question about changing bullets...

[triple tap]

hi there, ive been shooting 55gr vmax bullets out of my Mossberg mvp with good results but im gonna be trying out some 75gr bthp's... ive loaded up a ladder test with 5 rounds of each charge weight and im planning on seeing what charge weight will perform best...

my question is: ive heard people say that when switching bullets, you should shoot around 10 of the new bullets down the barrel with a low/safe powder charge just to lay down a new bearing surface of copper inside the barrel... is this true or hog wash?

 

[bearhunter]

Hog wash it is. It all depends on your rifle. If you have a barrel that shoots well clean you're lucky. Most need a bit of fouling to settle down.

One thing though if you're going to hunt with that rifle, do your ladder tests with a cold barrel. It takes longer but it will save a lot of issues later.

When hunting, you don't usually get enough shots off to warm up your barrel, unless you're shooting gophers.

That 75gr bullet should work well in that 1-9 twist barrel. It may even shoot tighter groups than the 55 gr bullets. I know my Tikka with a 1-8 twist rate shoots better with the heavier bullets but not much. Sometimes the heavier bullets are just better suited for the job.

 

[9.3mauser]

I would say that's nonsense. If you've already been shooting copper alloy jacketed bullets, what possible difference could it make to shoot more at low pressure, except to add more fouling to an already fouled bore?

 

[skypilot]

Unless it is a custom barrel and some form of voodoo is required by the barrel manufacturer, I wouldn't worry about it.

Shoot the gun about 60 rounds, then rough in the zero, then load develop or try numerous factory loaded brands/weights. Then pick the best load and fine tune the zero.

 

[Camaroguy]

I've noticed in my Remington 700 in 223 that I need to shoot 2 or 3 rounds of my handloads after shooting bulk Winchester ammo before the gun returns to it's accuracy potential and it's zero. The first 2 or 3 after switching back tend to scatter a bit.

 

[sunray]

Even a hog wouldn't bathe in that info. The copper is one of the things you're cleaning out when you clean the barrel.

 

[guntech]

hi there, ive been shooting 55gr vmax bullets out of my Mossberg mvp with good results but im gonna be trying out some 75gr bthp's... ive loaded up a ladder test with 5 rounds of each charge weight and im planning on seeing what charge weight will perform best...

my question is: ive heard people say that when switching bullets, you should shoot around 10 of the new bullets down the barrel with a low/safe powder charge just to lay down a new bearing surface of copper inside the barrel... is this true or hog wash?

What was observed in post 5 does occur.

Back in the 70's a friend of mine who was really into Benchrest accuracy told me if you are trying different loads with different powders it is best to clean the barrel before switching... sometimes the different powder residue caused a slight difference in accuracy until several shots were down the tube. Those first few shots were not indicative of the accuracy. He believed in some cases bullet material did the same thing. Most barrels require at least one fouling shot before grouping well.

I doubt many have a rifle accurate enough or the ability to distinguish these small differences.

sunray as usual has squatted, dropped and fled.

 

[krprice84]

What was observed in post 5 does occur.

Back in the 70's a friend of mine who was really into Benchrest accuracy told me if you are trying different loads with different powders it is best to clean the barrel before switching... sometimes the different powder residue caused a slight difference in accuracy until several shots were down the tube. Those first few shots were not indicative of the accuracy. He believed in some cases bullet material did the same thing. Most barrels require at least one fouling shot before grouping well.

I doubt many have a rifle accurate enough or the ability to distinguish these small differences.

sunray as usual has squatted, dropped and fled.

It might matter significantly for bench rest, but for this I kind of doubt it will be that significant. If you are really concerned load up five or ten extra rounds at minimum charge and send them first. At worst this will bring your barrel up to temp.

And doing the ladder on a cold bore each shot shouldn't really be a big deal. Your load should still be most accurate hot or cold, it's your point of impact that will change slightly.

Just my opinion here.

 

[OldDude]

I've noticed in my Remington 700 in 223 that I need to shoot 2 or 3 rounds of my handloads after shooting bulk Winchester ammo before the gun returns to it's accuracy potential and it's zero. The first 2 or 3 after switching back tend to scatter a bit.

I've read about a similar effect in Warren Page's "The Accurate Rifle", and I have noticed this as well. Apparently, this is from different types of powder, and the resulting differences in fouling. I'll take his word for it.....

 

[bearhunter]

I've noticed in my Remington 700 in 223 that I need to shoot 2 or 3 rounds of my handloads after shooting bulk Winchester ammo before the gun returns to it's accuracy potential and it's zero. The first 2 or 3 after switching back tend to scatter a bit.

Are you talking about doing so all on the same outing or on separate days. I don't know how often I see some inexperienced newbie, I'm not saying you are, sight in a rifle while the barrel is hot. For a hunting rifle this is a sure way to miss your target. Not only that, changing brands of ammo and the bullets they fire is also going to change a lot of things, especially barrel harmonics and points of impact. Also, cleaning between changing out the ammo will also cause bullet spread. Most rifles like to be slightly fouled.

I always sight my hunting rifles in before the season starts and don't touch the bores again until the season is over. The only time this will change is if I manage to get some crud down the bore, like mud, sand or tree needles.

Any time anything is changed in a load, something different is put into the equation. Especially on very accurate rifles you get different points of impact. One of the big issues with Bench Rest Shooters is getting enough powder, primers and bullets from the same lot to keep their rifles shooting accurately. Often the custom bullet makers would only send 500 at a time. We are talking hand swaged bullets with J4 jackets. You could guarantee that every time we got a new lot of any component point of impact would change.

Some guys would try to utilize every bullet and do so in a match. That is fine until you run out and have to switch lots. That is a guaranteed way to place in the bottom string on a match. I used to use the left overs for fouling rounds before a match and after the cleaning cycles. Some fellows offered to buy them from me but it wasn't worth it to me to sell them. That left me more bullets that were consistent to my scope settings for matches.

 

[triple tap]

I've noticed in my Remington 700 in 223 that I need to shoot 2 or 3 rounds of my handloads after shooting bulk Winchester ammo before the gun returns to it's accuracy potential and it's zero. The first 2 or 3 after switching back tend to scatter a bit.

ok maybe this is what I remember hearing... or maybe it was switching from cast to copper jacketed.... anyways, ill just give it a go and see what happens, I don't expect the first few low powder charges to be my most accurate ones anyways....

thanks for the answers guys