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Underperforming 7mm Rem Mag

10 Nov 2012
@ 08:02 pm (GMT)

Warrick Edmonds

Hi

My rifle is a 7mm Rem Mag Weatherby Vanguard (wooden stock) pre S2 model, blued barrel. Its fired around 200 rounds, half factory loads and the remainder my hand loads. I've had it bedded, floated and trigger set at just under 2lbs. Accuracy appears ok without being great, at 100m 3 shot groups = 4cm. I have been working up a hand load based on Hornady 154g SST for red and fallow deer, which we typically encounter at around 200m to 300m range in open farmland.

I was basing my loads on ADI published tables. I settled on 67gr of 2217, being their max load, and even took it on a hunt (but didn't get in a shot) with that. When I eventually got to fire through a chrono I almost fell over, getting a piddling ave of 2675ft/sec. I reloaded to Nick Hearvy's tables and pushed up to 68gr of 2217, his max load, but still only got an ave of 2750ft sec. My mate recons he can run down the range with a butterfly net and catch it before it gets to the paper.

The spread on five shots is only plus or minus 10ft/sec, so consistancy is good, speed is my issue.

Where do I go from here? I understand that I should be hitting between 3050 and 3100 ft/sec thereabouts. I also understand that magnums need to be up there for best accuracy, which is why I'm concerned about the speeds I'm getting. COAL is 83mm neat, which is 1mm off the lands. I'm not seeing any signs of pressure, no claw marks, polished spots, stiff extraction, etc, but am getting a little soot on the necks.

yours
Warrick

Replies

11 Nov 2012
@ 04:27 am (GMT)

im2lazy

Re: Underperforming 7mm Rem Mag
Hi Warrick
I'm no reloading expert but my advice is to keep working up with caution. Chrono every load, as this will give you more data to work with and keep a keen eye on the brass signs you made mention of plus primer pockets. The sooty necks will probably go away with a warmer load.

I have used the 154 SST on fallow, goats, pigs and reds and if you can get it up to 3000 f/sec + you will be impressed. I have used ADI 2213sc and with 69.5gr gave 3080 f/sec. Now this load is way over book max, but I used this for 7-8 reloads with only neck sizing and no loose primer pockets (but did get a shiny mark on the head of some cases)

I now use the 162 SST but don't see any large pros or cons over the lighter pill (maybe a bit better penetration on red deer) but then now I'm shooting it out of a "weak as dish water" 21 inch barrel at 2970 f/sec :-)

Good luck

12 Nov 2012
@ 04:57 pm (GMT)

Nathan Foster

Re: Underperforming 7mm Rem Mag
Hi Warrick, There are other posts here discussing 2217 (H1000). Jim is currently working up loads for his 7mmRM (see high velocity 162gr A-Max loads).

I cannot recomend the following for reasons of litigation and safety: For my own part, I start at 71 grains 2217/H1000 when testing 162gr bullets and 71.5 grains when testing 154gr bullets. I work up loads from there. Im2lazy has given the most appropriate reply. His 2213sc (H4831sc) is another of my go to loads.

The sooty marks are from poor case obturation (case isn't expanding properly to seal the chamber). This means that the case is somewhat underloaded. You need to get in and give the chamber itself as good solvent scrub to remove any caked carbon from the neck area of the chamber, otherwise the build up will increase pressures. As suggested, with increased loads, the sooting will go away.

Keep reading the brass as you have described.

In one Howa/Vanguard I worked on recently, the bore would not produce any level of accuracy above 2800fps. At 2800fps, it was a quarter minute shooter, anything else grouped 1.5" or more. The Howa/Weatherby rifles of the last couple of years have suffered from bore problems/limitations (since the Japanese earthquakes 2011). If you find that your rifle is not accurate at high velocity, go back to your soft loads, choose a soft high BC like the A-Max and make peace with the final velocity. You will still have a very good long distance rifle if for example, 2800fps is as fast as the rifle can be pushed.
12 Nov 2012
@ 06:42 pm (GMT)

Warrick Edmonds

Re: Underperforming 7mm Rem Mag
Thanks Im2lazy and Nathan for the help, I understand what you're saying and fully appreciate your position on safety.

I've since shot some more loads in the vein of tip-toeing up on speed.

68 gr 2217 = 2735ft/sec
68.5 = 2780
69 = 2819
69.5 = 2855

So I still have a bit of a ways to go. With these loads I'm still not seeing any signs of pressure, so will gradually creep further in half grain lots. I can't comment on accuracy yet, I was too occupied with speed when doing the above. I'll make sure I combine both tests from now on.

I gave the barrel and chamber a good clean as suggested, used the fine scotchbrite technique. Once again, thanks for your help.

Warrick
05 Jan 2013
@ 11:23 pm (GMT)

jason brown

Re: Underperforming 7mm Rem Mag
iv just done much the same today.
im using 2217 and 154 sst as well and the fed 210 primer.10 thou jump my speeds are just a bit faster.

68gr=2885
68.5=2920
69gr=2927
69.5=2966
70gr=2972
70.5=2987
71gr=3027
71.5=3068
72gr=3069
72.5=3085
73gr=3115, to me this one sounded a little different
73.5=3104, this one had the plunger mark on the case head, and speed had dropped back a bit. so i stopped here. none of them had a hard bolt lift, or any other signs i could see. except cratered/slightly flatend primers, but my rifle always does that.

my rifle is doing 3090 with the factory superformance rounds, same projectile.
i did one shot of each just to check pressures, and speed. now im going to do the group testing.
these are my first hand loads ever, so i was just pleased to see them go off without any problems.
as usual, the disclaimer.... dont try this at home, these are all over book max!

and thanks for the guidance nathan!
06 Jan 2013
@ 03:04 am (GMT)

jason brown

Re: Underperforming 7mm Rem Mag
i was wondering, does anyone have ideas on if the speed readings mean anything, as in...
going up in .5gr you can see roughly a 30 fps difference.
then i get a 3068 and then a 3069.
is this an indication there might be a low es/node somewhere there, or more likely the chrony is not quite right. ?

im just trying to make up my mind where im going to start my groups.
thanks.
07 Jan 2013
@ 07:18 pm (GMT)

Nathan Foster

Re: Underperforming 7mm Rem Mag
What you are describing is a velocity plateau which is quite common in the 7mm Rem Mag. It can indicate a good place to find a low ES. Here are two examples of what can occur:

Sometimes when a velocity / pressure plateau occurs, if you keep going up a grain or two, nothing changes, then all of a sudden ES goes right out of the window with deviations of 100fps and extremely high spiked velocities, an indication that pressure is way too high. If this is the case, you may find that best accuracy is below the plateau because the plateau is too close to max.

In other instances, it is simply a hump and going up a grain or so eventually gets over the hump. In these instances, both accuracy and ES can be very good.

One of the larger challenges occurs when a rifle produces a low (excellent) ES with poor accuracy while its accuracy sweet spot produces a high (poor) ES. This can be very frustrating. In such cases, it can pay to experiment with seating depth and neck tension as a means to minimizing ES with accurate loads.
07 Jan 2013
@ 09:04 pm (GMT)

jason brown

Re: Underperforming 7mm Rem Mag
thanks for that in-sight nathan.
the way i shot the rounds was kind of a rough ladder test as it turned out.
i know they dont always mean much, but i feel it gave me a hint as to where to start my groups and check es and accuracy. my main goal at the time was to check velocity and pressures. i wanted to experience high pressure for myself at least once to experience it for future reloading.

anyway... assuming my shooting was good 68gr and 68.5gr (2885,2920) landed in the same spot. and also later on at 72gr (3069). which was the higher side of the plateau. so im guessing there is an accuracy node about there as well. i could of just worked around the lower more obvious charge weight, but i really wanted the rounds to be going a bit faster than 2920.

so i thought id do some groups of 71.8, 72, 72.2 for starters and see how it goes.

the final two rounds i shot at 73gr (3115) and 73.5gr (3104)
the 73gr sounding ab-normal when fired (no case pressure signs) and the 73.5gr (first case signs) actually going slower than the previous round even though it has more powder.
are the sound of one round, and drop in speed of the next increase in powder charged round, a common indication of being at high pressure?
its just signs (if they are) that i hadnt heard of.

thanks.

13 Jan 2013
@ 01:42 am (GMT)

Warrick Edmonds

Re: Underperforming 7mm Rem Mag
I've just come back from range testing a few more loads. The conditions were perfect for this kind of work, being consistant rain and thirty knot cross winds. Or should I say conditions were normal.

From a previous session I got;
68 gr 2217 = 2735ft/sec
68.5 = 2780
69 = 2819
69.5 = 2855

this session I added;
70.0 = 2887
70.5 = 2926
71 = 2945
71.5 = 3001
72 = 3000
72.5 = 3035

I also shot off a number of Federal factory rounds with the 150gr projectile. On the packet it told me to expect 3100 but actually delivered 2998. By the way, I weighed their powder charge at 68gr of whatever it is they use.

I have to confess to getting nervous at the higher charges. The rifle didn't seem 'happy'. While I got no obvious signs of pressure at 72gr I did get the fine bright ring on the base of the brass prob from the bolt face, same as Jason mentions. Does that have any meaning?

I notice that my rifle is a good half grain slower than Jasons. Anyway I'm not likely to push any higher, but will settle for something around 3000ft / sec and 71.5gr. The records for the three shots at 71.5gr came in as

3003
3002
3000

So, can't complain about spread, and it suggests to me its a good place to start poking around for some accuracy.

Warrick
13 Jan 2013
@ 03:55 pm (GMT)

Nathan Foster

Re: Underperforming 7mm Rem Mag
If you are worried about pressures Warrick and not fully confident at reading the case heads, email me a photo or three. If you have a camera with a macro setting, that would be ideal.
14 Jan 2013
@ 02:30 am (GMT)

jason brown

Re: Underperforming 7mm Rem Mag
thats an awesome extreme spread!

i wish i could find something like that. my last groups were inconclusive (crony packed a sad)
23 Jan 2013
@ 09:21 pm (GMT)

Warrick Edmonds

Re: Underperforming 7mm Rem Mag
So, I sucked it in and got on with the job. Last Sunday was a free day at the range so I took the loading kit with me and kept going up in steps until satisfied. Here's the results;

following on from where I left it in posts above,...

72.5 = 3050
73 = 3029
73.5 = 3043
74 = 3075
75 = 3121
76 = 3175
76.5 = 3198

At this last I was just starting to see a small flattening of the primer, otherwise the brass was clean of pressure signs. Note the large speed plateau between 72.5 and 74. I was beginning to doubt it would ever get over the hump. The spread on five shots at 76.5 was just 10ft/sec, that's all good. All the same, my grouping sucked, I was too pre-occupied with getting the speed sorted. Now I know I can get the speed I want, my next job is fine tuning for accuracy.

I did take the time to run a ballistics programme on my results and set up for PBR, assuming a 6 inch diam target. I then tried it out on the swinging targets at 200m and 300m. I was impressed with the impact at the other end. The 154gr projectile got from here to there mighty quick and thumped in with a satisfying sound. I'm pretty keen to get it dialed in for accuracy and take it into the field.

Warrick

riflebirdknives.com
23 Jan 2013
@ 10:27 pm (GMT)

Nathan Foster

Re: Underperforming 7mm Rem Mag
I've never taken a 7mmRM up that high before Warrick. Just goes to show what some rifles can take- even in very temperate climates.
03 Nov 2013
@ 12:52 am (GMT)

Gregory Perkins

Re: Underperforming 7mm Rem Mag
It sure would be nice ( and safe) if the specific powder model and
primer type used could also be specified along with the specific
bullet model and weight. I'd like to assume everyong in this
thread is using same powder and primers and bullets but it
is not good to "assume" anything.
 

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