175 gr. SMK and 7mm Allen Magnum

Discussion in 'Long Range Hunting & Shooting' started by Fiftydriver, Sep 30, 2009.

  1. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    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

    [​IMG]

    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.
     
  2. Long Time Long Ranger

    Long Time Long Ranger Well-Known Member

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    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.
     

  3. ss7mm

    ss7mm Writers Guild

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    Thanks for the info Kirby. It's always nice to have some more data to file away. :)
     
  4. elkregulator

    elkregulator Well-Known Member

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    Speaking of WC872-
    Anyone know who has the WC872 in stock?
     
  5. esshup

    esshup Well-Known Member

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    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!! :D
     
  6. SkyScrapin

    SkyScrapin Active Member

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    appreciate the great write up!
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    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.
     
  8. Capt Academy

    Capt Academy Well-Known Member

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    Great write up on your rifle. Very interesting to read.
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Today I had to head out to the range and test a couple customers rifles so I decided to do a quick load development with the 175 gr SMK in my personal 7mm AM which is based on a trued Rem 700. Most that have been on LRH have seen this rifle many times as its taken a fair amount of big game over the past few years. The barrel is quite long in the tooth and it simply will not shoot the 200 gr ULDs any more, infact it has since before last hunting season.

    That is when I switched to the 160 gr Accubond which shot pretty well in the rifle, not steller but plenty good enough for big game hunting out to 800 yards or so. It however is not a real wind beater. I loaded the Accubond to 3350 fps which is relatively mild but still over what the 7mm RUM should be loaded to with this bullet in a 26" barrel length. I have loaded them up to 3500 fps but do not like to push the Rem 700 that hard.

    Anyway, after playing with the 175 gr SMK and knowing its jacket is much heavier then the 200 gr ULD or 180 gr Berger which are both based on the J-4 jacket. I decided I would see what it would do in my little green rifle.

    I also wanted to work up with Retumbo just to see how this powder performed with this bullet weight.

    Remember that I was driving this bullet to nearly 3500 fps in a 28" barrel but this was with a Nesika Bay model M receiver which is extremely strong and rigid. I had no plans on pushing my Rem 700 based 7mm AM this hard.

    Anyway, long story short, I worked up to 94.0 gr Retumbo under the 175 gr SMK, Fed-215 and seated to 3.570" OAL which was 10 thou off the lands. This load averaged right at 3320 fps. Being only 30 fps off my 160 gr Accubond load, I was plenty happy with that and there was no real sign of excessive pressure. Loaded some test ammo up and headed out to the range.

    The wind was a serious problem, 20-25 mph crosswinds. The customers rifles shot very well inspite of the wind so I was able to get them proven and packed up quickly and then I turned to my 7mm AM to play a bit. The listed BC of the 175 gr SMK is 0.608". In talking with BJ Bailey a couple days ago, he said that it may be closer to 0.677 from some test results he had seen in a reference.

    Since my rifle was set up for the 160 gr Accubond, I had to do some quick adjustment. Found a target rock at 650 yards and used the reference line for the accubond load just to see where the bullet would land. It landed about 1 mil high (I am using a TMR reticle 3.5-10x 40mm FFP Leupold on this rifle. Making an adjustment I realized that the 1.5 mil line was pretty much dead on the money to where the 175 gr SMK had landed at 650 yards.

    Then I switched to exbal and worked the numbers over and came up with a quick drop chart off 3320 fps, 0.680 BC and the 1.5 mil line dead on at 650 yards

    First test, 520 yards, ran the numbers and let one fly. Remember this is with a 20-25 mph wind ranging from my 3:00 to 5:00 depending on different ranges I was shooting at. For the wind, I had the exbal to list drop in mils but windage in moas and I simply dialed in the windage.

    First shot at 520 yards landed about 4" low on the left edge of the rock. Made a slight scope adjustment and also made a slight adjustment on exbal. Took a second shot and this one broke the right edge of the 5" diameter target rock.

    Found another target rock, this one at 835 yards. Ran the numbers and found the hold and dialed in the wind. First shot landed just on the top edge of the rock. Second shot was about the same impact but a few inches to the left, wind....

    Tweaked the drop chart slightly. Took two more shots and these two landed on either side of the rock, which was roughly 6" wide.

    Now I moved out to a rock that was 995 yards. Ran the numbers, found the hold dialed for the wind which was around 9 moa. This target rock was the smallest of the three shot at so far, 4" diameter at the largest. Had it not been bright white, I would likely not been able to see it to shoot at it.

    First shot broke the right edge of the rock and kicked it to the left about a foot. Shot number two landed just off the left edge, well within 1/2 moa of point of aim. Again, only variations I had seen were windage to be honest, very happy.

    Just to fully check drop, I found another target rock at 530 yards. 5" rock. ran numbers, dialed in the wind and took the proper hold, bottom edge of the rock crumbled to the impact.

    Then moved to 300 yards which should be a chip shot and again, the bottom edge of the target rock gave way to the 175 gr SMK.

    Looking over the notes of the range session it was very clear that 0.680 BC was much closer then 0.608 at least as far as developing an accurate drop chart and predicting the wind. At ranges from 0 to 500 yards it seemed the impacts were running aroun 2" low of point of aim on the drop chart. Well within my requirements as I seldom will be able to shoot that well in the field to see it. Some minor drop chart tweaking will correct for this.

    From 500 to 1000, the BC seems to be dead on the money for the most part from where the bullets were impacting compared to point of aim.

    I will not say I was suprised by the accuracy of the exbal predictions on the wind because I have come to expect this when you can get an accurate reading on a strong directional wind.

    Again, happy with 175 gr SMK and ballistically, it should be far superior to the 160 gr Accubond load. Terminally, I am sure it will not be quite as good as the Accubond but on deer size game it should still perform very well. Hopefully we will see here soon.

    I do have the parts for a Nesika Bay based Xtreme Heavy Sporter with a #8 Lilja 1-9, 4 groove, 30" finish length so I may put it together some weekend and see just what this bullet will handle!!!! The more I shoot this bullet the more I like it. More testing to come.
     
  10. SkyScrapin

    SkyScrapin Active Member

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    The more you keeping talking about the 7mm AM, the more I have started to like it. Maybe get us some range picks? :D I wanna see those wounded rocks.
     
  11. Festus

    Festus Well-Known Member

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    Kirby,

    Do you have to drive further and further from the house to find rocks? I'm thinking there's prolly a two mile radius of nothing but gravel. LOL

    Thanks for the report.

    Festus
     
  12. joe30007

    joe30007 Well-Known Member

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    Im trying to have a 7mm allen built but kirby has not responded to my emails. Does anyone have a fired case from one I can have or buy? Also where are the dies coming from? If you use a 338 lapua with a bushing for the 7mm how do you bump the shoulders back on the fireformed brass? This is my first custom and first wildcat. Building it on a bat model m 1.55 with a kreaiger 5r 1-8.5 twist 36" barrel. I want a large gun. Thanks for any help.
     
  13. esshup

    esshup Well-Known Member

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    I think Kirby is on a hunting trip. He's pretty good about responding to e-mails. He furnishes the dies with the gun.
     
  14. joe30007

    joe30007 Well-Known Member

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    If I build my own rifle will he sell the dies? Can I but a reamer does anyone have a formed brass I can buy? just 1