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> .280AI Build
.280AI Build
@ 02:32 pm (GMT) |
David GausepohlGuysI've been in treatment for lymphoma for the last 6.5 months and have just been given the "All clear" by the doc. During this time I've been unable to shoot centerfires due to my central line installed in my right shoulder for my chemo infusions. I did shoot the rimfires during this time. I put together a Mauser in military garb, but bent the bolt handle, installed a low swing safety, and mounted a scope. Taking a test drive Friday with the 170gr SSTs. Also during this time a friend gave me an older Rem 700 ADL in .270 in Tupperware stock. I'll have a .284 medium weight 1-in-9 barrel chambered in .280AI with long throat installed, add bottom metal, and a stock. A couple questions: 1) Since I'm using a medium contour barrel, what fiberglass stock will give me enough to hold onto in the forend? I like the Sendero HS Precision, but I'm not using a Sendero contoured barrel. 2) what barrel length would be optimal for the cartridge for a carry rifle? Thanks, David |
Replies
@ 05:03 am (GMT) |
Charles WyattRe: .280AI BuildGood morning, Sir.I enjoy shooting Skeet, Rifles, and Pistols at Hot Wells located in Cypress, TX. The Rifle range is limited to 100 yds., but it is covered, and the shooting stands are of concrete. They also provide spotting scopes and sandbags should they be required. Also one can shoot in the rain as long as there is no thunder. There are about 25 50-100 yd shooting lanes and 25 25-100 yd shooting lanes. Their link is http://www.hotwellsshootingrange.com. Currently I am shooting a CZ 512 Semi Auto at 50 yds using the IBS Rimfire targets. There are 29 targets per sheet. The target is somewhat small with the bull being a dot. The idea is that if one can put rounds next to each other near the 10 ring at 50 yds with a 22LR, then shooting a center fire at 100 + should be no worries. I currently shoot a P14 British Sniper rifle, a Weatherby 7mm mag, and a 6.5 Creedmoor. However there are others in the safe. I want to get reasonably accurate with the 3 mentioned and then go to a range that goes out to 1000 yds plus. The 280 AI is down awaiting a scope and bipod. I plan to mount a Zeiss Conquest V4 on it with a Sinclair Int'l bipod when funds become available. If you ever get close to Cypress or Tomball, let me know and we will arrange some range time. Have a good one... |
@ 07:14 pm (GMT) |
M.ARe: .280AI BuildI built a 280ai over a year ago. 26" contour3, 1/9 twist on a trued Remington action. Carbon fibre stock.Took a bit to get to shoot, results were finicky to say the least . I sent it back to the G/smith who blamed scope, 1st on a zeiss, 2nd Leupold, next up a sightron (which is shit hot!!) all were put back on other rifles and shot great, my shooting, the projectiles, the Match grade bedding job (which he milled out), loading technique and the 280ai itself. Then he gave to his friend to critique my shooting, which he went through same pattern as I diid, rather than send back to barrel manufacture. Its now had 300 rounds down the tube and I'm just starting to get results will my own loads ( .5" .6'' .7") 162 ELD-X and Sierra 160gr GK above N560 & RE23 powders. If I was to do again I would go 1/9.5 or 1/10 twist and wait for a cut rifled barrel, possibly a slightly shorter barrel and perhaps a little heavier contour. What I'm getting too is have everything out in the open with your GS on what you want and tell them you want it shooting the eye out of a trouser snake way out. MY question is for the oracle: I'm looking to form 280ai cases from 270 cases(as I have sheep loads), can I use trail boss and slightly jam the projectile into lands? Cheers M.A |
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@ 07:39 am (GMT) |
Nathan FosterRe: .280AI BuildHi M.A, it helps if you have a false shoulder for the cases. If you have a .30 or .338 cal FL die with a tear drop shaped button, then it would be good to neck up, then neck back down again using another FL die. The cases should be a tight fit in the chamber with the false shoulder. This will help to prevent stretching at the case head.After that, seat into the lands as you suggested. TB is fine, mild loads of 2213sc burn rate also fine (RE 22 etc). 1:9 is fine. The 3 contour finished at 26" can sometimes produce harmonic issues but is reflective of the steps taken to stress relieve the steel rather than whether it is cut or button rifled. But it may also be the reamer itself, issues at the throat. Or, the barrel may not have been lapped to finalize the dimensions. The finicky performance you describe was discussed in the PDF I put together regarding the Foster Manson reamers. I think that if you want a light weight build, it is worth taking some risks such as the 26" length. The barrel can always be docked later if it comes to it. But it does help to have a decent knox (see FMR thread). Other factors include a hand finished bore (regardless of the quality of todays CNC machining), an optimized reamer for modern bullets, sound bedding, concentric ammo (a major but generally ignored factor) and finally shooting technique. Just as an aside, you might want to try testing this rifle with the ELD-X on the lands. You'll need to use a fire formed and partially neck sized case to do this, not an OAL gauge (see reloading book as to why). Obtain your max OAL and set your seating die up with the same projectile at the same max OAL. Record both the test projectile length and OAL length. Start with a mild load as the close seating will jack up pressures. If you are say .2mm off the lands now, then drop 1 grain. If you were 1mm off the lands then drop 2 grains. When making up your ammo, you will need fairly good neck tension to ensure the projectiles do not get stuck in the chamber if you have to extract a case. This might help alleviate some of the issues with your rifle. If the throat is so long that you cannot get to the lands, then it may be best to quit soon. In these rifles, accuracy can be OK but as it falls away, you cannot chase the lands. Also be aware that I am making assumptions here, guessing as to what might help you. I could be wrong about any and all points made here as I do not have the rifle in hand. |
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@ 04:58 pm (GMT) |
Matthew AmonRe: .280AI BuildThanks for the reply Nathan,I tried the Trail boss fire forming using 270 brass to 280ai. Seemed to go well, need to run cases over concentricity gauge now. question: The bedding that I did with M/Grade compound was further down (just under 2" long past knox) I shot best group with this bedding and a load. This was milled out by G/Smith and a new bedding job was done just to know 3/4" long as he didn't like look of my job, little suck back either side of knox but other than that fine. He removed bedding around knox this was after I sent rifle back. So tang and receiver are only supporting the 26" contour 3. The rifle shoots no better no worse with this. Should I make him re-do bedding and have it running further forward as my first job. |
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@ 08:23 am (GMT) |
Nathan FosterRe: .280AI BuildHi Matthew, just leave it for now. Have a go with seating depth I talked about and see if this helps at all. If it comes to a re-bed, it might be good to go the DIY route (full length bed) unless the smith is willing to put a good 12 hours into the job. This is easy enough to find out - if the bedding quote is say $120, then you know that either the smith is either working for $12 an hour (unlikely) or that he is only going to spend around 2 to 4 hours on it (more likely).Again, these are precisely the issues I talked about in the PDF where the smith has low confidence in the customer, the customer ends up with low confidence in the smith and or barrel maker. It can be a really annoying affair and ultimately it may be that the reamer is not really optimal for the modern projectiles in use. This can be at its most dramatic when after exhausting all other options, we happen across the likes of a cheap and dusty box of Speer 160gr BTSP projectiles in a gun store, take a punt because we are now low on our expensive bullets and need something to plink with. We knock up some loads and almost magically, the rifle behaves. |
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