Well, I finally got my rifle built that I hope will be the one I use for my 1K hunt with Shawn Carlock in roughly four weeks!!! Nothing like cutting it close. This seems to be a trend over the past couple years, get my rifles down the week before general big game season starts!!! Maybe I need to stop selling my personal rifles!!! [img]/ubbthreads/images/graemlins/grin.gif[/img]
Anyway, Originally, the rifle was going to be built using a Lawton heavy fluted 1-9 twist barrel and chambered in my 277 AM but I received a special Rock Creek barrel in just in time to test so I decided to hold the Lawton barrel and try this new Rock barrel with a specially designed, thin land 5R rifling design.
The standard 5R barrel I tested has normal wide lands and as such was very hard on the 200 gr ULD RBBT in 7mm AM. In fact most bullets never made it to the target at all. Credit must be given to the boys at Rock Creek barrels for taking the time and effort to help out and design a barrel specifically for my rounds and the Wildcat bullets. I told them what I thought would work and they produced exactly what I wanted.
In the evenings and over the last weekend I was able to piece all the parts together and I was able to get the barrel broke in the last couple evenings and form 50 rounds of brass. Here is a look at the rifle:
The stock is a Manner Tactical Thumbhole which I really like. Only thing I would change on it would be a slightly wider forend but on a bipod this is of no concern. It is plenty wide for a solid footing on a bipod.
The thumbhole grip is extremely comfortable as is the nearly vertical position of the grip. There is a very nice palm swell and thumb rest on this grip. It is about 1/4" short for my trigger finger length but it feels so comfortable I hardly noticed that while shooting it on its first range test.
The barrel as mentioned is a Rock Creek 7mm, 1-8.7 twist 5R with a special thinned land. They are roughly 18 thou if I remember correctly. It is their heavy varmint straight taper design, 30" finish length and finished off with a Defensive Edge muzzle 1.000" 4 port muzzle brake
. Recoil of this rifle is so little its not worth mentioning. I would say its similiar to a 22-250 in a sporter weight rifle.
The heard of the rifle is one of Barney Lawtons M7500 BR receivers. It has a left hand loading port and right hand ejection port. It comes with a 20 moa steel rail and spiral fluted bolt.
The optical system is a Leupold Mk4 4.5-14x 50mm with the TMR reticle in Nightforce Ultralight 0.885" rings. Scopelevel and Harris BR bipod finish up the rifle.
I did some initial velocity testing at the shop and found that the new Rock barrel design needed significantly more powder to match that of the Lilja barrel but also allowed more top end velocity potential. At 105.0 gr US869 I was averaging 3265 fps with really no pressure signs at all. In my Lilja barrels I was stopping at 102.0 gr with 3175 fps and similiar pressure sign on the case head reading the extractor marks which are extremely faint but just visable.
I no full well I could run this barrel well over 3300 fps with no pressure problems but as time is short before big game season, I will put the throttle down harder after the season for some more vigerous testing.
I loaded up some test loads and headed up to my range to see what she would do at long range. First goal, see every bullet hit where it should with no bullet failures.
The conditions were very poor for long range testing. A constant 15 mph wind with gusts well over 20 mph would be playine heck with my windage holds so I simply was looking to set the rifle up and check for elevation matching actual bullet flight with the predicted drop chart I made up before leaving.
I set up and found a nice small white rock at 420 yards. This was to be my sight in rock. I want this rifle zeroed at 600 yards and that will allow me to use the TMR reticle out to 1350 yards without making any adjustments.
I bore sighted the rifle on the rock and took a shot at it. Landed about 2 feet high and perfectly centered windage wise. For this shot the wind was perfectly from my 6:00.
Made a scope adjustment and the second shot landed about 4" high. Made one more slight adjustment and the third shot broke the 3" diameter rock, now onto longer ranges!!
I let the barrel cool as I found a long range target rock to hammer. With the wind and the 45 degree temps this did not take long to cool the barrel down at all!!
I found a nice target rock at a measured 1330 yards. The wind was coming from about 4:00 on this shot but I was not correcting for windage. The rock was on a bare dirt hill side that was very wet from two inches of snow that had melted the day before.
I held the bottom hash of the reticle on the rock and let the big 200 gr pill fly.
The first shot was about 5 feet to the left and about a foot low. THe second shot landed within a few inches of the first but still low so I figured my rough zero had a bit of error in it.
I decided to find a closer target and make some fine adjustments to the scope to see if I could get a bit closer on vertical adjustment.
The next target was 1070 yards which called for a -3.1 mil hold. The rock was about the size of a volley ball. I dialed up one moa and took a shot. The bullet landed a couple feet to the left and about 5"high. I took one click out of the adjustment and shot two more rounds. They looked to land in the same crater in the wet mud. The splatter was probably 4-5" across so they could have been several inches apart but very close and perfectly level with the target rock as far as elevation was concerned.
I let the barrel cool again and then gave the rifle a wide range variation test. Started at a rock 620 yards out. The called for hold was -0.1 mil so I put the main cross hair on the 10" rock, gave her a 1/4 mil into the wind and busted the it on the first shot.
Next I found a close range 310 yard rock. The hold, +1.5 mils. Found the hold and at the break of the trigger the small white sand stone rock simply vanished into fine sand.
Next was 1106 yards. The called hold was -3.3 mils and 1.2 mils for windage. First shot landed 4" to the left of center of the rock and about that high. Easily in the vitals of a big whitetail buck. Second shot was 2" high and dead center of the 5-6" diameter rock.
Those were my last two shots. I had not even stopped to think about the bullets surviving the launch or not, they just did and after the fact, they did so extremely well. Now all I have to do is wait for a calm day and take her back out and fine tune any windage zero that may be needed and recheck the drop to make sure it is as close as it appears.
From the first range test it appears that all the componants are working extremely well together and 1K hits should really not be a problem at all. In fact they seemed pretty darn easy with this rifle when shooting at small rocks. Now on a live targets its always more of a challange but I am feeling very good about the initial test of the barrel, receiver and stock. All are top notch and I will do alot more business with all three down the road!!!
Much more testing will come as I will be really putting this barrel through its paces after the season just to see what she will take and what she will produce. I want to see if it will tear the 200 gr ULD RBBTs if I run them really hard. Not to dangerous levels but I hope to get well above 3300 fps and get a pretty high volume of rounds down the tube to test its endurance life.
SO far so good. More to come!!