7mm Rem Mag - 150gr NP - ADI AR2213SC (H4831sc) - Low velocities

[proload]

Hi there,

I'd really appreciate some help and/or advice.

I recently bought a Remington 700 XCR II in 7mm Rem Mag. 24" tube, 3.6" mag.

To date I have been breaking the barrel in (using factory ammo) and have just started reloading for it. The barrel has fired 120 rounds to date (excluding the tests below)

My first effort was a 150gr Nosler Partition in a Hornady case on top of ADI AR2213SC (H4831sc) powder and a Federal 215M primer. COAL was 3.280" (or 2.625" using a comparator), which gives me a seating depth 20 thous of the lands. Loaded rounds were then given a very light crimp with a Lee Factory Crimp die. Cases were FL sized to the point where the shoulder was bumped 2-3 thous and cases were trimmed to 2.490".

I loaded 13 sets in 0.5gr increments from 59gr to 65gr. The powder charge was the only thing that was changed between all the sets. Each set consisted of 4 rounds.

@59gr according to the ADI Manual/Hodgdon website should have produced 2775fps. I got 2572 avg.
@61gr according to the Nosler reloading guide #6 should have produced 2985 fps. I got 2765 avg.
@62gr according to the ADI Manual/Hodgdon website should have produced 2956fps. I got 2718 avg.
@63gr according to the Nosler reloading guide #6 should have produced 3023 fps. I got 2817 avg.
@66gr according to the Nosler reloading guide #6 should have produced 3075 fps. I got 2925 avg.

I got 3 loads of interest.

One group of 1/4 inch @2633 fps. ES=63, SD=25.4. Good group, but way too slow to be usable and poor ES/SD.
One group of 0.8 inch @2817 fps. ES=12.4, SD=5.4. Acceptable accuracy, but good ES/SD. Was hoping for more speed though.
One group of 1 inch @2886 fps. ES=30.2, SD=13.6. Acceptable accuracy, but the pace is getting towards what I was expecting.

I have another 50 of these projectiles and would really like to try and get more from them. I tend to feel that trying a different powder may be worth while as I really would like to get closer to the 3000fps mark, but I'm unsure which way to go. Do I try a faster powder such as AR2209 (H4350), or a slower powder such as AR2217 (H1000) or Retumbo. I would prefer to only use temperature insensitive powders as I hunt in both summer (25-30 deg C) and winter conditions (sub zero deg C).

Also, could anyone explain why I seemed to constantly get 200fps less than that the book said I should expect. I think that 200fps is quite a lot. Is it the 24 inch tube, or is something else at play? As a further point of interest, I chronied some 162gr Hornady Superformance Factory Ammo, and you guessed it ... 200 fps below what the ammo box claimed. Box claimed 3030fps, I got 2815fps as an average of 5 shots.

Cheers

 

[Robinhood493]

I get my best velocities in 7mm rem mag with IMR-4350. I tested IMR-7828, H-1000, and RL-22 for velocities and the H-1000 was the slowest by 200-300 FPS. The IMR-7828 was about 100fps slower than IMR-4350. The RL-22 was close to the IMR-4350, but I won't use it in my hunting guns due to its rumored temp instability. I'm just starting load development, but it looks like I will be able to get in the range of 1/2"-3/4" MOA in a stock Browning A-bolt. This is with 150g NP.

 

[proload]

I get my best velocities in 7mm rem mag with IMR-4350. I tested IMR-7828, H-1000, and RL-22 for velocities and the H-1000 was the slowest by 200-300 FPS. The IMR-7828 was about 100fps slower than IMR-4350. The RL-22 was close to the IMR-4350, but I won't use it in my hunting guns due to its rumored temp instability. I'm just starting load development, but it looks like I will be able to get in the range of 1/2"-3/4" MOA in a stock Browning A-bolt. This is with 150g NP.

Robinhood ... what velocities are you getting for the various powders that you tried?

Thanks mate.

 

[Robinhood493]

I will have to look in my book tonight.

 

[proload]

I will have to look in my book tonight.

Thanks. I'd really appreciate that.

If you could also mention projectile weight per load that would be very helpful.

How long is your barrel?

 

[Robinhood493]

Thanks. I'd really appreciate that.

If you could also mention projectile weight per load that would be very helpful.

How long is your barrel?

150g partition, 24" barrel with BOSS

 

[proload]

Perfect.

Your data will be very beneficial to me.

Thanks.

 

[g0rd0]

I have had the best luck with 150 grn etip / mag primer / 67.0grn IMR7828 3000fps
Recently I have been experimenting with 162 grn amax and have yet to find a good load so, once this box is finished I will try 175grn sp (I have 200) I have been told that I should try rl22 for the heavey bullets so I will pick up a can on my next trip to the shop.
If you are in a spot with a lot of gophers try 139 grn sp with 45 grn imr 3031 std primer. the 3031 is a bit fast for the 7mm RM but with the lighter bullets it is very accurate

 

[Robinhood493]

Perfect.

Your data will be very beneficial to me.

Thanks.

IMR-7828
64g--2909fps
69g--3161fps

RL-22
62.5g--2904fps
68g--3165fps

H-1000
65g--2705fps
70g--2999fps

IMR-4350
59g--2948fps
65g--3240fps

150g partition out of a 24" Browning A-bolt with BOSS.

 

[wbm]

One group of 0.8 inch @2817 fps. ES=12.4, SD=5.4. Acceptable accuracy, but good ES/SD. Was hoping for more speed though.

Have been a big fan of the 7MM Magnum for years. This load looks outstanding for long range hunting. With a low ES like that you may find that your accuracy at 300 is great!

What I noticed is that you are assuming that the chronograph is giving you accurate information. I would not assume that. What I would do is go to JBM and do a manual calculation of velocity. Set the scope at let's say 3" high at 100. Using the ballistic calculator fire the rifle at 300 and see what the drop is. For example, your BC=.456 for the 150 NBT. I did a calculation on that bullet with a temperature of 59F and 35 percent humidity at sea level. In order to get a a 250 yard zero at a velocity of 2817 you would set the scope 3" high at 100. Play with the numbers and set your elevation, temperature, humidity etc. into the calculator. You can get pretty close to actual velocity by measuring bullet drop at various distances. Besides it is fun!

JBM - Calculations - Trajectory

Personally I would forget the crimp and would not clean the rifle until accuracy drops off.

 

[proload]

With a low ES like that you may find that your accuracy at 300 is great!

Yes ... I plan to work more on this loading. It's the best option of the lot by a long stretch.

What I noticed is that you are assuming that the chronograph is giving you accurate information. I would not assume that.

Yip ... thats a good point, and I have already arranged for 2 of my mates from the gun club to bring their chronies in on the next range day ... we'll shoot the load mentioned above over all 3 chronies and see what they do.

Personally I would forget the crimp ...

Why no crimp ??

I have not crimped loads for many years, but my concern was projectile shifting even 10thous (either way) under a fair bit of recoil.

 

[wbm]

Your point about the crimp is a good one,especially for hunting loads, but I might choose a bullet with a cannelure. Checked out the Nosler reload data and their accuracy loads with the 150g NP, with one exception, were in the 2750-2850 range with a 24" Wiseman barrel.

The current 7mm Mag I have is a 22" heavy barreled Savage.

I found that 69.5g of H4831 with a 120g Nosler BT is moving at about 3100fps. Winchester neck sized brass and a Federal 215M primer. OAL=3.30" Wickedly accurate!
Another is 71.6g Retumbo with a 140g Nosler BT. OAL=3.250".

You might give these a go in your Remington and see how they shoot.