BSA Standards calibre efficiency?

[edbear2]

This relates to post ww1 guns I have been playing with yesterday and this morning..Basically I have 4 of the things......2 cs models and 2 s models...A couple of them seem to produce a lot more power, so messing about, I had the lot apart, and tried to work out why......now I know there are many reasons/variables, so one of the things I did was to clean and measure all the cylinders.......all unscored, and within a couple of thou in size...I had only the facilty to check bore size by visual means and the old pellet push through and check the skirt method.....next to the "power plant".I substituted the piston and spring assembly from the best gun (.22) power wise, with the innards from both the two cs models.......I did get a slight improvement on the power of both guns, but in all cases, the .22 gave more power (as measured in foot pounds).I also swapped pistons (one was the later type washer assembly with the large securing ring that threads over a post).......So........why do the .22's do this.......Logic surely would mean that the same piston/spring in both a .177 and .22 would give similar power........we are talking 11.11 in .22 versus 10.09 (both H+N FFTT in 4.52/5.54)

[pennineway.fswo]

Hi Edbear
In the past I have swapped and changed barrels on HW35s and I always noticed that power went down about 1- 2 ft lbs when going from .22 to .177

Gerald Cardew went into the physics of this in his books and I believe he found that the transfer of energy to the pellet from the compressed air is proportional to the cross sectional area of the pellet. Hence .22 cal usually gives about 15% more power than the same rifle in .177

Most of my Airsporters in .177 are around 9 - 9.8 ft lbs whereas my .22 Airsporters are all over 10 ft lbs and a couple are up at about 11.5 ft lbs
John

[pennineway.fswo]

I suppose back in the good old days, because the .22 developed more power than the same gun in .177, most shooters saw the .22 as the manly more powerful gun and hence most demand was for the larger of the 2 calibres

.25 cal was also an option I believe, but the .25 pellet was probably just a bit too heavy to give a satisfactory trajectory from a 12 ft lb gun for shooting at longer ranges
John

[edbear2]

Hi John......That makes sense when you think about it......and I must have have seen 10 + .22 standards for every .177, also the same ratio in airsporters....funny how things change around, I suppose people these days prefer the flatter trajectory of the .177 that allows easier estimation of holdover/less aiming off, and combined with modern pcp accuracy and optics, the calibre difference is less of an issue in hunting for example, as the less retained energy of the .177 is made up for by much more clinical accuracy, allowing repeatable shot placement, (plus more pellet selection...ie heavier weights in .177) at humane ranges........I don't hunt now, haven't since my early teens, but in those days, (very late 1960's/early 1970's) with open sights, or a plastic 4x20 scope, a hit anywhere was unfortunately seen as a result, and a coup de grace shot was often sadly the norm. Hopefully, I think things have moved on a lot, and today's hunters are generally a lot more conscientious in ensuring a clean kill on whatever they shoot at.

[kyairgunner]

had some free time to play with the guns. I too believe the 22 will have more energy due to area of the pellet. I had a friend years ago take a theoben eliminator in 22cal switch the barrels to a 20cal. He was shooting crosman pellets in each barrel so the weight was the same. Of course he did not change the strut pressure. Only the barrels. The 22 was shooting about 40-50 ftps faster than the 20cal. I would be interested to see how a bsa in 25 cal would perform with modern pellets. Bye- Chris

[Oldandshaky]

Hi Eddie, interesting thread I have an HW80 .177 running at 11.5 ft/lbs, it has a cut down barrel 12 inches long. I recently got a full length .22 barrel 19.5 inches which I will be fitting later today, I have heard that a shorter barrel can increase velocity ??
I will chrono the gun with the .22 barrel on and post back later..Dave...

[Oldandshaky]

I swapped the barrels over and now the gun is running at 15.78 ft/lbs
Dave...

[pennineway.fswo]

I swapped the barrels over and now the gun is running at 15.78 ft/lbs
Dave...

Hi Dave
Indeed
Unless you have an FAC then it is important to get the power back down ASAP.(and delete your post)
John

[Oldandshaky]

Hi John, no problem I swapped them back again the next thing is to get a Bonnie & Clyde .22 kit in there.
I wonder if that will have the reverse effect with a .177 barrel running at minus 4 lbs instead of the increase
Its a good job I have a chrono because just from the feel when shooting I couldn't tell there was a power increase, in fact my prewar BSA's feel as though they have much more power, so much for feel

Dave...

[edbear2]

in fact my prewar BSA's feel as though they have much more power, so much for feel

Dave...

.......I let a youngster have a go with my 45" imp model D .22 at work.......His only airgun experience before had been a s200 precharge, and unbelievably, he had never shot a springer......."bleedin hell, do you have to do this for EVERY shot" he groaned as he struggled to cock it

Then on firing....."OW.....that hurt my arm".I recommended that he didn't ever shoot a centerfire

[pennineway.fswo]

Although I own and shoot PCP's as well as springers, they don't give you the same satisfaction especially when putting together good groups.
My pre war BSA .177 CS model can match many of my more modern day springers at long range, and power is up there at about nearly 10 ft lbs.