.257 Roberts AI feeding issue

Anyone have trouble getting the .257 Roberts Ackley improved to feed out of a rem 700 long action? I have my rifle that I re barreled to a 6.5-284. that I'm now going to re barrel again to the Roberts. I bent the feed lips of the mag to work for the .284 case and I'm hoping that I can just buy a new standard magazine. As I'm sitting here playing with a dummy round for the Roberts it's not feeding from my modified mag at all.
Thanks

in what ways is it not feeding?

I've got a Defiance Classic long action and 257 Roberts AI feeds fine but I'm using a Wyatt's extended box and using hinged floorplate.

Bdl, adl, factory dbm? Or some other aftermarket dbm setup?

The 284 brass is different than .257 Roberts Ackley improved! I'm not surprised it won't feed!

The issue is the either the back of the case pops out and gets above the bolt or the front of the shoulder jams up on the back of the barrel. This is factory Remington detachable box mag

BUSTINDOGS said:

The issue is the either the back of the case pops out and gets above the bolt or the front of the shoulder jams up on the back of the barrel. This is factory Remington detachable box mag

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I assumed you opened up your feed lips for the .284 larger case on your action. Maybe I've behind the curve but didn't know a Rem 700 action could use a detachable magazine -- which it sound's like that's what you're saying. I have a Rem M-7 that was a stock 243 Winchester that I used to build a 257 Ackley Improved and It's always fed well. Are you sure your action is a Rem M-700? Maybe a M-788?

Yes Remington 700 had factory dbm actions, i have 3 of them.

It's a factory rem 700 I don't want to mess with the mag I have because I spent a lot of time fiddling with it to get the .284 case to feed. Was hoping someone has used a standard rem 700 either BDL or ADL or detachable box that has feed well. I guess I'll just order another mag and fiddle with that till it works for me.

BUSTINDOGS said:

It's a factory rem 700 I don't want to mess with the mag I have because I spent a lot of time fiddling with it to get the .284 case to feed. Was hoping someone has used a standard rem 700 either BDL or ADL or detachable box that has feed well. I guess I'll just order another mag and fiddle with that till it works for me.

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My M-7 Remington action that I used for my 257 Ackley build was originally a 243 Winchester rifle and 'to the best of my knowledge' the gunsmith who I had re-barrel it, didn't do anything to the feed lips on the action -- and it's always fed without issue! All the gunsmith did was to remove the 243 barrel and install the 257 barrel. So, if you buy a 270 or 30-06 magazine, I'd expect it to feed your 257 brass just fine because the base of those cartridges are the same as the 243/257/7mm Mauser etc! If you're expecting to shoot 'long for caliber' bullets, don't forget you need a fast twist -- nothing slower than 1 in10 inch. I did a 1 in 13 inch twist on mine because I never was going to shoot any bullet over 100 grains and it's been 3/4 inch 3 shot groups at 100 yards but I doubt it would be accurate with 117 or 120 gr bullets! I also get 3200 fps with any 100 gr bullet I've tried but usually only load to 3100 fps, so it isn't as hard on the brass! because I'm a handloader!

What was the original chambering of the rifle? Short action or long action? Seems the short action would limit best use of heavier/longer bullets. Did you change the follower in the mag for the 284 case diameter? If the mag is short action could the shoulder be interfering with the locator dent in the side of mag.

The rifle was originally a 30/06. I had a short action I was planning on using but after making a dummy round which ended up being 3.05 over all length with a 115 ballistic tip loaded with the boat tail junction at the base of the neck I decided to use this long action I have. On a side note and maybe I'll have to start another thread for this question. But does anyone know if I'll need to throat this longer to accommodate the longer over all length I want to run? I usually rent a reamer from 4D probably get the throater to go with it just in case.