Sub-sonic 303 loads


September 10, 2008, 06:02 PM
Iv started development of a sub-sonic load for the 303 British; strange i know, but i have my own reasons and USES for such a load.

My goal is to generate a reliable and consistent muzzle velocity of 700 feet per second with a 125gr bullet

i prefer Hodgdon powders, so i looked at powders from them that had 303 loads listed. Of those powders, Varget is the bulkiest. They recommended 45 grains of Varget for a starting load with a 125gr bullet. But I'm looking to produce roughly 1/4 of the velocity that their starting load produces...

Now Iv read FAR too many reports of cowboy action shooters blowing up their guns when a bullet gets stuck in the barrel from their weak loads. Im not looking to avoid recoil, I'm just looking to keep the velocity well under the sound barrier.

Iv also read that many of the cowboy shooters inconsistency problems come from the fact that there is SO much empty space in the cartridge that the powder doesn't burn consistently. I will need some kind of filler material to avoid this.

So what kind of filler will I need to start test loads? Also, what is an appropriate charge to start development? i was thinking 15 grains with filler?

anyone with an opinion feel free to chime in. I welcome all input, including criticism. :D

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September 10, 2008, 06:17 PM
Don't even think about trying it with jacketed bullets!

You can probably safely get sub-sonic with a heavy (220 grain) cast lead bullet, but even those at only 700 FPS raises a very strong possibility of sticking a bullet in the barrel and blowing up a gun.


September 10, 2008, 06:24 PM
Shooting a jacketed rifle bullet (assuming you mean a 125 gr bullet intended for the 7.62x39) at 700 fps is not a good idea. At some point, you will stick one in the bore.

You can probably use cast bullets or some of the 32 cal pistol bullets such as these for better results:

I would suggest a pistol powder (such as Unique) for reduced velocities rather than a rifle powder, unless the rifle powder is intended for reduced loads. Lyman has some cast bullet loads down as low as 1130 fps.

September 10, 2008, 06:46 PM
Actually, Speer makes a 303 diameter 125gr bullet.

I was originally considering using a 100gr half jacket bullet in 308. Would that be a better idea? I hadn't thought of using Pistol bullets and powder, but that sounds like a clever solution.

Would using slightly smaller .308 diameter bullets solve the sticking problems with jacketed ammo?

Jim Watson
September 10, 2008, 07:07 PM
Long ago, when they could do some shooting instead of lobbying, the NRA had a report on ultra light loads. They got good shooting with 1 to 5 grains of Red Dot and 80 - 100 grain cast bullets in 7mm Mauser.

If you will dig through it, the Finns did a lot of work on subsonic loads:
The end result with modern components works out to a few grains of N320 pistol powder and a light cast bullet.

My .30-06 shoots like a champ with the 165 gr Laser Cast bullet and 7 grains of 700X. Noise is mild, although I have not chronographed it to see if it is subsonic.

You cannot just reduce a 45 grain load of a rifle powder like Varget to something that sounds kewl. Extra light loads call for fast burning powder.

Bottleneck cartridges and non-powder crap as "filler" do not go together well. There have been reports of the whole neck and shoulder of the case being sucked down the barrel by friction from the filler. Puff-Lon says they have that fixed. Worth looking into.

If I wanted to shoot jacketed bullets, I would settle for high subsonic velocity in the 1000 fps range and have Rocky Mountain Cartridge make me some reduced capacity .303s to be loaded like a .300 Whisper.

September 10, 2008, 08:21 PM
Oh iv got no preference for jacketed versus lead. And admittedly, I'm in completely new territory here. Iv been reloading for about 2 years, but only mild loads for handgun cartridges.

Iv never reloaded for rifle, or tried any kind of reduced load. Thanks for the article, it was a huge help! :)

September 10, 2008, 09:06 PM
Words from the man....C.E. Harris

The following is a very good read with excellent information:


Cast bullets can make shooting that surplus rifle easy and economical.
And basic data works for many different guns.

BY C.E. Harris

Cast bullet loads usually give a more useful zero at practical field ranges with military battle sights than do full power loads. Nothing is more frustrating than a military rifle that shoots a foot high at 100 yards with surplus ammo when the sight is as low as it will go! Do not use inert fillers (Dacron or kapok) to take up excess empty space in the case. This was once common practice, but it raises chamber pressure and under certain conditions contributes to chamber ringing. If a particular load will not work well without a filler, the powder is not suitable for those conditions of loading. Four load classifications from Mattern (1932) cover all uses for the cast bullet military rifle. I worked up equivalent charges to obtain the desired velocity ranges with modern powders, which provide a sound basis for loading cast bullets in any post-1898 military rifle from 7mm to 8mm:

1. 125 grain plain based "small game/gallery" 900-1000 f.p.s., 5 grains of Bullseye or equivalent.

2. 150 grain plain based "100-yard target/small game", 1050-1250 f.p.s., 7 grains of Bullseye or equivalent.

3. 170-180 grain gas checked "200 yard target", 1500-1600 f.p.s., 16 grains of Hercules #2400 or equivalent.

4. 180-200 grain gas-checked "deer/600 yard target", 1750-1850 f.p.s., 26 grains of RL-7 or equivalent.

None of these loads are maximum when used in full-sized rifle cases such as the 30-40 Krag, .303 British, 7.65 Argentine, 7.7 Jap, 7.62x54R Russian , or 30-06. They can be used as basic load data in most modern military rifles of 7mm or larger, with a standard weight cast bullet for the caliber, such as 140-170 grains in the 7x57, 150-180 grains in the .30 calibers, and 150-190 grains in the 8mm. For bores smaller than 7mm, consult published data.

The Small Game or Gallery" Load

The 110-115 grain bullets intended for the .30 carbine and .32-20 Winchester, such as the Lyman #3118, #311008, #311359, or #311316 are not as accurate as heavier ones like the #311291. There isn't a readily available .30 caliber cast small game bullet of the proper 125-130 grain weight. LBT makes a 130 grain flat-nosed gas-check bullet for the .32 H&R Magnum which is ideal for this purpose. I recommend it highly, particularly if you own a .32 revolver.

The "100 Yard Target and Small Game" Load

I use Mattern's plain-based "100 yard target load" to use up my minor visual defect culls for offhand and rapid-fire 100 yard practice. I substitute my usual gas-checked bullets, but without the gas-check. I started doing this in 1963 with the Lyman #311291. Today I use the Lee .312-155-2R, or the similar tumble-lubed design TL.312-160-2R. Most of my rifle shooting is done with these two basic designs.

Bullets I intend for plain based loads are blunted using a flat-nosed top punch in my lubricator, providing a 1/8" flat which makes them more effective on small game and clearly distinguishes them from my heavier gas-checked loads. This makes more sense to me than casting different bullets.

Bullet preparation is easy. I visually inspect each run of bullets and throw those with gross defects into the scrap box for remelting. Bullets with minor visual defects are tumble-lubed in Lee Liquid Alox without sizing, and are used for plain base plinkers. Bullets which are visually perfect are weighed and sorted into groups of +/- 0.5 grain for use in 200 yard matches. Gas checks are pressed onto bullet bases by hand prior to running into the lubricator-sizer. For gas-check bullets loaded without the gas- checks, for cases like the .303 British, 7.62 NATO, 7.62x54R Russian and 30-06, I use 6-7 grains of almost any fast burning powder. These include, but are not limited to Bullseye, WW231, SR-7625, Green Dot, Red Dot or 700-X. I have also had fine results with 8 to 9 grains of medium rate burning pistol or shotgun powders, such as Unique, PB, Herco, or SR-4756 in any case of .303 British or larger.

In the 7.62x39 case, use no more than 4 grains of the fast burning powders mentioned or 5 grains of the shotgun powders. Theses make accurate 50 yard small game loads which let you operate the action manually and save your precious cases. These plinkers are more accurate than you can hold.

Repeated loading of rimless cases with very mild loads results in the primer blast shoving the shoulder back, unless flash holes are enlarged with a No. 39 drill bit to 0.099" diameter. Cases which are so modified must never be used with full powered loads! Always identify cases which are so modified by filing a deep groove across the rim and labeling them clearly to prevent their inadvertent use. For this reason on I prefer to do my plain based practice shooting in rimmed cases like the 30-30, 30-40 Krag, 303 British and 7.62x54R which maintain positive headspace on the rim and are not subject to this limitation.

The Harris "Subsonic Target" Compromise

Mattern liked a velocity of around 1250 f.p.s. for his 100 yard target load because this was common with the lead bullet .32-40 target rifles of his era. I have found grouping is best with non gas- checked bullets in military rifles at lower velocities approaching match grade .22 long rifle ammunition. I use my "Subsonic Target" load at around 1050-1100 f.p.s. to replace both Mattern's "small game" and "100 yard target" loads, though I have lumped it with the latter since it really serves the same purpose. It's report is only a modest "pop" rather than a "crack".

If elongated bullet holes and enlarged groups indicate marginal bullet stability, increase the charge no more than a full grain from the minimum recommended, if needed to get consistent accuracy. If this doesn't work, try a bullet which is more blunt and short for its weight because it will be more easily stabilized. If this doesn't do the trick, you must change to a gas-checked bullet and a heavier load.

September 10, 2008, 09:11 PM
This fella is launching 200 grain cast bullets from his .303 at sub-sonic velocities using ADI AS50N, better known as Hodgdon International Clays in this country.

This will be an unpublished loading, but seems entirely reasonable based on my experience with this type of handloading.

September 10, 2008, 10:00 PM
Wow, lots of good information here.

Ill start with a 125gr cast bullet, and 5 grains of Bullseye. And ill be sure to check the bore after every shot until iv got a good deal of the same load down the pipe. :)

Thank you everyone for your help.

January 20, 2009, 01:10 AM
Unsized lead .308 bullets are usually close to .311 or .310. Unique is the original powder used for reduced loads start with 7.8 grains for 1000 fps and go down , or try the new trailboss powder, start at 5.0 and go up. 210 gr. bullets

January 20, 2009, 11:00 PM
More info :)

January 21, 2009, 10:55 AM

Don't even think about trying it with jacketed bullets!

I'll second that:)

January 21, 2009, 11:53 AM
A 700 fps is going to be hard to safely develop. I rifle barrles are just to long to get that kind of speed, to much friction. 1000 to 1400 fps is a more realistic goal. You can try jacketed but in the long run I think you’ll find cast bullets are the only way to go. You might also consider lead round balls and buckshot. Your .303 is probably going to like bullets sized in the .312” to .314” ranged. A little bigger than you typical .30 cal bullet. Bullet size can have a HUGE impact on accuracy, even at short 25yd ranges.

Your also going to want to look at pistol powders and the very fastest rifles powders. Powders in the range from Bulleye up to Lil'gun. Low density "Fluffy" powders like: Unique, Trailboss, AA 5744; will better fill the case and do away with the need for having to use fillers, a practice which should be avoided.

Some food for thought:

From -- Trail Boss K.I.S.S. by J. Simon and R. Ted Jeo:


The Universal .30 Load by Rocky Raab:

Round Balls in a 30-30 Winchester Model 94 by Junior Doughty:

Lever Gun Performance Studies by Gregory J Mushial:

January 21, 2009, 08:22 PM
Lead balls leak by pass gas, unless there is a wad behind them.

The 303 case mouth can be used to cut the wad, if is is sharply chamfered.

January 21, 2009, 10:42 PM
One could extrapolate,, but only with lead.

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