Loading the 351 WSL

In a previous article, on the Winchester Self-Loading Rifles, we provided background information on the four centre-fire cartridges that made up the WSL family.  Now we are going to take a deeper dive into the most popular cartridge in the series, the 351 Self-Loading.

When one looks at this family, the first reaction is that none of the cartridges have enough energy to be practical hunting rounds.  Yet at the time they were introduced, a lot of classic cartridges were at the same energy level as the 32 and 35 WSL.

With the release of the 351 WSL, things were stepped up a notch and it was in the same league as new generation of smokeless cartridges (25-35, 303 Savage, 32 Win Spl, etc) and well above the classics like 38-55 Winchester.  When we look at the WSL cartridges and compare them to the 30-06 or 270 they appear to be anemic, but not next to the cartridges of the day.

Loading

If you are looking for reference material on this family of guns, the only book that discusses them in any detail is the softcover, “The Forgotten Winchesters” by John Henwood (published 1995).  It is a great reference to have and is recommended.  Reloading information is also limited but older Lyman manuals (#45) have a limited amount of data for the 351 WSL.  Also, Handloader published an article on the 351 WSL and it is referenced in the resources section.

Getting the rifle to function, for a straight blowback action is about matching bullet weight, velocity and residual chamber pressure.  Since the bullet weight is pretty well fixed for the 351 WSL, the only other variable is bullet velocity, which is connected to the powder type and charge weight.  Factory velocities vary depending on the source and the manufacturer.  In the Handloader article, Rem/UMC and Peters ammo were right around 1900 fps.  I have chronographed 1970s vintage Remington ammo at 1750 fps and Winchester (1990s, white box) at 1850 fps, although others have talked about velocities as high as +1900 fps for Winchester ammunition.  COTW listed 1850 fps for factory ammo.

The case capacity is limited, so to have a long enough impulse to work the action means that very fast pistol/shotgun powders may not work well.  The pressure can peak too quickly.  In the Handloader article a load of Unique that gave just under 1700 fps did not consistently function the action.  Yet at the same velocities with A5744 and IMR 4227, the gun worked.  I have had the same experience, which is why I stick with powders that have about the same burning rate as 4227.

Given that 4227 is the standard for the WSL family, powders around this burn rate should work well.  Using the Hodgdon burning rate chart (2024), the following table shows the five best options.

It should be noted that H110 has a burning rate of 66, which while it was not tested, it would be a viable option.

The 100% load density numbers are the amount of powder that can be held by the case with no compression when the bullet is seated.  They were tapped a few times to settle the powder but this amount of powder will fill the case to the base of the bullet.  Spherical powders (Lil’Gun and A1680) cannot be compressed to increase the charge weight but for the extruded ones, it is possible to increase the charge weight slightly. 

One advantage in having a case full of powder, is given the way the gun cycles, is that the powder column supports the bullet, preventing it from being driven into the case.  It should be noted that the magazine limits the overall length to a maximum of 1.90” and the factory COAL is 1.89” (Winchester).  All the loads were set at 1.86” for the cartridge overall length (COAL).

The relative granule size of the different powders, ranging from the large A5744 kernels to the dust-like A1680.

Getting brass for the centrefire cartridges may be expensive but fairly easy.  Used brass, of varying quality/age shows up on auction sites and new brass is made by Bertram.  The only brass that should not be used are very old balloon head cases.  Based on both age and mechanical strength they are not worth the risk.  Those who want an adventure, cases can also be formed from 357 Maximum brass.

The 351 uses an unusual bullet diameter of 0.351”, which limits bullet selection. We size our cast bullets to 0.352” to ensure a positive seal, prevent gas blowby, and reduce the potential for leading. Grafs periodically offers plated bullets for the 351 WSL, but they do not have a crimping groove. Any load for the WSL rifles, unless single-loaded, needs to be crimped. Fortunately, Lee makes a low-cost collet-style crimp die that does not require a cannelure and works well with the Grafs bullet. The bullet is seated with the standard seating die, and the crimp is applied separately with the Lee collet die. This helps improve ammunition quality by producing a consistent crimp.

Lyman formerly had two moulds (350319 GC and 350293 flat base) for the 35/351 WSL and they show up at gun shows and eBay from time to time.  If you have a choice, get the gas-check version since it will allow you to get close to factory velocities with less potential for leading.  The plain base bullet is easier to cast and if you hold velocities around 1500 fps, leading is minimal, although I have used them to +1600 fps with only limited leading. The condition of the barrel will have a major impact on the leading potential.

The two next tables show what is possible with different powders.  CCI 400 small rifle primers were used along with Bertram cases.  The plated bullets from Grafs measure 0.350” and are fully copper plated.  The cartridge overall length was 1.86”, the exception being for 20 gr of IMR 4227, which could only be seated to 1.92”. 

*          overall length 1.92”, will not work in magazine

**        slightly compressed, normal seating length

Lil’Gun (16 gr), IMR 4227 (18 gr) and A1680 (22 gr) all provided velocities right around 1750 fps.  This provided good ejection but not as violent as higher velocities do.  With a peep sight, the group size for these three powders was in the 1.5” range at 50 yards.  Reloader 7 is too slow and there is not enough case capacity for it.  It left carbon deposits in the cases and velocities were too low to recommend it.

The powder charges highlighted in yellow are ones that will not consistently cycle my 351 WSL.  This will vary depending on the rifle but in general the velocity should be above 1400 fps for consistent ejection.

The takeaways from the shooting are:

• Lil’Gun is too fast burning for 100% loading density but it is a low fouling powder.
• A5744 is clean burning and a maximum load (19 gr) is dictated by case volume and is mild.
• IMR 4227 at 19 gr will give 1800 fps and will meet factory COAL.
• A1680 fills the case and gives factory velocities, a strong alternative to 4227.
• Reloader 7 is too slow burning for the maximum load (18 gr) and is not suitable.

A1680 will provide velocities touching 1800 fps which is a realistic maximum.  The same can be said for IMR 4227.  Both of these powders provide full cases which guards against bullet set-back.  Lil’Gun is faster burning and could easily top 1900 fps but at the risk of wear and tear on the rifle.  However, any of these three propellants will allow you to craft reliable loads that are safe for a sound M1907.

Because the rifle uses a blowback action, the chamber can become dirty quickly if you are using cast bullets.  A blowback action characteristic is that it opens before the chamber pressure is zero and results in combustion gases, lube and even things like the glass powder in the primer being blown back into the action.  Furthermore, lubricant/soot/fouling from cast bullets tends to accumulate faster with less than maximum loads.

If your rifle is failing to eject brass, first confirm the bullet velocity.  It is worth noting that loads that are too hot can also result in failure to eject, since the residual pressure can be high enough to hold the case in the chamber.  In other words, either extreme (too fast or slow) can cause failure to extract.  However, if the load is sound, a thorough scrubbing of both the barrel and chamber will usually resolve the problem.  In some instances, the action may need to be cleaned. 

If you are having failure to eject but the cases are easy to manually remove, use your phone camera to video you firing a couple rounds and see what the video shows.  In slow motion you will be able to see if the action opens at all – if you see partial extraction the load may be too mild or the action/barrel needs to be cleaned.

The other comment is about how “hot” a load should be.  If you want the gun to eject, then the lowest velocity that will achieve that is likely the best option.  There is a buffer pad in these rifles and putting too much strain on it, will only serve to wear it out and both obtaining and installing a new one is a task best avoided.   Unless you plan to hunt with the rifle and need more power, loads around 1750 fps provide reliable functioning while not stressing the action.  In addition Lil’Gun, 4227 and A1680 all burn cleanly at this velocity.

Summary

Shooting the 351 WSL is a fun experience except for retrieving the brass.  Loads over 1700 fps eject the cases energetically and not to the same spot each time.  Whether it is cast or plated bullets, the 351 brings back visions of a simpler time when it did not take a magnum to harvest a deer.

Reloading Resources

Dies

CH Tool and Die (https://chtoolanddie.com/) all calibres

Redding (https://www.redding-reloading.com/)  351 and 401 (Series D)

RCBS formerly, 56337 (32 WSL), 56416 (35 WSL), 56423 (351 WSL)

Lee factory crimp die (#91224) from Higginson (https://www.higginsonpowders.com)

Brass

Beaks and Brass can supply 351 WSL cases

Bullets

Grafs (https://www.grafs.com) sell plated .351 bullets

Beaks and Brass can supply 0.352” cast bullets

Lyman moulds 350319, 167 gr GC or 350293, 165 gr plain base (these are no longer in production)

Reloading Reference

Handloader      #300                Feb/Mar 2016

Disclaimer

All loads mentioned in this article were safe in the author’s rifle.  However, since it is impossible to know the condition of other rifles and loading techniques, no warranty of suitability is implied or expressed and use of this data is solely at the risk of the user. In addition, any loads reported in the Handloader article, herein referenced, are not endorsed as safe by anyone other than Handloader magazine.