“toppling” 308 ammo 147grain out of a bolt gun?

April 18, 2018, 02:12 PM

So I just shot a new to me Remington 700 SPS tactical 308 today at the range and had picked up some 147gr PMC 308 and some 150gr Fiocchi 308 to try out with it.

While zeroing my rifle, and shooting the shoot n c targets, I noticed the bullet strike on both the target and the cardboard box was unmistakably bullet shaped just as if the bullet was “toppling” into the target....instead of striking with a nice football style spiral. This was only with the 147gr PMC brand ammo.

The Fiocchi 150gr made nice concentric round holes.

I’m new to bolt action rifles, but is this typical or odd to be happening out of a 20 inch bull barrel? The rifle had previously been shot very little.

This was at 50 yards. I did not try it at furher ranges today.

April 18, 2018, 02:30 PM

fritz

Can you provide pictures of the targets?

Sideways bullet impacts -- aka keyholing -- with the information you provided is quite odd. As an FYI, sometimes a bullet tears through thin target paper instead of punching a clean hole. This is especially true if the target paper doesn't have some kind of backing, say a sheet of cardboard or plastic. But this paper tearing is more common with slow-moving, blunt-nosed bullets, such as 45 ACP.

April 18, 2018, 02:50 PM

MNSIG

I'd pull a loaded round and measure the bullet diameter with a micrometer.

April 18, 2018, 03:14 PM

Fusternc

quote:
Originally posted by fritz:
Can you provide pictures of the targets?

Sideways bullet impacts -- aka keyholing -- with the information you provided is quite odd. As an FYI, sometimes a bullet tears through thin target paper instead of punching a clean hole. This is especially true if the target paper doesn't have some kind of backing, say a sheet of cardboard or plastic. But this paper tearing is more common with slow-moving, blunt-nosed bullets, such as 45 ACP.

Unfortunately, I did not take pics of the targets. It did have a strong cardboard box as a target backer.

April 19, 2018, 10:37 AM

Expert308

My Remington 700 Varmint Special in .308 had an oversized bore or something. It would stabilize bullets with a longer bearing surface, but the shorter 155gr Palma bullets wouldn't work in it. I don't think I ever shot any 147's in it.

April 19, 2018, 01:37 PM

fritz

quote:
Originally posted by Fusternc:
Unfortunately, I did not take pics of the targets. It did have a strong cardboard box as a target backer.

It's tough to say the cause. Tumbling shouldn't happen with your rifle, that ammo, and at such a close distance.

I suggest trying it again to see if you can replicate the problem. Then grab the cell phone if it happens again.

Try other ammo, both heavy and light bullet weights. I shot a box of PMC through my 308 a long time ago. I don't recall the details -- bullet weight, distance to target, accuracy. Since I don't recall the results, I suspect accuracy wasn't that great. Probably shot the ammo at 100 yards and something further -- maybe 350 to 500 yards.

I've never had bullets keyhole from my 308, which uses an 11-ish twist barrel that's 23" long. I shot factory ammo with bullets from 110 to 190 grains. Mainly match-grade ammo, but some hunting and FMJ ammo, too.

April 19, 2018, 02:16 PM

LDD

quote:
Originally posted by Fusternc:
So I just shot a new to me Remington 700 SPS tactical 308 today at the range and had picked up some 147gr PMC 308 and some 150gr Fiocchi 308 to try out with it.

While zeroing my rifle, and shooting the shoot n c targets, I noticed the bullet strike on both the target and the cardboard box was unmistakably bullet shaped just as if the bullet was “toppling” into the target....instead of striking with a nice football style spiral. This was only with the 147gr PMC brand ammo.

The Fiocchi 150gr made nice concentric round holes.

I’m new to bolt action rifles, but is this typical or odd to be happening out of a 20 inch bull barrel? The rifle had previously been shot very little.

This was at 50 yards. I did not try it at furher ranges today.

Did you shoot the 150 grain after the 147 grain or vice versa?

Bullet tumbling = failure to stabilize.

I usually see it as a result of a baffle strike on a suppressor, or someone shooting a round that is way to heavy for their twist rate. I suppose it could happen if you shot a round out of a barrel that was very shot-out (no more lands), but that doesn't seem to be the case here. You said the rifle hasn't been shot much, so I'm more inclined to go with barrel irregularity than excessive barrel wear.

The reason I'm asking about the order is that your 147s tumbled, but your 150s did not. That should not be enough weight to change the equation (plus, it's kind of going in the wrong direction: if excessive weight is the issue, the 150s should be tumbling).

Could the barrel have a burr in it that was shot out by the time you switched to the 150s? I'd check the barrel crown for any dings/chips, weird stuff before doing anything else.

The only other thing I can think of (which doesn't make a whole lot of sense, but might be possible) is that the batch of rounds you got was sub-par and your barrel is actually too fast for the bullet construction, and what happened was jacket separation--if that's the case, this shouldn't produce clean bullet shaped holes though, and your "groups" would be very inconsistent.

April 19, 2018, 03:38 PM

YooperSigs

What LDD said. Damaged crown or undersized ammo

April 19, 2018, 04:04 PM

Fusternc

quote:
Originally posted by LDD:
quote:
Originally posted by Fusternc:
So I just shot a new to me Remington 700 SPS tactical 308 today at the range and had picked up some 147gr PMC 308 and some 150gr Fiocchi 308 to try out with it.

While zeroing my rifle, and shooting the shoot n c targets, I noticed the bullet strike on both the target and the cardboard box was unmistakably bullet shaped just as if the bullet was “toppling” into the target....instead of striking with a nice football style spiral. This was only with the 147gr PMC brand ammo.

The Fiocchi 150gr made nice concentric round holes.

I’m new to bolt action rifles, but is this typical or odd to be happening out of a 20 inch bull barrel? The rifle had previously been shot very little.

This was at 50 yards. I did not try it at furher ranges today.

Did you shoot the 150 grain after the 147 grain or vice versa?

Bullet tumbling = failure to stabilize.

I usually see it as a result of a baffle strike on a suppressor, or someone shooting a round that is way to heavy for their twist rate. I suppose it could happen if you shot a round out of a barrel that was very shot-out (no more lands), but that doesn't seem to be the case here. You said the rifle hasn't been shot much, so I'm more inclined to go with barrel irregularity than excessive barrel wear.

The reason I'm asking about the order is that your 147s tumbled, but your 150s did not. That should not be enough weight to change the equation (plus, it's kind of going in the wrong direction: if excessive weight is the issue, the 150s should be tumbling).

Could the barrel have a burr in it that was shot out by the time you switched to the 150s? I'd check the barrel crown for any dings/chips, weird stuff before doing anything else.

The only other thing I can think of (which doesn't make a whole lot of sense, but might be possible) is that the batch of rounds you got was sub-par and your barrel is actually too fast for the bullet construction, and what happened was jacket separation--if that's the case, this shouldn't produce clean bullet shaped holes though, and your "groups" would be very inconsistent.

I shot the 150gr AFTER the 147gr.

Ive been running the sequence through my head, and another possibility I was thinking might have been the culprit was the bullets could have been skipping off the range floor and then striking the target (as I was adjusting a new to me scope and rifle) and possible causing the keyholing and at the time erratic grouping with the 147gr.

About the same time I switched to the 150gr I found I had to come way up on the scopes elevation adjustment to be even on the target. I’m hoping this somewhat embarrassing possibility is the cause.

April 19, 2018, 05:12 PM

sigfreund

quote:
Originally posted by Fusternc:
I’m hoping this somewhat embarrassing possibility is the cause.

That would do it.

Thanks for ’fessing up to that possibility because I was puzzled myself by your description of the problem.

I couldn’t figure out why the accuracy of some loads with my new 300 Blackout T/C barrel were terrible when using a suppressor, but were fine without it. Then I discovered that the threads on the barrel had not been cut in line with the bore and I was getting end cap grazes with the suppressor.