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175 gr. SMK and 7mm Allen Magnum

 
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  #1  
Old 09-30-2009, 11:08 AM
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175 gr. SMK and 7mm Allen Magnum

Finished up a rifle this week and decided to test the rifle with the relatively new to me 175 gr SMK. I had tested this bullet in one of my personal 7mm Allen Magnums but just threw a load together at around 3300 fps out of a 30" barrel just to see how they would shoot and they did shoot very well but at the time I was using the 200 gr ULD RBBT exclusively so did not spend alot of time on it.

Since then, over the past couple years, the 200 gr ULD was hard to come by so I started testing other bullets ranging from the 160 gr Accubond up to the 180 gr Berger. I like them both but the 160 gr AB lacks some BC for true long range work and the Berger does not particularly like to be drive much over 3250 fps which is pretty mild load in the 7mm AM.

Anyway, I decided I would run the 175 gr SMK through its paces to try to find the limits of this bullet if possible with the 7mm AM.

The customers rifle had the following componants:

Nesika Model M Hunter
Lilja SS, fluted 1-9, 4 groove, 28" barrel, #6 contour
APS Slim Painkiller muzzle brake
Jewell trigger
Manner MCS-GAT stock
HS Precision DM system
Nesika 20 moa SS rail base
NF Ultralight rings
NF NXS 5.5-22x50mm
Rail mounted ACI
Scope mounted scope level



Anyway, yesterday morning was pretty windy in the morning so I just did my regular, at the shop load development over the chrono. Started at 103.0 gr WC872 with the Fed-215 primer seated to 3.650" OAL which was 10 thou off the lands and bullet seated to the base of the neck.

Here are the velocity results:

103.0............................................. 3196 fps
104.0............................................. 3201 fps
105.0............................................. 3222 fps
106.0............................................. 3317 fps
107.0............................................. 3312 fps ?
108.0............................................. 3363 fps
109.0............................................. 3402 fps
110.0............................................. 3470 fps
111.0............................................. 3481 fps 100% load density

Velocity was pretty inconsistant from 103 up to 107 grs which is not terribly unusual with a chambering this extreme, especially with a bullet thats a bit lighter then needed and powder that may be a bit slower burning then needed for the bullet weight. My current lot of US869 would likely have produced more consistant bullet velocity increase per grain of powder but you would also likely be able to pressure out sooner so I just stuck with my old standby WC872.

As typical in the 7mm AM, as I neared the top end of load density, velocity gains really became much more consistant and predictable and remained that way up to 110.0 gr.

I figured that at 111.0 gr, I had topped the hill on the pressure curve with this bullet weight and barrel length as I only get an 11 fps increase over the 110 gr load so I just stepped back to 110 gr as my max working load with this combo.

Certainly not because of pressure. All primer pockets were virgin tight. I am going to say something that many may hammer me for but its a fact. When I seat the primer on the cornmeal fireforming load in the virgin brass and then compare that to the seating pressure needed to seat a primer in a formed case, the primer pockets always need more primer seating pressure on the formed cases and they again after firing with a full pressure load. Not sure why, just the way it is.

As such, all of these loads have primer pockets that required more pressure to seat a primer after each of these high pressure firings then before they were fired....... Call me crazy but its always been like that with the Lapua case.

The only hint of an ejector ring on the case head was on the 110 and 111 gr load and it was so faint you really had to look for it which tells me none of these loads are approaching the limits of this case which is good, I never try to push the limits of the Lapua case, never a smart thing to do.

I loaded up 15 rounds of test ammo and was going to wait until later in the week to test the rifle at long range but later in the afternoon the wind died down and I decided to get out to the range before a coming storm landed on us.

I decided to jump at the chance and packed up the rifle and drove up to my range. Set up at 1000 yards even. Took three shots and I was very close to point of aim. I was shooting at a rock that was a bit smaller then 1/2 moa and laying on a clean dirt bank so I could see bullet impact. A couple days ago we had gotten a light rain so when the bullets impacted, there was a light dust signature but a very visable dark hole from the wet under soil.

First shot after getting the scope dialed in close landed at 6 o'clock but around 4" below the bottom line of the rock. No problem, I was looking for group size here, did not really care if I hit the rock, In fact hitting the dirt would give me a more accurate idea of how the rifle would shoot. Second shot, the wind picked up a bit so I held on the right edge of the rock. That shot landed literally in the same crater as the first. Third shot, the wind rose a bit more so I added another 1/2 moa to the hold and again, the third shot dropped into the same crater. On the fourth shot, the wind caught me. At my location i called that the wind dropped a bit but that was not really the case down range so shot number 4 landed about 4" to the left of the first three. To redeam myself, I cranked in another round, added 1/2 moa windage and shot number five landed with the first three.

I got on the spotter and studied the impact sight and would say the first three and the fifth shot easily landed within 3" of each other, the fourth did open things up to around 3/4 moa but even with the error in my wind judgement, it was a real confidence booster in the rifle. Figuring this was before the barrel break in, I was extremely happy with the results.

That darn PK muzzle brake always amazes me, especially in a lightweight to moderate weight rifle. Recoil was about what you would expect out of a 22-250. Only one time did I loose sight of the target rock after the trigger was tripped and that was because of a slip of my offhand and the rifle rolled just slightly to the right but even then I was able to recover with more then enough time to see the bullet impact.

All in all, I was very happy with the results of the 175 gr SMK at long range out of the 7mm Allen Magnum. For another option for a big 7mm, its a great choice. Running the numbers, with the 175 gr loaded to 3470 fps and comparing it to the 180 gr Berger loaded to 3250 fps, both zeroed at 250 yards, the 175 will drop 15.25 moa at 1000 yards. THe Berger will drop 16.25 moa. Wind drift with a 10 mph crosswind is exactly the same at 4 moa at 1000 yards with both.

Compared to the big 200 gr Wildcat loaded to 3200 fps, the SMK is a bit flatter shooting but the big wildcat will do better in the wind with around 1.25 moa less drift but at 1000 yards or under, its a very viable choice for big game hunting.

Personally, I do not feel any 7mm is an ideal choice for elk hunting past 1000 yards. My recommendation is that if you intend to reach past 1000 yards on elk, go to a 338. Just my recommendation and not written in stone but it has worked for me and many others.

For deer, I see the limits of the big 7mm only dependant on bullet selection and where that bullets will stop performing terminally.

Anyway, for anyone that wants another good bullet choice, the 175 gr SMK is a decent one to look at especially for shooting out to 1000 yards.
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #2  
Old 09-30-2009, 12:44 PM
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Location: Wyoming
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Re: 175 gr. SMK and 7mm Allen Magnum

I took elk over a 1000 yards with the 175 sierra game king back in the 70's when we didn't have the bullet selection we have now. I was shooting a 7mm-300 weatherby and this bullet did very well with accuracy and performance. I have never shot the 175 MK and interested how it would perform on large big game animals. Thanks for the info from your testing.
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  #3  
Old 09-30-2009, 01:27 PM
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Re: 175 gr. SMK and 7mm Allen Magnum

Thanks for the info Kirby. It's always nice to have some more data to file away.
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Old 09-30-2009, 02:14 PM
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Join Date: Jul 2007
Location: Parker, CO
Posts: 312
Re: 175 gr. SMK and 7mm Allen Magnum

Speaking of WC872-
Anyone know who has the WC872 in stock?
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  #5  
Old 09-30-2009, 07:22 PM
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Join Date: Mar 2008
Location: N. Central Indiana
Posts: 550
Re: 175 gr. SMK and 7mm Allen Magnum

Kirby:

In the 7mm AM, how would the WC860 compare?

The rifle looks good, now to just get some color on the stock. See you Friday!!
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  #6  
Old 10-01-2009, 12:49 PM
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Re: 175 gr. SMK and 7mm Allen Magnum

appreciate the great write up!
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  #7  
Old 10-04-2009, 10:13 PM
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Re: 175 gr. SMK and 7mm Allen Magnum

Starting loads with WC872 should be perfectly safe using WC860 with the same starting loads. They may end up with different powder charges at the top end but starting loads for each should be plenty safe.

Both can vary alot from lot to lot. Some lots of 872 will be lower then 860, some lots of 860 will be slower then some lots of 872. Start low, shoot over a chrono and watch for pressure signs. same old game.
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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