OAL vs. magazine box length

[c. schutte]

Is there a rule of thumb so to speak for determining the maximum length of a cartridge in order to feed correctly in a magazine? Obviously there are max cartridge lengths in all manuals so all I would need do is follow that for sure. Just curious how close one can go before it might effect feeding.

Thanks.........chs

 

[erikc838]

Is there a rule of thumb so to speak for determining the maximum length of a cartridge in order to feed correctly in a magazine? Obviously there are max cartridge lengths in all manuals so all I would need do is follow that for sure. Just curious how close one can go before it might effect feeding.

Thanks.........chs

I have a Kimber Hunter Pro, where the length of the magazine measures 2.838". I tried them at 2.830" and has feeding issues. 2.820" worked well.

 

[1Shot]

Each rifle will be a bit different with different bullets. One bullet might like to jump a mile to the lands and thus will be loaded maybe shorter than the suggested COAL from a loading book. Another bullet may like to be close to the lands. The suggested COAL in books are lengths that will work through most actions and most often will not be the most accurate COAL your rifle will like. I always try to find the most accurate COAL for the powder velocity combo I will be using and most often this COAL will also work through the magazine. There are exceptions so nothing is set in concreate. One other thing I will throw into the mix is the use of a Lee Factory Crimp Die. I collect and shoot old military rifles. Many of these rifles have throats a mile long and in order to get bullets close to the lands where many shoot best the bullet is loaded out too long to work through the magazine. For example the Swede Mauser 96 in 6.5x55. Where it shot best with 140 Sierra MK was too long for the magazine so I experimented. I loaded rounds as long as would work through the magazine and used different amounts of crimp with a Lee Factory Crimp Die and BINGO accuracy found. I have done this with other rifles and it works for me. My thoughts on this is the crimp holds the bullet in the case for a nano second allowing pressure to rise to a consistent point before the bullet moves and hits the lands much the same as loading the bullet close to the lands will allow the bullet to be retarded a nano second before it leaves the cases totally and allow the same consistent pressure rise. I don't know if I am right or not but what I do know is that usually using a medium Lee Factory Crimp has increased my accuracy with these rifles.

 

[c. schutte]

My concern regarding this question is strictly for feeding. For the rifle in question accuracy is a secondary concern. Flawless feeding is upmost.

Thanks.....chs

 

[jimbires]

I run a couple rifles at .010 clearance , they feed with no problems .

 

[Guy Miner]

My concern regarding this question is strictly for feeding. For the rifle in question accuracy is a secondary concern. Flawless feeding is upmost.

Thanks.....chs

Long ago got in the habit of making some dummy rounds, with the bullet & cartridge case I intended to use. I make enough to fill the magazine, then do so, and cycle the bolt (or lever) briskly as done when hunting.

I've had to go back and shorten some to get them to feed smoothly.

Don't know that there's a "rule of thumb" for how much shorter they need to be, than the magazine. A "little" space works fine.

This was very important for my 308, with Remington's short action. I ended up simply loading them to factory length. Also ran into it with my 375 H&H Model 70. It feeds factory length ammo just fine, but if I try to load any longer, it isn't happy with me.

I understand completely the idea that a rifle simply must feed smoothly and work every doggone time, even if that means sacrificing a little accuracy.

Guy

 

[Darkhorse]

No big deal really. For hunting rounds I want to work everytime I load then .015-.020 shorter than the magazine.
As for accuracy it doesn't matter there either. When a barrel oscillates the pattern is repeated all or most of the way to the chamber, this means there are numerous nodes available to tune your loads.
I bought a Browning Stainless Stalker in .300 win mag to be my elk rifle. I went to a lot of trouble establishing my distance to the lands, then loaded one up and tried to put it in the magazine. Wouldn't fit, the round was .100" (hundred) longer than the magazine. So I seated .120" deeper and went to work. The rifle has the BOSS which makes this easier but I ended up with my deer loads printing well under 1/2", and my elk loads averaged .520"
I can work with rifle magazines, I've got 2, the Browning and a Tikka T3. But I prefer the Model 700 BDL with the hinged floorplate.

 

[ShadeTree]

I believe the general rule of thumb for reliable feeding is to give yourself around a .030-.040 cushion. That's not to mean certain actions with the feed lips different than another, or a particular bullet type, wont allow you to load much closer than that and still feed reliably. Like Guy said if you think you're pushing the limit and in doubt, run a bunch through to make sure.


Just measure any commercially produced gun and I think you will find that holds out. For example max saami AOL for 30-06 is 3.340. From what I've read Browning has the shortest magazine length in the long actions and it comes in at 3.385. So they've still got .045 clearance if loaded within saami specs. The magizine in my model 70 in 06 measures well over 3.4. Does me no good because that gun has a short throat so I end up loading pretty short anyways.

 

[hunter24605]

Usually I allow .020 to start and they do fine..The WSM's like a little more.

 

[SJB358]

I load to fit the magazine. I run three or four in and check them to make sure they aren't rubbing or interfering with feeding. If all is good, I don't put too much thought into it.. As long as you have serviceable mag springs in the rifles recoil will help them bump up a little too if they do move a bit.. Haven't had too much trouble with any of the guns other than a PF M70.. I am pretty sure my partner fixed that with a detachable magazine..

 

[grry10]

As a rule I try to keep 0.040"-0.050" short of the maximum magazine length. This avoids flatting the tips of soft point bullets. If you're using a tipped bullet you can seat them 0.015"-0.020" without feed problems.

 

[Polaris]

Depends on several variables. Magazine geometry, bullet profile, angle of cartridge at magazine lips (this can change with round count in the magazine), the mechanics of stripping and feeding a round from magazine. There really is no hard rule of thumb, only trial and error with dummy rounds or live ammo (assuming safe backstop and conditions). I have a match AR-15 that can be run out to nearly a friction fit. My mauser sporter and the wife's Savage M11 on the other hand are a bit fussier. These are 2 that will change depending on number of rounds in the magazine and bullet profile. Trial and error determined a significant cushion with these 2 for reliable feeding of all 5 rounds. With military rifles you can typically run a similar bullet style to the same COL as the standard military ammo and get very reliable feeding. Very important to remember when loading for an M1Garand or Swiss straight pull rifle. Also military mauser actions tend to be fussy with longer than standard seating even when there is ample room in the magazine.

 

[c. schutte]

Thanks folks..................