22 creedmoor: Anyone blowing up bullets with 7.5 twist?
- Thread starter jzerfoss
- Start date
I had a 22-250AI 8 twist that shot fantastic -- for 10 shots. After that I never found a bullet that wouldn't blow up on its way to a 600 yard target. It is barrel heat that is your enemy. I was using a big dose of H4831SC.
About 305krpm is your threshold for most 88-95gr 224s.
B23
Gold $$ Contributor
I agree, 3650 is humping for an 80 grainer and even though it's not showing any real obvious signs of pressure, the velocity is telling me it's definitely a full tilt load and then some even.
It'll be interesting to see what happens once this barrel gets a little age on it and if bullets continue to survive because doing the math, these things are turning 328,000 rpm.
I have a bit more case capacity with mine than you do but I'm loading 48gr of RL26 with those 80gr ELD-M's. What and how much are you using in your 22-250AI
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Can you tell me more about your barrel specs?
It was an 8 twist Krieger 30 inches long. 22-250 AI throated so an 80 Sierra was on the lands with the start of the boattail at the neck shoulder junction. If you could let the barrel cool it would work great.
Ranger188
Silver $$ Contributor
I quit running my 22 creed cause it was blowing up bullets.
It was a 7 tw and after 400+ rounds it started.
Tried Hornady 75g eldm's, Berger 90g vld's and Sierra 90 smk's
Was running the Berger to 3300 fps.(340,000 RPM's) Smith told me to keep the
RPM's under 310,000 and Berger wants under 300,000
So if you run a 7.5 tw and keep the fps under 3100, might have a
better chance of them making it to the target.
Here's a picture of a 90g vld blowing up at my range.
The little white dot in the center. It was a video but couldn't get it to
load, so I froze a frame and posted it here.
It was a 7 tw and after 400+ rounds it started.
Tried Hornady 75g eldm's, Berger 90g vld's and Sierra 90 smk's
Was running the Berger to 3300 fps.(340,000 RPM's) Smith told me to keep the
RPM's under 310,000 and Berger wants under 300,000
So if you run a 7.5 tw and keep the fps under 3100, might have a
better chance of them making it to the target.
Here's a picture of a 90g vld blowing up at my range.
The little white dot in the center. It was a video but couldn't get it to
load, so I froze a frame and posted it here.
wkdickinson
Gold $$ Contributor
I have Kieger 7.7 barrel on an AR which I can't shoot 50gr Vmax bullets from, 75% of them "blow up".
80 Amax at 315,000 and 90 Berger's at 301,000 and zero blow ups. The 8 twist is definitely the way to go. Unless your shooting a .223, faster than an 8 twist is asking for bullet failure issues.
Ranger188
Silver $$ Contributor
That's the biggest problem with running long very skinny, light bullets.
You have to have such a fast twist to stabilize them, then if you want any decent
drift and drop, then you have to run them fast. Catch 22
If you run a slower twist, you won't get 100% of the B.C. from a heavy bullet.
These 22 cals are good if you run lighter bullets and a slower twist and use it
for critter hunting. As a long range paper or steel weekly shooter, your on borrowed
time. Their are better choses out there.
My 2 cents
You have to have such a fast twist to stabilize them, then if you want any decent
drift and drop, then you have to run them fast. Catch 22
If you run a slower twist, you won't get 100% of the B.C. from a heavy bullet.
These 22 cals are good if you run lighter bullets and a slower twist and use it
for critter hunting. As a long range paper or steel weekly shooter, your on borrowed
time. Their are better choses out there.
My 2 cents
I think that as I said, the 8 twist for bigger .224 cartridges work great. Never had bullet failure running the 80s to nearly 3600 fps. They are lasers out to 800+ yards and awesome on coyotes, ground hogs and as one member posted, excellent on deer. While I have good deer medicine now, I'll probably stick to ground hogs and coyotes besides targets with mine. I personally do not like the slow twist barrels for the real high speed 224s. I'd rather run a .223 with 40-53s for critters out to 400+ yards and use my lasers for beyond 500. To each there own tho. I just have loved the fast twist high speed 224s since I started using them. My 223s are 9/12 twist guns and perfect for what I do with them.
I shooting a 22 Creed with 1 in 8 twist so far cannot get the 85.5 grain Burgers to shoot decent so if anybody has any load data for those would be appreciated tried 80 grain Berger vld running decent but still not impressed switch to Hornady 80gr ELD match with RL 22 got some incredible results speed seems to be running 3600 Plus
I contacted the Berger tech’s about my soon to be built 22BR w/ 7.5 twist to shoot the 85.5 Hybrid and after one of them tested several powders he gave me the feedback and RL16 was the best suggestion from 26.5 - 29 grn. Calling Sierra they had not run any tests but his advice was to try RL16 also. Two other powders to consider were Varget and N 550 .
Does this hold true for 90gn Bergers and 95gn Sierras? I know the older Berger 90s I used to use blew up earlier than the Sierras and I was hopin the new 95gn Sierras might have been made a bit tougher to withstand the high RPMs they need?
More so, they're a thin jacket too
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Ranger188
Silver $$ Contributor
The 90g Berger are what I was shooting and they go poof. (among others)
They (Berger) were getting a few complaints about that bullet exploding and think that's
why they came out with the 85.5g Guessing it has a slightly thicker jacket.
It's not just the twist, it's a combination of the barrel starting to fire crack, so you get a little
ruff barrel surface scaring the bullet jacket, due to a higher round count.
You could run a 7 tw. and just run the bullets slower.
A 8 tw will be better on them but might not stabilize the heavier bullets. It's a compromise.
Your putting a lot of flame into a smaller hole and trying to push a heavy bullet in a fast twist barrel.
Keep the rpm's under 305,000 ( a slower twist) and the heat down so the barrel doesn't fire crack and you'll
get more life out of your barrel.
FPS x 720 = # then divide that number by your twist = RPM's
So, 3400 FPS x 720 = 2,448,000 then 2,448,000 divided by your twist (8) = 306,000 RPM's
They (Berger) were getting a few complaints about that bullet exploding and think that's
why they came out with the 85.5g Guessing it has a slightly thicker jacket.
It's not just the twist, it's a combination of the barrel starting to fire crack, so you get a little
ruff barrel surface scaring the bullet jacket, due to a higher round count.
You could run a 7 tw. and just run the bullets slower.
A 8 tw will be better on them but might not stabilize the heavier bullets. It's a compromise.
Your putting a lot of flame into a smaller hole and trying to push a heavy bullet in a fast twist barrel.
Keep the rpm's under 305,000 ( a slower twist) and the heat down so the barrel doesn't fire crack and you'll
get more life out of your barrel.
FPS x 720 = # then divide that number by your twist = RPM's
So, 3400 FPS x 720 = 2,448,000 then 2,448,000 divided by your twist (8) = 306,000 RPM's
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