7.62x51 NATO (.308 WCF) in the Springfield M1A
This was the first try with cast boolits in my brand-new M1A, which has had a tad less than 500 jacketed rounds through the tube. It wears the issue iron sights.
For the first 'go', I took a leaf from BobS' Garand book, and went with olde H4831, charge weight 35.0 grains with both designs fired today. This load was the subject of much thought before I chose the charge weight, because it's basically uncharted ground. This is why I'm pleased to be able to post about it, so others don't have to do the same "interpolation" schtick.
The bullet designs were Lyman's 311672 and 311299. 672 is a bore-riding 167-grain job much like a SAECO RG-4 in profile, to my eye at least. 311299 is a reduced-diameter version of 314299, a famous bullet intended for the .303 British and other "fat .30s". My 311299s weigh 210 grains, cast hot and fast, and water-dropped in straight WW alloy, as were the 672s. Lube was the Felix stuff, of course. All bullets were sized at .311". Primers were CCI #34 "military" type. All rounds were fired with a timed one minute interval between shots, with ambient temperature at 59 degrees and NO wind. The barrel never got more than comfortably warm...easy to touch, in other words. Cases are unfired (new) pull-down Lake City 1988.
For the 311672s, I loaded two ten-round batches, one batch with a TINY dacron tuft (because there's not much room in a 7.62 NATO case above 35 grains of bulky powder) and the other batch without dacron.
I fired five rounds of the NO-dacron rounds first. The initial two rounds went through the same hole from 50 yards, PRECISELY on the point of aim/zero for 168 Matchkings at 2600 fps! "OOOooooh", sez I. The next three rounds landed progressively further down the target, and ended in a total group of about 3.5 inches.
Average: 1414fps; extreme spread: 102 fps; standard deviation: 47 fps
Hmmm. So, I switched to the 311672 WITH dacron, and this time the first THREE rounds cut into a single hole on point of aim, followed by one hole an inch out at 4:00 and the fifth an inch out at 10:00, for just over a two-inch group. Now, check out the readings WITH dacron, after the group being barely HALF of the no-dacron group:
Average: 1524 fps; extreme spread: 60 fps; SD: 22 fps
I admit to being surprised here. Over 100 fps higher speed, and about HALF the ES and SD, all for a truly MINISCULE bit of dacron!?!?
I refired both loads on the original target for each, and the groups did not enlarge over the initial five rounds. The chronograph readings also stayed very close to the original results.
Shifting to the 311299 load, the group formed about 1.5" above where the 672s were landing on their targets. 299s did not demonstrate the movement of successive impacts, and the entire ten rounds ended up making a 1.5" group These rounds had NO dacron.
311299, average: 1546 fps; ES: 117 fps; SD: 36.
Notice that with this same charge and a bullet 43 grains heavier than 311672, the velocity was just about the same as the 311672 with dacron..
Pressure with all loads was very mild. The cases were FILTHY, indicating marginal obturation (based on observations with the service-level Matchking loads). The primers are also VERY rounded compared to those same jacketed loads. Ejection was a great deal softer than with the jacketed loads, especially with 311672. The 299s were much snappier than the 672s, but still nowhere near the functioning speed with Matchkings.
It's my conclusion that these carefully-figured loads are operating on very safe ground, pressure-wise, and I can safely work them up without worry.
Here's one of the neat parts: even with some rounds dropping down into the high 1300s for speed, the rifle functioned PERFECTLY, even to the point of locking open on the empty magazine! This is awesome, to me.
On inspecting the rifle afterwards, (only 30 rounds fired, of course) I found no evidence of leading or excessive fouling anywhere. Since the flash suppressor prevents looking sideways at the surface of the bore at the muzzle, I contented myself with a hard look down the barrel and saw no visible leading. The inside of the suppressor can sometimes tell us a tale, but in this case I found it totally clean, without any of the gray wash I've seen in similar places on other rifles.
Am I happy? You bet! I've been looking forward to this day for months, and it went very well indeed. This is one IMPRESSIVE rifle. By the time NCBS 2006 rolls around, I'll be sure to have plenty of good, tested loads for y'all to shoot.
Going, and going, and going, and.....
Went to the gravel pit today for more work with the M1A.
Included were loads using 311413 (170 spitzer) 311467 (Loverin 180) 311672 (167 "semi-spitzer") and SAECO #305 (180 flat-tipped "spitzer"). Powders included H4831 Short Cut and H 335.
Although H4831 gave me that wonderful group referred to earlier, I'm now ruling it out as a long-term powder for the cast-bullet role in this cartridge, at least until I decide to try for much higher speeds-and-pressures to get the stuff burning better. This includes both regular and Short Cut 4831.
After observing over 400 rounds fired with H4831 at NCBS, and after firing a considerable number of rounds using it today, I see that there's just too much unburned powder left in the action and chamber (not in the barrel). This leftover powder has caused a number of malfunctions, so it is not a viable candidate. Note that the #34 primer I'm using is generally considered as being a Magnum-intensity sparkplug, too.
H335 is a much more satisfactory powder, so far. It's burning quite cleanly at rather low speeds, and accuracy is good enough to warrant a lot more research.
I have my Logbooks from both the home bench and Der Schuetzenwagen here at work with me, but unfortunately failed to either enter the target results in the books, or bring the targets with me. I'll try to recall the high points as I list the loads, anyway.
As usual, all the boolits are straight wheelweight alloy, cast fast and hot, water-dropped, sized .311" and lubed with Felix lube. Gator checks on the SAECOs today! NO case fillers were used.
311413, 26.0 H335: 1752 average, 44 extreme spread, 14 std deviation,
1.5"/10 rds/50 yards
same boolit, 28.0 H335: 1857 av, 82 es, 21 sd group about 2"/10/50
same, 30.0 H335: 1974 av, 66 es, 19 sd
same, 35.0 H4831SC: 1667 av, 76 es, 27 sd.
same, 37.0 H4831SC: 1812 av, 126 es, 38 sd
311467: 30.0 H335: 1970 av, 80 es, 22 sd
same, 35.0 H4831SC: 1675 av, 131 es, 41 sd
same,37.0 H4831SC: 1817 av, 81 es, 22 sd
311672, 35.0 H4831SC: 1528 av, 57 es, 20 sd
same, 37.0 H4831SC: 1649 av, 98 es, 30 sd
SAECO #305, 26.0 H335: 1735 av, 60 es, 19 sd ....1.2"/10 rds/50
same, 28.0 H335: 1830 av, 77 es, 20 sd
same, 30.0 H335: 1940 av, 53 es, 16 sd........1.1"/10 rds/50
same, 36.0 H4831SC: 1769 av, 49 es, 14 sd
Also fired 38.0 H4831SC with SAECO #305 but chrono battery went flat and I got no valid readings for the string.
All the above readings are based on ten rounds per load. All rounds were magazine-loaded for firing, ten rounds per magazine. Pressures are quite low in all cast-bullet loads tried in the M1A to date. The H335 loads function much more "snappily" than the H4831, as we might expect. The fastest loads today were starting to actually feel a bit like a service load should....
It was cool enough today (mid-40s) that the barrel never got beyond mildly warm, and I was able to fire about every 15-30 seconds without heating things up at all. A curious phenomenon showed itself in three of the groups with 311413. Even though the first five or six rounds scattered with gay abandon across two or three inches of paper, the last four or five grouped VERY TIGHTLY in just about the middle of the previous impacts, and by that, I mean one small ragged hole for four or five rounds! I certainly didn't change anything in the shooting technique, and it did happen three times, not just once. Hmmmm...?
I'll say it again! The more I shoot this rifle, the better I like it.
It's the Bunny Again...! (Energizer Bunny, that is...)
"HELL-oooo, Boys, I'm BAAAAaaack!!!!" (just before the F-15(?) crashes in a vertical climb into the alien ship's control center, "Independence Day")
Yep, I'm back with more results obtained yesterday with the M1A. I took about 18 loads to the range, ten rounds per recipe, and a few were so bad that some of the rounds are awaiting dis-assembly on the bench. It'd be a waste of the components to fire them!
I was bumping the velocity upwards on purpose, and it seems that at a certain point the boolits just gave up, as may be expected. However, there were some encouraging results, as well. Since abandoning H4831 for the reasons already stated, I moved down (up?) the burning-rate ladder to some faster powders, namely, commercial H4895, IMR 4320, and IMR 3031. All these powders function the rifle with authority in all loads tested yesterday, and in all cases as well, the brass was FAR cleaner than with 4831, indicating a much-better sealing of the chamber with the higher pressures obtained with faster powders.
I made one of my usual "calculated guesstimates" with the 4320 loads, and sure enough, the starting level was very safe and comfy. The next increments were a leetle hotter, and in the next go-round, I'll be loading DOWN from my initial level with 311467 (Loverin 180).
So:
All boolits were sized .311", water-dropped WW, Felix lube, all LC88 brass, CCI #34 primers.
SAECO #305, 167 grains, 28.0 H4895 NO FILL: 1865 fps average, 72 extreme spread, 24 std deviation, 1.4"/10 rds/50 yards.
same, WITH DACRON, 28.0 H4895: 1986 av, 71 es, 20 sd, 1.6"/10/50...dacron didn't do much except raise the speed a tad.
same, 30.0 H4895: 2038 av, 76 es, 26 sd, FOUR INCHES/10/50
same, 32.0 H4895: 2186 av, 59 es, 17 sd, 2.5"/10/50
311467, 180 Loverin, 28.0 H4895: 1891 av, 78 es, 21 sd, 1.5"/8/50 (two rounds called out)
same, 30.0 H4895: 2024 av, 80 es, 28 sd, 1.5"/10/50
same, 32.0 H4895: 2181 av, 102 es, 34 sd....this is where 467 quit on me...FIVE inches for FIVE rounds at 50! Brought the other five home with me.
same, 36.0 IMR 4320: 2275 av, 88 es, 27 sd: 4"/10/50
311291, 170 RN, 36.0 4320: 2242 av, 72 es, 22 sd, 3.8"/5/50, again, the last five came home with me. This VERY "roundnosed roundnose" functions perfectly in the M1A, BTW.
311413, 170 spire-point, 36.0 4320: 2243 av, 18 es, no sd, SIX inches for THREE rounds at 50!! (Sigh), seven more rounds to break down. All three boolit holes showed tipping, too.
311672, 170 semi-spitzer, 30.0 IMR 3031: 1936 av, 103 es, 31 sd, 2.0"/10/50
same, 31.0 3031: 1968 av, 118 es, 33 sd, 2.2"/10/50
311466, 150 loverin, 30.0 3031: 2047 av, 70 es, only 4 rds fired... FIVE-plus inches for FOUR rds/50. Guess where the remainder are? Didn't even fire the 31.0 load, and all ten are in the breaker's yard.
I seat both 311466 and 311467 to the same overall length, as they have identical nose shapes. I discovered yesterday that the length I've been using is TOO LONG to allow loaded rounds to be extracted from the chamber....they leave the boolits jammed in the throat! I'm rather surprised at this development, because the rounds function fine and have no hesitation in chambering. However, after two doses of 'powder-in-the-action-and-get-the-cleaning-rod-Charlie', I again am taking a hint and will check more carefully when I adopt a NEW seating depth for these boolits.
At about the 2000 fps mark, the rifle begins acting more like a service rifle and actually lifts off the rest a bit in recoil. Below that point, it's just a big ol' baby on
the bench.
After firing these higher-speed loads, inspection of the bore shows no particular fouling of any description, let alone leading. The interior shines like a mirror.
Again, I'm reporting in some detail in hopes that the info will be useful to other casters in the future. I'm really trying to establish safe-level loads for others to START from, not defining "the very bestest, most accuratest load" ....just good working levels with which to begin. There's not very much data out there for cast boolits in autoloading rifles.
Back to the drawing board.
More Edjumacation from the M1A
In yesterday's episode, I found that while my starting-load selection with 4320 was right where I expected it be for velocities and pressures with the different bullets, the loads did NOT perform at all well as the charges were increased.
I therefore loaded three different bullet types with three incrementally-decreasing charges of 4320. The boolits were 311672, 311291, and 311467. The charges (of 4320) were 34.0, 32.0, and 30.0 grains, decreased from that starting load of yesterday, which was 36.0 grains.. I fired them in order of weight with each bullet...that is, I shot the 311291 loads in order from 30 to 32 to 34 grains, hoping to see any changes in behavior that might arise. I did see them, too.... The same order-of-fire was used with the other designs,as well.
Beginning with 311467, the 180 Loverin, the first round fired with 30.0 grains was over FOUR INCHES left of the point of aim. The next nine rounds were right in the x- and ten-ring of the 50-yd pistol center that I'm using at 50 yards (but folded in half to create a black semi-circle aiming mark). Velocity was 1816 fps average, 29 fps extreme spread, 9 fps std deviation. Group was 2.0"/9 rds/50 yds.... I didn't include the first round in the group measurement .
311467, 32.0 4320: 2000 av, 67 es, 18 sd...... and again, the FIRST round was fully four inches to the left of the group which developed in the x- and ten-rings! The remaining 9 rounds grouped 1.6".
311467, 32.0 4320: 2141 av, 63 es, 19 sd. All rounds landed within the so-called "group", which was 3.1"/10/50.
The flagrant straying of the first rounds absolutely mandates that I re-fire these loads with the addition of a dacron tuft. I strongly suspect that there's something going on with the powder positioning in the chambering of the first round, even though I just pull back the charging handle and release it to slam closed by itself. Since the same phenomenon repeated itself with 311291, although to a lesser degree, it may be that the powder is just on the edge of good burning, and the different positioning in the case might make the difference.
311291, the roundnose, illustrated clearly that yesterday's loads were driving too hard for its tastes.
311291, 30.0 4320: 1866 av, 95 es, 28 sd, 2.2"/10/50. The group was only 1/2" high, but spread pretty wide across the ten-ring.
same, 32.0 4320: 2055 av, 89 es, 27 sd, 3"/10/50.....just a loosely scattered group with nothing unusual about it.
same, 34.0 4320:2161 av, 124 es, 37 es...and a HORRIBLE 'group' (HA!), six- inches- plus in sprawl.
311672 did pretty well to begin with.
311672, 30. 0 4320: 1868 av, 79 es, 30 sd, 1.3"/10/50. Nice group, compared to some others!
same, 32.0 4320: 1976 av, 80 es, no sd reading, 1.6"/9/50... the tenth round was a flyer two inches out at 10:00, no explanation. It was called "good".
same, 34.0 4320: 2116 av, 116 es (high!), no sd reading, 2.5"/10/50....just a general loosening of the group as it neared the load levels from yesterday.
All rounds fired today functioned the rifle perfectly.
The Nevada zephyrs were out in force! It was so bad that I eventually found a BRICK (no kidding) which I used to dampen the flailing-around of my chronograph boom. I did this by duct-taping from the brick on the ground up to the outer end of the boom with considerable tension on the tape. I also had to run duct-tape from the boom just outside the rear doors of the van to the upwind side of the vehicle, to keep the boom from slewing violently down-wind in the gusts (I did this first, and added the brick rig later). The normal retaining notches were not up to the job in the gale.
I estimate the gusts at around 40 mph, and today was the first time I've felt the van actually moving very much in wind. It has a one-ton suspension, so it's pretty stiff. In the lulls which came occasionally, I'd sometimes fire three or four rounds in quick succession to take advantage of the condition. All the wind whistling through Der 'wagen kept barrel heat well under control. At only fifty yards, and with the wind mostly fish-tailing or quartering from behind, I don't believe it affected my results very much.
The learning process goes on....
Independence Day on the range...
What better way to spend a few hours on July the Fourth, than exercising one of the great American Freedoms which are so rare in most of the world??
Changing the methodology a bit, the loads tested yesterday all used the Loverin 311466, nominally 150 grains cast in water-dropped straight wheelweight alloy, sized .311" and lubed with FWFL. No stunning accuracy resulted, but again I learned some info about different powders, etc. 311466 has worked very well for me in other .30 cartridges, so I expect some good things from it in the M1A as well.
All cases were new LC88, all primers were CCI #34. No fillers were used. The rifle functioned perfectly with all loads listed, and the range was fifty yards.
28.0 H335: 1893 fps average, 111 extreme spread, 33 sd. This load put the first three rounds under a half-inch at 9:00 in the ten-ring of the NRA 50-yard pistol target, then the POI shifted radically, two inches up and right for the next five rounds, which again grouped pretty well. The impact shift had me wondering, until I recalled a tendency for the gas plug to unscrew itself....sure enough, it had come out two full turns! Tightening the plug with a 3/8" box-end wrench which lives in the van just for that reason, I netted ANOTHER serious POI shift, this one placing the last two rounds of the ten a good three inches above the five-round group! These two holes were touching, five inches above the point of aim, and centered for windage. I lowered the sight setting before firing the next set of ten rounds.
30.0 H335: 2025 av, 57 es, 17 sd, 1.5"/10rds/50 yards
32.0 H335: 2144 av, 35 es, 10 sd, a scattery 3-inch horizontal-oval "group".
34.0 H335: 2256 av, 44 es, 15 sd, 2.25"/10/50
The earlier loads with 4831, discontinued due to malfunction-inducing unburned powder in the action, gave rise to the following attempts with IMR 4350:
35.0 IMR 4350: 1915 av, 93 es, 29 sd, 1.6"/10/50
37.0 IMR4350: 2080 av, 53 es, 16 sd, 1.4"/10/50.
There was NO unburnt powder visible anywhere in the action or bore, even with the 35.0 load. Both groups were nice and round, with no "strays". I'll definitely be doing more work with this powder-and-bullet combination! That second load looks very promising, so I'll re-fire it, plus loads with 1.0 grains lower and higher, just to see what they do. The 37.0 load is considerably more consistent in ballistic performance as demonstrated by the much-smaller extreme spread and standard deviation. The powder was obviously getting into a pressure range where it burned more efficiently.
I wasn't too impressed with IMR 3031's performance in a few previous loads, although I left a lot of stones unturned with it and will likely go back to it with different boolits. 4064 looked like a decent possibility, so:
28.0 IMR4064: 1762 av, 63 es, 21 sd, 1.1"/10/50.....not bad at all!
30.0 4064: 1923 av, 47 es, 19 sd, 1.2"/10/50, and seven rounds were clustered into 0.7"
32.0 4064, 2063 av, 115 es, 37 sd, groups starting to enlarge at 1.75"/10/50
34.0 4064: 2201 av, 76 es, 23 sd, 3.25"/10/50, but 8 rounds in 1.70".
Again, all the loads fired yesterday used 311466. One minute between shots, five minutes between strings, all rounds loaded into the magazine. Everything was loaded on the Dillon 550.