After years of using only 39 or 40 gr bullets in my 204 I decided to try the 32 gr Sierra Bks. I used CFE 223 and did loads at the minimum recommended by Hodgdon of 29.0 gr and at 29.5 and 30.0 gr.
The max load is 30.9 gr. The starting load was reasonably accurate but on both the higher ones I got one keyhole out of 10 rounds. These were the first keyholes I've ever gotten in the years of reloading my own rounds. 40 gr Vmaxes shot great. What could have caused the keyholing and how can I correct it? My rifle is a Remington 700 SPS with a factory barrel so I assume it's a 1:12 twist.
Try turning the target 90 degrees
That's amazing. Never seen one go through completely sideways. I'm certainly interested in hearing theories as to how that happened.
Dan, I just got off the phone with technical services at Sierra. I was told the keyholing was probably caused by excess velocity. He said knock the loads back to what I use for the 39gr Bks, which are 27.9 or 28.5 and I should be fine.
Tokimini wrote:Dan, I just got off the phone with technical services at Sierra. I was told the keyholing was probably caused by excess velocity. He said knock the loads back to what I use for the 39gr Bks, which are 27.9 or 28.5 and I should be fine.
That's a good lesson for anyone trying to squeeze every last fps out of their loads!
Did you chrono those loads?
Tokimini wrote:Dan, I just got off the phone with technical services at Sierra. I was told the keyholing was probably caused by excess velocity. He said knock the loads back to what I use for the 39gr Bks, which are 27.9 or 28.5 and I should be fine.
Kind of goes along with one of my old sayings " A slow bullet in the right place is better than a faster one not". Accuracy first and velocity second, just works. Bill K
I had the same problem with my 1:12 Savage. 39's were fine, but the 32's needed to be backed off a tad.
Good thing I never had someone at the target marking hits, because There was a distinct "wizzzzzz" sound a couple times, and only the Almighty knows where the bullet went... it never placed on a fresh 4x8 carboard target backing...
I'm pretty sure the good recipie was 26.5 gn Benchmark... its here in the "favorite Loads" thread. 'Shot really, really well.
I don't have a chrono. It would have been interesting to see what they were zipping along at, but my main criteria has always been accuracy, not velocity. If you can get a round to go over 4000 fps but it wont hit anything, what good is it?
Bill K wrote: Kind of goes along with one of my old sayings " A slow bullet in the right place is better than a faster one not". Accuracy first and velocity second, just works. Bill K
Bow, my son was spotting when I shot the keyhole round. He always calls out my shot placement. "1/4 inch left, 1/8 inch down" stuff like that. The keyhole round was " 1 foot left, 2 feet down". Was that ever embarassing.
Tokimini wrote:I don't have a chrono. ... my main criteria has always been accuracy, not velocity. ...
I hear ya. Accuracy should always come first, unless your quarry is barn doors.
But the chrono can be pretty handy for analysing those stray shots. If they're all travelling around the same speed, fast or slow, then you can eliminate the charge as a "maybe I didn't weigh it properly?"
Let us know how you go with the backed-off loads.
No chance of me testing any loads today - Yesterday we had 30-35 knot winds (35-40 mph), and today it's stepped it up a notch (have to be 40 knots + at times). I could almost throw a bullet out the window and let the wind take it to it's prey
When guys have problems with velocity dismantling soft lead core bullets in flight, and want the highest velocity possible, try a box of Barnes .204 dia. 26 grain Varmint Grenades. Their cores are a solid compressed metal powder similar in texture and hardness to that of a stick of chalk - hard chalk. The heat, pressure, friction and rotational speed won't effect these bullet cores. I have driven them well over 4,100 fps from a 1:8.5" twist barrel and they shoot in the .2s - .3's. Don't worry about the low B.C. or the fact that they all measure a bit wild on the tip to base length, just load them to 2.260" with something like RL-10x and enjoy splattering varmints. Another alternative is the Nosler 32 grain BT Lead free, same powder, same fun, and a plastic tip! Talk about a laser! Lead cores actually become plastic at high temperatures and pressures, I used to load 40 grain Hornet bullets to a little shy of 4,000 fps in a .22-250 and watch the smoke trail trace a route toward a squirrel. Looked like a sidewinder missile shot. If the bullet held together long enough to arrive at fur, the results were predictable, if the squirrel was too far the bullet never made it. Lucky squirrel.
I did some more load developement with the 32 gr BKs using CFE 223. I tried my most accurate loads for the 39 gr Bks. which are 27.9 and 28.5 gr. They weren't bad but the best accuracy was with 27.5 gr. I don't quite know what happened with that flyer but the load shows promise. John, I'll give the Noslers a try. I really enjoy trying out new powder/bullet combinations.
There's no way too much velocity could cause a bullet to loose stability unless the bullet was flawed. Bullets can fail in flight but they essentially explode or disintegrate, they don't tumble. The "1 foot left, 2 feet down" tells me that bullet was tumbling. Whoever you spoke with at Sierra was either ignorant or blowing smoke up your skirt.
Fred_C_Dobbs wrote:There's no way too much velocity could cause a bullet to loose stability unless the bullet was flawed. Bullets can fail in flight but they essentially explode or disintegrate, they don't tumble. The "1 foot left, 2 feet down" tells me that bullet was tumbling. Whoever you spoke with at Sierra was either ignorant or blowing smoke up your skirt.
As you can see by pic I posted the bullet was intact and definately tumbling. I inspect bullets twice, once when I sort them by weight to a tenth of a grain, and once again when I seat them, so hopefully I would have caught a deformity large enough to cause a bullet to tumble to such an extent. As I said in my initial post I have been reloading for a few years and never had this problem before. I backed the loads way down like Sierra suggested and the keyholing stopped and the group size shrank. Everyone is entitled to an opinion, but it's hard to argue with success. Sierra said back off on the velocity and the problem should cease. It did.
