When I first heard of these bullets earlier this spring I was immediately intrigued. I have had great success with Matrix 190gn VLD's in 7mm and was eager to give the .277 175gn bullets a try.
My platform is a wildcat based on the .376 Steyr, the boltface is similar to a .284 Win, but the case is longer, and my wildcat has minimal taper and an Ackley shoulder. Case capacity of the 7mm Stair is 77gn. Since I had invested alot of time in these cases I decided to build my .277 on the same platform, going from 7mm to 6.8mm involved a simple bushing change in my die.
Below is my analysis of the .277 Matrix VLD's, 175gn projectiles, fired in my 6.8mm Stair.
General Analysis...
Ballistic Coeficients...
I did this by shooting a total of 20 rounds, this was my accuracy load with N570 67.8gn, COL to Ogive 2.735.
Each of 10 rounds were randomly selected to get either 10 unpointed bullets and 10 of the aggressively pointed bullets (more on pointing later). Bullets and brass had been weight sorted. ALL charges were weighed initially on a Hornady dispenser and then verified and adjusted on a Acculab Vic 123, to the nearest 0.05gn, for this powder that means essentially plus or minus one particle.
I fired 5 of each group across a chrony at 10 yards and then again at 300 yards. I used the average of each to calculate BC with the Knights Armament program Bullet Flight for the IPOD.
Pointed Vel at 10 yards
3109 FPS
Range: 8.8
Stdev: 3.6
Un-Pointed Vel at 10 yards
3113 FPS
Range:33
Stdev: 14
Pointed Vel at 300 yards
2760 FPS
Range: 42
Stdev: 17
Un-Pointed Vel at 300 yards
2751 FPS
Range:35
Stdev: 15
BC Pointed
G1: 0.786
G7: 0.391
BC UnPointed
G1: 0.759
G7: 0.376
When I did this work with the 7mm 190gn bullets I underestimated the BC for G1 by 8.5% and G7 by 11.6% when compared with the later work of Brian Litz, assuming the same error these bullets COULD have a BC of G1 0.823, and G7 of 0.420.
Pointing:
These bullets do not like to be pointed, at least not by me !
I used a Whidden '0' die insert, and followed the same protocol that I had successfully used with Matrix 7mm 190gn bullets.
I fired groups pointed mildly and aggressively (Die dialed down 10 thou beyond the setting used for mild pointing) and compared these to untouched bullets.
The attached images show a five shot group of the aggressively pointed bullets, and an 11 shot group of the mildly pointed bullets (left over from the Ontario Provincials).
I had fewer of the unpointed bullets, The last image is representative of the unpointed groups, these averaged 0.8 to 1 inch of vertical. I shot several of the pointed bullets none of them approached the accuracy of the unpointed.
With Matrix 7mm VLD 190 gn bullets I was able to improve them with pointing and have never seen such a decrease in accuracy
Others may have more luck, but I am happy with the unpointed bullets and for the future I will not mess with them.
I have used these (mild pointing) at practices at 900 and 1000 yards, and shot the 300 and 500 yard matches at the Ontario Provincials, I plan to use the unpointed bullets for future matches.
My platform is a wildcat based on the .376 Steyr, the boltface is similar to a .284 Win, but the case is longer, and my wildcat has minimal taper and an Ackley shoulder. Case capacity of the 7mm Stair is 77gn. Since I had invested alot of time in these cases I decided to build my .277 on the same platform, going from 7mm to 6.8mm involved a simple bushing change in my die.
Below is my analysis of the .277 Matrix VLD's, 175gn projectiles, fired in my 6.8mm Stair.
General Analysis...
Ballistic Coeficients...
I did this by shooting a total of 20 rounds, this was my accuracy load with N570 67.8gn, COL to Ogive 2.735.
Each of 10 rounds were randomly selected to get either 10 unpointed bullets and 10 of the aggressively pointed bullets (more on pointing later). Bullets and brass had been weight sorted. ALL charges were weighed initially on a Hornady dispenser and then verified and adjusted on a Acculab Vic 123, to the nearest 0.05gn, for this powder that means essentially plus or minus one particle.
I fired 5 of each group across a chrony at 10 yards and then again at 300 yards. I used the average of each to calculate BC with the Knights Armament program Bullet Flight for the IPOD.
Pointed Vel at 10 yards
3109 FPS
Range: 8.8
Stdev: 3.6
Un-Pointed Vel at 10 yards
3113 FPS
Range:33
Stdev: 14
Pointed Vel at 300 yards
2760 FPS
Range: 42
Stdev: 17
Un-Pointed Vel at 300 yards
2751 FPS
Range:35
Stdev: 15
BC Pointed
G1: 0.786
G7: 0.391
BC UnPointed
G1: 0.759
G7: 0.376
When I did this work with the 7mm 190gn bullets I underestimated the BC for G1 by 8.5% and G7 by 11.6% when compared with the later work of Brian Litz, assuming the same error these bullets COULD have a BC of G1 0.823, and G7 of 0.420.
Pointing:
These bullets do not like to be pointed, at least not by me !
I used a Whidden '0' die insert, and followed the same protocol that I had successfully used with Matrix 7mm 190gn bullets.
I fired groups pointed mildly and aggressively (Die dialed down 10 thou beyond the setting used for mild pointing) and compared these to untouched bullets.
The attached images show a five shot group of the aggressively pointed bullets, and an 11 shot group of the mildly pointed bullets (left over from the Ontario Provincials).
I had fewer of the unpointed bullets, The last image is representative of the unpointed groups, these averaged 0.8 to 1 inch of vertical. I shot several of the pointed bullets none of them approached the accuracy of the unpointed.
With Matrix 7mm VLD 190 gn bullets I was able to improve them with pointing and have never seen such a decrease in accuracy
Others may have more luck, but I am happy with the unpointed bullets and for the future I will not mess with them.
I have used these (mild pointing) at practices at 900 and 1000 yards, and shot the 300 and 500 yard matches at the Ontario Provincials, I plan to use the unpointed bullets for future matches.
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