300 blk out accuracy with cast bullets and seperate jacketed bullets

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

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farright
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300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by farright » Sat Jan 13, 2018 5:43 pm

i was reading a post below on the accuracy of the 300 blk out and it got off topic and started listing 222 rem 308 etc.
Now what i would like to know is an honest discussion on the black out. listing group size separately of the cast and jacketed bullets.
my CZ has yet to shoot a one-inch group at 100 yards. I have loaded and shot cast bullets Eagan 30x Lyman 311331 311679 311644 NOE 165 fp rcbs 180 sp and a few others. my best cast groups are around 1.25 inches and average closer to 2.5 inches.
Jacked bullets used 110 gr speer. ( this shot the best group of just over an inch) sierra and Hornaday 165 gr. used powers of 4198, 1680 2200 2230 4759 aa9 and unique. best cast group was with unique.
i listed the above to let you know i have put the rifle through its paces and so far not happy with the accuracy. My next step will be to bed the stock as it is not in the center of the barrel channel and rubs against the right side of the barrel channel.
it is my opinion that one small group means nothing it has to be repeatable to have value. Please be honest and list real results with the make and model of the rifle, thpe and weight of bullet and powder.

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TRshootem
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by TRshootem » Sat Jan 13, 2018 9:49 pm

To get groups tighter than 1 inch requires some match style case prep (annealing, trimming, etc.) and the right powder choice. 110 Vmax's and 125 TNT's will shoot inch or less, OAL is often the variable making the accuracy difference. I have had nice results with H110, 300 MP and 296 for these lighter bullets. Squeezing out that last little bit of what a load has to offer takes a bit of patience. Your CZ should do what you want, eliminate you as the chief issue in your shooting form and then tinker...lots of tinkering :)

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farright
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by farright » Sat Jan 13, 2018 10:06 pm

i have been bench rest shooting for over 50 years and this is this rifle has been one of the most challenging. now i know it takes tuning just to get repeatable results. one time 1.5 inches then same load etc shoots 3 inches. i have a feeling i am not the only one finding the black out a bit of a challenge. if it is possible and i think it is i will figure it out in the near future. bedding the stock is the next move. and i am using new brass cast bullets sorted by weight or jacketed bullets using good quality components

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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by cdakers » Sat Jan 13, 2018 10:14 pm

I assume you have inspected the bore of the barrel? Widely differing groups with identical loads would have me seriously taking a magnifying glass to my rifle.

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dellet
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by dellet » Sat Jan 13, 2018 11:20 pm

With what you listed for components I would run the Sierra 165 .010”-.030”off the lands or as long as possible for your magazine if you use it. Somewhere around 19 grains of 1680. Looking for 105% case fill and 1900-1950 fps.

You said new brass, new brass kinda sucks. The shoulder is so small, most new brass has a very poorly formed shoulder. Once fired, minimal set back on the shoulder will really make a difference.

In bullet choice your looking for something jump friendly, SMK’s are a good choice as well as the Amax and ELD line. The Berger 155.5 full bore is another. 125 SMK, or SST.

If you want lighter supers I’d look into H110/296 or VV N110.

I think you’ll find a powder change will probably tighten your groups.
300 Blackout, not just for sub-sonics.

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farright
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by farright » Sat Jan 13, 2018 11:42 pm

thanks, that kind of information is what i am looking for. the blk out is so different than most of the cartridges i own. my Mauser in 7.62x39 will do an inch with 2 different cast bullets but likes the nei 72 the best. i have shot an argentine Mauser in 7.65x53 in cast bullet matches for years. it is my goal to shoot cast in the blk out, but i want a good jacketed bullet load also. i do know for sure i won't give up till i get a load that is repeatable accurate.
when i said new brass what i meant was it is not brass formed from 223 Remington, but i am not sure there is anything wrong with 223 brass cut down. i am not sure military has the same tight standards of commercial.
i do know there are a lot of half-inch groups shot at the gun counter a lot more than at the range. just like the 800-yard elk one shot kills.
and 3 inch groups at 1000 yards.

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farright
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by farright » Sat Jan 13, 2018 11:45 pm

i forgot to mention my computer hates me and makes spelling mistakes just to make me look stupid. it is not my fault i think micro soft hates me because i vote republican and does their best to make me look like those people who cling to their guns and religion. at least they got that part right. joe g.

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dellet
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by dellet » Sun Jan 14, 2018 12:12 am

The biggest problem with cut down brass is the necks. It’s not uncommon to have a .002” taper so neck tension can be hard to control. It has to do with what part of the case becomes the neck.

As far as cast bullets, I think the tough part is balance and spin rate. The difference between 1/7 vs 1/9 is about 50,000 rpm at 2000 fps. Or a 1/7 at 1500 fps is spinning about the same as 1/9 at 2000.

The other thing to keep in mind is tolerances, in a lot of loads one grain is worth about 100 fps. .2 grain change is 1%. There’s just smaller windows of accuracy.
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certifiable
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by certifiable » Sun Jan 14, 2018 1:20 am

My experience with cast bullets is very limited but I have found the accuracy to be acceptable

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dellet
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Re: 300 blk out accuracy with cast bullets and seperate jacketed bullets

Post by dellet » Sun Jan 14, 2018 1:45 am

certifiable wrote:My experience with cast bullets is very limited but I have found the accuracy to be acceptable
Pay no attention to any groups that certifiable posts, there seems to be some debate as to if he is actually human or machine. :mrgreen:
300 Blackout, not just for sub-sonics.

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