Tried out some new loads today. <20 grains of IMR 4198 wit a 52 grain Hornady Match grade BTHP, and CCI 400 primers. These grouped a little better than my H4895 loads, but about 1/2 or the rounds either short cycled the action or didn't cycle and eject at all.

I also had some 68 grain BTHP Untramax rounds with me and they grouped the best with several 3 round groups under 3 inches. I would think the lighter rounds would group better than the heavier and longer 68gr, expecially from the 1in9 Mini.

My hope was to work up a load for 52-53-55gr bullets using the IMR powder. I've got 500 Remington PSP 55 gr flat based bullets ready and waiting. So.....,my question is......................

(1) What experience does everyone have with Flat base vs Boat tail rounds with the Mini. Is one more accurate than the other. I have read that the Mini likes flat based bullets and is more accurate with them.

(2) Are 55 grain bullets the upper limit when using IMR 4198?

(3) What have you found to be your most accurate combo of powder/bullet/primer for your mini?

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Perfect is the enemy of good.

Your 4198 load works well in .222 so I would say that it is a little light for .223.
as far as flat base over boattail accuaracy will likely be the same, will depend on your rifle boattail bullets hold velocity better at longer ranges.
Now days I shoot my ARs more than my mini,I have an old 181 series and it is not a tack driver.

I shoot the 52's with 24 grains of RL10 (close to 4198) and I think that is the minimum this bullet needs to cycle completely in a MIni and Dependably in a Mini. kwg

My best so far is 24.0 grains of AA2230 with a Hornady 55GR FMJBT and a CCI 5.56 primer(white box). You will probably get a little better accuracy with a boattail vs a flat base. BTW this lod works well in my AR with a 1x9 twist. Sounds to me you just need a faster burning powder like AA2230.

I've checked several burn rate charts and from everything I can see IMR 4198 is rated as a faster powder than AA2230. IMR 4198 is the fastest recomended powder for .223 I'm thinking I just need a higher powder charge and not a different powder. I'll post some additional results when I get back to the range.

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Perfect is the enemy of good.

I haven't looked recently but I thought 4198 was close to RL10, 322 and AA2015. I shoot 2230 at 25 grains and get good results. I shot 25 grains of RL10 with a 55 grain bullet and my primers were pretty flat. I highly recomend no one else do this. 24 grains is a good start and with 55 grain bullets I stop at 24.4 grains of RL10 as my max load. kwg

Just back from the range. I increased the charge and the rifle functions flawlessly. I tested this load with a heavy and light crimp. Both grouped about the same, right around 3 inches at 100 yards. I may do some more work on load development latter, but for now this will work. I have 500 cases ready to load. Thanks everyone for your help.

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Perfect is the enemy of good.

Years ago I used 4198 and had good success. I went to Winchester 748 for 55-63 gr bullets and had good success also. Couldn't really see any accuracy difference. I've never had a FTF or FTE with either powder

The reason I switched was only because I was using it in other cartridges and is merely convenience of using the same powder. I used CCI standard small rifle primers with 22gr IMR 4198 w/55gr and CCI Magnum with 27.5gr W748 w/55gr bullet.

These were for a Mini 14

FWIW

IMR 4198 is an outstanding powder for 222, 223 except in semi's. It's too fast burning and most accurate loads don't develop the port pressures required to cycle the action, not the same thing as chamber pressure. I had to bump up loads for the AR15 but got flattened primers.
Still have a bunch of reloads that shoot outstanding groups in the AR but won't eject the empty. Have rare problems in my Mini 14 but I've also reduced my port diameter.

I like using 4198 for my 55 gr loads in my mini 14, I run about 22 gr and it works well in my mini 14 and I also use it in my 6.8 mini.

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" If our greatest need had been pleasure, God would send an entertainer..... our greatest need was forgiveness, so God sent a Savior."

I use accurate 2230 & 2200 the 2200 is hotter by a little 55gr IMI OAL is 2.230 in my Savage 12 target rifle getting .45 at a hounder yards. I am disable so that is good for me.

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man that loves guns Big Little X NAVY 375 Dan 357 M 41 M 44 M Long guns 22 223 243 25.06 270 30.06 Black powder 45 cal 50 cal hand and longe guns. I load all that I shoot

Ed. Harris who worked for Ruger and did lots of testing on the Mini's has this to say. For an accuracy load I suggest 21-22 grs. of 4198 (either IMR or Hodgdon) with the 52 or 53-gr. Sierra bullets loaded to 2.25" OAL, or 23-23.5 grs. of H322. The 52-gr. Nosler solid base also is quite accurate.