[DIY] Tikka T3 Magazine Round Count Holes

Here is a great how to from Marko Bernyk aka giggit from the Ausvarmint.com forums. Thanks Marko a great little article.

I know there is really nothing out there on the net on T3 modifications… here is a simple and effective modification that can also be used on other magazines.
I have always like my BRNO mod 1 Metal Magazines as they have holes drilled into the sides so you can see how many rounds you have left… or need to fill’er up when out in the field.
I have been frustrated with the 6 round Tikka T3 Magazine for my 204 as there is no way to tell how many rounds are loaded. Trying to stuff a round in just in case there is only 5 is hit and miss cause there could be 4 or 6. It sometimes gets hard to load at round 5 and 6 due to the offset stack especially when the rounds double up on one side of the magazine… I need some Holes in the side to see how many rounds are in the magazine.
So I pulled apart a Magazine.

To pull the spring and tongue out… Stick a pen into the magazine like you are going to load a round then tilt the point of the pen down into the magazine and the tongue will now pop up and you can remove the tongue and spring as one piece. The spring just slides out of the tongue and in this magazine can only go back in one way. You can split the Magazine in to 2 to clean by sticking a finger into the top and try and push out the middle part between the 2 locking tabs while you push the bottom half in from the outside. One side will just unclip, then do the same to the other side and the bottom will be free from the top. Reassembly is just a quick clip together.

As you can see this magazine has a built in block to keep the rounds forward in the top half, but the lower half has a just a central divider. These keeps the rounds in position while you load another on top. It also limits your OAL when it comes to reloading to just over factory spec. If you want to modify the magazine to allow for a longer OAL, the block and divider will have to be trimmed. The block face will probably be cut out as it is only about 2mm thick and will need to be replaced with something else to keep the rounds aligned, like some Acrylic or wood.
So how do we find out where the rounds sit into the magazine, well you need to consider the following…
The magazine stacks the rounds is a slightly offset vertical stack. The rounds tend to get further side to side the lower they go into the magazine. This means the center of the rounds are closer together the further in the magazine they go – it is a slight difference. The T3 Magazines also only come in 3 sizes and each Magazine size is universal for a few similar sized cartridges… and so the center mark for viewing could be slightly different for each cartridge used. and therefore you will have to work out you own spacing for other cartridge sizes.
So to measure where the rounds actually sit in the magazine I loaded it up with 6 empty cases.
Then using a pen I slid the top round forward.

Taking my Digital Calipers, I used the depth gauge end to measure the height of the round below.

I then slid the 2nd round forward and measured its height and so on till I measured all 6 heights. Now this measured the top of the cartridge, but you want the hole to see the center of the cartridge. This makes it easier to see in low light as the brass is closest to the hole at the center of the cartridge.
I then measured my cartridge waist at the point where I measured the height from, divided by 2 and added this to get my cartridge center.
So my measurements for my 204 rounds are from the top of the magazine rails to the top of the cartridge:
2nd round: 9.60 -> 9.5mm
3rd round: 19.03 -> 19.0mm
4th round: 26.99 -> 27.0mm
5th round: 35.95 -> 36.0mm
6th round: 44.14 -> 44.0mm
Add half the cartridge width at this point = 4.75mm
and the actual center height of the cartridges are:
2nd round: 14.25mm
3rd round: 23.75mm
4th round: 31.75mm
5th round: 40.75mm
6th round: 48.75mm
Measure and pencil in the hole location on the side of the magazine.
Now drill 3mm holes, deburr and you are all done!
The finished job.
All 6 rounds:

The Magazine on the right was the guinea pig. You can see round 6 is closer to 5 by about 2mm. It still works as desired.
4 and 3 rounds in the magazines

Related posts:

1. HS Week End Round Up

Tags: DIY, hunting, magazine, rifles, t3, tikka, tikka t3

Category: Guest Blogs