, 3009. ES of 73 and sd of 36.
Measured 0.55" centre to centre.



Second group went: 2996, 3030, 3009.
ES 34 and sd of 17. The second shot which is the far right impact felt like a bad shot, I definitely felt the rifle move sideways when I squeezed off. Measured 1.070" centre to centre. Should have been more like 0.65" if I hadn't messed up the second shot.



Group number three, the bolt had a slight resistance with the second two, I out this down to heat it was bloody hot down here today. Speeds were: 2989, 3030, 3044. ES of 55 and sd of 28.



I waited at least 5 minutes between groups and at least 1 minute between shots.

I like group 3 best because it's the smallest at 0.55" but the es has me thinking the second load is the one to go with. Thoughts?

Personally I think the spread is too much on all but that's me, I like to get mine under 20fps preferably under 15fps or better.
Consistent speed is where you will find accuracy especially at longer ranges.
Find consistent speed then fiddle the seating depth to to shrink groups.
Don't be afraid of loosing a little speed even 2900fps is dead deer out to a long way with a 162gn pill.
Do an experiment if you like, take your fastest speed and your slowest speed and plug the details into your balistic app and check the variance in drop at your maximum range your comfortable shooting at.
If your comfortable the difference wont affect your outcome then that's your call.
No hate but you can definitely do better with that powder and pill combo.

Yeah I would like better results too but I'm under a bit of a time crunch, leaving on Saturday morning for a 5 night tahr hunt and need a load that will do the job.

It's interesting you say that about the fastest and slowest into ballistics app. I was doing exactly that earlier and the difference at 400 yards was around 0.05 mil for all the groups here.

I could cheat and blame my chroni as it seems weird to me that the first shot for each string was significant slower than the folowing shots. Chroni is a pro chrono.

What type of chrony are you using?

My bad, pro chrony! Aren't familiar with those are they known for accuracy?

I would suggest testing over a different chrony its a good bullet:powder combo you have

Greetings Rated M for Magnum,
Looking at your three groups with the one called flyer Your rifle is delivering excellent accuracy. I wouldn't get too hung up on on Extreme Spread or SD, it is accuracy that you should be looking for especially at longer range. I assume that you will test the loads at least at 300 metres. One three shot group is not enough to draw any conclusions but the three groups averaging well under 1 MOA are. Pick any one you want.
Regards Grandpamac.

Hi. I run and load a 7mm Rem Mag (Tikka 595 totally stock standard s/s barrel and very shitty plastic stock) and support the views that the highest velocity is not necessarily the most accurate and that the most important consideration is to get the speed as consistent between shots as possible.

I have managed to get this rifle to shoot 1" groups at 200m with a 160gn projectile at an average velocity of 2762fps which for the 7mmRemMag is quite low as you know. I must say however that the only way I could get this particular rifle to shoot at this grouping was to individually ream out the case necks of my Norma brass and friction fit the projectiles to the correct depth. This means I have to load each round individually. If I put 3 pills in the magazine then the recoil resets the projectile. I don't use this as a long range hunting rifle as most of my hunting is <100m so it is just a bit of an experiment on my range at home to see how well I can get a Tikka shooting versus my mates rather expensive Sako 7mm Rem Mag that he paid 3 times the price for :-) Over the 40 years I have reloaded ammo I have personally come to the conclusion that crimping is a quick way to upset consistent velocity. I now only crimp for my tubular magazines as most of my hunting is close up and a fast 2nd shot is always on the offering but in reality with the .444 Marlin I have never had to use a 2nd shot LOL

I have a pro chrony, i use it as a guide only. I wouldn't worry about es if you can consistently shoot groups like the first and third group. Numbers are great but the real truth is where the bullet hits the paper

I have a pro chrono too, id say that is your problem with ES.

I tend to find my shots cut laterally across if im pulling the stock in too tightly to the shoulder. But dont dismiss that group. I reckon that could be ok, maybe make up a few more and confirm it.

My first group of the day sometimes looks this way. I settle in and then all is well.

I work on vertical spread = load, horizontal spread is heavily dependent on the shooter. Not a rule but a guide. So if I have low vertical spread and some horizontal spread, I’d be inclined to rerun the load test.