Thoughts on subsonic 300 Blackout for deer hunting

[Yondering]

You'll definitely want to use more than 1 or 3 shots for good velocity numbers. You'll probably find some loads with up to 100 fps velocity variation between shots, so single sample numbers don't mean a whole lot. You also may find situations where the first shot is consistently faster or slower than the rest.

[Rob]

Definitely.  Just running into time constraints as well as those bullets are spendy!

I am feeling pretty good about that 9.1 grain load being in-between 900 and 1000 fps.  Will load some of those up and test them out.

[Yondering]

Yep the Lehigh stuff is good but definitely not cheap. BTW if it hasn't been mentioned before - you can get them cheaper from MidwayUSA than direct from Lehigh.

[Rob]

That's where I picked mine up!

[Rob]

I was able to get out to the range and do a little shooting.  Obviously the sample size of data points are not good enough to give scientific results, however I am not seeing anything alarming here.

Spent most of my time at 50 yards and left with a 50 yard zero on the rifle.  I was most interested in the Lehighs but I did shoot 3 groups of 3 in the Sierras.  I did not have a chrony, but as far as my ears could tell, everything stayed subsonic.  Observations:
- All four load/bullet combo shot about the same in terms of group size – averaging about 1.25 at 50 yards and 1.50 at 100 yards.
- The 9.2 grain loads grouped a bit tighter than the 9.0 grain loads in the Lehighs.  The averages in the table below don’t show it, but two of the groups of the 9.2 grain loads were under an inch.
- As expected, both the Lehighs and Sierras had similar zeros at 50 yards regardless of powder charges used in my tests.  At 100 yards the 11.5 grain loaded sierras and the 9.0 grain loaded Lehighs had similar POI.  But bumping the Sierras to 12 grains moved the POI up by 3 inches!  I was out of 9.2 grain loads of lehighs so I could not do a similar compare.
-For the Lehighs, they all fed and cycled flawlessly and the bolt catch engaged properly to keep the breech open after the final round in the magazine was fired.
-For the Sierras, all rounds fed and cycled flawlessly - however about 50-75% of the time the bolt catch did not engage on the final round in the magazine to keep the breach open.  Some gas block tuning might resolve that.

Net/Net:  I am satisfied enough with the accuracy and performance of the Lehighs out to 100 yards to use them in a hunting situation.  The bullet drop makes me nervous though.  As zeroed right now, I feel good with 0 to 75 yard shots.

Not positive I can get back out to do one more set of tests, but if I do, I want to look at the following:

1: If I zero at 100 yards with the 9.2 grain loads on the Lehighs, what will the POI be at 50 yards?
2: Would like to get chrony data for at least 10 more shots on the Lehighs.

Thanks again to all for the recommendations – I hope this data is somewhat useful to others! 

Will report back if I get back to the range, and again after I see how they perform on deer (should I get a shot)

[Rob]

Side note.  I slapped the suppressor on my bolt action 7mm Rem Mag and shot a couple groups at 200 yards (both with and without the suppressor)

POI dropped 4 inches with the suppressor.  I understand this is due to barrel harmonics, but I would be interested to do this again over a chrony to see if there are any velocity changes.

[birdshooter1189]

When I put a heavy 30 cal suppressor on my lightweight .223 I have to adjust 34 clicks up on the scope to compensate (8.5" at 100 yds).

My opinion is that due to recoil, the rifle starts to climb before the bullet leaves the barrel.  With more weight on the end of the barrel, it rises less, thus making it hit lower.

[Yondering]

Side note.  I slapped the suppressor on my bolt action 7mm Rem Mag and shot a couple groups at 200 yards (both with and without the suppressor)

POI dropped 4 inches with the suppressor.  I understand this is due to barrel harmonics, but I would be interested to do this again over a chrony to see if there are any velocity changes.

First about the 50 yd POI with 300 Blk subsonic zeroed at 100 yards, you should expect ~3.5" high at 50 if you have a fairly typical AR setup.
You'll also be about 3.5-4" low at 120 yards, so you need to be very careful with your range estimates; I use a rangefinder a lot but when estimating by eye I still find it easy in the woods to be off by 20-40 yards and that can make a big difference with any subsonic loads. I do zero mine at 100 yards.

On the suppressor changing POI - yes it is partly barrel harmonics, but mostly just that you've hung a weight on the end of the barrel. A drop in POI is to be expected with all but the stiffest heavy barrels; if POI goes somewhere else other than down your suppressor may be affecting bullet flight, either through misalignment or just baffle design.
POI drop in most of my rifles ranges from 0.5 to 1.0 mils down; that's something you have to test on each rifle and just write down or remember for future reference.

[CP]

On the suppressor changing POI - yes it is partly barrel harmonics, but mostly just that you've hung a weight on the end of the barrel.

Bingo - I have a pretty heavy suppressor and when I hang it on my 10" bull barrel there is hardly any change on POI - On my 16" pretty stiff barrel there is a 3" shift at 200 yards, on my 22" thin tapered barrel there is a 7" shift at 200y.  Always down.

[Rob]

Dropped a small deer on the opener with the blackout (hunting private land on a tree farm where the goal is to reduce #'s, not trophy hunt).

I had put an 85 yard zero on it and my range testing had me 2 inches high at 50 and 2 inches low at 100.  Figured that was a "minute of deer" for a vitals shot out to 100, with some reasonable hold-overs out to 130..

The deer came in at 100 yards and I waited till it was at 85 and took the shot.  Dropped it like a sack of flour.  Bullet did not exit - although I looked for it and could not locate it.  It was last light so it must have been in there somewhere, I was just unable to find it.

Anyway, Thanks to all for the help.  The Lehighs worked most excellent, and the advise was greatly appreciated. 

[Yondering]

Nice job!

[TooTallMike]

Great job!

I have experience with the Lehigh bullets and I'm curious as to what your twist rate and barrel length are. Because they play big factors when it comes to sub loads.

My current go to recipe is
9.8gr of H110
2.275 COAL
Get 1055 fps all day
Sub moa at 50yds.

My gun set up is a Remington 700 pistol with a 9 inch custom barrel
Have a 1/7 twist but wish I'd went with a 1/5.

Congrats on the deer 👍

[JohnVH]

Awesome, Im reloading IMR4198 11.5gr under a 210gr bullet. going 1050-1070fps with a can on a 16" barrel

[Rob]

Sure.  It is an AR platform I assembled. For the barrel I used:
-Proof Research Carbon Fiber 416 SS .980 16 in. 1:7 twist Contour PR15C160220BAA with matched bolt.  Journal size .750 .  Muzzle 5/8x24 thread.  Carbine length gas system

My velocities are in the table above - I am very precise with my loading but I see a +/- 50 fps with my chrony (not sure if that is my gun, my loading, or my chrony!)

I was not able to do much with accuracy testing due to time.  I was getting 50 yard groups that ranged from 6/10'ths to 1.5 inches.  Consider also that I am also a lousy shot...

I was shooting the Lehigh Defense Maximum Expansion 01308194LP

[TooTallMike]

It's not your chrony or your reloading process. It's Lil Gun. I tried to make a load using it as I have around 2 lbs laying around. The issues I ran into were what you just mentioned, the ES is way too erratic.. between a 10 shot group I got something like 120 fps ES. When I switched over to h110 they really tightened up as well as the SD and ES.