- One heck of a shooting extreme magnum in 277 caliber;
- 170 class offerings making very frequent pleasing hits on rocks at distances out to 1700 yards (range finder ranged the rock multiple times one morning. Never to range anything shootable again. Another story);
- Complete unavailablity high bc 277 offerings that “will” hold together out of my rifle.
- Rifle was purchased with the intend of yote harvesting beyond 600 yds.
- Unwillingness to ‘settle for’ any bullet that would perform on yotes to deer to 1500 yds.
- A two car garage with only one car
- Some power outlets
- An ancient almost unusable Chinese mill that was traded from a farmer
- A head full of “wonder how this would work” ideas
- No machinist capability/ability/experience (If it rotate around my place it was a vehicle wheel or a mower blade)
I’m revealing personal deficiencies here so please by kind. Not too smart but lots of drive.
First lets settle for this attempt: Testing had shown that Hornady SPBTs, and any Nosler offering shot lights out from the rifle. I liked the looks of the 140 and 150 Nosler offerings better. Nosler 150gr Ballistic Tips were tried first. 140s had been recommended by the rifle build as they were Accubonds. I’ve harvested many mule deer with the the 140 Ballistic Tip, thus ballistic tips it. Even with the same bc as the 140 offering 150 offering must somehow be better. When reaching way out there as much deliverable energy as possible the way I think.
For 30 decades or so prior to long range shooting by one and only rifle was a ’66 vintage DIY custom 270 Winchester. Yep! I’m one of those hopelessly addicted 270 shooters. And why not? Its a better bore size for lighter higher bc bullets than 7mm/280 and a better bore size for heavier high bc bullets than the 6.5. So why do there bounding calibers get all the attention? Its just the way things are. So buck up or innovate!
Load development with the lesser bullets + other learning experiences.
Here’s where I learned about loading cartridges which are more overbore that typical overbore.
The 270 Allen Magnum is designed for use of the more bore friendly ball powder. Why more bore friendly? I don’t know that it is though it is reported by believers that little round balls rolling down the bore is better than short sticks bouncing. Who knows? Not me.
Guarding my 8 pound container of US-869, due to its variation from lot to lot, in my experience, and me being to tight to purchase 16 pounds, different powders would be an option. Bad idea, really.
Initial attempts with such stuff a RL-25, Retumbo and H-100 started pretty well. That is, I didn’t blow anything up when applying algorithms developed between my ears over the years when determining starting loads for an unlisted cartridge from one that is pretty close to it. The fly in the ointment raised its ugly head when I got beyond the point of delay ignition occurred and powder bridging took place. It took place quickly and only a couple of times. It occurred only a couple of times because for once I was smart enough to stop shooting those suckers. I had no idea of what was going on and couldn’t justify it from anything I was doing and emailed the cartridge designer. His quick an informative description of powder bridging exactly described my experience.
Another challenge to be over come, darn. In as much as I seem to have to do things now and not next week, trips to the city to purchase several pounds of various offering of ball powders with a bit faster burning rate wasn’t acceptable. Plus there is bound to be something among the powders on the selves in the loading room that would fit the bill
I put my brain to work on the project. The shooting record book for the rifle revealed the bulky/larger stick powder bridged a few more times than did it counter parts. Hmmmm, me thinks, smaller is better. A quick look at powder burn rate charts, a couple of runs of my between the ears quick-load program (I otta purchase that thing. I would but I have a Mac!) and I suddenly have a starting load for the 150 NBT ahead of 7828ssc.
Calculations were close enough that delayed ignition didn’t occur giving a bit of confidence that bridging may not happen. Being careful, using safety glasses and face shield I chrono’d till I got close to desired velocity. With no incidents!
How desired muzzle velocity is determined around my place.
When I started this project I had acquired literately a Pgh Steeler game bucket full of primer loosened cases. I knew how much pressure to set as max by typical extraction feel. 5 loadings is the limit now, after the impact hammer extractor ignition incident.
With the safety glass and face shield gone a cheek weld was possible for group and velocity shooting started. My upper limit of velocity is determined by thoughts such as, there is no way that Jack O’Connor ever thought a 270 Win should shoot a 130gr offering over 3200 FPS MV. So, back in the day, I stopped at 3200. And I stopped at 3200 for the 140 grain offerings also out of the Winny.
In the Allen Magnum I felt I could determine the pressure limit with confidence. What velocity would be good enough and not significantly reduce barrel life from the rifles already short projected barrel life?
Some JBM runs said that somewhere around 3600 would be adequate. An arbitrary value at best but a decent sounding number.
Got to 3600 well before any pressure indications. Thought about it a bit, caved, and with to 3650 FPS @ 15 feet . 3650 is so much better sounding than a measly 3600. Like a yote or woof is gonna know?
Loads were very pleasing accurate. Zeroing groups (3 shots) under 0.6 MOA @ 200 yds.
Some JBM runs, a couple of trips to confirm drops to 1200 and I went to the hills to practice.
When to my favorite elk ambush spot, a which by the way I’ve seen plenty of elk but never harvested – tag and gender problems. I set up for a pleasant morning of shooting. Rolled out the shooting mat (DIY) with its sun shading attachment, spotting scope & tripod, binos, weather measurement device (there is no way I’m calling anything handheld a station), rifle with bipod (DIY), log book, camera drop charts for that particular elevation and environmental conditions (no hand held ballistic gizmo).
A beautiful day it was. Did range finding before the sun came over the mountain I was on. Developed a range chart by marking ranges on printed images that I had taken earlier. Just a nice relaxing morning. All I could get out of the Leica 1200 scanner was 1417 yards on a very alluring well under MOA rock on a very nice loose shale bare slide. In that particular spot when the sun is high the 1200 won’t come close to 1000. (I’m working on that.)
Shooting went wonderfully. Drop chart was spot on. There was no wind. A shot every 20 minutes or so. Load was shooting well enough that if the rock didn’t break apart the second shot either busted it or left a mark close enough to the first impact that if I’d had cell service I would have called someone. Not that all shots went that way. I’m not yet sufficiently consistent with my shooting form. If I stay in position a series of shots goes well. If I get up and walk around its not quite the same.
It has been a great morning. The 1417 yard little rock sure looks inviting. No shots over 950 or so have been taken. Hmmmm. . . Check drop chart. Click elevation turret. Check dope. Click windage turret. Get behind the rifle. Settle in. Chamber a round. Release the safety. Get breathing synchronized. Ready – set – send …choke! Laugh at self. No pressure, eh? I repeat this at least twice. Finally . . . the trigger breaks. Very observable POI. Darn! If I’m judging sizes correctly (Zeiss plex reticle), dope is spot on, POI maybe 1/2 MOA low.
That little rock is now gonna die! But how is one to adjust elevation when you only think the hit was 1/2 MOA low. Target size is unknown. Well its pretty simple. Dump the click idea and hold the difference between target dead center and first POI. Oh, and do all of this thinking while never changing anything regarding shooting position except for motion necessary to extract empty and rechamber the next load. Stress, I’d say.
Anyway, bang flop, little rock done gone! Longest shot to date.
Good enough? Nope, with any wind at all that rock was safe all day? 0.496 bc is unacceptable for distance shooting. Thus the quest.
Note to reader: I’m in room 6334 University of Utah Hospital, had a kick butt procedure this afternoon with a truly great knock out drug and its 0200. Oh, nothing but saline solution, jello and broth for 4 days. So what if I ramble a bit. :^) Get over it! LMAO