.338 cartridge overall length and AI Mag

[DLMsniper]

I recently purchased an AIAW from one of our SN sponsors. Since I don't reload, yet, I purchased some factory rounds. I purchased a couple of different brands. The overall length of the .338 Lapua BVAC Match HPBT 300gn is too long for the AI magazine. The other 300gn rounds from HSM are also too long. The 250 gn rounds are significantly shorter and appear to be OK with the AI magazine.
(I'm relatively new to shooting so please excuse the basic question.)
Since these cartridges are not returnable is there a problem feeding these things indidivually???

 

[USMCj]

Re: .338 cartridge overall length and AI Mag

Nope, single feed those suckers!

 

[desertHK]

Re: .338 cartridge overall length and AI Mag

I load both the 250 scenars and the 300 SMK at 3.600" in my AIAWSM. They both shoot just fine, damn fine I may add. I can't comment about manufactured ammo and howe it would behave if you were to seat them deeper, because I don't know where on the powder curve they load their rounds. If you work up your load, then at least you know.

 

[Lt. Arclight]

Re: .338 cartridge overall length and AI Mag

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DLM</div><div class="ubbcode-body">I recently purchased an AIAW from one of our SN sponsors. Since I don't reload, yet, I purchased some factory rounds. I purchased a couple of different brands. The overall length of the .338 Lapua BVAC Match HPBT 300gn is too long for the AI magazine. The other 300gn rounds from HSM are also too long. The 250 gn rounds are significantly shorter and appear to be OK with the AI magazine.
(I'm relatively new to shooting so please excuse the basic question.)
Since these cartridges are not returnable is there a problem feeding these things indidivually??? </div></div>

Just be aware that SAAMI spec for 338LM is shorter than the new C.I.P. spec for 338LM the latter being 3.850". About 3.605 is about max for the AI magazines. I don't recall how deep the throat is in my Factory AI barrel but 3.850" may put the bullet into the rifling.

When you feed them one at a time,you obviously have to push down the magazine follower to allow the bolt to close but if you feel resistance closing the bolt on the longer rounds it would be the bullet being forced into the rifling which,depending on the load, may give you some excess pressure signs. Being new to the game-you should consult someone familiar with the 338LM and reloading before shooting the longer rounds.

Worst case scenario is when you are setup to reload, you could pull the bullets and reload the case. Simply seating the bullet deeper isn't a good idea unless you KNOW what load is in the case. This too could create a pressure issue. The whole idea making the standard length longer is to allow more case capacity to get more velocity out of the 300gr. bullets.

 

[DLMsniper]

Re: .338 cartridge overall length and AI Mag

Lt. Arclight, thanks for the info.
I can put the round in the chamber without having the magazine in place.
I think what I will do is place the longer round in the chamber and close the bolt then see what it feels like. I will eject the round without firing it then place the shorter round and see if there is a difference in resistance when the bolt is engaged. If the longer round has more resistance then I will know the bullet is being forced into the rifling, which may be a bad thing. Does this make sense???
I will measure the overall cartridge length when I get my calipers (should be here soon).
Can't make it to the range until maybe Sunday.


Thanks
Dave

 

[Lt. Arclight]

Re: .338 cartridge overall length and AI Mag

First thing,it might be obvious- but safety first. Strip the bolt and take the firing pin out-then one no accidental discharge is possible-two you'll be able to feel any resistance chambering the round.

Take a black sharpie and blacken the bullet first- if you chamber it and feel resistance-stop and carefully eject the round-if the bullet is into the rifling you'll see marks on the priously blackened bullet. If the bullet is forced into the rifling and it is already a HOT load-firing it isn't going to result in your immediate demise-but you may get a very sticky bolt lift or in worst case-not be able to eject the fired round-which will need to be dislodged with a cleaning rod or by using force to open the bolt.

Once you get your reloading gear,I'd advise that you carefully study the reloading forum here-as well as reading as much as you can. Most don't "start" on 338LM's but in reality it is no different than any other centerfire rifle procedure wise.

Measuring the loaded round is important-but what is more critical is the relationship between the OGIVE of the bullet and the distance from the rifling with a chambered loaded round.There are tools made to assist you in finding that spec-many of us just make a dummy round and measure it using a bullet comparator.

When you get your calipers,let us know what the length of your longer rounds are. Just be aware that "most" factory loaded 300SMK rounds are going to be on the hotter side and jamming them tight against the rifling-especially in very HOT ambient temperatures and firing them MAY very well result in obvious pressure signs.

Hope this helps.

 

[DLMsniper]

Re: .338 cartridge overall length and AI Mag

Thanks again.
This will be work for tomorrow.
I'll give a report assuming I'm not dead or disabled.
Ambient temp will be in the mid to high 90s tomorrow.
I'll do some homework so I can speak intelligently regarding OGIVE/bullet comparator/etc.

Dave

 

[DLMsniper]

Re: .338 cartridge overall length and AI Mag

Range report:
No death or disability today.
Long round fit smoothly into chamber. No resistance.
Zero'd in scope.
1/2" to 3/4" three shot groups at 100 yards.
Not so good at 200 yards.
Need to increase the butt length and raise the cheek height.
Recoil more than my 18" POF .223, but not bad.
Next I will probably go to the 1000 yard range. Can't make it there for a couple of weeks.

Dave

 

[rsilvers]

Re: .338 cartridge overall length and AI Mag

Basically the 338 LM was messed up because the OAL was too short for the case length with 300 and up grain bullets.

The solution is the 338 Norma mag, which has a case that is .234 inches shorter.

The shorter case has 2 grains less volume, but when a bullet is seated to the same full SAAMI length, it actually has 3.3 grains more capacity.

 

[DLMsniper]

Re: .338 cartridge overall length and AI Mag

Do you mean the overall cartridge length is too long because the case length is longer with the Lapua and with the shorter case length of the Norma, a 300gn projo will fit in my AI magazine?
So, are you advising using a Norma mag case with the 300gn projo in the AIAW?
Is there a down side???'

Thanks,
Dave

 

[Lt. Arclight]

Re: .338 cartridge overall length and AI Mag

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DLM</div><div class="ubbcode-body">Do you mean the overall cartridge length is too long because the case length is longer with the Lapua and with the shorter case length of the Norma, a 300gn projo will fit in my AI magazine?
So, are you advising using a Norma mag case with the 300gn projo in the AIAW?
Is there a down side???'

Thanks,
Dave </div></div>

rsilvers post concerning the 338 Norma Mag is rhetorical.The 338 Norma Mag is a completely different caliber.Although physically shorter at the same coal the Norma has more capacity and is able to reach higher velocities with the 300gr. bullet. YOU CANNOT USE IT IN YOUR GUN.

The original design and use of the 338LM in the AIAW was to shoot the 250gr. bullet. Now that faster twist barrels are available for the AI the case length of 3.6" or so limits the case capacity to shoot the 300 grain bullets at higher velocities.Hence the new longer CIP length and the new AX series of 338LM rifles by Accuracy International.

You didn't state what twist barrel your AI came with. If its a 1/11" twist-you should be shooting 250gr. bullets anyway. Most shooting 300gr. 338 bullets have found that the 1/10 or even faster 1/9.5" twist stabilize the 300gr. bullet better.

Don't get sidetracked.He didn't even suggest using the Norma case. You have an AIAW and you are limited to magazine length and at that length you can get performance out of the 250gr.Scenar or 250SMK exceeding 1500 yards.

You got some studying to do......

 

[DLMsniper]

Re: .338 cartridge overall length and AI Mag

Thanks a million!!! You're right, I have some homework to do, but where do I find this info that is specific for my AI?
Wikipedia gives a brief history and mentions the AX variant and the advantages of the new design to accept the longer cartridges, but is there an "AI Bible" that gives the best recommendations for everything from bullets/loads/maintenance recommendations??

Thanks for your time
Dave

 

[Lt. Arclight]

Re: .338 cartridge overall length and AI Mag

Well, first the owners manual for maintenance. Find out what barrel you have-ie is it a 1/11" twist or a 1/10" or faster.

1/11",some guys get good results with 300SMK's-some don't. IMO,you need a faster twist if you want to shoot the 300gr. bullet long range. If you have a 1/11"twist-when you buy your components-buy either the 250gr. Lapua Scenar or 250gr. Sierra Matchking.

There are plenty of us here that have 338LM's and AI's- spend some time in the forums- you'll find what you need.

 

[Maelstrom]

Re: .338 cartridge overall length and AI Mag

[/quote]The original design and use of the 338LM in the AIAW was to shoot the 250gr. bullet. Now that faster twist barrels are available for the AI the case length of 3.6" or so limits the case capacity to shoot the 300 grain bullets at higher velocities.Hence the new longer CIP length and the new AX series of 338LM rifles by Accuracy International. [/quote]

Sorry for the hijack and stupid question but can the new CIP mags fit and work in a standard .338 action that uses the original AI mag?

 

[Badshot308]

Re: .338 cartridge overall length and AI Mag

I posted a question quite a while back about the new CIP length mags working in an original AICS. I believe the answer was that the chassis can't be modified to accept them. Were you asking about using the CIP length mag with a custom action or a non CIP AIAW?

 

[Maelstrom]

Re: .338 cartridge overall length and AI Mag

I was curious about using it on a GAP .338 LM using a Defiance action and badger bottom metal.

 

[Badshot308]

Re: .338 cartridge overall length and AI Mag

Don't know if the Badger bottom metal can be modified but there are a few companies such as Seekings and Accurate Mag offering bottom metal with larger CIP length mags. These mags may be proprietary to each company.