Since beginning the work of experimenting with and building a few rifles for shooting sabotless bullets, It must be said that I have become spoiled! Excellent accuracy was achieved right from the start with minimal effort and at very high levels of performance. I had never shot so many nice targets in such a short period of time using a wide range of different bullet weights and types at the highest load levels possible. Elimination of the plastic sabot eliminated the associated problems and limitations of sabots and resulted in production of a rifle that is more versatile and capable of significantly higher performance levels than previously possible.
What are the
limitations or problems associated with plastic sabots? They are as follows:
1.
Load pressure is limited.
In a rifle using saboted bullets, the sabot serves as the link between the bullet and the rifles bore. Since the sabot is made from plastic, it has only limited strength. If load pressure goes above certain limits, the sabot will fail and loose its ability to function with resulting poor accuracy.
2.
Accuracy at very high velocity is difficult to achieve.
Accuracy at very high velocity levels is much more likely to suffer because the limited strength of the sabot may not be able to withstand torsional forces imposed by the barrels rifling.
3.
Barrel rifling twist rate which determines what weight and speed bullets can be shot is limited.
If a rifle barrels rifling twist rate is too fast, it becomes difficult if not impossible to shoot a saboted bullet at highest velocity because the soft plastic sabot will not withstand the high shear / torsional forces imposed by the fast twist rifling. If shooting plastic saboted bullets from a barrel with fast rifling twist then velocities must be slower to achieve accuracy.
If high velocity is to be achieved with good accuracy using saboted bullets then the barrel rifling twist must be slower. The use of the slower twist rate limits the weight of bullets that can be shot. If the longest and heaviest bullets are to be shot at high velocity then, faster twist rifling must be used which eliminates the possibility of using plastic sabots if expecting accurate results.
4.
Plastic sabots are affected greatly by temperature.
If best accuracy is to be obtained when shooting saboted bullets, then careful attention must be paid to temperature. As barrel temperatures rise the plastic sabot gets softer and loses strength which degrades accuracy. That means that a significant waiting period between shots is required to avoid overheating the rifles barrel if best accuracy is desired. Also, hot weather makes things even worse even to the point that a load may require considerable reduction if any accurate shooting is to be done.
The
advantages gained through the use of sabotless bullets are therefore as follows:
1. There is no limit to the "safe" load pressure that can be used because an unsaboted solid copper or copper jacketed bullet can easily withstand maximum safe working pressures without blow-out or other failure.
2. Unsaboted solid copper or copper jacketed bullets are strong enough to withstand any obtainable velocity and still give excellent accuracy.
3. Any sufficiently fast rifling twist can be used when shooting sabotless copper or copper jacketed bullets because the bullet material strength is more than sufficient to withstand torsional forces.
4. Temperature is of much less concern when shooting sabotless bullets and great accuracy is still obtainable without long waits for barrel cool down. Hot weather is also of little concern.
What are some
disadvantages associated with shooting sabotless bullets?
As with anything, there are always some negatives that need to be dealt with. One disadvantage is as follows.
1. The bullet size as related to barrel bore size is very critical. If the bullet is too loose a fit in the barrel bore, misfires or poor ignition with inconsistent results and poor accuracy will result. If the bullet is too tight then loading will be difficult if not impossible. Many bullets may require resizing to obtain the proper fit. A bullet sizing die or dies are provided with Swing-Lock sabotless rifles to assure the customer can obtain bullets to the exact size needed.
To be fair, it should be mentioned that the above disadvantage regarding sabotless bullets brings to light an advantage with regards to saboted bullets which is the fact that the barrel bore to saboted bullet fit is not nearly so critical. The soft plastic sabot allows for errors which cannot be tolerated when shooting sabotless bullets.
RESULTS WITH THE NEW SWING-LOCK SABOTLESS
HIGH PERFORMANCE RIFLE
The two targets as shown below are a good representation of just how versatile the above rifle shown can be. The target on the left was shot using the possibly impractical yet interesting Hornady 185 gr XTP bullet at a velocity of over 3300 fps and group size of about .91 In. It is plenty accurate enough for obliterating varmints at shorter ranges. While, the target on the right was shot using the Barnes solid copper Super Shock 500 gr X bullets at approximately 1870 fps with a group size of approx. .59 In. Considering that bullet can be shot at over 2130 fps it could certainly do the number on an elephant or buffalo over in Africa! A very neat thought indeed.Varmints or elephants all with one rifle!
The picture below is a line-up of those bullets tested with the above rifle. They are all .45 caliber and are as follows from left to right: 185 gr .4515 dia.Hornady XTP, 250 gr .452 dia. Hornady SST, 300 gr .452 dia. Hornady SST, 300 gr .458 dia. Barnes copper X, 350 gr .458 dia. Barnes copper X and 500 gr .458 dia. Barnes copper Super Shock X. With exception to the 185 gr XTP bullet, all of the other bullets required resizing to make usable. The rifle shot all of these bullets with very decent accuracy as shown by the targets above and below.

The five targets shown below were shot using 250 gr and 300 gr Hornady SST bullets. The three top targets are from the 250 gr bullets and the two target below were done using 300 gr bullets. Velocities approaching 3200 fps can be achieved with the 250 gr bullets with great accuracy while the 300 gr bullets can be shot at over 2700 fps. Parker 250 gr and 275 gr Ballistic Extreme bullets will be tested in the future. All targets shown were shot at 115 yards.

The next set of targets shown below starting with the top row were shot using Barnes 300 gr copper X bullets. The lower target was shot using the Barnes 350 gr copper X bullet. All of these targets are under 1MOA and considering the limited amount of time spent on testing these bullets it is quite certain that further testing will produce even better results.

These three targets were shot using the Barnes 500 gr Super Shock X bullet. The target on the left was shot using a lighter load which produced approx. 1870 fps. You will notice the group size gets larger as the load was increased. This bullet can be driven at over 2130 fps with still very decent accuracy.

PREPARING BULLETS FOR SABOTLESS SHOOTING
PLEASE READ THE PAGE REGARDING NEW ADJUSTABLE BULLET SIZING DIES WHICH OBSOLETE THE DIES MENTIONED BELOW AND ALSO PROVIDE THE MEANS TO PRODUCE FULL FORMED BULLETS WHICH HAVE GREAT ADVANTAGES.
Many bullets such as those shown above which are really very desirable to shoot must first be sized to the exact correct size before they can properly be loaded. For bullets to load properly, after sizing they will measure approximately .0001 to .0002 In. over the rifles bore diameter. If bullets are of proper size, they will load with approximately the same force as a snug fitting load using a sabot. Dies provided with Swing-Lock rifles are custom made for the rifle to produce bullets to the correct size. (all
new sizing dies are now adjustable)
When sizing .458 diameter bullets, two dies are used. the first die sizes the bullet down approximately half way while the other die brings the bullet to final size. (new dies are now adjustable " full form " for .458 dia. bullets) The photo below, shows a typical bullet sizing die and brass punch which is used in a standard loading press.

To size a bullet, the bullet is first given a very thin coat of lubricant and the bullet is then pushed through the die using the punch in a standard loading press as shown below. It is a very simple and very easy operation.

Bullets can also be sized using a small arbor press as shown below. That is what I used for sizing the solid copper bullets but only because the loading press above was not of the heavy duty type. The solid copper bullets were actually easier to size than I at first thought they would be and it seems likely that a good husky loading press would provide sufficient force. As it turned out, the same finishing die as used for sizing the Hornady SST bullets also gave the correct size for finishing the Barnes solid copper .458 dia. bullets.

Solid copper bullets are much easier to resize if they are first annealed before resizing. In the case of bullets sized with a smooth shank, they must be annealed. Otherwise, they will not obturate and expand to take the rifling upon firing. I know this from experience. Without annealing they will not stabilize and will be lucky to even hit the backstop. Full form sized bullets do not need to be annealed for accuracy but they do size much easier if they are annealed.
Annealing copper bullets after sizing is really quite easy using a propane torch or electric hot plate and container full of cold water for quenching as shown in the photos below. Multiple bullets can be done at a time.
If a propane torch is used, the bullets are placed close together on a narrow metal bar which is placed on top of the can. Heat the bullets until they just begin to turn red and then knock them over into the water.
Using a electric hot plate is much easier. Just stand a number of bullets up on the burner and set on high. For .45 cal. bullets, I leave them on for about 20 minutes. If you let them sit on the hot burner until they turn black, that is long enough. The larger the bullets, the more time they require. Then, pick the bullets off with a pair of pliers and drop into the water.
Quenching leaves the bullets annealed or dead soft and ready to resize after drying. The annealing has no affect on dimensions, but does cause discoloring of the bullets which seems to have no affect on how the bullets load or shoot.


When shooting the Barnes 500 gr copper bullet, the very long bearing surface made loading quite difficult so a different die for finish sizing was used which sized the bullets a very slight amount under bore size. I then knurled the bullets after annealing using two bastard files as shown below by the two pictures. As shown the bullet is placed squarely on the end of one file which is layed flat on the corner of a work bench. The end of the other file is then placed squarely on top of the bullet and while applying downward force by hand, the bullet is rolled between the files. This treatment as shown by the last picture produces a very shallow knurl type raised pattern on the bullets surface which can be compressed during loading of the bullet thus producing a perfect fit. The bullets were rolled only once to obtain the required fit and tension for loading.
Although this is obviously a useful technique, this is the only time it was seriously used during this testing. Because it is a technique that requires some manual dexterity and consistency, it is not a technique that I really recommend.
Using the new adjustable bullet sizing die, the below knurling operation could have been avoided because the bullets would have been calibrated to " exactly " the right size for loading. They would also have been full form sized.

Above picture shows bullet positioning on end of file waiting to be knurled.
Below, bullet is being knurled as above described.

Picture below shows bullet after knurling. Discoloration of the bullet is the result of annealing.

LOAD COMPONENTS
SABOTED Vs SABOTLESS
Unfortunately there are no more pictures but to make this short, there is little difference in loading procedure when comparing a saboted bullet load with a unsaboted bullet load except that there is no sabot. One major quality present in a saboted bullet load is that the sabot base serves very effectively to seal the powder gases behind the bullet upon firing. In a sabotless load, a seal is provided by substituting a wad ( in place of a sabot ) over the powder before loading the bullet. The wad used during my testing was a .460 diameter 1/16" thick vegetable card wad or 1/8" thick lubricated felt wad ( wonder wad ). There are other types of over powder wads that can be used as well but for now the vegetable card has worked very well.
One thing that was soon observed is that the use of an over powder wad in a sabotless bullet load is essential for accuracy. On a few different occasions when the over powder wad was not used, the bullet was a major flyer from the group, key holed or missed the back board completely.
A saboted bullet load is built on the following components:
Powder
Ballistic Bridge Wad ( if needed to support higher pressure)
Sabot
Bullet
Primer
A sabotless load is built on the following components:
Powder
Wad
Bullet
Primer