300 blackout loading

[Jeepocabra]

My new 300 blk upper is having an incredibly difficult time getting less than 2moa at 100 yards. It's a 16in Douglas air gauge from compas lake who also chambered it 1 in 8 twist. I'm using converted lake city brass. I have tried both annealed and unannealed cases and all cases have been primer pocket uniformed and deburred. 1680 and h110 both give somewhat hopefull results. My ES is generally lower than 50.

Im getting flyers often using the 1680 and h110 with both 220 smk's and 208 a max'sI am loading short to avoid airspace in the case as it has seemed to reduce the ES. Is the large jump that the bullets are taking hurting my accuracy? I'm at 2.090 oal with the best amax load I have now.

My annealed cases also seem to have a harder and less smooth seating. Has anyone experienced this with annealed cases?

 

[country888]

Re: 300 blackout loading

Bullet seating is where is saw the biggest improvement in my loads. Im not home right now to see what my OAL is for the amax, but can give you mine when I get home this evening. Im geting .75 or better with mine. Are you shooting suppressed? How many gr of 1680 are you using with the amax?

 

[onajoyride]

Re: 300 blackout loading

I load all my subsonic hornady 225 bthp 300BO to 2.210 and I have grat accuracy out of my 9" 1:8 twist

 

[Jeepocabra]

Re: 300 blackout loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: country888</div><div class="ubbcode-body">Bullet seating is where is saw the biggest improvement in my loads. Im not home right now to see what my OAL is for the amax, but can give you mine when I get home this evening. Im geting .75 or better with mine. Are you shooting suppressed? How many gr of 1680 are you using with the amax? </div></div>

10.5 gr of 1680 with an oal of 2.130 with the amax, that group had 26fps ES. I also tried some today with 10gr of h110 at 2.235 (about max mag length for pmags) and was rewarded with a 3in group and an ES of 15 for four shots and a first shot nearly 100
Fps lower.

With supers I'm not having much luck either. 110 vmax with most loads are running 2-2.5 inches at 100

 

[Jeepocabra]

Re: 300 blackout loading

I also have solved my seating pressure issue, I resized the cases twice and the effort became less and smoother.

 

[country888]

Re: 300 blackout loading

Sorry it took me awhile, but here is my loads.

208 gn a-max, OAL 2.185, with 10.6 gn of 1680
110 gn v-max, OAL 2.085, with 21.4 gn of H-110

Both loads are using CCI small rifle primers

I know barrels are like finger prints all are different but both of my barrels like these loads.

 

[Jeepocabra]

Re: 300 blackout loading

The vmax load worked very well, if a bit too hot. The other load however looked about like my others.

 

[country888]

Re: 300 blackout loading

Yea but your talking about .055 difference in seating depth between what you posted as yours and what mine is for the amax. That is a lot. Mine showed a big accuracy difference in just .005 to .010 in depth. I adjusted my seating depth until I got good groups then adjusted my powder to the velocity I wanted. Yours may be seated alittle to deep, to much jump. Just my 2 cents.

 

[ChadTRG42]

Re: 300 blackout loading

I have played with 6 different powders for my 300 blk out ammo. When it came to the subsonic ammo, I had the hardest time finding a good powder and load combination that worked. I finally found a good one. It is with a powder not listed on any reloading data sheets or websites. So, I would experiment with other powders that fill the case better.

 

[killerwaffles]

Re: 300 blackout loading

I found this a while back. This is what AAC recommends for the 300 blackout. Hand loads are on the bottom of the last page. Hope this helps

 

[AMG04]

Re: 300 blackout loading

I have some 220's loaded up but have not had a chance to shoot them. I will update you once I do. I have them set with an OAL of 2.210" From what I understand is this will aid in reliable feeding, but not sure about accuracy.

With the 110gr Barnes bullet and 20.0gr of H110 I am getting 1" groups at 100 yards from my 10" Noveske rifle. OAL is 2.247" This is a max load! Please work up if you try this bullet/powder combo.

I will try to load some of the Hornady 110's and see if I can find an OAL they like.

You may also want to run a quick test where you load 3-5 rounds varying the OAL by 0.010" while keeping the powder charge the same. One of those OALs should produce noticibly better groups.

Best of luck to you and I will let you know how the 220s shoot this weekend.

 

[dddoo7]

Re: 300 blackout loading

seems that everyone is using sierra 220's for sub sonic in 300 blackout. the Hornady 225 BTHP are about $8/100 cheaper than the matchkings. will a 1:8 stabilize the hornady 225?

 

[cchurchi]

Re: 300 blackout loading

My 8" noveske does. 11.5 gr A1680, 1031 - 1060fps across 10 rounds, 2.180 coal.

 

[jkonzal]

Re: 300 blackout loading

I have a S&W M&P with 1:7.5. It seems to like 10.5 gr of A1680. I am shooting the 220 gr Seirra Round Nose bullets. Have not crono'd them yet, but will asap. The recommended load of 11.2 gr's of 1680 shot all over the place for me. Now I am at less than 1moa.

 

[725franky]

Re: 300 blackout loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">I have played with 6 different powders for my 300 blk out ammo. When it came to the subsonic ammo, I had the hardest time finding a good powder and load combination that worked. I finally found a good one. <span style="font-weight: bold">It is with a powder not listed on any reloading data sheets or websites. So, I would experiment with other powders that fill the case better.</span> </div></div>

Chad,

Looking at QuickLoad I notice that I could get a little more pressure, case fill and propellant burn percentage with AA2200 than I would with AA1680; am I correct in my assumption that using the AA2200 should result in more consistent loading?
I hope that my questioning doesn't come off as trying to pry about your load; but, I am pretty new (ie wet behind the ears still) and am having a hard time coming up with a consistently accurate subsonic load... I've gone through about 75ish 208 A-maxes and 90ish 225 BTHP's, all using AA1680; which, while is seems to function decent at higher velocities, is not giving me consistent functionality and / or accuracy (could be me, haven't shot an AR much as I mostly shoot a bolt gun).

I loaded up 4 rounds @ 9.8gr (should have been ~ 1030fps according to QL) AA2200 last night and they functioned fine (locked back the BCG after the last round) albeit the velocity was more like ~ 750 fps with a 20somthing SD. Based on that miniscule morsel of data I think that AA2200 may have some potential around the 10.5 - 11.5gr charge range.

Gun: Self assembled flat top upper, ARStoner 16" Carbine BBL
Bullet: Hornady 225Gr BTHP
OAL: ~2.188"

Frank