I sent some of these to Kirby Allen since I didn't have a 30 cal rifle to try in myself. Here's his detailed report:
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Got the load development and testing done with the McGuire Ballistics 30 cal 178 gr. My initial thoughts were that i assumed they would have a personality similar to the Barnes triple shock bullets. As such, expected them to be consistent and likely shoot well. I was a bit suspicious of the advertised 0.600 g1 BC but thought the small meplat may boost BC a bit.
The 178 gr is about as light as i would recommend for use in my 300 Allen Xpress. Bullet weight just helps with consistent powder ignition and consistent powder burn resulting in consistent muzzle velocities.
I tested this bullet with Retumbo powder and a fed-215 primer. Started at 95.0 gr and worked up to 106.0 gr. Here are the results of load development testing using a 3.820” oal which is roughly 0.010” off the lands. Test rifle, Raptor 300 AX w/ gen 1 Razor 5-20x 50mm, mil reticle, 32” Lilja barrel, 10tw, 6 groove. 65* F, 26.7 bar pressure @ 3400 ft elevation, 30% humidity
95.0 gr……….3357 fps
96.0 gr……….3401 fps
97.0 gr……….3419 fps
98.0 gr………3445 fps
99.0 gr………3465 fps
100.0 gr…….3521 fps
101.0 gr…….3544 fps
102.0 gr……3560 fps
103.0 gr……3591 fps
104.0 gr……3623 fps *** consider this max load with this combo. ***
105.0 gr……3652 fps noticeable ejector ring, no primer pocket loosening
106.0 gr……3674 fps MORE noticeable ejector ring, primer pocket loosening
From 95.0 gr to 99.0 gr velocity gains were somewhat inconsistent. This is not unusual or unexpected with this size of a cartridge. This happens until pressures start to approach the 60,000 psi level in large capacity magnum chamberings using slow burning powder.
At 100.0 gr and up, velocity gains per grain of powder became much more consistent at roughly 20 to 25 fps per grain of powder increase. Producing very consistent, predictable velocity gains which is as expected similar to what one would see using a barnes TSX or LRX bullet. These did seem a bit faster then the barnes bullets on average for bullet weight. This is likely due to the sub caliber bullet diameter ahead of the first seal band on the bullet body.
103.0 gr proved to be a comfortable load pressure wise and also produced a quality extreme spread at 23 fps for five shot string. Know this is a relatively short string but with limited bullets, i would see more data shooting at long range as far as velocity consistency was concerned.
Loaded 25 rounds up with the 103.0 gr load @ 3591 fps. Again, remember the 32” barrel length!! Likely would expect 20-25 fps drop per inch shorter then 32” down to 28” length, then likely 25-30 fps drop per inch from 28 to 24” in barrel length estimated.
This morning on the range, to test, again i used my 300 AX Raptor which is set up for my 215 gr berger @ 3350 fps load. Did not want to mess with rezeroing the rifle after these tests so i shot at an initial zero target at 550 yards. Once i was zeroed at this range i recorded the vertical turret adjustment setting which was 0.8 mil.
Ran the numbers on my ballistic program and produced an initial drop chart out to 1500 yards. I would then use this to test and compare actual BC to advertised BC.
First at 550 yards, it was easy to keep three shot groups inside 4” ctc. Most were 3” or less ctc. What variation there was in group size seemed to be vertical in nature but not bad at all. Shot very well. There was a decent amount of mirage which without that would have likely easily broke 1/2 moa at 550.
Accuracy test went as follows:
- Zero rifle at 550 yards.
- Let rifle cool
- fire two, three shot groups at 550 yards to confirm zero and visually check accuracy
- let barrel fully cool
- dial up and test at 860 yards, fire one three shot group, record point of impact to test drop chart(BC) as well as monitor consistency
- let barrel fully cool
- move out to 1010 yards, record point of impact for BC, observe consistency
- let rifle cool, return to original 550 yard zero.
- take two shots each at 550, 850 and 1010 yards as quickly as possible and observe any change in point of impact and group size. This tells us how the bullets will perform as a barrel heats up.
Test results:
- Again at 550 yards the 178 gr averaged just slightly over 1/2 moa in group size
- for 850 yards, dial up was 1.6 mil. Point of impact was pretty much dead on and group size maintained 1/2 moa class groups.
- at 1010 yards, dial up was listed at 2.7 moa. Actual impact was probably closer to 2.5-2.6 mil but close. Seems BC dropped off slightly from 850 to 1010 yards but its so close more testing would be needed to know that or if there was a slight down draft or up draft causing this slight variation. Close though. Group size was surprisingly good as well. Very happy with that.
Returned to 550, shot two rounds, 850, shot two rounds and then finished again at two rounds at 1010 yards. All were within 1/4 moa of point of aim at all ranges. No sign of consistency drop off as barrel warmed.
Final thoughts on the 178 gr. Impressed with them. Easy to load, consistent, predictable pressure build. No dramatic pressure spikes at top end. Good consistency, advertised BC actually seemed pretty close, this did surprise me a bit. In this rifle, easily a 1k yard class projo.
Only question would be terminal performance on game but ballistically, very good. At least as good as barnes LRX with a bit better BC but very similar loading personality.
