500 yard ammo testing

I remember those dayz, Ganderite. Machine rest testing was a pleasure.

I had, and still have two tops (7.62 & 5.56) for the old MR. Actually an unlimited rifle (6mm PPC) with a fine track record in unlimited BR competition.

Two loads stand out for accuracy at 500 yards in the 7.62 top. One that you sent for testing and the other sent by a friend in Terre Haute, IN. Both used the Sierra 175 Mk and both shot ten shot groups of 1/4 minute, or under. Very impressive, and memorable.
The 155 grain bullets shot very well, but I never saw 1/4 minute with them.

The machine rest has been resting for at least a decade, but I would bet that it will still do bidness.

Best to all.
 
Thanks for sharing Ganderite, now I will not listen to the remchester shooter's advice :)

Its good there are people out there who are willing to put the effort into raw hard scientific testing and dispell some myths.

I was about to buy a primer pocket uniformer but now I will hold off.

I'd like to know whats better, weighing or measuring case volume. Good to know weighing helps, because I already did that and it was a tedious enough process. Not sure I want to measure volume as well.

Thats interesting about neck tension. I wonder if crimping a neck would have the same result? I recall Lee claims improved accuracy with crimping somewhere in some of their literature. I have never heard of it in the precision shooting world (although I am a newbie) May be worth a try.
 
Vertical flyers? This is TR ammo made with store bought bullets. A group under 2" at 500 yards has no "flyers". A BR rig shooting custom bullets might like to get rid of the "flyers".

Tight neck tension. A TR chamber has lots of neck clearance and the bullet is about 20 thou off the rifling. If the bullet is a bit out of kilter, the sloppy chamber eats it all up. A tighter chamber might shoot the tight neck worse. Only one way to find out.

I used to have a down range video camera aimed at the target. When transfering the camera tape to VHS, I ran the camera on fast forward, so the groups form very quickly. I happen to have the tight neck test on tape. Shot 2 ten shot groups tight and 2 ten shot groups ordinary. Group area was about half with the tight neck. It was shocking to see the first time. I don't recall what lead me to try that test. Bench resters use a very light neck tension, so this was going the wrong way according to conventiona wisdom.
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Of course only boat tail bullets are used. A flat base would not start in the neck to be seated.

On the Dillon, we were loading 50,000 round lots, so case prep was out of the question. Case mouths could not be champfered, so I was concerned about scatching bullets as they seated. This risk was increased with a tight neck.

We set the Dillon up with a Lyman neck sizing die in position one (no decapper rod or button). Brass was always virgin primed brass being fed by a case feeder. Cranked out a loaded round every 3 seconds. The second die was a 8x 57 FL sizer die, backed out so it did not touch the case. The expander button was set to just kiss the case mouth on the down stroke. This flared the mouth enough that the bullet side did not touch the case mouth as it was seated. Then the powder thrower and then a Forster precision seating die adjusted to taper crimp enough to take the mouth flare off.

We made a lot of ammo. Bullets were bought by the ton (40,000 to the ton, as I recall). Brass came in big barrels. And my pickup maxed out at 1300 pounds of powder per trip. Every lot was pre-tested for die set up and powder charge by me shootng a few groups. (Our range is about 100 yards from the manufacturing building.) (Indoor firing position - heated and air-conditioned.)

There were always buckets ot rejected ammo or set-up ammo. This is what I got to use in competition. It was good ammo. SD in the 10 to 15 range.

This ammo grouped around 3" at 525 yards in the rail gun.

One more thing. I have shot thousands of 10 shot grouping tests over the years. At one point I had about 20 308 rifles, so i could make sure a given ammo or idea was not rrifle-specific. Anyway, groups are shot with a 36X or 24X scope. It is easy to watch the group form. Many, many times the 5 shot group looked terrrific, but after 10 shots it was just another half to three quarter minute group.

Only 10 shot groups have much statistical value. In a target rifle, 5 shot groups can do more harm than good by leading you down the wrong path.

Also, ammo testing should be doen at a standard ammo temperature. I put the ammo in my shirt pocket, inside my jacket, in the winter. This keeps it around 98 F. Ammo goes to the range in a cooler packed with 2 2-litre Coke bottles full of hot water.
 
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Corbin.

I still have some of the original targets. The one pictured here was shot (by you) 2 August 1995. It was 155 Sierra (the old, original bullet) and an un-noted load of VHT 140. I could check the log book, but would guess it was around 44 to 45 gr.

Your testing was so important for the project because the rail gun took away so much of the error, resulting in a better test of the ammo. Of course it was also important that your barrel/chamber was very similar to what most TR shooters used.

I did not remember sending you any 175gr ammo to test. That was police sniper ammo we made for various forces. They liked it. I coached a police sniper at 700 yards once, using that ammo. On a windy day he hit a playing card 7 times (15 shots) that we had in the center of the Fig 11 target.

Too bad you did not have a 50 cal rail gun. I have no idea how good that ammo really was, but the buyers seemed to like it.
 
Budweiser

Powder can lid left off.

In the 90s I worked with a powder company R & D department to try to develop better powders. The lead guy was a PhD chemist. My role was to explain the needs of shooters. None of the people there were shooters.

One of the things I learned was that the moisture content (water) is one of the controlled characteristics of a powder. It is used as a speed modifier. They use a little more or less water to get the powder speed just right for a canister powder.

As a powder dries, it speeds up. This is why a new can of powder can seem slower than the old can.

What I learned from this was to keep can sealed and to put powder back in the can when done.

From what you posted, I can see that if a can of powder is allowed to dry out a bit, it might then be more speed stable therefter, but it would be faster.

The fact that we load ammo with fresh powder and also old powder means that load data can only be a start point next time.

I buy powders in 8 pound jugs and decant it to one pound cans for use on the bench. This should reduce drying.
 
Ganderite said:
Budweiser

Powder can lid left off.

In the 90s I worked with a powder company R & D department to try to develop better powders. The lead guy was a PhD chemist. My role was to explain the needs of shooters. None of the people there were shooters.

One of the things I learned was that the moisture content (water) is one of the controlled characteristics of a powder. It is used as a speed modifier. They use a little more or less water to get the powder speed just right for a canister powder.

As a powder dries, it speeds up. This is why a new can of powder can seem slower than the old can.

What I learned from this was to keep can sealed and to put powder back in the can when done.

From what you posted, I can see that if a can of powder is allowed to dry out a bit, it might then be more speed stable therefter, but it would be faster.

The fact that we load ammo with fresh powder and also old powder means that load data can only be a start point next time.

I buy powders in 8 pound jugs and decant it to one pound cans for use on the bench. This should reduce drying.
Click to expand...

Did you work with guys from EXPRO Tech?

Frank
 
When you say tight neck vs not, any idea what the amount of sizing was?

Did you do any tests to see the affects of barrel heat on groups?

How did you account for wind and ambient conditions? I know flags are the obvious but there is a lot of stuff that can go on between the flags. Any tips on how you avoided 'clouding' the data?

Jerry
 
Frank Oui

Mystic. The necks were very tight. You could see the neck pinch in, under the where the bullet stopped in the neck.


Heat - My 308/7.72 rifles all had lots of clearance under the barrel. They were well floated. A lot of heat was a given. I would test 100 to 200 rounds in a session and could not slow down for cooling, so barrels got very hot.

This did not bother me because in a team match, where the shooter shoots single string, the coach might very well ask the shooter to shoot as fast as he can. barrel heat is a fact of life.

Just like a team match, you must be ready to shoot promptly once you close the bolt, becasue the very hot barrel will cook the round if it is there more than a few seconds, making it shoot out of the group.

Corbin can chime in here, but I am guessing he fired his 10 shot groups in about 30 seconds.

My testing is done from an indoor firing point, shooting towards a port in the wall, looking 200 yards down range. After a half hour of rapid fire shooting the barrel would be very, very hot. I am not aware of any wear issues. I got 5,000+ rounds out of each barrel.

But, I needed one or two fans blowing air across the barrel so I didn't have a mirage problem through the scope. After 3 shots the mirage becomes a broblem if there is no fan.
 
I got a question by PM. You might find this interesting....

Question: Would it be safe to say, The load that gives you the lowest spread in velocity would give you the best group at distance?



No. This is why long range loads have to be tested at long range.

Consider this chain of simple truths:

Some bullets are faster than others.

The slower ones will print lower on the target.

The muzzle is vibrating before the bullet leaves.

Depending on the average velocity, the muzzle will be either moving up or down when the bullets leave muzzle.

Assume muzzle is moving up when bullets leave, the slower ones will leave muzzle aimed a bit higher. This will compensate for their printing lower due to less velocity.

Group improves over what it would be, based on velocity SD alone.

If muzzle is moving down when bullets leave, the group will be much taller than the SD would suggest.


Therefore, find a bullet, powder, primer combination that gets a good SD over a range of velocities, and test them all at long range.
 
Isn't working up a load ultimately an individual thing, in the end? Can you really generalize by the experience of a rail gun? Can you conclude that because a load shoots consistently out of a rail gun at 500 metres at Connaught, it is going to work out of Joe Blow's (or Bob Pitcairn's) 1-12 twist, .3075 Krieger?

I fully confess to being nowhere near the kind of expert as most of the posters on this thread. But in my experience, such as it is, some simple truths seem apparent:

1. A top action, properly mated to a world-class target barrel (i.e. Krieger, McLennan, etc.) with proper bedding is the number one factor in success.

2. A good action/barrel combo will shoot decently with most REASONABLE load recipes (not talking about varmint bullets pushed by IMR 4350 in a .308), but won't be truly competitive (in a world-class sense) with any but a few loads.

3. Truly excellent loads often present within a range of a particular powder charge (i.e. 46.7 to 47.2, for example), and somewhere in there is the best compromise spot.

4. This best compromise spot generally varies from rifle to rifle.

5. Testing at 100 and 200 will show you the ideal range of charges, and tweaking within that range will show the best compromise.

6. This has to be followed by actual shooting at longer ranges with the actual rifle and load in question. For those of use who don't have a 1,000-yard range in our province, this can prove to be a real challenge.

Finally, regarding your comment about the tight necks: this has been my experience, too, but I never really turned my mind to it until I read your post and looked back over the years -- and saw a correlation between tighter necks and better accuracy. Conversely, it explained why some of the softer brass I used didn't shoot as well: it was so soft that it did not hold the bullets as securely as, say, my hard Winchester cases that had been neck sized small.
 
Each rifle is different. If it works in the rail gun it may not work in your rifle or mine.

My challenge back then was making cheap ammo that would well in most rifles so that the DCRA would have an alternative to IVI ball ammo.

The rail gun was a way to test some variables. I also did a lot of testing in the lab with pressure guns. And a lot of shooting on our range.
 
p17, all your points are excellent but I still see alot of power in the rail gun testing. If I used such a device I would be looking for gross trends and remove the error of the shooter.

Like the testing with primer pocket uniforming. If the shooter was biased to a result, maybe, just maybe, the shooter would 'create' the results he wanted to see. A rail gun wouldn't care either way. So you can focus on changing one variable and expect the system to reflect the changes of that one variable alone.

I have gone to the range under less the perfect physical/mental condition (tired, cold/hot, rushed to get back to the family, whatever). Are you shooting to the same level of consistency you did last time? Does the data created from this test valid for comparison to past tests?

I am in no way saying that testing with a rail gun will provide shooters with an ideal set up for their competition shooting. NO way. It just gives you a solid baseline to test all the different steps we take in our loading to isolate cause/effect.

Some stuff I would love to test would be bullet runout, temp stability of powders, affects of fouling/cleaning, annealing, neck tension, affects of powder charge variance, affects of POI due to sun location, affects on accuracy due to variance in ambient light/humidity.

The lists would be endless.

With this data, I feel you could make better choices about what has the greatest affects on your shooting.

NO different then the bullet data from Bryan Litz. Bullets are all tested under a similar procedure so data is comparative. Now we have a much better way of comparing potential bullet ballistics and making a more informed decision.

It most certainly would not tell you that bullet from Brand Z was going to shoot best in your rifle. But you may not choose that bullet if the performance didn't meet your baseline needs.

Jerry
 
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