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MG 180 HP vs. MG 180 RS CMJ (Which One)


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At present I'm shooting Berry Plated 155gr. HBRN, 5.0gr. TG, Fiocchi Small Rifle Primers (no problems), 1.137 OAL, 170 PF. No problems with the load and it is accurate. Was thinking of switching to either MG 180 HP, MG 180 RS CMJ or MG 165gr HP. Still want to use small rifle primers & TG powder. Some pros, cons, & advice would be greatly appreciated. For shooting USPSA Limited Major.

Thanks,

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First, when you are changing bullet types (JHP, FMJ, or CMJ) and weights the actual bullet length will be quite different. These different bullet lengths will dramatically change the internal case volume that is consumed when you seat the bullet to the same OAL. So you need to account for this internal case volume change between bullet types/weights and adjust your powder drop accordingly.

In my own testing the Montana Gold Bullets require more powder to achieve the same velocity as other Jacketed bullets (such as Zero Bullets). I think this is because the brass jacket that MG uses is harder and does not seal as well as a copper jacket. Having an exposed lead base, like what the FMJ's have, will help this issue because the lead will vaporize and assist in sealing the bullet in the rifling. The JHP's and CMJ's are usually "Slower" than the FMJ's because their bases are covered with a jacket. I am not saying that MG bullets are bad. They are good. They just need a little more powder (0.1 - 0.2 grain more) to achieve the same velocity as other copper jacketed bullets.

The calculation of Power Factor in USPSA favors heavy bullets. Heavy bullets also shoot softer than light weight bullets. If you are building Major PF .40 rounds I would suggest you use a 180gr weight bullet or 200gr bullet. You will be able to produce a Major PF load with these heavy bullets that does not have a harsh recoil. It will feel more like a "Push" recoil instead of a "Sharp Crack". The light weight bullets need to be pushed pretty fast to make major power factor and the recoil feels pretty harsh once you get them going the right velocity to make major PF.

Lastly, Tight Group is a pretty hot burning powder that produces a pretty harsh recoil impulse when used to make Major PF loads. Tight Group is a good powder for Minor PF loads, but usually not the best choice for major PF loads. I would suggest trying an alternate powder such as Winchester Super Target or VV N320. Both of these powders will produces a less smokey shooting condition when shooting plated or jacketed bullets and have a recoil impulse that is far less harsh than Tight Group.

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180 grain is a good all around weight for major pf loads in most guns, especially the standard heavy 5" used by most shooters. Tons of data out there with different powders. If you're running a light 6" gun like me though, consider a lighter bullet. 180's didn't quite feel right with the gun so I use 165's as recommended by the builder.

Used to use Titegroup, it works OK but I didnt care for the recoil impulse and the soot it left behind along with how hot it made the gun get during practice sessions. Moved on to other powders. As for FMJ vs CMJ vs JHP, I'd build a load around the JHP as they seem to be a little more accurate than the other types but it its not always the case. As always you'll have to try different bullets to see what your gun likes as far as accuracy. If you have an STI type gun then loading longer to about 1.180 oal will decrease pressure and increase reliability. For me reliability and controllable recoil impulse is more important than absolute accuracy.

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I believe the main reason people choose the M.G hollow point is because the base is jacketed. The complete metal jacket has a copper plug in the base and the full metal jacket has an exposed lead base. Just in case you were not aware of that.

I, personally, would not use Titegroup in a 40 caliber major load. A pressure spike with such a hot powder can be . . . damaging.

Oh, and you will not find Montana Gold bullets available, at this time.

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TG and MG 180 HPs is a very popular combination. I've used it for years, it's probably the most common combination among people I know.

N320 is probably better, just hard to find and more expensive.

155s and 180s will feel different. If your 155s feel fine and are accurate.. I'd just say 'Why switch?"

Just a few difference from the above

The difference in PF/fps between Zeros and MG for me.. was withing 20fps on the chrono

TG, for me, was a lousy minor powder. Didn't seal the cases, and was very sooty.

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