Factory Ammo Overpressure?

[Sartori42]

I am relatively inexperienced in the world of precision rifle shooting. Something happened this past weekend that I think I should share. I also have a number of questions at the end. I apologize for the length of this story.

For reference, I have a Tikka T3X Varmint (223 Rem) mounted in a KRG Bravo chassis.

I recently purchased five boxes of Sellier and Bellot 69g. Precision Rifle ammunition (No. 1380). Part of my preparation for shooting any ammunition is to measure four different parameters of each round in a 40-round set (2 boxes). I measure base-to-shoulder (headspace?), base-to-ogive, overall length, and bullet runout. From the first two measurements, I calculate the shoulder-to-ogive length, and sort the ammunition based on that dimension into eight groups of five for firing.

With the S&B ammo, I immediately noticed a large variation in the base-to-shoulder (B2S) measurement. Normally, I measure between .001” and .004” of variation with the factory ammo I shoot. With the B&S, I measured .013” variation in the 40 rounds measured. That’s huge! Normally, the base-to-ogive (B2O) measurement gives me a .002” to .009” spread. With the S&B, I again measured a .013” spread. More, but not so much. The OAL and runout measurements were actually pretty good, better than average. I was interested to go to the range to see how well the ammunition would shoot based on these measured variations.

The published velocity of this ammunition is 3018 fps. I take the manufacturer claims of velocity with a grain of salt – sometimes a large grain. Federal Gold Medal 69g. (GM223M) claims a muzzle velocity of 2950 fps, but in my rifle, I get an average of 2831 fps. Fiocchi Exacta 69g. (223MKC) claims 2850 fps, but in my rifle, I get an average of 2741 fps. Winchester Match 69g. claims 3060 fps, but I get an average of 2693 fps. This Sellier and Bellot claimed 3018 fps, but at the range I was measuring velocities of between 3017 and 3072 fps. When I saw these values on my chronograph, my eyebrows went up, but that was all. Here is where more precision rifle shooting knowledge and experience probably would have paid off, but I didn’t have it.

After 25 rounds, 5 groups of 5 shots without incident, I started on the 6th group. When I pulled the trigger on round #26, I felt a blast of air/gas/something hit my face. It startled me. I could see that the round hit the target in the expected location. I thought I noticed a different smell from the shot. When I tried to eject the round, the bolt was very difficult to lift. With some effort, I was finally able to eject the casing, which I examined. To my untrained eye, there didn’t appear to be anything wrong with the casing, but I saved it anyways. I reinserted the magazine and fired round #27. The same thing happened, but maybe with less severity. Not as much “blowback”, and not as difficult to lift the bolt. More difficult than normal, but not as bad as round #26. I again examined the casing and also removed the bolt from the rifle to examine that. To my eye, everything looked fine. I was able to run the bolt normally without a magazine inserted into the rifle. So, I reloaded and fired round #28. This round went off much the same as #26 with a noticeable slap in the face from some sort of high-speed pressure wave. At that point, I discontinued shooting and packed up. I saved casings from rounds #26, #27 and #28, and also grabbed 5 more casings from earlier rounds that I didn’t have a problem with.

At this point, on the drive home, I suspected there might have been an overpressure issue, but I hadn’t expected this from factory-produced ammo. Once home, I did some research on the signs of overpressure and that is exactly what I think happened. The five casings I collected and #27 had cratered primers with raised edges around the firing pin dent. Rounds #26 and #28 had very deep pockets in the primers from the firing pin; almost like caves. The faces of all primers seem very flat to the edge. Also, upon inspecting the bolt face of my rifle, I can see a primer-sized ring around the firing pin hole. In my opinion, this ammo is not safe to use.

I am surprised that factory-produced ammo is loaded this hot. Knowing what I know now, I should have inspected the primers after I first saw such high velocities. They were 200 to 350 fps faster than other 69g. ammo in my rifle. At the range, I didn’t know how much faster these rounds were, but I knew they were pretty fast.

So, for those who have stuck with my story to this point, a few questions:
1. Do I need to have my rifle inspected by a gunsmith?
2. What components of the rifle could have been damaged by these high-pressure rounds? I looked at the barrel with my borescope, but don't see anything abnormal there. Could something within the bolt assembly be damaged?
3. Should I contact the company where I bought the ammo to advise them of what happened?
4. What should I do with the remaining 3 boxes of ammo? I don’t think they would be safe for anyone to fire. Correct?

I learned a valuable lesson here and I hope others can find some value in my experience. I’m happy that I wasn’t hurt. I hope my rifle escaped unscathed.

Cheers.

Steven

Photos: Boltface1 and Boltface2 - not cleaned after the range to preserve coloration.
Photos: Normal1 and Normal2 - a casing I have fired in the past. Just for reference.
Photos: SandB01 and SandB02 - a casing from shots 1 thru 25. Note cratering on the primer.
Photos: SandB26a and SandB26b - casing from shot #26. Deep hole in primer. #28 looks very similar.

 

[DownhillFromHere]

I had a Tikka Varmint .223 for about a year and a half. A few thoughts...

• Tikka barrels' velocity typically runs slower than many others... and you're right that manufacturers' box velocities are almost always optimistic.
• My Tikka Varmint cratered primers too. I only fired one brand of factory ammo (Defender Ammunition, which is manufactured about 90 minutes from where I live), and didn't experience cratering with it - even when I shot 5.56x45-stamped 77SMKs, whose velocities were pretty low for the caliber - e.g., not "hot." I saw some cratering on mild to moderate handloads, especially with CCI 400s.
• It sounds to me like you definitely have some overpressure signs. You have a borescope... so there is no carbon ring in front of the chamber/before the leade?
• While I don't use factory ammo anymore, I personally - this is just me so save the flaming - would never use Sellier & Bellot before I started handloading .223. I won't even use their brass. Why? Because the majority of even once-fired S&B 9mm brass I tried to load was inconsistent and swollen at the web to the point it wouldn't pass gauge testing. I learned to just pitch it in the recycle bin.
• I don't think you need to have a smith check your rifle, but if you have one close by & convenient, it surely wouldn't hurt. It's never been clear to me why my Tikka Varmint exhibited pressure signs with even the mildest loads when using thin, soft CCI 400 primers while other .223-chambered rifles seemed to run them just fine.
• I'd certainly each out to S&B with this story. I've only reached out to an ammo company once regarding "bad" factory ammo, and that was to Winchester back in the '90s because their 28-gauge AA shotshells had an extremely high percentage of split case mouths after the initial firing. Seems like they sent me coupons or something for replacements.
• I wouldn't shoot any more of that ammo myself. Others may disagree.

I hope you'll update this thread as you learn more. Good luck.

 

[Sartori42]

Downhill,

Thanks for the reply. To clarify my question #3... I'm not necessarily thinking about trying to contact Sellier and Bellot, a Czech company. I bought the five boxes of ammo over the internet from an American online retailer. I'm wondering if I should contact them?

 

[GrumpyOleFart]

S&B were notorious years ago for hot .303 rounds.
A few collectors spread the word about them, I recall.
That's about all I know of them.

No harm in getting your Tikka checked out.

 

[hlee]

The S&B 300 blackout ammo that I bought seemed really hot. Just another data point...

 

[Sartori42]

So, questions #1 and #2 have been answered. I called my gunsmith and explained the situation. Their work backlog extends to about 2 months, but because I'm something of a "regular" there, the guy said to bring in the rifle and he'd take a look at it while I waited. The rifle checks out good, so I'm still in business. No more Sellier and Bellot for me, tho...

 

[DownhillFromHere]

Downhill,

Thanks for the reply. To clarify my question #3... I'm not necessarily thinking about trying to contact Sellier and Bellot, a Czech company. I bought the five boxes of ammo over the internet from an American online retailer. I'm wondering if I should contact them?

You can contact them, but I seriously doubt you'll get any satisfaction/remediation. One option is to see if someone with an AR (either 5.56x45 or .223 Wylde) or a .223 bolt gun throated long to take the heavier bullets seated long would want your remaining ammo.

As I said, I had a Tikka like yours and found that even the mildest handloads primed with CCI 400 primers exhibited pressure signs (the harder CCI 450s were fine). My newer .223 bolt gun - actually chambered in 5.46x45 - happily digests 75-grain bullets at 2900+ fps primed with 400s, no pressure signs at all. I'm simply reinforcing the point that the hot S&B ammo will probably be fine in a longer-throated rifle.

 

[AKMarty]

Any idea how close to the lands your cratered rounds were? Tight or short chamber that would jam the bullet?

 

[Sartori42]

Downhill,

Actually, I'm pleased to report that the seller agreed to take back the unused ammo and refund part of my purchase. He said the following : "Most of the commercial ammo you buy is reduced pressure loaded near the bottom or middle of the SAAMI spec range, the factories underload to intentionally circumvent potential pressure problems in a wide variety of firearms. When you get into government contract ammo the ammo is optimized for a more narrow range of firearms and typically loaded to CIP spec at the higher end of the pressure range than commercial sales material, and occasionally that is going to have some issues in some commercial firearms and there are a number of factors that can play into that. When you get into 223 and 5.56 the long heavy 69 to 77 grain bullets add to the issue as well. We have seen this issue with IMI 5.56x45 77 and 69 grain pretty commonly back when they were loading at full mil-spec pressure, they had to reduce in 2016 and even after that, we see it occasionally."

He also reported that he has never had any issues reported with this ammo. While my Tikka is damned accurate, it may not like to be pushed to the limits.

 

[Sartori42]

AKMarty,

No, don't know where the lands are in my rifle. It's something I plan to work out, but haven't done it yet.

As I stated in my original post, I measure 4 parameters of the ammo I shoot. Of the 4 types of 69g. ammo I have tested, the base-to-ogive average measurements are as follows:

Sellier & Bellot = 1.838"
Fiocchi Exacta = 1.849"
Federal Gold Medal = 1.853"
Winchester Match = 1.860"

The S&B ammo is shortest of the four. So, it would seem like these rounds would have to jump MORE to the lands, not less. The two rounds that really popped in my face were 1.838" and 1.833". Measurement-wise, they were right in the middle of the pack of the S&B ammo I tested.