Reduced and Subsonic Loads

Andy

Andy

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There have been several threads recently requesting guidance for either "reduced" or "subsonic" loads. A "reduced load" is a load that is below published Starting Loads, and a "subsonic load" is a load whose Muzzle Velocity (MV) is at or less than 1125 fps (the speed of sound at sea level at a specific temperature and humidity). Most use 1100 fps as safely under the speed of sound under all likely conditions.

This article provides a good overview of that: https://www.handloadermagazine.com/reduced-rifle-loads

Here's a link to a number of subsonic loads: http://www.gmdr.com/lever/lowveldata.htm

I direct you to a point made within it that is often overlooked and to which some object: that cast bullet loads can be used with jacketed bullets. Be it loads from the excellent "Lyman Cast Bullet Manual" or Ed Harris' venerable "The Load" (13.0 grs of Red Dot in some cartridges), these published loads are an easy way to get started.
 
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I have been dabbling in reduced and the somewhat more challenging subsonic jacketed realm for a while now and much of the info that I used came from you in this very sub-forum...still have both eyes and all fingers!
With current powder prices as well as unknown restocking schedules folks are starting to turn more and more to the reduced loads.

4grs of trailboss under a 55gr bulk .224gr Campro is what I'm shooting right now...and I cringe everytime I light off a primer as they are gold these days!
The particular load above is traveling subsonic with "minute of mandarin orange" accuracy @ 50yds and really smacks the steel compared to 22lr and I enjoy shooting it more than rimfire.
 
Sun_and_Steel_77 said:
I have been dabbling in reduced and the somewhat more challenging subsonic jacketed realm for a while now and much of the info that I used came from you in this very sub-forum...still have both eyes and all fingers!
With current powder prices as well as unknown restocking schedules folks are starting to turn more and more to the reduced loads.

4grs of trailboss under a 55gr bulk .224gr Campro is what I'm shooting right now...and I cringe everytime I light off a primer as they are gold these days!
The particular load above is traveling subsonic with "minute of mandarin orange" accuracy @ 50yds and really smacks the steel compared to 22lr and I enjoy shooting it more than rimfire.
Click to expand...

My last subsonic project was in the 223, but I wanted to see if a load could be developed that was subsonic and would cycle the action of an AR-15.

I don't think it's possible, but am not ready to believe that until I've at least tried. If it is possible, it will need sufficient pressure and gas volume (powder). My thoughts are that a heavy bullet (~77+ grs) and a "slow" powder would be required. Among the challenges are that the slower the powder, the higher the pressure required for it to burn consistently, and the higher the pressure the higher the MV.... The notion of lightening the bolt assembly return spring might help with ejection and cocking, but it still needs enough tension to strip a round off the mag and chamber it. It's a real balancing act.

I had a list of powders to try from US869 down to H4350 and was going to try both Magnum and Standard primers with loads that were promising.

Then I was no longer permitted to leave the house with the test firearm.....

From Quick Load -- some different starting points. All full cases (100% load).
Cartridge : .223 Rem. (SAAMI)
Bullet : .224, 55, Mil FMJ - M193
Useable Case Capacity: 26.469 grain H2O = 1.719 cm³
Cartridge O.A.L. L6: 2.260 inch = 57.40 mm
Barrel Length: 16.0 inch = 406.4 mm
---------------------- -----------------------------------------------------------------
Hodgdon H4350 100.0%, 24.3 grs, 2349 fps, 29699 psi

Hodgdon H4831 SC 100.0 24.7 2128 25181

Alliant Reloder-22 100.0 24.7 2061 22166

Alliant Reloder-25 100.0 24.3 1907 18996

Hodgdon H1000 100.0 24.1 1801 17993

Hodgdon US 869 100.0 26.0 1547 13692

This is with a 55 gr bullet - substituting a heavier bullet would raise pressure, reduce the amount of powder, and lower the MV, but even for US869, it would likely remain above 1100 fps. I further doubt that US869 would fire at around 15K psi.
 
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I was testing some subsonic load for my 308 16" barrel Remington 700 SPS for some 50 - 100 yard plinking and to introduce my rifle to my wife.

Components:
Campro 147gr FMJ
Trail Boss
WLRP

9.5gr @ 1140 fps average
9.0gr @ 1107 fps average
8.7gr @ 1070 fps average
8.6gr @ 1050 fps average (final plinking load)
8.5gr @ 1040 fps average
8.4gr @ 1027 fps average
8.0gr @1030 fps average

All loads produced stable bullet flight... no key-hole out to 100 yards.
 
Glad to see this thread. I love playing with subsonic and reduced loads. Its hard to get started as it almost feels wrong using 5-10gr of pistol powder in a 308 case lol and there isnt much published data.

I had a bolt action 44-40 (build on a lee metford receiver) that i use to load 300gr Sierra JSP at 430fps. No practical use at all but it was fun, you could watch the bullets go.

I always have a cast bullet 950fps load for every cartridge i reload for . Just for plinking, shooting in the yard or taking to the range when my kids come.

When you get into casting or shooting cast Subsonic/reduced loads makes more sense then when you shoot jacketed bullets but like stated a few post above, power cost and availability may come into play sooner then later
 
I’ve found I like the IMR4198 loads in medium cartridges like 308 and 30-06. Easy to simulate 30-30 loads and good accuracy. Barsness mentions in the article the 2002 IMR guide where the data is found. I’ve also had good luck with 5744 in 270, creating an accurate load with 110 bullets. Trail Boss under a 150 gr bullet in the 308 at 1500 fps is an excellent training load and also surprisingly accurate.
 
Snider shooter said:
7.62x54R or 303 British
Seven to nine grs of 700x under a 205 cast bullet makes a nice plinking load. Sites need to be raised up a fair bit but military rifles have lots of adjustment.
Click to expand...

700X has been my go to powder for plinking loads for most of my old milsurps. Various bullet weights, reasonable powder charges. An example of one I use: 5 gr. 700X under a 93 gr LEE ww in 30-30. I can shoot these loads indoors at our range. Unique and Trail Boss are also versatile powders.

With the little 30-30 loads, I get close to 7000 loads. Not your elephant killer loads, but fun to shoot. Strict attention needs to be paid to loading these types of reloads. Double charges are a possibility.

I have a nice old 99 Savage 30-30 TD that shoots like a darn with 150/155 gr. LEE cast. I don’t have the data right here, but it is a light load of Unique, IIRC.
 
Unique is another powder I use for reduced loads. 9 grs of unique works well with 150 to 170 gr loads with a lead bullet. 2400 I have been using a lot of in 303 British and 7.62x54 R. 18 grs with 205 gr lead. I have tried many of the shotgun powders in many military surplus calibers.
 
Love my subsonics out of my Marlin SBL 45-70. 10gr of unique under a 405gr hard cast lead pill. Easy on brass, shoulder and powder. Accurate enough for plinking steel. Just put a scope on it for my hunting load development (have skinner peep normally). Interested to see what the actual accuracy is
 
Titegroup is my favorite powder to use with subsonic loads. W231 also works very well even being a ball powder.

H4895 and IMR3031 are my favorite for reduced loads.
5744 and 2400 are well up there to but the 5744 costs to much so i wont but any more when mines used up.
 
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