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bjornborud
I finally found time to shoot my 30 XCB rifle today, bringing along several loads that I had prepped after last week’s outing. Today I was going to shoot ball powders, both Hodgdon LeveRevolution (LvR) and Winchester 760 have given higher velocities compared to extruded powders in earlier trials. All HV shooting today was done using Tim Malcolm’s breech seater, as max powder capacity and highest possible MV was the goal. To recap, my 30 XCB rifle is a target rifle from the 1950s, built on an FN Mauser blind single shot action. The barrel is a new Shilen Match, 31 inches long, 1 in 14 twist. Tim Malcolm (Goodsteel) recently re-barreled and re-bedded the rifle.
I had devised a “ladder test” of sorts, to figure out at which MV the bullet/lube/powder charge combo would lose accuracy. Not to be confused with the Creighton Audette ladder test, this was simply a series of charges starting at a known level, increasing by 2 grains per charge for the LvR and 1 grain per charge for the W760. Here are the targets for these 2 “ladders”:
At this point I picked one charge from each “ladder” and shot a 10-shot group of each. I picked charges that I believed would stay together:
Finally I upped the charge of the LvR powder by one grain and shot another group. This turned out to be where accuracy went south:
I did not bother to measure this group.
I have to say that this outing was very encouraging, and it certainly proved to me that the NOE 310-165 FN (XCB) is an outstanding bullet, and that White Label 2700+ Carnauba Red is an outstanding lube.
With this shooting I consider myself done with the breech seater, I’m sending it to Larry Gibson in Arizona so he can use it with his Oehler Ballistics Lab to plot the pressure curves in some of these loads. After the 55 grain load of LvR today (MV 3316 fps) the bolt handle was hard to open and I didn’t increase the powder charge any further. Primers were starting to flatten, but I have seen them much worse on heavy jacketed loads.
bjornborud-
Replies
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frankelliott
Very, Very good, Brad. When you get the BSer back, you need to work with different primers and 1/2 gr charges. I think you can get the grouping down to 1″ if you can get the ES to <25 and single digits for the SD. That will get your barrel harmonics in tune.
What does your rifle weigh and hows the recoil at those velocitys?
Frank
sgt.mike
Very, Very good, Brad. When you get the BSer back, you need to work with different primers and 1/2 gr charges. I think you can get the grouping down to 1″ if you can get the ES to <25 and single digits for the SD. That will get your barrel harmonics in tune.
Frank
LOL Brad LOL its too cold weather wise for Brad,,,now Bjorn that is a differant story
as a shootist he has ice in his veins LOLLarry Gibson
Bjorn
Excellent test. Obviously that which several of us have been predicting for several years is coming to fact. Given the 14″ twist I would suggest the 1st LvR load of 51 gr at 3099 fps was probably a tudge over the RPM Threshold as evidenced by the probable 2 flyers of that group and how accuracy really went south with one more grain of LvR. Be interesting to see what happens with 50 gr LvR at 3000 fps +/-. Particularly when noting the 1.43″ group at 2987 fps with the 760 powder. The LvR powder will have the slower time/pressure curve and should do well at 3000 fps. Additionally it will be interesting to see how seated bullets in the 30×60 will compare to the BS’d bullets in the 30 XCB given the case capacity will be close to the same given the different bullet seating and how much difference the 16″ twist will make vs the 14″ twist.
Again we have reached the goal of 2 moa or less at 2900+ fps as we predicted we would. Now we can concentrate on tweaking the loads and bullet alloy seeking best accuracy.
Again, excellent test and congratulations are in order……well done.
Larry Gibson
timmalcolm
Outstanding Bjorn. I thought that by using the breach seater you might push into the upper 2900s but the other day when you told me you were going to break 3000 with accuracy I admit I was skeptical.
This is phenomenal.
I have never seen anybody shoot this fast with a standard cast bullet and hold groups this size.Very, Very good, Brad. When you get the BSer back, you need to work with different primers and 1/2 gr charges. I think you can get the grouping down to 1″ if you can get the ES to <25 and single digits for the SD. That will get your barrel harmonics in tune.
What does your rifle weigh and hows the recoil at those velocitys?
Frank
Frank,
thanks for the kind words. I’ll be shooting fixed ammo for a while, I would like to try to get itty bitty groups WITHOUT the BS device.
I’ll put the rifle on the scale tomorrow and get back to you. There was very little felt recoil even with the stiffest loads today.Bjorn
Excellent test. Obviously that which several of us have been predicting for several years is coming to fact. Given the 14″ twist I would suggest the 1st LvR load of 51 gr at 3099 fps was probably a tudge over the RPM Threshold as evidenced by the probable 2 flyers of that group and how accuracy really went south with one more grain of LvR. Be interesting to see what happens with 50 gr LvR at 3000 fps +/-. Particularly when noting the 1.43″ group at 2987 fps with the 760 powder. The LvR powder will have the slower time/pressure curve and should do well at 3000 fps. Additionally it will be interesting to see how seated bullets in the 30×60 will compare to the BS’d bullets in the 30 XCB given the case capacity will be close to the same given the different bullet seating and how much difference the 16″ twist will make vs the 14″ twist.
Again we have reached the goal of 2 moa or less at 2900+ fps as we predicted we would. Now we can concentrate on tweaking the loads and bullet alloy seeking best accuracy.
Again, excellent test and congratulations are in order……well done.
Larry Gibson
Thanks guys. After speaking to Tim this afternoon he mentioned that he was sending a barrel to Larry for use specifically with the breech seater. I’ll hold on to the BS device until this barrel is in place and shoot a few more groups with the powder charges suggested above.
daveridenour
Bjorn,
Wow! That’s very impressive! I also like the fact that you numbered the shots in some of the groups. That gives us something else to study and think about.
I really want to that you and the others who are pushing the limits in cast bullet shooting to show what really can be done when you try new techniques, rather than relying on the same old stale approaches used in the past. You guys are true pioneers.
Thanks again,
Dave
timknowles
Nice work. Good write up. Thanks for sharing. I find the 9th shot in series 6 interesting. One grain more powder but less velocity than shot 8 and it impacted higher.
Tim
Funny you should comment on that Tim. While loading the charged cases, up until that point (including shot 8 ) I had been plugging the charged cases with a very small piece of floral foam. At that point the next case (shot 9) was difficult to load, so I fished it back out and shone a flashlight into the chamber. There were small droplets of melted plastic on the chamber walls. Not wanting to clean the barrel in the middle of a shooting string I carefully cleaned the chamber only with an M1-style chamber brush, not entering the bore. That cleaned up the floral foam residue. I then plugged the case for shot 9 with a small disc of lube and fired the shot. It went high, and the MV registered lower. Thereafter the remainder of the strings were fired with lube as a powder stop. That’s the only explanation I have for the POI vs. MV readings, and maybe it taints the string. However I don’t pretend it to be a scientific test, and the difference in the stop plug material could have easily caused the POI variance. Good catch.
I’m somewhat perplexed at the lack of posting on this breaking 3k with 2 MOA.
Even if it was using Lino/and a breechseater in lieu of conventional loading methods used today, still further than anyone else has shown in my observations.Shell shock maybe???? 😮
Or they are waiting for Bjornb to switch back to conventional load techniques???
I dunnooo but curiousier and curiouser it is …….
I’m just glad that it’s been done, documented satisfactorily, and posted publicly.
So many make claims. Only one has backed them up.If you don’t have consistency, you don’t have anything. You can’t win a match without it, and you can’t post a picture (to say nothing of measured chronograph readings) and talk is just talk if you can’t back your claims like has been done here.
This is how it’s done, and I extend a hearty thumbs up to Bjorn for taking the tools I made for him and being gentleman enough to use them in public with an open mind. Progress is easy to make that way.More rifles are coming that will bolster these results, and their groups will be posted openly as well.
Big thanks to Al for giving us a nice place to post these things so that others can learn and see how easy and cost/time effective it can be.JRR
adamsutherland
OK gentlemen.
There is good work being done here, let us not spoil it by bringing personal differences into it.
Stick to the subject, discuss as robustly as you want and keep the personal differences out of it, it would be shame to have to lock threads like this.
It is new forum here and a chance for everyone to have a fresh start at pushing the cast bullet envelope, let us not spoil it with ego and over sensitivity.
This isn’t up for discussion, back on topic and stay there please.
frankelliott
sgt.mike
Larry Gibson
timmalcolm
daveridenour
timknowles
ianharris
JRR
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