Are the lands in a barrel supposed to cut the bullet?

[oldFred]

Dumb question I know... but are the lands in a barrel of a 1911 supposed to cut into the bullet?

I have a new 1911 and shooting it I have noticed the first few rounds shoot lower than my aimpoint (from 2 to 6 inches). As 25 rounds or so pass through it and the gun gets warm the target is right on the mark at 15 yards. So when the gun is warm it's more accurate. Keep in mind this just might be my perception as I am a novice handgun owner.

Not long ago I shot some rounds downhill at a target and several rounds went into the dirt and put 4 foot skid marks on the grass. I dug up one of the rounds and noticed that the lands had cut through the FMJ and exposed lead strike marks. Is this normal?

Also can I expect this to get better as I get some wear in the barrel?

 

[wrc376]

totally normal

 

[wrc376]

as far as bullet trajectory, different grain bullets have different stabilization characteristics... a 230grain bullet tends to fly a little more stable than others... 185 grain seem to drop to the left. it is also possible that you are not holding the gun correctly. 1911s need a firm base!

 

[GRIZ22]

The lands are supposed to "cut" into the bullet. That is how the bullet engages the rifling and the rifling makes the bullet spin.

I have a new 1911 and shooting it I have noticed the first few rounds shoot lower than my aimpoint (from 2 to 6 inches). As 25 rounds or so pass through it and the gun gets warm the target is right on the mark at 15 yards. So when the gun is warm it's more accurate. Keep in mind this just might be my perception as I am a novice handgun owner.


I would say this might be your perception. You may be paying more attention to the sights or your trigger pull with subsequent shots making it "more on target". Are your first few rounds in a group but low? If so what I said above might be the reason.

I dug up one of the rounds and noticed that the lands had cut through the FMJ and exposed lead strike marks. Is this normal?


The break in the jacket more likely is the round hit a stone in the ground not from the rifling. If you are shooting plated (not jacketed) bullets the rifling may be cutting through the much thinner (than jacketed) plating.

Also can I expect this to get better as I get some wear in the barrel?

Most barrels tend to get more accurate when they are broken in. This is more prevalent in rifles than handgins as you shoot rifles at longer distances. The diffrence in accuracy is not that much in most cases.

 

[748]

It doesn't really cut the bullet. The 21,000 psi of peak pressure in the chamber causes the copper jacket or lead to deform like plastic.

 

[doubs43]

A better word would be "engrave". The bullet fills the lands and grooves as it moves down the barrel but retains 100% (for all practical purposes) of it's full, unfired weight. The lands engrave the bullet and cause the spin that stabilizes it.

 

[tipoc]

I have a new 1911 and shooting it I have noticed the first few rounds shoot lower than my aimpoint (from 2 to 6 inches). As 25 rounds or so pass through it and the gun gets warm the target is right on the mark at 15 yards. So when the gun is warm it's more accurate. Keep in mind this just might be my perception as I am a novice handgun owner.

Most likely this is just your perception and is caused by you're "settling" into shooting the gun. It often takes folks a few rounds to find their groove.

The spiral grooves cut into your barrel are known as rifling. It's from these grooves that rifles got their name. Before these grooves we had smoothbore muskets with round ball ammo, literally balls of lead. Generations back it was discovered that if you cut a spiral groove in a musket barrel two things happened, one the ball traveled further and two the shot could be more accurate.

What was happening was that as the soft lead of the bullet entered the spiral groove it compressed and took on the shape of the grooves. This allowed the bullet to develop a certain rate of spin which helped to stabilize the bullet in flight allowing it to travel further and be more accurate. This led to a great deal of experimentation in bullet shape and the rate of twist of the spiral in the barrel. This experimentation has not ended. All unfired bullets are slightly larger than the bore of the barrel. All are also softer than the material from which the barrel is made. So when they enter the rifling they compress, or swage.

Hope this helps.

tipoc

 

[oldFred]

Thanks! Excellent dumb question on my part!

 

[tipoc]

If you didn't know, well you didn't know. When I don't know something, that I want to know about, I figure the smart move is to ask, get an answer, think on it, study some, think some more. Dumb not to ask. That is if you want to know in the first place.

tipoc

 

[Jim K]

The bullet doesn't swell out into the grooves, the lands cut into the bullet.

In a modern breech loading firearm the bullet is at groove diameter, not at bore diameter. For example, in a .308 Winchester, the bore is .300 inch and the groove diameter is .308 inch. The bullet is .308" or .3085". (Some tolerances on all those measurements, of course.)

Jim

 

[The Lone Haranguer]

The bullet is forced into the grooves, which causes the metal to displace (i.e., pushed to the sides), not really slice through. If it were literally cut, there would probably be long spiral strands of bullet material (similar to drill shavings) left in the barrel.

 

[Jed Carter]

If the "jacket" was cut through the bullets may be billed as fmj but are actually "plated" lead. The metal covering is only a few mils thick, or .002 to .004 millimeter. Many of the reloads, cheaper ammunition is going to plated lead bullets, ok to shoot except in polygonal barrels, ie; Glock and others.

 

[Jim K]

The metal is not "pushed to the sides", it is compressed where the lands squeeze it.

Jim

 

[Odd Job]

Uncle Jim, would you say it is similar to tube swaging?

 

[rcmodel]

cheaper ammunition is going to plated lead bullets, ok to shoot except in polygonal barrels, ie; Glock and others.

Plated bullets are perfectly safe to shoot in Glocks or any other polygon rifled barrel.

Do you think those ammo manufactures would be selling ammo that might Kaboom a Glock because they were loaded with a plated jacket bullet? Of course not!

It's lead bullets that, according to Internet lore, cause problems.

rc

 

[jjohnson]

Cut? Engrave?

I dunno, IMHO, it's more of a swage than anything.....

Anyway you look at it, though, if the bullet's outer surface didn't conform to the rifling, it certainly wouldn't have enough spin on it to keep it stable very long.

 

[Jeff F]

I shoot a couple of 1911's that when clean do not shoot to POA until I fire a few rounds and foul the barrel. Could that be the problem?

 

[The Mayor]

My vote is that the bullet is extruded through the barrel.