Distance from the end of the bullet to the end of the cylinder ?

[gray wolf]

I don't think I have seen this addressed much on our forum so I will ask the question.
In a perfect world when a revolver has everything else working correctly just how important is getting the end of the bullet as close to the end of the cylinder ? For clarification in this case the front band is .100 and is a nice snug fit in the throat. So it will be just the part of the bullet from the front band on forward we are talking about. Do we see an effect in accuracy when the jump to the forcing cone is lessened ? I get confused a little when I think how accurate a full WC bullet can be seeing it is many times loaded flush with the case.
I have left out specific calibers, but if it plays a roll in my question please say so.
Also crimp jump or tying up the gun is not a factor here. So lets assume the bullet is not going to move out of the case. The question is specific to accuracy.

Sam

[MtGun44]

I think it is either irrelevant or longer is better. My convertible .45 Colt/.45 ACP is more
accurate with the .45 ACP cylinder. Even with that super long smooth bore (throat) it
is definitely more accurate than the .45 Colt cylinder and both have been reamed and
polished to .453 and use properly fitted boolits. Many others report the same results.

I was really surprised, expected the "too long" cylinder to harm accuracy, and have
tested the results many times with consistent results.

Bill

[paul h]

The most accurate revolver I own is a Ruger SRH 480. If I do my part, it will repeatedly put 5 shots into 1" at 50 yds, and it has done that with about a dozen different cast bullet designs. Here are just a few of the different cast bullet designs I've shot through it. Honestly I think that revolver with the right load is capable of moa accuracy, but I've never put the effort into getting my skills to the point to shoot such groups. Some of those bullets have the meplat very close to the cylinder face, some of them have the meplat over 1/8" away from the cylinder face, they all shoot exceptionally well.

http://forums.accuratereloading.com/evefiles/photo_albums/3/4/4/344100033/744100033_3339F6808143EE14AD3755B7E8638787.JPG

I can't say the nose design has no affect on accuracy, but I'd say that I'd be much more concerned with having a decent bearing length and a good proper diameter front driving band than worrying about the nose perse. Also on lighter bullets I would lean towards choosing a design that put more of the bullet mass in the driving bands portion of the bullet than in the nose. For the heavier for caliber bullets I prefer to put as much of the bullet in the nose as possible to maximize powder capacity in the case.

[gray wolf]

Very good answers fellas, I was concerned the question was a silly one. Thank you for taking the time to help.
Nice pictures BTW

[KCSO]

As long as you do't have to trim the nose with your pocket knife...

In about 1973 or so we were looking for super accurate revolver and loads for 38 wadcutters. We took a K 38 and trimmed the cylinder so that it was just about flush with the loaded round and then set the barrel back to .004 clearance same as the factory barrel thinking that the long jump was hurting accuracy. With 10 different load there was NO change in accuracy at all from regular cylinder to the shortened cylinder.

[John Boy]

just how important is getting the end of the bullet as close to the end of the cylinder ?
* All cylinder lengths are cut by the manufacturer for optimum rotation & travel to the barrel throat
* All rounds are based on a SAAMI maximum length
Just reload the rounds at SAAMI length or 0.005 less and forget about how important it is getting the bullet as close to the end of the cylinder

[paul h]

When loading for maximum accuracy, one is highly advised to take into account the physical dimensions of the gun they are loading for. Cylinder lengths vary by manufacturer, as do chamber and throat dimensions. Loading to SAAMI dimensions does not gurantee the best accuracy for a given revolver, it only gurantees the ammunition will function through all revolvers of a given chambering.

[runfiverun]

if cylinder throats were cut for "best results" based on saami, we wouldn't have different length cylinders from the different manufacturers.
I don't think length of travel is as important as straightness of travel, the nose could be helpful to accuracy if it can [or is allowed by the gun] to pull everything in alignment just before the main bearing length enters the barrels throat.
unless it's trying to do it at an angle.
having contact between lead and steel at different points along the powders rise to peak pressure could affect accuracy as well as the efficiency of the load.

[Bret4207]

Back in the day there was a fad of taking a 45ACP revolver, cutting the cylinder to the shortest length possible and setting the barrel back, as KCSO did. They found no appreciable difference either, but by the time they had the money tied up in it, they just had to "think" it was a smidge better!

[fredj338]

It doesn't matter at all as long as the bullet does not stick out beyond the cyl face. For a hunting gun or SD gun, I would want a little distance cushion.

[fredj338]

* All cylinder lengths are cut by the manufacturer for optimum rotation & travel to the barrel throat
* All rounds are based on a SAAMI maximum length
Just reload the rounds at SAAMI length or 0.005 less and forget about how important it is getting the bullet as close to the end of the cylinder

I am not so sure about that. The older M27 have really short cyl, shorter than their smaller K & L frame cousins. Then there are some cast bullets, like the long 170gr LSWC, that will just not fit the M27.

[Scharfschuetze]

I'm a bit late to the thread and can only confirm what has been written above. When I was shooting PPC as an LE officer, a member of the department team sent his L Frame S&W off to have the cylinder trimmed to the length of a flush seated WC and a heavy match barrel fitted. In the end it was no more accurate than my PPC revolver with a standard cylinder. Both revolvers would just hold the X ring of a B-27 target at 50 yards from the prone position with HBWCs.

I think that in the end he was a bit disappointed with with his project as he was limited to cartridge OAL and that ruled out shooting the department issued practice ammo which was loaded with SWC boolits.

[theperfessor]

My most accurate big bore revolver is a 5" M625 in .45 ACP. Of course it is a fairly low pressure/low velocity round. Wouldn't want a full bore magnum round to have too much travel just because of the stripping issue.

[JWFilips]

I am not so sure about that. The older M27 have really short cyl, shorter than their smaller K & L frame cousins. Then there are some cast bullets, like the long 170gr LSWC, that will just not fit the M27.

+1 on what fredj338 said as far as the old M27's: I have a 1953 model and the cylinder is short ( and needs a fat boolit) I couldn't load a 358311 RN boolit unless I crimped in front of the first drive band otherwise it jammed my cylinder.
However I found some magic in the lee 158 gr SWC TL boolit. At first I crimped in the first lube band but then found out accuracy ( from a bench rest ) improved very much by loading that boolit long into the throat so I now crimp in the second TL groove & I also beagled my mold for this gun to get a .360 " boolit The throats were .359+

So to answer the original posting (For me anyway), I got more accuracy by moving that Lee SWC boolit out beyond SAAMI specs and into the chamber thoats

[Shiloh]

Lots of room with LEE 125 gr RNFP. Just enought wiht a Lyan 358429 in the .357

Shiloh

[9.3X62AL]

A bit different question, slightly related to the cylinder jump and forcing cone matter under review here.......I've noted that bullets/boolits of sufficient length to be fully engaged within the forcing cone and leade before their bases clear the front of the cylinder's face will shoot more accurately. My view is that one possible reason that the 110 and 125 grain bullets don't shoot as well as their heavier/longer caliber counterparts is that the shorter projectiles are not fully aligned and engaged within the revolver barrel prior to the bullet base clearing the cylinder face, and random misalignment occurs. Lyman #358101--a 75 grain wadcutter--when shot one at a time does not do good work past 15 yards, about 6"-8" groups. If "doubled" into a 2-piece 150 grain wadcutter, a curious thing occurs--or has with 2 of my 38 Special revolvers. Half of the boolits form a reasonably close grouping at 15 yards, about 3"-4". The other half of the hits are scattered throughout the target, spanning 12"-15". I have no clue as to what causes this behavior, and by the time the boolits have traveled 25 yards a significant number of them are hitting as if cocked/canted. The smaller "group" occurring with the doubled boolits hits fairly close to where the sights are directed, too. IDK!

[geargnasher]

I think it is either irrelevant or longer is better. My convertible .45 Colt/.45 ACP is more
accurate with the .45 ACP cylinder. Even with that super long smooth bore (throat) it
is definitely more accurate than the .45 Colt cylinder and both have been reamed and
polished to .453 and use properly fitted boolits. Many others report the same results.

I was really surprised, expected the "too long" cylinder to harm accuracy, and have
tested the results many times with consistent results.

Bill

All I can say is "+1".

Gear

[44man]

No difference at all and my most accurate revolver needs a flashlight to see the boolit down in the cylinder.
One gun maker still uses short frames and cylinders for all calibers and needs special crimp grooves on factory stuff. The thought was a short jump but the other was to not make a larger revolver because of cost. The result is a pulled bullet from recoil will lock the gun when you need it most, bear breath stinks. Some factory loads lose boolits fast from recoil.
I just measured boolit jump, it is 9/16" plus the gap, plus contact to the cone and does 1/2" at 100 and has done 2-1/2" at 500.
We have all been through this hodge-podge false stuff and now so many here agree it was false.
Look at Mark V Weatherby rifles that shoot lights out with a freebore. How about the Swede?

[BeeMan]

All I can say is "+1".

Gear

What about the shorter case case of the ACP providing a more uniform combustion scenario? Might this not be a bigger improvement in uniformity than is lost in the longer jump to lands? The 45 Colt case is often noted as having too much internal volume for smokeless propellants, due to being developed for black powder. Is the same thing going on with wadcutters in 38 and 357?

[paul h]

I think the small case capacity and lighter bullets makes for top accuracy in a given caliber.

But in terms of absolute revolver accuracy, all the people I've known who have shot 1" groups at 100 yds with a revolver have done it with the 44 mag, 45 colt, and 454 casull. I have no doubt the 357 mag, 41 mag, 480 ruger, 475 linebaugh, 500 linebaugh and others are capable of such accuracy, in the right gun, with the right bullet and the right load.

I don't think a magnum will achieve that accuracy with the lightest powder puff loads, but with medium to max loads. The best group I fired with my 480 was with a 310 gr lfn over 9.7 gr of unique for 1000 fps. Plenty of air space over that powder charge and well below maximum velocity for the bullet. The 400's @ 1200 fps which are pretty much max loads likely shoot as accurately, but I've never tested them at 100 yds. One of these days I'll put a scope back on the 480 and see what the heavy loads do at longer ranges.

[bedbugbilly]

Interesting thread. I may be "talking through my hat" but I have a question. Aren't there other factors that play in here besides how close the boolit sits near the end of the cylinder? In regards to accuracy? I'm guessing that most of this is basically insignificant in regards to accuracy - sort of proven by what has been said of shortening cylinders and setting barrels back. My quest is in regards to other factors such as cylinder gap? I never had physics so I'm flying by the seat of my pants here but if you have a longer chamber and a shorter chamber - same bullet - when the bullet in the longer chamber reaches the forcing cone and enters, is there more energy behind it than the same bullet fired in a shorter chamber due to a higher burn rate of propellant? (Insignificant I'm sure). But, when you throw in a loose cylinder gap as opposed to a tight one, will not the loose one cause more loss of energy and thus affect the accuracy - negating any of the factors in the chamber length/cartridge length?

I find this interesting as I just picked up a Smith pre 15 and a Smith pre 10. The 15 is 4" and the 10 is 5". Both are in great shape and neither appear to have been fired much - but in looking at them closer, the 10 appears to have a greater cylinder clearance than the 15 - I haven't measured it yet but I'm guessing it does. The 15 you can't see much clearance when held up to the light, the 10 a little more. I haven't shot either yet as it's deer season right now and I don't like to shoot here on the farm when season is going on. One of the things I want to try is to experiment with both revolvers - same cartridge and see just how much affect the greater cylinder clearance in the 10 makes. Probably not very scientific as it's two different revolvers but I have a feeling that the accuracy on a revolver is probably more affected by the cylinder gap than the bullet jump. Am I thinking wrong?

[BeeMan]

Interesting point about the magnums maybe having better absolute accuracy. However, bringing 'magnums' into the discussion obviously changes a lot more than relative volumes between combustion chamber from ACP to Colt. Higher velocity reduces barrel time, projectiles very likely move from subsonic to supersonic flight, etc. Powders that push the heavier loads will burn more completely at 'magnum' pressures, too.

And yes, it is not unusual to find a particular low density load that behaves well. My example is a Ruger only 45 Colt load using 231. A slower powder would provide better case fill and still burn at good pressure while not pushing velocity and recoil too much higher. This particular 231 load beats those loads for raw accuracy though.

My hunch is that a load providing uniform ignition and burn pressure, whether mild or wild, is a much bigger factor in revolver accuracy than the size of jump from case to forcing cone (and rifling.)

[9.3X62AL]

Bed Bug Billy's question as to relative accuracy between his M&P and his Combat Masterpiece I can't answer......but I would predict with some certainty that velocity between the two revolvers will vary. Case in point--I have pre-Model 27 x 6.5" with a .011" cylinder/barrel gap, and a Model 686 x 4" with a .004" cylinder/barrel gap. Both cylinders have throats of .357" diameter. Consistently and unfailingly, using 4 different 357 loads--the 4"-barreled 686 will provide 80-100 FPS MORE velocity than will its longer-barreled caliber counterpart. These results occur in hot weather--cold weather--mild weather. Both barrels are within .001" of one another in groove and land diameter, also.

So, the shorter "throat jump" in the pre-27 pays no dividend, but its larger flash-gap extracts a significant velocity tax--and consistently so.

[44man]

Accuracy from any revolver or caliber can be hard to explain. It has been repeated over and over in gun rags about reducing boolit jump for the best and most everyone believed it. I fell into that long ago until I started to shoot other boolits and revolvers.
It is the same as saying certain calibers and velocities need a GC. I remember when I bought the Lee .475 mold, a PB, wondered about it since it was the first mold for my new revolver. Then I started to shoot it at max loads. As I make my molds now I have made all later ones PB, even for the .500's.
It has been a learning curve, some things are not what they appear.
Now velocity has been mentioned along with case size but in every revolver I ever owned, shorter brass was never as accurate, .38 in .357, .44 S in .44 mag, .480 in .475, etc but I attribute that to not reaching the velocity and spin needed by a certain boolit while other boolits might be good.
Some short barrels ARE faster then a longer one but I can't say it is gap. Maybe the powder used stops expanding and friction slows a boolit in the longer barrel. Like a .22 that reaches max in 16" so an 18" barrel can be slower. Tests were done with single shots and autos against revolvers where a revolver was FASTER with the same barrel lengths. This is just to hard to make sense of, two identical guns with the same gap can have one faster.

[44man]

Here is another to think about. Take a bolt rifle that needs a workup. I had few bullets and little powder so instead of working loads, I worked seating depth with the same powder charge. Just .020" more or less made a tack driver over another depth. It is exactly the same as working a charge.
Now a case where a crimp is needed like a lever gun or revolver, you are stuck so powder charges must be worked.
Had a .45 ACP, S&W revolver here, full length cylinder. Nothing my friend or I did could make it shoot at 25 yards. It was a 7 yard gun! I sat at the bench staring at the brass, said the LP primer is too much in a revolver with a small case and taper crimp. I bushed primer pockets for a SP primer and cut some very small groups at 25. He has bought Speer brass for a SP primer and they even work better in his 1911.
Some would blame boolit jump but it is boolit pull from a strong primer.
Use a slippery lube in a revolver and watch a shotgun appear, you defeat case tension.

[9.3X62AL]

There are A LOT of variables in play every time we squeeze off a shot--no two ways about it, 44 Man. The flash gap issue I illustrated is an aggravated example, where a reasonable gap vs. an excessive gap produced some counter-intuitive results as far as barrel length goes. I don't LIKE the velocity loss in the longer barrel, but unless and until accuracy falls off markedly I'm leaving the condition unaddressed. It may not be *perfect*, but it works and shoots rather well. Just stand well behind me, or well to the side when the revolver is fired. It WILL spit powder granules just a bit more than normal. If I need to extract every last FPS from the 357 Magnum, I have a Ruger BisHawk x 7.5" that is well-dimensioned in all respects and just DOTES on the #358156 at 1500 FPS+. Its report is almost as obnoxious using such loads as that of my Blackhawk in 30 Carbine with full-snort factory loads. Of course, most of us here enjoy anything that turns money into noise.

[Forrest r]

Wow!!!! Allot of good questions, answers & experiences in this thread.

I’ll try to add something to this thread & will only comment on the 38spl/357 calibers/revolvers.

I bought a new s&w 586 back in the mid 80’s. The 2 boolits I used in it for decades was the h&g #50 wc and the Lyman 358311 rn. It didn’t seem to matter what I did with the 358311, the pistol ate them like candy. For example I could load that bullet with 4.2gr of universal clays (38spl) or 4.7 gr of universal clays (38spl p+), they both shot excellent groups. Or the same boolit with 7.5gr of Herco or 15gr of 2400, didn’t matter (mild or hot 357 loads) had the same group size for both loads. Now the h&g was another story, ended up loading/crimping that boolit in the 2nd lube groove so the boolit stuck out in the cylinder. Used 3.2gr of ww452 & that boolit seated sticking out & that load shot bug holes in paper. If all 6 shots didn’t touch @ 50ft, it was operator error. This went on for 50,000+ rounds in that pistol. I also shot allot of full house loads (countless 1000’s) in that pistol using the 358311 & jacketed bullets with the ww820 pull down powder. Eventually the pistol got sent back to s&w, the timing was wore out & the accuracy was out the window. They rebuilt the revolver, new trigger & timing parts & recut the forcing cone & re-installed the bbl. I still have that revolver to this day.
Cylinder/boolit fit:
I believe that how a boolit fits (loose/tight) in the cylinder is more important than the boolits jump (long cylinder/short cylinder). The h&g #50 is a good example of that, when I extended that boolit out further in the 38spl cases it matched up better/tighter/straighter with the taper in the 357 cylinders. Oddly enough, my brother also has a 586 (bought in the mid 80’s) & that same h&g load shot the same bug holes with his 586.
Cylinder gap/forcing cone:
After my 586 was rebuilt it never shot the 358311’s as good, accuracy with the same loads was mediocre at best. I tried to work up new loads but the pistol wasn’t having nothing to do with it. I believe this was from the recut forcing cone & the distance/gap from the cylinders/leade of the bbl. basically what 9.3 x 62al has already stated in post #16 of this thread.
Boolit velocity:
The revolver has lost some velocity (30 to 40fps) with the same loads it shot for decades. I believe this to be from a combination of old iron & boolit jump. The rifling’s are worn uneven, there’s some pitting/flame cutting in the forcing cone end of the bbl. In general the bbl’s about shout out.

I also have/own/use/shoot 3 different dw’s (Dan Wesson’s) 15-2’s, they are 357’s. The interesting thing about the dw’s is that the shooter can adjust/set the cylinder gap to anything they want. Dw recommended a .006” cylinder gap but I’ve shot them with gaps from anywhere from .0015 to .008. I’ve also had the ability to check/test/modify different bbl’s for the dw’s. I currently have 3 different 4” bbl’s, 2 different 6” bbl’s & 2 different 8” bbl’s.

88307

Cylinder gap:
I do adjust the cylinder gaps for accuracy with these pistols. The best accuracy is when the front of the boolit is in the leade of the bbl & the base of the boolit is still in the cylinder. The cylinder gaps can also be set to reduce flame cutting. There is a little loss of velocity between a tight cylinder gap (.002) compared to a loose cylinder gap (.008) but no more than 10fps or so comes to mind. I’ll have to take one of the pistols out with a high pressure load (around 40,000psi) & setup the chronograph & do some tests with the same load, same revolver/bbl & start the cylinder gap out at around .008 & move it in to .0015 as I test for any changes in the velocities of the load/cylinder gap relationship.
Difference in bbl’s:
I believe this to be the biggest contributing factor to the velocity spread with different revolvers/bbl lengths. An excellent example of this is the bbl’s pictured above in the heavy side slabbed target shrouds with the muzzle breaks. Those are custom bbl’s with a short forcing cone/leade with a 1 in 12 twist (fast twist for loooonnnngggg bodied boolits/short leade/cylinder jump for excellent boolit alignment/accuracy) that I worked on when I 1st got them. Before I ever used/shot them I polished them with jb bore paste & treated them with moly bore paste, it takes 3 treatments for a normal bbl. Started with the 4”bbl & when it was done I used it as a baseline for the 6” bbl. After the 1st treatment on the 6” bbl I took both pistols to the range. The 4” bbl was doing 1200fps+ & the 6” bbl was struggling to do high 1100’s with the same load. 2nd treatment & the 6” bbl was beating the 4” bbl & by the 3rd & final treatment the 6” bbl was getting to the 1300fps mark & the 4” bbl was still just over 1200fps with the same load. I used the same bbl & load and just by polishing/slicking the 6” bbl I ended up gaining 100+fps.

Something else I wondered about was I’ve read allot of thread about which boolit is more accurate. It seems that it comes down to either the rnfp or fp boolits verse the swc’s. In general the fn boolits have a longer body than their swc counterparts. The longer body will allow the boolit to reach/seat further into the leade of the forcing cone while the base of the bullet is still in the cylinder. A tighter bbl, shorter cut forcing cone & smaller cylinder gap will level the playing field between a short & long bodied boolit. Just something to think about.

[gwpercle]

Not that important at all.

What is important is that the end of the boolit does not stick out past the end of the cylinder.
Ooops that mould is not going to work...

Gary