Measuring Projectiles

Strangely, an inquiry earlier today from a 500mFlyShooter forum member got my attention. I thought it might be a worthwhile topic if it hasn't been covered before???

So for each projectile measurement (e.g. bearing surface, base-to-ogive etc.) you take, list the following:

1) What is your measuring methodology?
2) What equipment do you utilise, including it's resolution and repeatability, if known?
3) Do you employee any calibration techniques or other controls (room temperature)?
4) What tolerances are you finding within a batch, or from batch-to-batch?
5) If you take multiple measurements, is one more significant than the other with your rifle set-up? Does it apply across all your rifle set-up?

I don't think there is any need to mention any projectile brands and I'm not looking to be critical of anyones choices. It's a forum, not a royal commission.

Generally speaking, with forum questions, I also find it useful if you mention any processes you stopped doing and why. I can gaurantee I'm making the same mistakes with my bullet swaging that they did 150 years ago. It's just a shame most of it never gets documented.

Lead Core mass.

1) What is your measuring methodology?

    Swage lead cores at least twice and measure mass of core on the scales at least once. Repeat swage until weight within tolerances.

2) What equipment do you utilise, including it's resolution and repeatability, if known?

   A&D FX-120i electronic scales - resolution 0.02gr; repeatability - 0.02gr

 3) Do you employee any calibration techniques or other controls (room temperature)?

  Grade F1 masses - 2g, 5g, 10g, 20g, 50g.
  Calibration at start-up to 50g only. Use check mass more frequently than I care to remember.
  Closed room, and scales always stored in the room. Scales powered up for >30min prior to use.

 4) What tolerances are you finding within a batch, or from batch-to-batch?

  Holding lead cores to +/-0.06gr or +/-0.05gr depending on average jacket mass.

5) If you take multiple measurements, is one more significant than the other with your rifle set-up? Does it apply across all your rifle set-up?

  Critical to final projectile mass tolerance, as the jacket mass is fixed with it's own tolerances. Target total tolerance is <0.20gr for the batch with 75% of the batch <0.14gr.

Hi Aaron,

Frankly, unless you have countless hours available, all farting about with bullet grading etc will stack up to jack-shit until your skill-levels as a shooter get you up at the pointy end of the results at least reasonably consistently. This sort of attention to detail is possibly worth about 1 to 2 points out of 300 in a match in my opinion.

Pete

Pete van Meurs wrote

Hi Aaron,

Frankly, unless you have countless hours available, all farting about with bullet grading etc will stack up to jack-shit until your skill-levels as a shooter get you up at the pointy end of the results at least reasonably consistently. This sort of attention to detail is possibly worth about 1 to 2 points out of 300 in a match in my opinion.

Pete

Hi Pete

I know of at least one incident where shooters have given away measuring projectiles. Did you have an experience/trial which brought you to your opinion specifically?

I agree that 'bullet grading' should be one of the last skills you need to aquire, if you're already using a high quality match grade projectile. I'm certainly a big fan of the '80-20 rule' given my limited resources. I certainly prefer to build 'quality controls' into the production steps, instead of weeding out duds at the end. I wish brass cases didn't require as much work!

I think there is probably an opportunity for shooters with more time than coin, to go into 'bullet sorting' some of the mass produced match grade projectiles. Practice with the outliers and shoot matches with the ones measuring the least variance from the norm.

Aaron

Hi Aaron,

My experience over many years of working with custom varminters, short and long range bench rifles has lead me to a couple of conclusions.
Ogive variations are only of  consequence if  you seat the bullet close to the lands. If jammed in .010" to .015" you will not be troubled. Conversely the same applies if you jump the bullet at least .025". Minute variations in weight will also not be a worry.
There are many unseen possible faults that will only be discovered by test firing. Once you have established that a particular 'Lot' is good buy heaps more! Shooting one group is no real test - you should use as much as half a box.
Also remember that every barrel is a law unto itself  and some perfectly good barrels will not shoot well with some perfectly good bullets. If comparing notes with others re bullets always state that brand X did not work in YOUR barrel rather than suggesting that they are simply no good at all.
Every match that I have done well in or shot smallest group has been with 'out of the box' bullets from a batch or lot  that showed up well in testing.

Pete

Very interesting topic and good to see lots of points of view. I am an advocate of measuring projectiles, batching ogive to base, weight to 1/10 grn, diameter of projectile. I also meplat trim and bullet point, and then place the projectiles on the Juneki which checks the lead concentricity of the projectile and don't shoot any outside of 3 deviation units for a match. All others get shot in the practice target or running new barrels in. The shape and design of the bullet comes into play when you are seating of you don't have a VLD seater stem in your die and you don't check your Overall length with a gauge you may well be off the lands completely or jammed hard.

When load developing it depends a lot on what you are trying to achieve, my over all goal is accuracy over speed so I don't shoot the high pressure accuracy nodes I think the band width is to small and temperature variations across a whole day can play havoc with high nodes. Also when shooting and developing loads some bullets don't like to be blown out of the barrel at 3100fps.
Bergers I think are once such bullet that if you stoke them right up they don't shoot as well as when it is a moderately high load in this accuracy node they bug hole. Sierra's on the other hand you can punch it into them without any worries. Anthony and Belly have had tremendous results with the Copper head 103 in the 6mm derivatives. I shoot 105 grn
Berger hybrid and 107 sierra's in the 6x47l both shoot very well.

Pete has shoot fantastic groups straight from the box and those groups have been tiny but it is 500m away there are lots of considerations in shooting tiny groups conditions on the day as well as the right load must come together.

From the other topics in the forum list you will see there are lots of top line shooters who are prepping everything they can to gain that edge. Some don't it would be an interesting summation to identify which of the shooters that have finished consistently in the top 5 are doing, that may give a do or don't option to others.

One more thing I would like to add is load development for a 500m gun with a tight twist barrel is best done at over 200meters. When I do my development it is done at 300m which allows the projectile to achieve stability and continuity of flight.

The 6PPC topic was very interesting and I think that there are a lot of people out there that have done some work with this calibre at 500m. It was very interesting to note that most of the short range fraternity shoot 29.6 grains for Bench mark 2 which is a hot load in my opinion at a distance of 100 yards and 200yards. So if the little case can withstand this pressure then they must also handle pressure of a larger projectile with a faster twist rate one would think.

your thoughts
Les

Les Fraser wrote

Very interesting topic and good to see lots of points of view. I am an advocate of measuring projectiles, batching ogive to base, weight to 1/10 grn, diameter of projectile. I also meplat trim and bullet point, and then place the projectiles on the Juneki which checks the lead concentricity of the projectile and don't shoot any outside of 3 deviation units for a match. All others get shot in the practice target or running new barrels in. The shape and design of the bullet comes into play when you are seating of you don't have a VLD seater stem in your die and you don't check your Overall length with a gauge you may well be off the lands completely or jammed hard.

When load developing it depends a lot on what you are trying to achieve, my over all goal is accuracy over speed so I don't shoot the high pressure accuracy nodes I think the band width is to small and temperature variations across a whole day can play havoc with high nodes. Also when shooting and developing loads some bullets don't like to be blown out of the barrel at 3100fps.
Bergers I think are once such bullet that if you stoke them right up they don't shoot as well as when it is a moderately high load in this accuracy node they bug hole. Sierra's on the other hand you can punch it into them without any worries. Anthony and Belly have had tremendous results with the Copper head 103 in the 6mm derivatives. I shoot 105 grn
Berger hybrid and 107 sierra's in the 6x47l both shoot very well.

Pete has shoot fantastic groups straight from the box and those groups have been tiny but it is 500m away there are lots of considerations in shooting tiny groups conditions on the day as well as the right load must come together.

From the other topics in the forum list you will see there are lots of top line shooters who are prepping everything they can to gain that edge. Some don't it would be an interesting summation to identify which of the shooters that have finished consistently in the top 5 are doing, that may give a do or don't option to others.

One more thing I would like to add is load development for a 500m gun with a tight twist barrel is best done at over 200meters. When I do my development it is done at 300m which allows the projectile to achieve stability and continuity of flight.

The 6PPC topic was very interesting and I think that there are a lot of people out there that have done some work with this calibre at 500m. It was very interesting to note that most of the short range fraternity shoot 29.6 grains for Bench mark 2 which is a hot load in my opinion at a distance of 100 yards and 200yards. So if the little case can withstand this pressure then they must also handle pressure of a larger projectile with a faster twist rate one would think.

your thoughts
Les

Argghhh not the Junke! I'm sure it's the rod in the back of every projectile manufacturer. Very clever device in the hands of someone who knows what they're doing. Excellent $2000 anchor weight in the hands of those not familiar with it's workings. Unfortunately I don't see how I can use the device to manufacture better projectiles yet. What is your increase in group size above 3 deviations, +25% group size?

In terms of load development, I've read a number of reports. Either way, 100m/y groups for the top performers (long range shooting) seems to be less than 0.25MOA for a 10-shot group and velocity spreads are in the single digits. The yaw developed by fast twist barrels at ranges <300m can be reduced through minimal throat tolerances, minimal loaded round concentricity and high neck tension. I defintiely think the sooner you can start testing further back, or at 500m the better you are.

Hello Les    just as a bit of information  --  do you know how many of the top Fly shooters  --  the shooters who get into the top 10  in the SOTY each year  --  actually use a Juenke  bullet comparitor  --  and what other measuring devices do they use   --  would it be possible to do a survey  of  our better shooters  --  i think that it could help a lot of newer members of our fly shooting sport  -- and maybe save them some money by not rushing out and buying gear that will not raise they scores

           just my 10 cents worth
                   john mc

Hi John i put a post up on measuring tools for you to look at and comment
cheers Les