Power Pel­lets

John Milewski stud­ies the cal­i­bre con­tro­versy from a vin­tage per­spec­tive

Airgun World - - Contents -

John Milewski in­ves­ti­gates the ‘power myth’ of the .25 BSA Im­proved Model D

The BSA Im­proved Model D in No 3 bore or .25 cal­i­bre has al­most a myth­i­cal sta­tus among col­lec­tors. Very few come to the mar­ket and th­ese big bores can be dif­fi­cult to source, ir­re­spec­tive of how much you are will­ing to spend on ac­quir­ing one. Sto­ries abound of the power th­ese BSAs are ca­pa­ble of achiev­ing, so over the next two is­sues, we are go­ing firstly to test a .25 and then com­pare our re­sults with a con­tem­po­rary .22 BSA. We will see how the big bore per­forms on the range and de­ter­mine what caused its un­timely demise after just a year of pro­duc­tion.

When the BSA un­der­lever was in­tro­duced in 1905, it was not un­til 1908 that a cal­i­bre other than .177 was of­fered, when the .25 came on to the mar­ket. Ini­tially of­fered in an over­all length of 43¾ inches, the stan­dard length cylin­der was not quite pow­er­ful enough to of­fer much other than a pro­nounced tra­jec­tory and power around 6 ft.lbs. This was soon reme­died when a longer cylin­der was fit­ted, which re­sulted in an in­creased over­all length of 45¾ inches. This longer cylin­der re­sulted in muz­zle en­ergy in­creas­ing to nearer 12 ft.lbs., al­though with no power limit in place un­til 1968, BSA ad­verts tended to make more of pen­e­tra­tion than muz­zle en­ergy or ve­loc­ity.


The .25 long cylin­dered BSA on test ini­tially pro­duced 7 ft.lbs. muz­zle en­ergy and a longer spring in­creased this to an en­ergy level too near the le­gal limit of 12 ft.lbs. A slightly shorter spring, with very lit­tle pre-load re­duced the en­ergy to 10.8 ft.lbs. and re­sulted in less diesel­ing too. This demon­strates the im­por­tance of know­ing your ri­fle’s muz­zle en­ergy, par­tic­u­larly when chang­ing springs, in or­der to stay on the right side of the law. A lighter gauge spring also re­sults in a smoother fir­ing cy­cle and less re­coil. Pel­let choice is cru­cial with the .25 BSA be­cause not all brands are suit­able. Many mod­ern .25 brands weigh in ex­cess of 20 grains and are in­tended for FAC-rated air ri­fles, so they are too heavy for sub-12 ft.lbs. ri­fles and not the best per­form­ers. I used older Mil­bro Rhino, BSA Py­larm and Marks­man pel­lets, all of which weigh in the re­gion of 18-20 grains, and whilst all grouped to­gether, ev­ery one of th­ese brands pro­duced oc­ca­sional fly­ers, even at 6 yards. Marks­man pel­lets are made on pre-war ma­chin­ery by de­scen­dants of Ge­orge Lin­coln Jef­fries, the orig­i­nal in­ven­tor of the BSA un­der­lever, so I was will­ing this brand to shoot well sub­con­sciously, which was per­haps a lit­tle un­fair on the other brands. The Marks­man pel­lets are cer­tainly good enough for in­for­mal prac­tice, but the odd pel­let does fly off at a tan­gent, thereby ex­pand­ing group size.


I wanted to ob­tain con­sis­tently ac­cu­rate groups be­fore ad­just­ing the sights and there was one more brand left to try. I had less than a tin of .25 H&N Field Tar­get Tro­phy pel­lets left over from a pre­vi­ous test, and was as­tounded at the im­prove­ment in ac­cu­racy when th­ese 20-grain pel­lets were tested from the stand­ing po­si­tion. All four of my five-shot strings landed within an inch at 6

“the .25 comes into its own, be­cause the heavy pel­let hits its tar­get with far more clout”

yards and the pel­lets seemed to re­coil less than the other brands, too.

After ad­just­ing the ri­fle’s sights, I found my groups were form­ing around ¾” above my point of aim at 6 yards, when the sights were set as low as they would go. This in­creased to an inch at 10 yards and dropped to point of aim at around 20 yards. From this, we can see the .25 has a tra­jec­tory, which is a lot more pro­nounced than the .22 BSA from the same era. The .22 pel­lets are lighter at around 14-15 grains and a ri­fle pro­duc­ing around 11 ft.lbs. will zero down to point of aim at 6 yards.


So much for ac­cu­racy. Now let’s look at what hap­pens when a tar­get is hit with the 20 grain .25 pel­let. I placed tins filled with wa­ter at a dis­tance of 15 yards and the .25 launched a tin into the air along with the wa­ter with a re­sound­ing wal­lop. This is where the .25 comes into its own be­cause the heavy pel­let hits its tar­get with far more clout than a lighter .22. The No 2 bore also launched a tin into the air, but it was clear to see the .22 H&N FTT pel­lets were go­ing straight through the wa­ter-filled tin with plenty of en­ergy to spare.

I found the .25 an ac­cu­rate ri­fle, which will group well, but the tra­jec­tory is no­tice­ably pro­nounced, so it is vi­tal to know the dis­tance to your tar­get and know where to aim. Nei­ther is im­pos­si­ble and in ac­tu­al­ity, a lot of fun to set up be­cause it gives you an ex­cuse to shoot the .25! Next month, we’ll com­pare the per­for­mance of a near iden­ti­cal BSA, but in .22 cal­i­bre. I

There are far fewer .25 pel­let op­tions that .177 or .22, but one of th­ese should fit the bill.

Pre-WW1 BSA Ad­der pel­lets in .177, .22 and .25. The .25 is be­lieved to be an Ad­der pel­let and was kindly given to the au­thor by John Atkins.

Lin­coln Jef­fries of­fered ri­fles in .25, too, as this page from a C.1908 cat­a­logue at­tests. This wa­ter-filled tin was launched into the air by the force of the .25 pel­let’s im­pact.

This is what all BSA col­lec­tors look for – a prom­i­nent 3, des­ig­nat­ing the big bore! The shot­gun-style, straight-hand stock on the .25 re­sulted in a fast tar­get ac­qui­si­tion.

‘Bessie’ might not be in the best con­di­tion, but she is a real rar­ity.

The .25 cal­i­bre BSAs can mostly be found with se­rial num­bers in the 19000 to 23000 range, but oth­ers do ex­ist. Note the numeral 3 sig­ni­fy­ing the cal­i­bre.

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