Match Grade Accuracy, Velocity and the Bullet

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frnkeore posted this 29 November 2016

I would like to ask those that shoot in the target rifle classes (HVY, UNR & UNP) of CBA matches, what do you think is the thing that effects the accuracy, at the target the most, at 200 yards? And the same question of those that shoot in the lower velocity classes like Production, Hunter and Milsurp. Frank

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45 2.1 posted this 29 November 2016

I don't shoot in any CBA competition anymore, but when I did, the environment (sun, varying shadows, mirage, wind and it's direction, temperature etc.) caused the most problems.

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RicinYakima posted this 29 November 2016

I can only speak for the Military classes I shoot: firstly environmental factors of light intensity, cloud cover, wind speed and direction; second is ability to see the iron sights, especially issue sights. Then it is shooting technique, as our bullet velocity is low with long barrel times.

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Larry Gibson posted this 29 November 2016

<user=50>RicinYakima wrote: I can only speak for the Military classes I shoot: firstly environmental factors of light intensity, cloud cover, wind speed and direction; second is ability to see the iron sights, especially issue sights. Then it is shooting technique, as our bullet velocity is low with long barrel times. I shoot military (scoped) and Heavy Rifle. 

 

With the Military rifle (I shoot a Sako built Finn M39 7.62x54R with a Weaver T6 scope).  In Heavy Rifle I have used 2 rifles; a M70 .308W target (factory rifle with a Leupold 6.5x20 scope) and a 30x60 XCB built on a VZ24 Mauser with a 31” Broughton barrel.  It has a B&L 6x24 target scope with 1/8 moa adjustments on it.   As to accuracy at 200 yards the environmental factors Ric mentions are the primary concerns especially the wind conditions.  Consistent bench position is the next concern in both classes, particularly in Heavy Rifle class.  Since you move from target to target after as few as just one shot I find repositioning the rifle on the front rest and rear bag to be a concern.  Small changes in positioning the rifle, especially if just the rear bag is used to make the adjustment, can cause small shifts in the center of the group/zero on target.  May not seem like much but the CBA target is a very tough target and subtle shifts can move you right out of the 10 ring or worse.  It's not that much of a concern with the military rifle as the target used for that is the NRA 600/200 with the 10 ring being 2 moa with 30 caliber bullets and 10 shots are shot on the same target consecutively without a change of position.    As to the precision on target at 200 yards the cast quality of the bullet and consistent internal ballistics are the major concern.  Using a correct alloy, correct casting, culling for any visual defect and weight sorting prove beneficial to me.  Proper loading technique, case prep and bullet prep are very important also.    Whichever either class I shoot in, good precision (group size) can be had with a very poor score (accuracy).  The trick is to have excellent precision (group) over the center of either target (accuracy).  Much easier said than done.    LMG

Concealment is not cover.........

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OU812 posted this 30 November 2016

Earths rotation. I think all ranges should face east to west or west to east. Just kidding.

If me, my rifle and load was capable of shooting 1/2 groups consistently in perfect weather. I would say the weather has the greatest effect.

Edit: I have never shot in competition, but I bet you can learn lots from those guys. What is your secret Frank?

BTW I have shot my best groups on calm misty overcast days? Far from nice pretty sunny weather.

...

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R. Dupraz posted this 30 November 2016

Without a doubt,

 Marksmanship skill and consistant bench technique!

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muley posted this 30 November 2016

I agree with R. Dupraz, with the addition of a rifle and bullet combination that has the capability to shoot small groups. some rifles will not shoot, no matter how u caress them.

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frnkeore posted this 30 November 2016

I must applozie for my tardiness of not getting back to this before now. My wife has had (not resent) a stroke and I spend most of my time at the rehab and I'm not very good at typing with my “smart” phone. What I'm trying to bring to light here, is the bullets roll in producing accuracy.

All things being equal at the bench, after leaving the muzzle, it's the bullets roll to do it's best to make only one hole. It's the shooters judgement and responsibility to aim the shot to compensate for what ever conditions may lie between the muzzle and target and this is where the wheat is separated from the chaff on the scoreboard in most cases.

I'm sure that all of us shooters have either over or under compensated for conditions for a shot and here is where I want to make my point. The ballistic coefficient of a bullet (wind bucking ability) can help minimize compensation, and there for minimize over or under compensation. In many cases by quite a lot. Also, it will minimize outliners if, your not seeing a condition, to hold off for.

For about 100 years, in single shot competition, it was said that only flat nosed bullet could produce accuracy but, starting in the 1980's, spitizers arrived and in the hands of the better shooters, they started winning matches and now, almost all match winners use a spitzer bullet. It's my contention, that the dramatic increase in scores since about 2000, is, in part a refection of the increased use of spitzer bullets. Better barrels and faster twist rates, to stabilize the longer bullets, have also played thier part. I know us CB shooters are resistant to change and, let's face it, we're cheap, too, or we would be shooting jacketed bullets into one small hole. We can, in some cases, buy a bullet mold for the price of 250 jacketed bullets. So, whats not to love about that? What I'm going to show you, is the calulated BC of different bullets and how that you can get less wind drift at slower velocity if you use a higher BC bullet. Calulated and real BC's can be different but, the trend will alway be the same. i. e. A bullet design with a higher calulated BC design will in the real world produce a higher BC at the target than design with a lower calulated BC. If that makes since. ALL bullets are made up of dimensions that produce thier shape. BC is real and it will do want it says it will in getting to the target, that being reduced wind drift. BC is a product of the differential of the vel at the muzzle and at the traget.

If a bullet leaves the muzzle at 2000 fps and arrives at the target at 1500 fps, it will have a lower BC that that same bullet leaving the muzzle at 2000 and arriving at the target at 1600 fps. BC can be increased by adding weight to the bullet or changing the nose shape to a longer ogive or both, together. We will start with the accurate and popular MX4 30 ARD. it has a calulated BC of .270, drift is 10 mph wind @ 90 deg to the bullet travel for both bullets. Started at 2000 fps it arrives at 100 @ 1725 fps, with 2.43 of drift and @ 200 it's going 1485 fps with 8.82 of drift.  Next is a popular Paul Jones mold of 32 caliber with a BC of .42 Started a 1500 fps, it arrives at 100 @ 1363 fps with 2.14 of drift and @ 200 it's going 1247 with 7.29 of drift. A drawing of the MX4 30 ARD:

frnkeore posted this 30 November 2016

The PJ mold of larger caliber but, almost the same weight SD is less with it. .319 30 cal, .302 for the 32 cal. Regarding the calulated Vs the real BC, I've done testing with Barry Darr's M43, that measures the BC of bullets. What I have found in that testing is the the real BC's are very, very close to the calculate BC and that the real BC can be about 10% higher that calulated on some bullets. I'm NOT advocating that people slow thier bullets down, what I am advocating is that they try higher BC bullets at the velocity they are now using.  Yes, I know that you can't just go out there and buy anything you like in the way of bullet designs > but, it is something to consider when looking for a mold. And just because it has a pointy nose, dosen't mean it will have a high BC.</p>

<p>Frank</p>

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OU812 posted this 30 November 2016

I like the nose radius of this bullet. Scaled up versions would be nice.

http://s69.photobucket.com/user/swedenelson/media%20PICTURES/NOE_Bullet_Moulds_227_80Gr_SP__78_gr_Sketch.jpg.html>

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Scearcy posted this 09 December 2016

I think it can be very difficult  to determine whether ones accuracy issues are due to the rifle/load or technique.  I am speaking here of Hunter and Production rifles as I have no direct experience with 3” fore ends and 2 oz triggers.  At times I took a pet 223 to the range to see if I could still shoot or had my technique deteriorated.  Only later did it occur to me that shooting an eleven pound rifle with little recoil and muzzle velocity approaching 3500 fps well did not indicate much about my technique with a 9# 308 at 1700 fps.

I don't own a Lead Sled or anything similar so at this point I haven't devised a way to reliably separate my technique (or lack thereof) from the accuracy of the rifle/load.  FWIW after 20+ years shooting production, military and hunter rifles, I believe that many more 2” groups have been spoiled by poor technique than by an inaccurate rifle.  I also believe our better shooters who are shooting well (likely beating the rest of us) but not  great  are limited by their load or rifle - in the 3 classes where I have experience. No science here, only my opinion.

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Ken Campbell Iowa posted this 10 December 2016

i think that most shooters are better than their cast bullet loads ...

if

we are talking about the 90 per cent of cast loads that give 2 to 4 moa groups ... ...

i suspect that no shooter that posts here can not shoot 1.0 moa with a bolt rifle bedded correctly and decent mj bullets with minimum load development ..... over a couple of simple sandbags .

...now for those miracle workers who are shooting cast below 3/4 moa .... yep, they have superior technique... but also a killer load and equipment .

IMHO the biggest obstacle to a higher level  understanding of cast accuracy is simply lack of adequate funding combined with finding the obsessive researchers people ... ...  this isn't NASA with gov't. grants .... and i doubt that there is sufficient reward for the suppliers of cast bullet equipment to have much of a sponsorship budget ... i think we are very very lucky to get the support we do have .... we don't attract much of a spectator crowd ... 

**********

if i were shooting 30 cal., and wanted to check my technique, i would buy a box of sierra 165 gr matchkings and load to about the same velocity as my cast bullet .... probably take me 8 shots to determine my level of bench technique ... .

ken

 

 

 

 

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mtngun posted this 10 December 2016

Frnkeore, you make some excellent points and give us something to think about.

To my eye the unsupported nose of the Paul Jones bullet is too long.    It might suffice at low velocities but will be prone to tipping and yawing if you push it too hard.   There is a reason cast bullets do not have long ogives like jacketed bullets.

The bullet below has a calculated G1 BC of 0.34 despite a conservative ogive length.    10 mph wind drift at typical CBA velocities:

2000 fps, 100 yards = 1.6", 200 yards = 6.7"
2100 fps, 100 yards = 1.5", 200 yards = 6.2"
2200 fps, 100 yards = 1.4", 200 yards = 5.8"
2300 fps, 100 yards = 1.3", 200 yards = 5.5"

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mtngun posted this 10 December 2016

IMHO the biggest obstacle to a higher level  understanding of cast accuracy is simply lack of adequate funding combined with finding the obsessive researchers people ... ...  this isn't NASA with gov't. grants ....ken

 

Agree, Ken.   The jacketed benchrest crowd does not receive NASA funding, either, but they seem to be mostly affluent -- they don't bat an eyelash at the price of Nightforce & March scopes -- whereas casting has always been a working class hobby.    The working class has not done well in recent decades, and what budget they do have for shooting seems to be going into the semi-auto fad, not into traditional target shooting. 

(I don't know how to turn off the italics when replying to a quote in this new forum?)

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Larry Gibson posted this 10 December 2016

Certainly agree Mtngun about cast bullets with long noses at higher velocities.  They just do not have the bearing length to support the bullets long tapered nose during acceleration, especially with the faster twists needed to stabilize the longer bullet.

 

What looks good on paper in design does not always pan out in reality with cast bullets.  I measure the actual BC of bullets in flight with an Oehler M43.  What I've found is bullets with BCs calculated to be .290 - .30o in reality have BCs in the .240 - .250s at 2200 to 3000+ fps.  Thus with cast bullet design for HV use I've found a short somewhat pointed ogive with 65%+ bearing surface to perform best at accuracy with higher velocity.  This is why your 7mm bullet is doing well and why the 311465, 311466 and the NOE 30 XCB in .30 caliber do so well.

 

Larry Gibson (LMG) 

Concealment is not cover.........

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OU812 posted this 10 December 2016

Match Grade Accuracy, Velocity, Bullet and Owning and Operating a Lathe.

Man I wish I owned a good lathe.

 

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John Alexander posted this 11 December 2016

"if i were shooting 30 cal., and wanted to check my technique, i would buy a box of sierra 165 gr matchkings and load to about the same velocity as my cast bullet .... probably take me 8 shots to determine my level of bench technique ... ."

ken

============

I agree Ken for those odd folks that shoot 30 caliber. Often when you do that you can relax about all the ways you could be screwing up -- not that we can't all screw it up with shooting technique. Your suggestion is also one advocated by the late Ed Doonan for checking out whether the rifle/scope is worth working with to shoot cast bullets.  If it won't shoot match grade MJs well at CB velocities it isn't likely to shoot CBs well.

John

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John Alexander posted this 11 December 2016

Ken sez,

"IMHO the biggest obstacle to a higher level  understanding of cast accuracy is simply lack of adequate funding combined with finding the obsessive researchers people ... ...  this isn't NASA with gov't. grants .... and i doubt that there is sufficient reward for the suppliers of cast bullet equipment to have much of a sponsorship budget ... i think we are very very lucky to get the support we do have .... we don't attract much of a spectator crowd ... “

=====

I think an even more potent obstacle to understanding cast bullet accuracy is that most people attracted to CB shooting have little inclination to pay attention to the results from the small amount good experimentation that is done.  We don't so much need funding as more open minds and a willingness to let go of the old rules passed down to us.

Dr. Mann destroyed many of the rules, assumption, and beliefs shooters held sacred in 1900.  Others have repeated his experiments since.  Yet, 2016 CB shooters believe many of things disproved over a hundred years ago.

Most CB shooters seem to approach shooting more as an exercise in a fundamental religion with a strict, inconvenient, rigid, far-fetched, and never changing set of truths rather than a body of knowledge that can be added to by the scientific method. More funding is not going to cure this problem.

John

 

 

 

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mtngun posted this 11 December 2016

 

Dr. Mann destroyed many of the rules, assumption, and beliefs shooters held sacred in 1900. 

Most CB shooters seem to approach shooting more as an exercise in a fundamental religion with a strict, inconvenient, rigid, far-fetched, and never changing set of truths rather than a body of knowledge that can be added to by the scientific method. More funding is not going to cure this problem.
....
Yes, John, but Dr. Mann was able to do what he did because he was independently wealthy.   I'm guessing that Colonel Harrison had a military pension while he was doing his CB experiments, because the NRA didn't pay its editors that much?   Harold Vaughn was comfortably retired when he did his experiments.   Most CBA competitors seem to be retired folks?   I'm not sure how Veral found time to do experiments in his early days?

The jacketed benchrest community seems to be mostly well off and, unlike the CB community, they run out and buy the latest technology no matter how ridiculous the price.     $2500 scopes, $600 rests,  $3000 carbide swaging dies, $1300 actions, etc..  

But I agree that the CB community has a conservative slant.   It's my observation that casting has always been a predominately working class hobby.   Most of us started casting because we wanted to save money.   Eventually we became fascinated with casting & cast bullets as a hobby in and of itself.

 

 

 

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45 2.1 posted this 11 December 2016

John said,


I think an even more potent obstacle to understanding cast bullet accuracy is that most people attracted to CB shooting have little inclination to pay attention to the results from the small amount good experimentation that is done.  We don't so much need funding as more open minds and a willingness to let go of the old rules passed down to us.

Dr. Mann destroyed many of the rules, assumption, and beliefs shooters held sacred in 1900.  Others have repeated his experiments since.  Yet, 2016 CB shooters believe many of things disproved over a hundred years ago.

Most CB shooters seem to approach shooting more as an exercise in a fundamental religion with a strict, inconvenient, rigid, far-fetched, and never changing set of truths rather than a body of knowledge that can be added to by the scientific method. More funding is not going to cure this problem.

John

 

A lot of people ignore what is done because they don't want to shoot a bench rest rifle. Most of these folks buy top of the line commercial that can be carried and used in the field for hunting, varminting etc. To negate any other form of non bench rest rifle experimentation is a crime, because some of those folks can make you set down and examine what you, as a bench rest shooter, are doing wrong.

We are far ahead of Dr. Mann in terms of knowledge of cast now. The problem is very few use it. One MOA cast results doesn't mean you know what you're doing.

The scientific method allows infinite choices. Why don't you use it? Match results allow people to copy the accuracy level, not make a break thru in dramatically improving that level.

 

 

 

 

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David Reiss posted this 11 December 2016

Just moving the thread back to the latest.

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
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