Home Forums Hunting & Shooting Custom Rifles & Wildcats 338 Sin

I figured I would post this over here as there are a few long range hunters and people who like the big 338 cartridges.

The 338 Sin is a cartridge designed to fit any std long action with a magnum bolt face. I have built a lot of 338 edges and most people can't seat the bullets out long enough in a std action with out a new mag box or dbm. That is why I developed this cartridge. Below are some links that you can read more about it but basically it has the performance right between a 340 weatherby and a 338 Edge or Lapua. What I like about the 338 Sin is that there is Norma brass (330 Dakota) available.

225gr Bullets ~3200fps (accuracy loads are ~3150)
250gr Bullets ~3000fps (still doing accuracy tests)
300gr Bullets ~2800fps (still doing accuracy tests)

Hope you guys enjoy the read, this isn't a cartridge for everyone but some it will be perfect. PT&G has my reamer prints if anyone wanted to get a reamer.


338 Sin development

338 Sin load testing

nice work! I like wildcats and have a few myself. however, I fail to see how this bests the 330 Dakota or the 338 Bin (338/375 Ruger) in any way. Having said that, It looks like it should do well for your intended purposes.

advntrjnky

I don't have case specs on the 338/375 ruger or case volume but I would say I am 2-4gr mor capacity then the ruger and I am 13gr more than the 330 Dakota. I am even 4.5gr more than the 340 weatherby. It is the maximum case size you can fit in a std long action with the std magnum bolt head. Also has the benefit of using Norma brass unlike the 338 Edge (338-300 Rum) and 338 Rum. It isn't for everyone but it defiantly has its purpose, especially in pack rifles. a Rifle weighing 6lbs 3oz bare that can fling a 225gr bullet (with a bc of .640) at 3200fps accurately (under 3" at 600yrds)with a 24" barrel is no slouch and is actually pretty amazing. It will be tested out to 1,000yrds and maybe 1,500yrds. Not bad for a rifle that costs under $900 ready to go.

Need details on the "ready to go" rifle under $900

Factory Tikka T3 light 338 Win mag ~$600, rechamber and install/supply muzzle break ~$300.

Factory Ruger 77 ~$600

Factory Savage SS ~$600

Factory Howa SS ~$600

and so on.

All you need is a 338 Win mag rifle and you can have a long range rifle on a budget. You can go all out with custom barrel and action if you want, that is up to who ever would want one.

How are are you getting 2800 fps with a 300 gr. ? The 338 RUM holds a little more powder than the 338 SIN and it would be fairly tough to hit 2800 especially in a 26 inch or less barrel.My edge leaning on it fairly hard was running 2850 fps with a 30 inch barrel and 300 gr bullets. The 338 SIN does sound like a great round !

I hit 2803fps with a 300gr SMK during the initial testing. I will be doing some accuracy test with the 250gr+ bullets shortly. I would say it works on the same principal as the wsm cases in a short action. Reloader 19 is one of the best shooting/velocity powders for the 225gr in the Sin which isn't a powder for the Rum (usually at least)

Sounds like it is very effecient.In my 338 ultra RL25 ran 225 gr accubonds at 3250 fps.I like the fact that the OAL is Less on the SIN getting rid of Mag length frustrations.Those are great number out of a case with less powder and not needing a longer barrel.

I am very happy with the results so far with the results and I can only see it getting better.

Shot the sin again today, under 1" groups with 250gr bullets all the way to 3050fps. More info to come.

a post by Don Lewis on loading/shooting the 338 Sin

Went out this morning to do some more testing. It seems with the lighter bullets this rifle likes the faster burning powders. I tried some new loads for the 185 grain Barnes ttsx. H-414 was the clear winner over several powders. 89 grains with a fed 215 match primer averaged 3515 fps and was by far the best load with accuracy, velocity, and velocity spread. I have had extremely good performance out of this powder shooting light bullets in the 338 winchester, 338-300 wsm and the 300 wsm along with a few others.

I shot a 3 shot 100 yard group for zero and all three shots were touching. I carried it out to 800 yards and shot a 8 3/8" group. The BC on this bullet still amazes me. Last year I did quite a bit of shooting with this bullet in my 338 winchester and had to plug in bc's around .5 for it to match my drops. I know this bullet should not have this high of a bc but it did the same thing today. Later I am shooting it over two calibrated chrono's and get it down instead of doing drop tests. I just haven't had time to do that yet.

The rifle is a 24" barrel 1-10 twist. I also shot some 225 CE bullets with several different powders. 93 grains of Wichester WMR averaged 3121 fps, 96 grains of Magpro averaged 3114 fps, 86 grains of I-4831 averaged 3153 fps and 85 grains of RE-19 averaged 3160 fps. All of these loads are max in this rifle. This rifle shoots best with max loads. Velocity spreads got smaller and accuracy got better as the powder got faster. They improved exactly with the powder burn rates. So in my rifle the faster the powder the better to RE-19 with this bullet. I may try something faster later like H-414 that did outstanding with the 185 grain bullet.

The best accuracy and least velocity spread (8 fps) was with 85 grains RE-19. The 100 yard group was all touching and the 800 yard group was 7 1/4".

What I am finding is this cartridge performs very well with faster burning powders than what you would normaly see in a 338 cartridge with this level of performance. This is due to the efficient design of the cartridge similar to the wsm cartridges. Because of utilizing faster burning powders this cartridge does great in short barrels which is what I was looking for in a lightweight backpack style rifle. A 225 grain .65 or so bc going 3160 fps out of a 24" barrel lightweight rifle that weighs a little over six pounds is pretty amazing.