Effects on barrel fouling with a change in bullet.

[Norm]

Without cleaning the barrel.
What effect, if any, is there between shooting a group with one brand of bullet on the next group shot with a different brand of bullet.

Thinking jacket metal differences, friction changes etc.

Should a barrel be cleaned when changing from one brand of bullet to another?

Anyone notice that a barrel may need a few shots down the tube to settle down after changing bullets?

[IanP]

Norm, a bit more info would be helpful to be able to understand your question. I assume you mean the same weight and type projectiles but from different manufacturers.

The simplest answer is that if the two bullets (assuming same weight and load) from two different manufacturers have the same ballistic coefficient (G7) then the two groups shot with the same load should be very similar.

In reality though different manufactured projectiles have different weights, shapes and BCs and therefore will never be the same or come close to being identical.

Its best to shoot one type (brand) of projectile in a competition in the 10 shot string. Its ok to mix brands, weights, BCs, etc, for different ranges in a competition once you have worked out the drop charts for them. Dont mix bullet types in a 10 shot (whatever) string unless you want to drop points or have run out of one type of ammo and have no choice in the matter.

Test for yourself by making up some loads the same but use different projectiles and then come back and post your results. As far as barrel fouling goes the same load with the same weight bullet should produce a similar amount of barrel fouling.

IanP

[AlanF]

Norm,

With regards fouling, I've been warned about mixing powders, but can't see any need for concern about mixing projectiles, apart from an obvious one which is mixing molyed with naked (its best to stick with moly if you go that way). In any event, common sense says that fouling can only be as bad as for the worst of the projectiles - I don't believe there would be any multiplier effect.

But that's just an opinion based on limited experience. Beware of some of the theories you hear around the ranges. Get plenty of opinions, discard the extreme ones and settle for the middle ground until you see convincing evidence to the contrary.

Alan

[johnk]

Norm,

There's an obvious difference (based on colour) between Hornady & say, Sierra projectiles which you might reasonably assume correlates to some difference in the constituents of the bullet jackets. Whether or not that results in a deleterious outcome when shooting one after another, why risk it? Components are expensive enough without potentially wasting them with abortive testing.

I'm as sure as I can be at my age that I at least once read admonitions not to mix powders AND projectile brands at a single test without cleaning between.

On the other hand, back in the days of my youth, I recall shooting a 15 shot group MOA out of my .222 Magnum which consisted of the tag ends of eight different brands & weights of projectiles from 50 to 55 grains, all with the same charge of powder.

John

[Norm]

Thanks for the help.

I am actually shooting Sierra Matchkings and Berger VLD hybrids against each other in some load developement work. Both bullets are the same weight. Initially I used the same powder and charge but have played a bit since then.

I have mostly ever shot SMK's in this rifle and it works well with them.

Only using three shot groups at 1000 yards initially until I get something that looks good. Only firing one group with the Bergers each day at this stage. Then after the test I do a bit of practice with my standard load on SMK's before I pack up.

I have been firing one three shot group with the SMK's and then after the barrel cools I fire a three shot group with the Bergers. Getting vertical with the Bergers but not with the SMK's.

Have changed the powder and charge a bit without any luck so far.

Thinking there might be a difference between the fouling left by the SMK's and the Bergers. Making the first couple of shots on the change over from one to the other a bit unreliable. Not real sure.

[AlanF]

Norm,

In my opinion, it'll be the different projectile shape that will be the cause of the performance difference. The ogive shapes, and bearing surface diameters will almost certainly be different, and apparently the SMK suits your throat/rifling/bore better. That's why its good to have a selection of projectiles available. Out of interest, what is the calibre and projectile weight?

Alan

[Norm]

Alan,
It is .338 calibre and I am shooting two different bullets. The 300gn SMK and the new 300gn Berger Hybrid.

Be great F-Open rounds if permitted but might get a few complaints about the noise from the other competitors.........LoL.

Trying to get a handle on this verticle stringing so that I have options for when my .284win F-Open build is ready in a few weeks.

I will be trying the 7mm SMK's and Hybrids in that rifle also.

[RAVEN]

Norm
In some cases the brand doesn’t matter because the bullet makers buy in the copper cups and the shape is determined by the bullet die they use I would clean between different bullets or any component change as it gives you a common starting point.
Cheers
RB

[Chopper]

Good question Norm, i like those type, maybe you could tell us if you put it to the test, be worth knowing , Regards Chop.

[Norm]

Chopper,
Yes putting it to the test alright. Hope to get it sorted.
Going to try sticking with the one brand of bullet instead of changing between groups.
Also going to try seating depth changes and a ladder test with powder changes.