.280 ACKLEY IMPROVED
One of the finest all-around cartridges there is and an excellent "fix" for 7mm-08 factory chambers.
I do a lot of .280 Imp. rechambers and also offer custom dimensioned chambers starting with no factory chamber using unchambered barrels from Match Grade Machine.
The factory 7mm-08 chambers rechambered to .280 Imp. work well, but will always be fuller proportioned and bulge cases a bit more at the head. Starting from an unchambered barrel, I can cut tighter proportioned chambers.
.280 Rem. Ackley Imp. or ".280 Imp.", gives 7mm Rem. Mag. ballistics in a smaller diameter chamber more friendly to the stretchy Encore mechanism. The longer .280 Improved chamber cuts out misaligned 7mm-08 Rem. factory chamber throats permitting cutting a new closer tolerance custom throat in fresh rifling aligned with the bore for best accuracy such as in the targets below.
Loading data available in current Nosler reloading manuals as well as original data in P.O. Ackley's "Handbook for Shooters and Reloaders." As with all Ackley "improved" rounds, cases are formed by shooting standard ammo in the straighter sided, 40 degree shoulder Ackley Improved chamber. Or, what is proving to be the best choice is to buy pre-formed .280 Ackley Improved Nosler brass.
Nosler wisely recognized that the long sloping case shoulders DO in fact collapse a significant amount when shooting standard ammo in the improved chamber. Thus they shortened the distance from the case neck/shoulder junction to headstamp by .014" to compensate for this phenomenon. I now set up all .280 Imp. chambers for the shorter bodied, preformed Nosler .280 Improved brass and ammo, but you can still fireform standard .280 Rem.
ammo in the Imp. chamber with the additional "pre-crush" at the neck shoulder junction to minimize case stretching at the head of the case. .280 Rem. Ackley Improved dies are commonly available from most of the die manufacturers. However, for compatibility with rechambered 7mm-08 factory barrels, Redding is the preferred choice.
Redding dies tends to be the most compatible with the original factory 7mm-08 barrels rechambered to .280 Improved. Full length 2-die set $95, checked against the chambers I cut and shortened IF necessary.
Starting from the original diameter of factory 7mm-08 chambers, I of course can make them larger, but not smaller. Thus the fired case diameter of .280 Improved at the "expansion ring" will be at least as large as the original 7mm-08 chamber, and in some instances must be enlarged a bit more in order for Redding dies to size the expansion ring any at all. But the result is a very nice match up of fired v. resized case diameter
Nosler reloading data for .280 Rem. Ackley Improved
DO TAKE NOTE!
NOSLER'S DATA FOR BOLT ACTION GUNS IS IN MY OPINION AND EXPERIENCE A BIT TOO HOT FOR ENCORES!
STICK WITH THE "MIDDLE" LOADS THEY LIST.
The Encore mechanism is NOT as strong as most all bolt actions made for comparable cartridges. Therefore, bolt action guns will stand up to higher pressures without problems than will the Encore. My advice for the Encore is to stay with loads with the slower powders that push 140 gr. bullets approximately 3,150 fps, which in the real world is normally all that factory level 7mm Rem. Mag.
loads produce. This is the approximate pressure level you should be operating at in the Encore. In other words, resist the temptation to squeeze out all the velocity Nosler established for bolt guns.
140 gr. is the optimum bullet weight for most hunting situations unless the game requires more penetration or if shooting longer ranges where a higher ballistic coefficient is called for.
With any load worked up, harder unlocking of the barrel is your signal to back off the powder charge! Don't overwork the Encore frame.... or "Pro Hunter" frame. They are one in the same.
If you opt to push the Encore to its limits and stretch the frame or bend the lower lip of the barrel lug, you are the one responsible for any damage done, not me. Be a maximum velocity freak at your own risk. Best respect this most excellent long range cartridge for what it offers in the Encore without stretching the limits.
If you REALLY do NEED more horsepower, step up to factory level .300 Win. Mag. And if you do shoot .300 Win. Mag. DO have me extend the extremely short throat for better accuracy! Factory throats are both too short and cut too large in diameter for best accuracy. Extending the throat at minimum diameter boosts accuracy a bunch! ...... both with factory ammo and handloads with bullets seated out.
7mm-08 rechambered to .280 Ackley Improved at work in New Zealand.
From Mike F. : Mike/Kurt, I know you guys are busy, but I through you might like to see some pic's of my son's recent trip to New Zealand with a Bellm TC in 280 AI.
Everything was taken with one shot each.
My son said that his guide was kinda rolling his eyes over the single shot, but he changed his mine when he saw this Red Stag drop in his tracks with one shot at 170 yds from the 280 AI
Thanks for helping me put togather a real shooter!!
.... and his ram.
TC "Pro Hunter" factory 7mm-08 rechambered to .280 Imp. 100 yard accuracy. As with all data, user assumes all liability for use of published data. Always start with charges 10% lower than listed, then work up in small increments watching for any indications of excess pressure.
Courtesy C. Guntert
Two holes, 3 shots!
The load specifics are:
TC Encore Frame and TC ProHunter Barrel Converted by Mike Bellm from 7mm-08 to 280 Ackley Improved
1x hinge pin
Barnes 140 Grain TSX Boat Tail Bullet
57.5 Grains of IMR 4831 Powder
Federal GM210M primers (Gold Match)
Seated to lands
Results: 3 shots at 100 yards = 0.268"
200 yard .918" group at approx. 3180 fps.
200 yard .918" group at approx. 3180 fps.
Load was 58 gr. IMR 4831 with 140 gr. Barnes TSX BT bullets.
The End Product We Work For,
Courtesy C. Guntert
in this case a nice Mojave Desert buck.
Impressive accuracy with Nosler 140 gr. FACTORY ammo at 200 yards.
Bergara standard contour 24 in. 280 AI custom chamber cut by Mike Bellm. Nosler factory 140 accubonds 200 yards. Kinda makes me not want to reload!!!!! Getting boring. Gonna have to get another barrel from ya'll....
Excellent TC Dimension Rifle Accuracy, 7mm-08 factory barrel rechambered to .280 Ackley Improved, Bellm muzzle brake machined into the barrel.
I am set up to rechamber TC Dimension rifle barrels as well fixtured to index muzzle brake ports without having the rifle receiver here.
Eric Ebbinghaus of Haus of Arms shows us how the TC Dimension .280 Imp. shoots!
...and the results in the field:
Marty Ebbinghaus and his son, Eric, above, share our passion for the TC guns, Good folks, too!
Special note from Redding regarding size die adjustment:
Richard Beebe at Redding informs me their .280 Ackley Improved size dies are made .008" shorter than SAAMI minimum and should permit bumping case shoulders back. This may or may not be enough shorter.
Frequently shooters are not able to push shoulders back simply because the shell holder is not hitting solidly on the bottom of the size die.
In other words, if your resized cases stick out of the chamber too far, be sure the shellholder presses solidly against the bottom of the die before you decide the shoulders cannot be pushed back as required.
Flexing of the press can leave a gap between the shell holder and the bottom of the size die. So make sure there is no gap IF it appears the size die is leaving the cases sticking out of the chamber to far.
If cases still stick out too far, then it may be necessary to remove material from the bottom of the die so as to permit bring the shoulder inside the die closer to the shell holder/headstamp of the case.
Redding and/or CH-4D .280 Ackley Improved dies are kept on hand, $95.
Dies are checked against the chamber I cut for the best matchup available and shortened as needed so you can bump case shoulders for correct headspace.