.224 - 95 SMK bullet failures

[linebaugh]

Well yesterday was not a good day. The new barrel blows bullets up the very first shots. I was doing barrel break in and cleaning between shots while trying to ger on paper at 100 yards. The first 5 shots of shoot/clean/repeat ended with 5 bullets gone in the air. Sick to my stomach.

Shot 35 rounds yesterday and every time I cleaned I blew 1-3 bullets until dirty. This will be the last 7 twist barrel I own unless I build my 223AI back up to shoot 80-88s. There is some hope that when fouled and broke in better this will go away but I know it's gonna rear its ugly fricken head again. I'm done. Brux is on the way with a .219 8-twist for 88 elds or 90 SMKs.

I purposely shot 20 rounds in a row after a good cleaning. After 3 rounds of blown bullets I printed a 1.25 and 1.5" group at 250 yards with no load development at all and a hottt barrel. Bullets just set to zero and 2 loads in .5gr incriments. Again it appears the 3000-3030 fps range is going to be accurate, when I can get the bullets to fly past 50 yards.

Will keep updating but the plan is now to find a node in the 2900-3000fps range to limp this barrel through the season and then tomato stake it. May shoot more today and for sure more this week.

 

[jelenko]

I agree. I think the Berger calculator has lead a lot of people to a faster twist, mistakenly believing that the couple percent loss in BC is a problem. I, perhaps arrogantly, thought it wouldn't matter much to me if I blew up a bullet here or there since I mostly just target shoot for fun. I was thinking it'd be fun to experiment with the slightly cheaper 22 heavies as an alternative to the commonplace 6mm. My reality, however, is that blowing up bullets kills all the fun and stresses me out, regardless of if I'm just shooting for fun or trying to compete at a match. I'll stick with conservative, safe bullet and twist choices from here on out and never again have that sinking feeling of "why isn't there a hole in that target?"

It was the Berger stability calculator that got me to buy 7 tw barrels so I didn't loose any BC on their 80.5 223 bullets.
After my H75's started poofing [that's the official term] on the way to the target, I've had to back off 1.4 grains of powder to find the first accurate node that's below 280K RPM.
Murphy ensured that I bought a bunch of barrels at the 7 tw just to remind me of not knowing what I'm doing.

 

[Evan]

Again it appears the 3000-3030 fps range is going to be accurate, when I can get the bullets to fly past 50 yards.

My 22BR falls in and out of tune with the 95s all the time. One weekend it'll shoot 0.5" at 300. Next weekend, the exact same load shoots 1.5" at 300. It's infuriating. I shoot them right about 3000fps - same as you are. I'm about ready to sell the ~300 I have left. I'm going to start over with them with some Shooters World powder I have and see what shakes out, but I'm currently disappointed. The 88ELD blow up relatively easily, but they are super consistent and accurate all the time - they aren't finicky about jump and they seem to work the same across broad velocity ranges and powder choices. It's really a forgiving bullet design. I'll probably finish shooting the rest of what I've got for this barrel ~700 assorted bullets, and then pull the barrel and call it quits.

 

[linebaugh]

Small update.
Cleaned the 22 GT very well after the initial 35 rounds. To my surprise the first shot made it to the target and on track and I experienced no losses today, which surprised me. Nothing spectacular but have not done any real load work and mirage was terrible. My guess is my load is about 2950fps and I hope to get some actual load development in tomorrow. Up and down .2gr and then on to seating. Don't anticipate having an issue getting close to .25MOA when done.

But the BIG surprise was I loaded exactly 10 rounds of 95gr SMK in my 223AI with what I would guess to be a slower load of about 2500-2550 fps (no chrony) and at 250 yards they printed an inch and mirage was terrible today. I am going to load another small batch of exactly the same load and seating to see what they do out at 500 and perhaps 750 yards. Plan is to use the BC data generated with the 3030fps load to see what happens but mostly I just wanna see if I can get there stable and still drop some realistic groups.

Is there anyone shooting 88 ELDs by chance in a 223AI? I'd be curious to hear what FPS can be had with reasonable brass life of 5-7 loadings??

 

[linebaugh]

223AI

 

[linebaugh]

Little more info today along with some words of wisdom.

I shot the 223AI to 500 and 770 today with 95SMK at a whopping 2525 fps. ALL BULLETS went through straight despite a 1.3 SG and only 260K RPM. Groups were even reasonable but strange. At 500 the group was 6.5" and horizontal. At 770 the group was 7.5" and vertical.
By my calculations based on Zero and drops at distance I lost around 12% of my BC value by going that low.
I absolutely do not recommend nor do I advocate repeating this as it was just a curiosity to me and I happen to have the means available to play with it. Its not realistic IMO but an interesting test just the same.

Okay back to the 22 GT and the 95gr SMK. 7 twist at about 3000 fps and today I lost 2 out of 30 rounds. I do have a load that with no seating adjust has shot between .38 and .5 MOA on six groups and I will fine tune that tomorrow with seating depth testing. I expect to end up better than persent but you never know I guess.

Okay all of the above said I will repeat what has been said by Evan and others repeatedly. If you run any of the heavies above 300k RPM you are going to live with bullet failure. I am to the point where I would even suggest to go lower.

So what does that mean? THIS IS MY OPINION. Very specifically to those who may read but not be up to speed with RPM thing. Do not run any 88-95 bullets in a 7 twist out of a .308 base cartridge if you want to stay happy. Those 7 twist barrels are made for .223 based cartridges using 88-95 only. If you are going faster than 7 twist in a .223 based cartridge you are also taking chances.

I don't think I will bother reporting after this post. If you wanna know what happens next... I shoot about 750 rounds in this barrel, get completely fed up with blowing bullets and I switch to an 8 twist with 88 ELD, 90 SMK or 95 SMK and live happily ever after. That 7twist gets shortened 2 inches and becomes a 223AI shooting 88s. The end.

 

[jelenko]

That 7twist gets shortened 2 inches

I'm having a similar issue with H75's in a 7 tw 26" barrel. At my go to load, they were exiting at 2800 fps => 288K with some going missing.
I thought about cutting 2" off, but decided to go with a lower node to keep the balance in off hand. If it weren't for the off hand stage, all 5 would be 24".

 

[Evan]

I don't think I will bother reporting after this post. If you wanna know what happens next... I shoot about 750 rounds in this barrel, get completely fed up with blowing bullets and I switch to an 8 twist with 88 ELD, 90 SMK or 95 SMK and live happily ever after. That 7twist gets shortened 2 inches and becomes a 223AI shooting 88s. The end.

Thanks for sharing. It reinforces that I didn't just get a bad barrel and that it's a pretty common phenomenon.

 

[highdrum]

I know I'm reviving an old thread here. But in the process of building a 22br. Already have a 22gt, 7tw 219 bore hawkhill 4gr barrel. Have 700 rounds on that pushing 90 atips and 88eldm from 3000-3250 and have never lost a bullet. I also have an 18" 22 creed 7tw 219 bore shooting 75 eldm eldm at 3250 fps, 88s at 3000, no poofers. So I'm not convinced it's the twist/rpms, more the bore diameter.

 

[Ned Ludd]

Trust me on this, it's mostly the bore diameter and barrel length, at least in the context of realistic loads people are developing with .223 Rem cartridges up through some of the larger capacity .22 cartridges being used currently. Jacket failures are all about friction. The twist rate only becomes the "straw that broke the camel's back" when everything else has been already pushed right up to the limit. Barrel lengths of 28"-30" (or longer) with tight bores exacerbate jacket failures BIGLY. Barrel lengths of perhaps 24" or less do not. It is often possible to get away with doing things in a short (< 24"-26") barrel that will cause immediate jacket failure issues in a longer barrel. For example, running a tight 0.218" bore, running twist rates faster than 7.0 (i.e. 6.5 to 6.0 twist), excessive velocities that generate bullet rotational values in excess of 300K RPM, and land/groove geometries that may engrave/affect the bullet jacket more deeply. These things simply do not seem to have the impact with regard to jacket failures in a short barrel that they do in a barrel of 28" or greater. Perhaps the best evidence in support of the importance of bore diameter would be that things which clearly become the "straw that broke the camel's back" in 28"+ 0.218" bore barrels, such as twist rate, velocity, etc., pretty much become complete non-issues in the exact same barrel length if a 0.219" bore is used.

Although I would in no way be surprised if one could find a new set of "limits" where everything that is a deal breaker in a longer barrel also becomes limiting in a shorter barrel, that would likely depend on what the realistic upper limits are for velocity/pressure are in some of the larger capacity .22 cartridges currently being used to push "heavies".

 

[urbanrifleman]

Shoot 6 Tubb TMS bullets through your barrel at 2000 fps. I bet the problem goes away and your accuracy improves.

 

[WSnyder]

Trust me on this, it's mostly the bore diameter and barrel length

I'm going to test a bit of this before long (waiting on a reamer). I've got a 7T .218 barrel I think I'll do at 20-22" in 22CM. Lets see what it'll do. I have a few bullets to test so lets see how fast and if or when she blows

 

[Ray123]

I have a 6 twist 5.65 19" ready to try with the 95s...tried them in a 7 twist AR with modified mag but wasn't convinced the twist was fast enough...we'll see when the testing begins...when the weather warms.