Revolver chambers

[kevmc]

Until recently I thought that Revolver chambers were cut so that the front band of a Keith/SWC would enter the throat, that has proven incorrect!!
101025
This chamber cast from my SW 657-3 PC (41 mag) shows that the OAL to the start of the .4105 throat is 1.440".
Max case length is 1.290" plus a .100" front band means that the bullet has to jump .050" to reach the throat. Bullet will lay on bottom of chamber, not aligned with the throat.....

101026
This is consistent with my SW 629-4 PC (OAL to throat is 1.440, case 1.285 + .100" front band = 1.385)
and with my SW 586-3 (.357) (OAL to throat is 1.395)(case of 1.280" would need a front band of .115" just to reach start of throat, not enter....

Are all SW chambers cut this way???? Rugers??? others??
What chambers do you know of that are cut so the front band enters the throat??

[Outpost75]

Welcome to the real world! You managed to catch the plane off Fantasy Island.

My Ruger single-actions do not suffer the affliction to the degree you have demonstrated, but it is there to a much lesser degree.

[kevmc]

The .357 actually meets SAMMI specs ( sammi 1.399 vs my measurement of 1.395) even though most boolits won't reach into throat.
The .44 and .41 measurements are both about .080" longer than sammi calls for in their chamber drawings......

[gray wolf]

When we talk about reaching the throat are we also counting the .100 or so taper before the throat.
My 44 mag ruger hunter had a space of .150 after the case mouth before the taper even begun.
So with a front band of .100 my front band was still .050 from the taper, let along the actual throat.
The cylinder throats on that gun would lead up terribly, not the barrel, but a lot of lead in the taper and a pain to clean.
The replacement Super red hawk has the end of the case at the beginning of the taper taper, so the front band on the bullet occupies the space in the taper before the throat. With the same left over loads from the hunter I get NO leading in the cylinder at all. After a long post we all decided the chambers were cut wrong.
My GP 100 has the same fit as the SRH and all is fine.

[kevmc]

Sounds like what I've got.........
the .44 has .170" from the case mouth to where the taper meets the throat ( .431")
the .41 has .155 " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " ""(.410)

[DougGuy]

I use the Lee RF boolits in my .45 and .44 seated long in the bottom crimp groove, these boolits are more of a borerider than the Keith type, they go all the way into the throats, past the taper, when you chamber them. That's my way of getting around that issue.. Interesting photos, thanks for posting..

http://i1202.photobucket.com/albums/bb374/DougGuy/Reloading/a93849e1-8296-4617-b4ff-6ae3e1b9b1c0_zpsdf33f23a.jpg (http://s1202.photobucket.com/user/DougGuy/media/Reloading/a93849e1-8296-4617-b4ff-6ae3e1b9b1c0_zpsdf33f23a.jpg.html)

http://i1202.photobucket.com/albums/bb374/DougGuy/Reloading/b0365352-e008-4573-ae2e-859b8a99fe82_zps7c72c5cb.jpg (http://s1202.photobucket.com/user/DougGuy/media/Reloading/b0365352-e008-4573-ae2e-859b8a99fe82_zps7c72c5cb.jpg.html)

[kevmc]

I've got a Lee 235 RF for the .44's, and a 125 RF for the .357, they are more accurate than SWC's, probably for this reason.
Your bullet looks heavier and 2 crimp grooves, which one is it?

[220]

Don't know if it a concern when it comes to accuracy or not.
I deep seat the Lee 105 swc in 38spl cases, nose of the projectile 1/10" below the case mouth, out of a 686 they shoot well. I would hate to work out how far they are from the throat, probably 1/2" or more.

10 shots last weekend at 25m (82feet)
blame myself for the flyer
http://madmick3006.com/ahngallery/upload/files/2014-03/2c574503.jpg

[DougGuy]

I've got a Lee 235 RF for the .44's, and a 125 RF for the .357, they are more accurate than SWC's, probably for this reason.
Your bullet looks heavier and 2 crimp grooves, which one is it?

The top pic is the Lee C430-310-RF in .44 Magnum brass, the bottom pic is the Lee C452-300-RF in .45 Colt brass.

[gray wolf]

BTW Nice shooting, in the pic.
My black hawk hunter showed excellent accuracy but the cylinder taper leaded horribly. We have been over this many times, -- why flush seated WC bullets shoot well being so far from the throat.
Do they lead throats or form lead in the taper before the throat ? some say yes ( me ) some say no and some have no opinion. These pics are at 30 yards so accuracy is not a problem for me.
Getting back to what we were saying, I measure from the case mouth to the beginning of the taper not the actual throat.
If a bullet is somewhat of a passive fit through the throats and the front band extends into the throats past the taper it will seat.
If the front band is a snug push through fit through the throats , or any part of the bullet is a snug push through fit, it will enter the taper but will need additional pressure to fully seat it, depending on how tight the push through fit is. If the throat is tapered it may show differently.

[kevmc]

From the sammi chamber drawings, OAL to throat for .44 mag is 1.373 ( mine is 1.440)
With a case length of 1.285, and a .100" forward band, the leading edge of the forward band would be at an OAL of 1.385", or .012" into the throat of a sammi chamber. That would align the boolit with the bore.

"If the front band is a snug push through fit through the throats , or any part of the bullet is a snug push through fit, it will enter the taper but will need additional pressure to fully seat it"
Not if the front band is still .055" short of reaching the throat.......as mine is.
They'll fully seat, but not be in alignment with bore.....my concern, as accuracy with SWC's is not good.

[gray wolf]

Not if the front band is still .055" short of reaching the throat.......as mine is.
They'll fully seat, but not be in alignment with bore.....my concern, as accuracy with SWC's is not good.
How about the other specs ? throat size, bullet size, barrel groove and how many loads tested ?
powder ? bullet hardness ? Your chambers may be cut on the long side, what is the speck for the throat length ?
If the chambers are cut long then the throat must be short, can't have both if it's a standard cylinder. If there is such a thing. The targets I showed in my post were shot with bullets that were not locked into the cylinder throat. I know this cause they were .0005 over throat diameter and would not have seated if they were into the throat. That's why I asked about the other stats.

[220]

Nice shooting yourself gray wolf
My group was shot from a freshly cleaned gun, I've never been concerned with the jump but Im getting acceptable accuracy. I do get leading in the tapper but have shot 1000rds without it effecting accuracy so again not an issue for me.
Jump may effect accuracy but my feelings are there are plenty of other things that will have a far bigger impact on group size with a revolver.

[Messy bear]

to answer the first post - freedom arms 454. they have no funnel just short taper like most rifles.

[MtGun44]

Keith wanted to have the front band engage the throat while the body of the boolit
was still well inside the case, helping get the boolit lined up properly. I have
pointed out that it is not possible to have the band actually in the throat proper
and this has been discussed a good bit.

Just hitting the taper and guiding quickly into the throats is apparently
helpful for accuracy.

Bill

[Piedmont]

Back in the era that Elmer came up with his loading procedures most S&Ws had throats in the .432-433 range. (This is from my reading. I can confirm that true for the late 70s through mid 1980s but unfortunately do not own any old .44 Smiths.) He recommended sizing to .429" with an alloy soft enough to obturate the base band. So he talked about the front band trueing up the bullet in the cylinder throat, but it was too small to do that. One thing it did do is hit the forcing cone in the barrel with less jump than those bullets where the only full diameter portion was behind the crimp groove.

I have run into the problem of not being able to get a bullet in the chamber all the way because too much bearing surface was out in front of the case. This discussion just drives home to me that each gun is an individual, but if you tailor your ammo and bullet selection to your specific firearm you can optimize the features and improve your performance. For example, the revolver that the throat slug was taken from could use a boolit with a long front band ahead of the crimp groove.

BTW I have a Ruger that I by chance and reading the articles section on Mountainmolds website designed with a .08" front band and a slight step down after that. It is a perfect fit in the revolver I bought it for -- slight resistance with full chambering. This was by chance because I did not do the castings like the original poster in this thread. So not all are set up with overly sloppy leades into the chamber throats, but most probably are because less griping from customers will result. Though I guess most customers just shoot factory loads to begin with.

[Tatume]

The RCBS 45-270-SAA enters the throats of many revolvers. It has a longer than usual front driving band. The LBT WFN series also often enters revolver throats. Both of these bullets will require sizing to throat diameter in order to chamber ammunition in some of my guns.

[DougGuy]

The RCBS 45-270-SAA enters the throats of many revolvers. It has a longer than usual front driving band. The LBT WFN series also often enters revolver throats. Both of these bullets will require sizing to throat diameter in order to chamber ammunition in some of my guns.

I choose the boolit I want to shoot, sized .001" over groove diameter, and size the throats to use that boolit, usually half thou over, or .4525" for a .452" boolit.

Had a couple of Ruger cylinders go through the shop this week @ .450" and .4505" would not accept a .451" pin gage no kind of way. I would not think it a good idea to be sizing boolits to accommodate tight/undersize cylinder throats, very common with .44 and .45 caliber Ruger cylinders.

[captaint]

I pin guage measured my GP 100 throats. It's a new gun. Made in January. I was very pleased to barely get a .358 pin guage in every throat. Very pleased. Mike

[youngmman]

Interesting post. I had a similar problem with a 629 and Mo.28 using the LBT WFN bullets and using .44special/.38specials with the same bullet. The problem was two fold: 1) the taper toward front of the chamber was rough on both guns and to my surprise the forcing cone was also. The chamber throat has to be about .001 larger than bore diameter for the cast bullets not to lead just ahead of the forcing cone. How I fixed it: Brownell's has a chamber polishing hone. It doesn't remove any metal just smooth's it out. It's just a smaller version of what they sell to polish shotgun barrels 2) Brownell's makes a forcing cone reamer/polishing kit. With it I cut the right taper for the forcing cone and lapped it with grinding compound and finally (I don't know if this was part of the problem) I squared the barrel end with the cutter that came with the set. As long as the gap is below .007 everything works ok. Hope this helps.