@ 03:01 pm (GMT)
I have some 75gr A-Max for my .223. The rifle is a Tikka T3 with 1:8 twist and only 16 inch long barrel.
With my current 55gr load I get good results with BM2, but I also have AR2206h and 2208 on hand.
Where to start ????
@ 09:25 pm (GMT)
Re: Loading .223 with 75gr A-MaxWithout modifying the magazine the 75gr A Max will have 4.55mm jump... The bullet would still be supported by 3.5mm - 4mm of case neck when it meets the lands.
Is this safe?
I can extend the mag if I need to.
@ 09:01 am (GMT)
Re: Loading .223 with 75gr A-MaxOk, often when hunters dock barrels back, then decide to run heavy bullets, there is a temptation to use fast burning powders which is understandable. Nevertheless, it is worth experimenting with slower burn rates to minimize pressures, looking for high velocities with heavy bullets. In the .223, the two slow burners are 2206H (H4895) and 2208 (Varget). Varget can be a slouch in short barrels, just a touch too slow and unresponsive with powder cramping sometimes occurring before full velocities are reached.
Have a go with your stock of 2206H. The suggested max load is 24.5gr, velocity in your rifle will be about 2700fps which is about what it should be producing. If you want to work up and through maximum, I would suggest a .2gr ladder test rather than our traditional 3 shot tests. This is because, if doing three shot tests, you will still need to work up in .2gr increments due to the nature of the .223 which pressure spikes very easily, meaning you'll go through a lot more ammo. Half grain jumps can sometimes result in locked actions/blown primers (especially with BM 2 / BLC1 and 2207). You can still look at trialing 3 shot groups after your initial ladder test, the point of the ladder test being to determine maximum pressures versus case capacity / powder cramping. You never know, your rifle may very well be capable of producing velocities in 2800fps range which would be great from a 16" barrel.
If you want to start with 2208, go for it. My suggestion of 2206H is based on past experience but is not the only way.
If 2206H is also a slouch in your rifle (full powder cramping with low pressures), then Bench Mark 2 (BLC2) will be the go. One of the goals of the initial ladder test is to keep the round count down so that you can cut your losses and move to BM 2 if need be, without it being an overly frustrating exercise. You already have load data for for BM 2 so a reduction of 2 grains powder from your current load (for 55gr bullets) should re-establish the same sweet spot. Note- I said 'should' not 'will'.
The long bullet jump is not so bad, its no different than loading for the AR platform and your description tells that the projectile will be supported and guided into the lands without problems. Do your preliminary ladder test and if you run out of case capacity and want to move the projectile forwards (remembering to keep the boat tail junction at the case shoulder / neck junction or lower), then make the magazine changes as you see fit. Same goes if accuracy cannot be obtained with the initial trial loads. Experiment with single shot feeding longer COAL's and if a long COAL/short bullet jump is called for, you have the evidence you need to make the decision on a magazine alteration.
If you get stuck, come out for a visit.
@ 03:49 pm (GMT)
Re: Loading .223 with 75gr A-MaxJust an update.
So far I've only carryed out a ladder test with 2206H.
23.7gr = 2761 f/sec
24.0gr = 2832 f/sec
24.3gr = 2902 f/sec
24.6gr = 2971 f/sec
24.9gr = 2960 f/sec
25.2gr = 2964 f/sec
25.5gr = 2978 f/sec
25.8gr = 3015 f/sec
Total group size of 1 1/2 inch at 100 yards.
All loads compressed at mag lenght = 58.60mm.
At this stage I'm very happy with the velocity of 2206h but will try some BM2 when I get a chance.
Watch this space!