I made some dummy rounds with 178bthps to measure things and to see how will it work etc.. and came across an issue. I get 2.254" at the lands on average based on 10 diff bullets from 3 diff boxes. The COAL averages 2.935". The max OAL that fits in AICS mag is 2.880" or so. So if I want to use the mag I have to have the bullets seated about 0.055" off the lands at a minimum! I dont mind single loading even though it gets old after 30 rounds. I do it in my AR with 80g SMK and 78g AMAX but would like to avoid it if possible. So the q is for the guys that use longer bullets like the 178g bthps and want to use magazines, do you just seat them at mag length and play around with different charges until you find something that works? And second q is there a way to do OCW when at a minimum I have to be 0.055" off the lands? Is there even a point in doing OCW test if I cant exactly adjust seating dept? Thanks
- Thread starter Bach
- Start date
I would set them at max mag length and test from there. Do your ocw test, and find a good node. If you need to adjust seating depth, just keep seating deeper. Make adjustments in .003- .005" .
OCW does not care at what OAL you're at. But each OAL will have its own OCW.
I guess im just not used to seating the bullets that deep. I always got the best loads between at lands and off 0.015" or so. 0.055" is a pretty big jump. I'll see if its even possible without compressing
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It appears that you have a rifle with a rather deep throat. Likely a R700. Fear not, as others said, seat to your max mag length. Find a tight group or OCW node. Then slowly seat deeper and see if things improve.
Yeah. Im going to try both at mag length and 0.020". The rifle is a Savage with Bartlein barrel. I dont think the throat is long. Both 175SMK and 178 AMAX fit in the mag when seated at lands. The 178 bthp has a shorter ogive by design. Ill measure the 3 to compare when I get home
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That bullet in my 700 is seated to fit the mag, 2.825" and shoots fine like that, and I mean really fine.
Get yourself some Alpha mags. OAL in them is 2.920 and I think it's 2.940 for the type 2. I have the Type 1 mags, they are very reliable and allow me to load longer.
I thought about different mag but thats only half the problem. Even if the round fit in the mag they wont feed unless I do some mods. Im doing parralel load dev for mag length and 0.020" off the lands. So far both gave the same OCW results and average MV, but the ES for the 0.020" load was lower by 53fps and SD was lower by 22. If the 0.020" ends up being the better load when im done then so be it ill just single load. Im going to use the 178bthps for 1000yds anyways to its not a big deal
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