Best oal for 300 blk from AI mags

[al redneck]

I am running AI mags in a Rem 700 with Sako extractor . I can load to approx 2.4 = just touching the lands with Hornady 225 Match bullets . I ran some ss 147 gr loads to break in the barrel . When I tried a few of 225 gr bullets .005 off rifling sd was good but the bolt would override base of cartridge occasionally . I thought oal might be responsible . If I work the bolt from prone with shorter oal , feeding improves (seems to be 100%) . If I try offhand and rapid bolt manipulation , the problem reappears . I have tried down to 2.280 oal . I am stumped . Anyone have any ideas . Thanks .

david

[dick]

I have no expierience with AI mags. However did you look at the possition of rounds in the mag. Are the rounds touching the feed lips, are the feed lips holding the rounds at an angle in the mag or too low to be picked up. Are the rounds binding do to a centering rib in the magazine. Is the mag held in the rifle square, and close enough to the action to properly opperate. Pictures may help.

[LouBoyd]

Could you be specific about what AI mag you're using? Is that the 10 round polymer body mag sold by Accuracy International you're referring to?



Considering it's designed for .223Rem or 7.62x45 it would just be luck if it works with the 300 BLK cartridge which has a much shorter body. If it was a metal mag adjusting the feed lips would be the typical solution, but that's not easy to experiment with on a mag with plastic lips. I don't have an answer.

[al redneck]

[QUOTE=LouBoyd;35156]Could you be specific about what AI mag you're using? Is that the 10 round polymer body mag sold by Accuracy International you're referring to?


The only mags that I know of for 300 blk from AI are the plastic ones , which I am talking about . They will handle up to 2.5"+ oal . The mag seats right next to the bolt rails of the action, the bolt is engaging a little over 1/2 the outer ring of the bolt when it strips a round from the mag . I have tried 2 different mags - didn't make a difference . I am using dummy rds I made up . Some times after rd has 'popped up' out of the mag , the bolt binds and I have to pull back slightly to enable me to be able to chamber a rd . These rds are approx 2.280 oal . By looking at mag and bolt relationship it looks like it should be feeding fine . I don't know why it seems to function 100% when bolt is operated moderately but doesn't when worked at speed . I am running a PTG bolt . Thank you to the boys who are trying to help . I really appreciate it !

david

[Hoser]

I had the same issue with mine. Regular 223, perfect.

A little work with a sanding drum to the inside of the feed lips made both 300 WTF and 223 Ackley feed 100%.

All you have to do is let the round sit a touch higher and sand the front so the nose rests higher yet.

[al redneck]

Originally Posted by Hoser

I had the same issue with mine. Regular 223, perfect.

A little work with a sanding drum to the inside of the feed lips made both 300 WTF and 223 Ackley feed 100%.

All you have to do is let the round sit a touch higher and sand the front so the nose rests higher yet.

Hoser,
Thanks for the info !! I'll have to borrow my shooting partner's dremel . I've had a 300/221 and had to load around 2.2 oal with 220 mk's . This is my first 300 blk . Should I be loading slightly off riflings (2.4") or around 2.260 like all the reloading data recommends ? Mine is a bolt gun so I don't have to worry about mag length for an AR . Once again - Thank you very much for the advice . That makes perfect sense to me .

david

[al redneck]

Hoser

I just spent about an hour using diamond files and sandpaper on the feed lips of my 3 AI plastic mags . My dummy rds are now feeding when I work the bolt smartly . Thanks alot for the advice ! My dummy rds are around 2.280 . I would still appreciate advice on oal . I am going to send my rifle off to be nitrided and would like to have some trial loads when it comes back . It was just shot enough to break in the barrel .

david

[Hoser]

For my boltgun I run the Sierra 220s about .015-17 off the lands. That gives me the best accuracy. Sierras tolerate bullet jump pretty well.

My bolt gun was chambered with a PTG 300 Hush reamer (aka 300 WTF) so I cant help too much with an OAL for a 300 BLK chamber.