If you don't trust your instruments, you should not leave terra firma. Thinking you are going to straddle the two you will end up in worse shape than the fellow who has one foot in the canoe and the other firmly planted on the boat dock.
So, there I was helping a buddy with a new firearm. While sighting it in, the fellow a few positions to the left very kindly offered to let us play with his new toy. I think maybe he was trying to amortize the cost by getting more use out of it. "Look, honey, I helped out a couple of hobos at the shooting range today..."
Bullets that were "expected" to have a muzzle velocity of 3100 fps were reported to have a muzzle velocity of 2750 fps. Bullets that were "expected" to have a muzzle velocity of 2700 fps had reported velocities of 2200 fps.
Results were replicated with a second chronograph.
A second generation of load development (different smokeless propellant) produced a velocity of 2460fps with the same bullet that produced 2200fps in the first try. That load has promise.
Hmmm!
It is widely accepted that reputable companies that publish reloading data use SAAMI standard test barrels that are cut with "maximum material, minimum clearance" chambers, throats and barrels. That is, the tightest chambers, the shortest throats, the steepest allowable leads and the minimum diameter barrels.
Safety over-rides all other considerations. The maximum powder weights listed in the manuals are under SAAMI standards for those one-in-a-thousand barrels. Because if a manufacturer makes 100,000 rifles, then 100 of those weapons will be TIGHTER, and have higher pressures than SAAMI standards.
There are "fast barrels" and "slow barrels". Fast barrels are closer to SAAMI minimum standards. Slow barrels have more generously cut chambers, longer free-bore (throat) and so on.
It appears that my friend has a barrel with very generously cut chamber and free-bore.
Pressure makes velocity and...
John Barsness, a better-than-average gun-writer claims that higher-than-expected velocities are evidence of higher-than-expected-pressures. A 30-06 load that might be expected to produce 2900fps but chrono-ed at 3100 fps has "issues". One reloader experienced this and after double-checking found out that he was using very hot Magnum primers and elderly, pull-down powders. Maybe not a great combination.
On the flip side, Barsness claims that if you are using a "canister grade" smokeless powder of recent manufacture from a reputable supplier and your velocities are very consistently and significantly lower than published data, you can undoubtedly well below SAAMI published maximum pressures.
Range estimation
Humans suck at estimating range.
When LASER range-finders first became commercially available, they were incredibly expensive.
One gun-store in a western state (Wyoming?) had a display model. The store suggested that customers estimate the distance from the front door of the gun-store to the flag-pole in front of City Hall. Most estimates ranged from 440 yards ( a 1/4 mile) to 1000 yards (almost a mile).
Please bear in mind that this was in a state of far horizons, pronghorn antelope and long shots.
Trusted patrons were allowed to step outside the door and "shoot" the flag-pole with the LASER range finder to test their judgement. It was 225 yards from the gun-store's front door.
Not believing that, many patrons paced off the distance and had to admit that the device was on-the-money. Who knew?
What that means is that very few mere-mortals (excluding Marines...and one can argue that they do not fall under the category "mere-mortal) will ever launch a bullet at a target more than 200 yards away. Maybe one-in-ten-thousand.
If you are following my logic, then the criteria for muzzle-velocity and maximum range becomes maximum-mid-range-deviation-from-line-of-sight of 2" and an impact velocity between 2800fps-and-2000fps to keep bullets in the sweet-spot for terminal ballistics.
Using that criteria, the 2200fps load drops below 2000fps at 125 yards and has a +/- 2" trajectory of about 185 yards. That makes it a 125 yard load.
Adding a puny 300fps (to 2500fps) stretches that to 225 yards for terminal ballistics and 200 yards for +/- 2" trajectory excursions.
To be excruciatingly explicit: at 2200fps, the load is the limiting a factor in how far proficient hunters can reach out and ethically harvest big-game animals. At 2500fps (77gr, 0.44 G1 BC) the shooter becomes the limiting factor in 9999/10,000 cases.
And, in all fairness, bow-hunters routinely harvest deer with arrows traveling at 300fps at ranges of less than 30 yards and thugs with knives and sharpened screwdrivers murder humans at much shorter ranges.
Joe, what is your opinion of how long the shelf life of powder is? I have some unopened for several years. Is it safe to use? --ken
ReplyDeleteSpoiled powder has a sour smell, so I have read in reloading manuals. Sniff some fresh powder first.
DeleteI just finished off the H4831 and H4895 that my dad bought by the bucket 60 years ago. Military pull down stuff I'm sure. Never saw any variations over that time. It still chronographed right where it was expected to after all that time.
ReplyDeleteOne of the only remaining advantages 450 Bushmaster has over 350 Legend is, if you really need to go to 200, it does that a lot easier with a standard ballistics setup than 350 Legend.
ReplyDeleteI'm not in the market for me, but in a decade when older Kiddo is I expect 350 Legend will be first up.
Handloading probably can fix the gap though with a bolt action and some customized loads, at a lot less recoil.
When manufacturing M781 40MM Practice rounds, we used to keep a spreadsheet with reference velocities from testing a known load from a single lot with different barrels on the same receiver. That way we could select the barrel to use for the lot acceptance test that would likely keep us near the center of the velocity specification. We measured the bore and lands of each of the barrels and included that data.
ReplyDeleteLoose is slow, tight is fast was proven repeatedly.
I've thought for some time that a *very little* money could be made with a radar chronograph, a laptop and a few micrometers and ogive gauges at gun ranges. If BC is unknown, pull one bullet, measure weight, diameter, length, gauge the ogive, determine ballistic coefficient, fire 6 rounds to get average velocity, compute trajectory with a ballistic program for several zero distances, charge $$ for the service. As a sideline, give customers the opportunity to *visually measure* distance to range stakes then provide a sheet with actual to-the-inch measurements for $.
ReplyDeleteI figure between equipment and software costs one could achieve bankruptcy in less than 30 days but one could learn a lot in the process.
"...the criteria for muzzle-velocity and maximum range becomes maximum-mid-range-deviation-from-line-of-sight of 2" ..."
ReplyDeleteHollywood has convinced nearly everyone "point blank range" is directly in front of the gun. It is not.
"Point Blank Range" is the maximum distance at which a bullet strike can be achieved on a target of specified size with a center hold from the muzzle to that maximum range and will vary between firearms, calibers, bullets and loads.
EX: Using an 8.5" X 11.0 inch sheet of copy paper in portrait mode as a target the center will be 5.5" from top and bottom; that means for whatever distance the firearm is zeroed the maximum midpoint trajectory above line-of-sight cannot be over 5.5" and drop below line-of-sight beyond the zeroed distance cannot be over 5.5". A smaller target will have a shorter point blank range, as will a slower and/or less ballistically efficient bullet.
Gravity is a constant, velocity declines over distance due to air resistance so gravity has longer to act on the bullet as range increases which is why trajectory ("ballistic arc") declines more steeply as distance increases.
To verify this, attend a baseball game and sit as far from home plate along the third base line as you can; watch fly balls to deep left field (most hitters are right handed so probability favors left field to center-left for most long hits) and observe the ball's path.
It is also why so few people understand shooting uphill or downhill which results in misses; the angle of the hill is irrelevant, it is the horizontal distance between muzzle and target that is important because that is the distance in which gravity acts upon the bullet.
Huh? "the angle of the hill is irrelevant, it is the horizontal distance between muzzle and target that is important because that is the distance in which gravity acts upon the bullet."
DeleteBut when shooting at an angle, you are no longer shooting horizontally, or am I off base here?
To an extreme, If I am shooting at a target 10 feet away from me horizontally and 300 feet vertically or at about an 88 degree angle.. I'm so confused!!!
sam
That is why you set your range finder for horizontal instead of actual slope distance. That way it automatically compensates for inclination.
DeleteThose bullet performance thoughts above is part of why the 30-30 Winchester bullet are so reliable in expansion and terminal effects on animal. Expecting a bullet shot from a magnum cartridge with 3200 fps at the muzzle and 2600 fps far down range ON SAME ANIMAL is very hard, if not impossible to accomplish. Up close, bullet self destructs. Far away, little expansion. The 30-30 is meant to shot up to moderate distances and so that rounded SP bullet expands to spec reliably.
ReplyDeleteI agree regarding the 30-30.
DeleteFrom the standpoint of the bullet designer, he only has to design the bullet for one cartridge, the 30-30 so he has a very well defined range of velocities to work with.
Projectiles of 0.277" used to be similar because nearly all were for the .270 Winchester or for short magnums of similar velocity. The recently introduced 6.8mm cartridges designed for AR type platforms screwed that all up.
On the flip-side, .257" bullets could end up in anything from a 25-35 to a 25-06 with a huge range of velocities. .308 caliber also has a huge range, from the .300BO to the .300 Winchester Magnum.
I think Hornady does a good job publishing the impact velocities various projectiles are designed for.
https://www.defensivecarry.com/attachments/xtpvelocities-jpg.300854/
I’ve seen this before. My theory (and it works, based on my anecdotal experience) is that the component companies deliberately publish low powder charge weights for legal and liability reasons. The important figure look at is the velocity.
ReplyDeleteIf the manual says your bullet should be moving at 3100 FPS, and you’re only getting 2900 and you’re at the max published powder charge… start bumping up your powder charge. You need a chronograph to do this, and you have to be smart about it.
If your max powder charge is 54 gr of 4350…make five rounds at 55 gr., then another five at 56 gr., another five at 57 gr. Watch your brass and velocity like a hawk. If you get pressure signs, STOP. If you get your published velocity, stop, you’re done.
My prized beloved old .25-06 needed 5 whole grains over max with its pet load to hit published velocity and it had a 24” pipe. Exceeding max charges is not a big deal PROVIDED you use your noggin and a good chronograph. This is not a job for Cletus and Bubba… it’s one for a professional rifleman and reloader.
Roger that! My neighbors first rifle, as a teenager was an aught 25. He was a poor farmers son, but needed to cull various pests. So reloading was the way to go, he loaded up his pet 85 or 90 grain load to Max pressure using Filthies methods (yeah, he worked through stuck bolts and flattened and leaking primers). He says he was never that great at range estimation, but didn't need to be, that rifle was like a laser. He's not a boaster, but says he would drop deer and feral dogs in his fields out to 500 yards, you get good with repetition.
ReplyDelete"will ever launch a bullet at a target more than 200 yards away. Maybe one-in-ten-thousand."
ReplyDeleteI think you will find western hunters typically shoot longer distances. My caribou were taken at ~195 and 425 yards. One advantage is the distance gives the hunter time to take the best shot possible. Most of my whitetails have been under 100 yards.
I was in a camp hunting in BC and the guide told a fellow hunter that he should be prepared to take a 300 yard shot. The fellow laughed and said in 40 years of deer hunting he figured his longest shot was 50 yards. He hunted in the mountain laurel thickets of central Pennsylvania. Visibility is usually much less than the open parkland of much of the west.
You know, after writing that I was in bed about to go to sleep when I had the passing thought, "I am going to get roasted for that comment."
DeleteI owe you guys an apology.
I went on-line and there were 20,000 caribou harvested in the US on sporting licenses and about 6 million deer. Simple math shows that to be about 1:300 and not 1:10,000. And that does not even count all of the long-range pronghorns, woodchucks and prairie dogs.
I let my frustration take the reins.
My apologies.
Several thoughts:
ReplyDeleteI read an article a while back that a powder company had a canister of powder (smokeless) that was manufactured in 1898, they tested it and it was still in spec.
I agree with Glen to a point, I have one reloading manual that I don’t trust, I had a shell stuck in a 30 30 with a minimum charge
and other issues with other calibers.
Years ago I worked up a load for a friend 308 win. Browning BLR 165 gr sierra SBT with IMR 4064. I don’t remember the charge, anyway he missed the first 3 antelope he shot at, at that point a friend asked him where he was holding. He told him the top of his back. I zeroed this gun at 200 yds ( actual ).
The next one he shot at they told him to hold right on, he did and dropped it. He thought he was shooting 300 yds, but it was really 150.
Grumpy Old Macdonald
That canister of powder was probably "Unique" that had been stored in the bottom of a barrel of water and samples had been taken out once-a-decade to verify that the burn rate had not drifted (and by comparison, the relative burn-rates of the other powders they manufactured had drifted).
DeleteI am guessing the Spear manual? They tend to run hot.
No actually Lyman #50
DeleteYes it was Unique
I am still using H 4895 that I bought in 80’s
I have a collection of reloading manuals dating all the way back to the '40s.
ReplyDeleteFrom what I can tell either..
A) year after year powder got stronger.
B) actions got weaker.
OR
C) lawyers got involved
My guess is "C"
Let me offer a couple of other possibilities.
DeleteElectronic instrumentation has become much faster and more precise. It is now possible to see pressure excursions on the order of 1/10,000 of a second (or smaller). Spikes got smashed flat when sampling rates were heavily filtered or copper pellets were used to estimate pressure.
Another factor is that SAAMI standards use "statistics" to estimate possible excursions based on the variation in pressures seen in the samples tested.
Suppose you tested a gunpowder that was difficult to measure by volume and found a wide scatter in pressures. Shouldn't that powder's loads be penalized compared to a powder that flows-like-water and is extremely consistent from throw-to-throw? SAAMI standards make an attempt to capture that characteristic with statistics.
Is "you can undoubtedly well below SAAMI" missing a word?
ReplyDeleteAND, I just realized the drop-down menu to choose "comment as" keeps going back to anon because my google account is up on a flavor of browsing different than the one I'm using here. I think.