Change of primer impact on accuracy

[rainwalker]

This might be hard to give an exact number on but I suspect the primer is one of the lesser influences on accuracy compared to powder charge, bullet etc.

If you had to put a number on it, how much could a different primer effect the accuracy of a proven load?

1%, 2%?

Thanks.

[Jack V]

Gee mate 1 to 2 % is still a very narrow margin to quantify something that has a small effect to start with, but an affect none the less.

Any effect of changing primers is not in any way a linear thing. It can't be observed in every case, if a rifle is very accurate it will give a far better chance of seeing slight accuracy changes but if it's not very accurate the changes could be lost in the normal group variations. Also the number of variables in load components, loading techniques and gun manufacture is staggering. For example in a 243 W case you may change from a Winchester LR primer to a Federal 210 and see a slight accuracy change but do that same change with another cartridge in another gun and it may show nothing that you can observe.

We are getting into an area of contention. Like one person with a super accurate BR gun might be able to see a certain effect but the other guy with an average factory gun can't see that same effect so he says it's all BS. If you are shooting consistent average.25 groups you have a far greater chance of seeing a.1 average change than the guy shooting groups that vary from 1.00 to 1.5 inch groups.

However on average it does have a low effect on the average reloader but it still should not be ignored when using loads approaching maximum loads. Once the pressure is high any component change can have a more magnified effect than it would other wise be at safer pressures.

[Carter]

To have any hope of measuring a clear difference you would need to be a shooter of consistently top accuracy, and shooting over long enough distances for the change to present itself.

I don't know what that distance is but it won't be 100m for average Joe shooter.

Sounds like you're not the super-shooter described above (no offence, just saying. And neither am I ) but it'll be so small for you you wouldn't see a difference.

[6mmdasher]

I had to do a bit of experimenting to get the average velocity spread down to acceptable levels (10 fps) or less on a 260 Rem target rifle. I had been using BR4 primers and couldn't get better than 20fps spread. I changed to Mag primers and that made it worst( 40 fps). I made the same load up with Fioccoci primers and some std Federal primers and the spread dropped to the 10 fps and the groups at 100 yds were nice and round. Shooting the loads at 500 yds and 600 yds made for a very flat groups and high centre counts. It is probally off the topic a bit but primers can have a significant effect at longer ranges.

[Jack V]

It's not off the topic , it's right on the money. If you have that tuned accuracy to start with and are going even further with a chronograph then you can detect that primer change . The longer the range the more you could see a slight improvement in the groups as long as wind is not an issue .
I can see the difference between a Winchester primer and a Federal in a .243 with just shooting at a 100m paper . However when I did the same thing in a 308 I can't see the difference . I'm sure if I used a chronograph and re tweaked the loads it would show a clearer winner . However the groups are good enough for what I need so I don't bother even though I have a CED m2 chrony . If I was shooting at 600 m though I would probably bother .

[rainwalker]

I had to do a bit of experimenting to get the average velocity spread down to acceptable levels (10 fps) or less on a 260 Rem target rifle. I had been using BR4 primers and couldn't get better than 20fps spread. I changed to Mag primers and that made it worst( 40 fps). I made the same load up with Fioccoci primers and some std Federal primers and the spread dropped to the 10 fps and the groups at 100 yds were nice and round. Shooting the loads at 500 yds and 600 yds made for a very flat groups and high centre counts. It is probally off the topic a bit but primers can have a significant effect at longer ranges.

Nah helpful stuff, Dasher

Thanks

[Aussier]

I'm no match shooter, but for hunting purposes bugger all impact.

[tom604]

^^^^^^^this i do wonder just how much difference a primer would make long range?

[SendIt]

i do wonder just how much difference a primer would make long range?

I'll borrow 6mmdashers figures to give you some idea... his best was 10fps variance and worse was 40fps variance in velocities so we can work on the 30fps extra.

Take a 155gr, .467BC .30 calibre bullet with 100 yard zero.

At 3,000 fps muzzle velocity this has -46.5" drop at 500 yards and -314.7" drop at 1,000 yards.

At 2,970 fps muzzle velocity this has -47.6" drop at 500 yards and -322.3" drop at 1,000 yards.

Up to an extra 1.1" vertical spread at 500 y, up to 7.6" vertical spread at 1000 yards. Would only get worst from there.

That's just considering velocity, the resulting change in harmonics would also have some effect. Can probably skip that conversation though as it will be the same ..... Minor change, no impact for hunting, some impact for match shooting compounded over distance.

[5Tom]

With my .243 at 100m, I tested the differences between Winchester LR and CCI200 primers with identical projectile, powder, case lengths, seating depths and anything else that could be the same.

I shot multiple groups from each batch of ammo and found the CCI primers showed a tighter group on average over Winchester LR.

Looking back over previous groups with my m91/30, I had better results with Winchester LR primers than I did with CCI 200!

So with my own experiments and my own results, yes. Primers make a difference.

[bigfellascott]

Boy am I glad I only hunt, if I had to go to all this trouble to hunt I reckon I'd give it a miss.

[VICHunter]

Boy am I glad I only hunt, if I had to go to all this trouble to hunt I reckon I'd give it a miss.

I hear you.

[sally-bee]

Not worth the bother for hunting?

[Tiiger]

There is just no need for hair splitting accuracy for hunting.

If you can hit the vital zone which from 3" - 10" or whatever depending on the animal size it will drop.

A 10th of an inch improvement from a primer change means nothing.

No harm in doing it, but most couldn't be bothered.

[Lorgar]

Not worth the bother for hunting?

Well, as an example I can tell you my Tikka shoots about 1" groups at 200m. Easily enough for any kind of hunting here.

I could spend hours and 100 rounds trying different primers, but even if one improves my accuracy I don't actually gain anything. Still hitting the animal same as before, it's not any more dead for the group being a few % smaller.

No reason to bother with it.

[bigfellascott]

Not worth the bother for hunting?

Nope not for me anyway, I don't shoot groups on em - 1 accurate shot is all I'm after.

[sally-bee]

True.

Over thinking things

[bigfellascott]

True.

Over thinking things

I wouldn't say over thinking it at all, just that shooting targets and hunting are two different disciplines needing two different approaches for want of a better word, ones required consistent accuracy for each shot the other I guess only requires 1 good shot with reasonable consistency so to speak.

Target/long range shooting requires a high degree of consistency of ammo to achieve the best results

Hunting only requires 1 good shot to get the job done well and most ammo is good enough for that at average hunting ranges

Varminting well that requires a more tuned version of ammo to hunting but not to the same degree as target ammo (although some will of course disagree with that and say the more tuned the better) and of course they are right but for me I'd rather be sending let down range on fur than spending a heap of time and money to achieve a few mills diff at the pointy end - each to their own of course, for my needs that sort of effort isn't required hence my lack of willingness or interest in doing so, mind you if I wanted to do extreme long range shooting on fur well I'd probably put the effort in to achieve a more consistent outcome.

I guess at the end of the day it depends on what you're trying to achieve as to whether all this fine tuning of ammo etc is needed or warranted.

[melanie]

Well, as an example I can tell you my Tikka shoots about 1" groups at 200m.

You can shoot groups that size hunting?

I feel like a real novice now

[tom604]

don't sweat it Melanie, Logar would be settled in with a bipod or backpack as a rest to get those groups (good groups by the way) not many people , if any, will get those groups standing up leaning against a tree branch

[brett1868]

It's all about consistency of the burn when it comes to primers. You're standard generic primer is mass produced to a particular standard and tolerance where as match grade primers are made to a tighter tolerance with a higher price as well. Standard primers may have very minor differences in the amount of compound used which will cause a change in how the main charge is ignited which leads to different velocities if only minor. Distance compounds the irregularities as the math has shown by Sendlt but at normal hunting ranges poses no issues. I only "Match" load a few calibers I use for extended range but for hunting I do as most do and that is prime, charge, seat some lead and shoot.

For hunting I use CCI 250 LMR or CCI200 SMR
For long range Federal GM215M
416 / 50 Plinking CCI 35
416 / 50 >1000m RWS

[Lorgar]

Well, as an example I can tell you my Tikka shoots about 1" groups at 200m.

You can shoot groups that size hunting?

I feel like a real novice now

Ha ha. No

That's not free hand shooting, that's off a bipod and bench at the range.

What I was saying is my rifle and hand loads are capable of shooting 1" groups at 200m which is more than enough for any hunting. If I miss a target anywhere between 0 - 200m it's because I missed, not because of inaccurate ammunition.

There is no point me trying another primer because it won't add anything to my hunting.

[rainwalker]

Distance compounds the irregularities as the math has shown by Sendlt but at normal hunting ranges poses no issues.

Yes, I see.

Thanks for taking the time to work out the math Sendit.

And everyone for their answers.

[SendIt]

No problem.