PP Friendly chamber?

[montana_charlie]

We have had a number of threads in which we discussed what it takes to make a chamber that is 'friendly' to paper patched bullets...as friendly as the old original chambers that were used by the Sharps factory.
Those chambers assumed the bullet would be patched to bore dimension, and were sized accordingly. But, they also provided a low-angle transition from the case to the 'throat'...and on into the rifling.

Yes, the old chambers can be duplicated in a newly cut barrel, but the threads examined modifications to SAMMI chambers intended for grease grooved bullets...which would remove some of their unfriendliness to the paper. Basically, the fix was to shave the 45 degree chamber step (transition at the case mouth) down to a gentler angle. 15 degrees and below have been considered, with five to seven degrees coming close to being ideal for patched-to-bore bullets.

I saw a recent reference to the 45 degree chamber step in a Pedersoli rifle being referred to as the 'leade'. Knowing that the actual leade angle in a Pedersoli is not 45 degrees, I opened an old email I have from Dick Trenk wherein he describes the current Pedersoli chamber...and it's 'throat'.

That's the first time I ever noticed that Pedersoli 'chamber steps' are NOT 45 degree angles. Instead, they are much closer to 10 degrees.
10 degrees, 12 minutes, and 14 seconds to be exact.

Wishing I could visualize such a topography, I'm hoping Tom Meyers can help out with one of his excellent drawings.
I have sent him the particulars...along with a rendering of the PGT bullet (for those interested in the 'correct' GG bullet for Pedersoli guns) and a Money bullet patched to groove diameter (because that's what I do, and it's my project).

Hoping he has time to draw this up...

CM

[Gunlaker]

We have had a number of threads in which we discussed what it takes to make a chamber that is 'friendly' to paper patched bullets...as friendly as the old original chambers that were used by the Sharps factory.
Those chambers assumed the bullet would be patched to bore dimension, and were sized accordingly. But, they also provided a low-angle transition from the case to the 'throat'...and on into the rifling.

Yes, the old chambers can be duplicated in a newly cut barrel, but the threads examined modifications to SAMMI chambers intended for grease grooved bullets...which would remove some of their unfriendliness to the paper. Basically, the fix was to shave the 45 degree chamber step (transition at the case mouth) down to a gentler angle. 15 degrees and below have been considered, with five to seven degrees coming close to being ideal for patched-to-bore bullets.

I saw a recent reference to the 45 degree chamber step in a Pedersoli rifle being referred to as the 'leade'. Knowing that the actual leade angle in a Pedersoli is not 45 degrees, I opened an old email I have from Dick Trenk wherein he describes the current Pedersoli chamber...and it's 'throat'.

That's the first time I ever noticed that Pedersoli 'chamber steps' are NOT 45 degree angles. Instead, they are much closer to 10 degrees.
10 degrees, 12 minutes, and 14 seconds to be exact.

Wishing I could visualize such a topography, I'm hoping Tom Meyers can help out with one of his excellent drawings.
I have sent him the particulars...along with a rendering of the PGT bullet (for those interested in the 'correct' GG bullet for Pedersoli guns) and a Money bullet patched to groove diameter (because that's what I do, and it's my project).

Hoping he has time to draw this up...

CM

CM, One thing I don't recall ever reading was whether changing the 45 degree angle to a gentler one would be detrimental to grease groove bullets. If it is not, do you know the reason for the sharper angle in modern chambers?

I remember reading about a chamber design in one of Dan Thedore's rifles that apparently shot both grease grooves and "patched to groove" PP bullets with good accuracy. Now that sounds like a nice combo!

Chris.

[Red River Rick]

45 degrees, 35 degrees, 25 degrees.................what ever. If the transitional step from the end of the case is too abrupt............your asking for trouble.

Does this look like a 10 degree, 12 minutes, and 14 second angle? And this is a un-modified Pedersoli chamber. I don't think so.

The other pic shows what the chamber should look like, before and after being modified if you want to shoot PP bullets without problems.

I tried patching to bore...............that didn't work worth $hit. My next step would be try patching to groove, and if that don't work..........then it's time to recut the throat/leade portion of the chamber and hope for the best.

RRR

[Tom Myers]

I'll get started on drawing up the Pedersoli chamber in the morning.

I made a copy of the image of the chamber cast in Red River Rick's post, enlarged it and then used some screen caliper software to scale out the length of the step from the chamber mouth to the begining of the grooves. My crude estimation shows the step to be about 0.0745" in length.

The step angle is usually referred to as one half of the included angle formed by the cone of the step or, in other words, the angle formed by the slope of the step in relation to the axis of the bore.

If we assumbe that the chamber mouth measures 0.4815" and the Bore diameter is 0.4585 then the difference of the two is 0.023". Divide that by two and the rise from the groove radius to the chamber mouth radius is 0.0115"

Dividing the 0.0115" rise by the 0.0745" length of the step returns a ratio of 0.15436.

The ArcTangent of the ratio, 0.15436, is 8.775 degrees.
However I am assuming two measurements, so it is probably off somewhat.

(If you dont have a calculator that does Trig functions, for shalow angles of 10 degrees and under you can just multiply the ratio of rise and length by 57 to get a fairly close estimation of the angle.

Hope this helps.

P.S. The Image of the modified chamber was smaller and difficult to get a good scale on but it appears to have a step angle of about 3.5 degrees

[montana_charlie]

CM, One thing I don't recall ever reading was whether changing the 45 degree angle to a gentler one would be detrimental to grease groove bullets.

As a matter of fact, the modification only affects the 'step'...not the chamber, or the rest of the 'throat' elements (freebore and leade) if it is not excessively long.

Therefore, it does not (or should not) degrade performance with grease grooved bullets.

Does this look like a 10 degree, 12 minutes, and 14 second angle?

Well, using a handy little helper called 'Screen Protractor', I took this screen shot with the protractor aligned as carefully as I could on the enlarged image.

It's 'close' to 10 degrees.



It certainly isn't 45...

I think Kurt said his throater cuts a five degree angle on the step.

Here's a screen capture with the protractor on Kurts chamber cast.
Not counting alignment problems due to resolution and the cast not being perfectly horizontal, it does read 'close' to 5 degrees.



I haven't had this Screen Protractor very long, and I'm still learning how to use it well.

CM

[Red River Rick]

Okay, I'll re-phrase my comment..............................

The angle isn't 45 degrees, but whatever it is..................it ain't worth darn for P/Ping.

When I took the chamber cast, it measured 0.484", at the end of the case. The bore diameter in my rifle is 0.4480" and the groove diameter is 0.4605".

RRR

[Lead pot]

Here is my chamber reamer specks for the cast Rick posted.
It is a compound lead of 5 degrees to groove depth than 2.5 degrees to the top of the lands.
This lead is friendly to a lubed bullet as well as the PP bullet.
This is as close to the original 1877 Sharps except for the 5 degree lead that I changed from a 3.5 degree. I did not want a very long lead.
I since had a throating reamer cut with a 4 degree for the .40-70 SS and used it in the .40-65 BPCR because it had a bad chamber from the factory and it turned out very good.

Kurt

[montana_charlie]

The angle isn't 45 degrees, but whatever it is..................it ain't worth darn for P/Ping.

Disregarding the angle for a moment...how badly would you want PP to work for you?
Namely, would you be willing to wipe between shots?

That practice seemed so useless to me I used to swear I would never try PP if it was a requirement.
Do you feel that way, too?

CM

[Red River Rick]

MC:

You know me. I'm currently NOT a target shooter like some of the other BP worshippers here, but I do hunt with BP.

To me, it doesn't matter weather I have to wipe between shots or blow tube it. As long as I can get decent accuracy with shooting PP, that'll make me happy.

So, Wiping or Blowing.......................what's it going to be?

RRR

[Don McDowell]

Rick you can load a paper patch bullet with a lubed felt wad and not have to wipe between shots and still hold something between hunting and "target" accuracy. Powder charge plays a part, along with the lubed felt wad or grease cookie. Final wrapped diameter under bore size also helps, because most of the reason needed for wiping is the fouling left makes chambering almost impossible.

Alot of hoorah has been put forth about "special" paper patch chambers. While it's true that the gentle slope into the rifling of the old chambers was good, all one needs do is look at what Kenny W, Rick Mulhern, and others can achieve accuracy wise with box stock standard modern chambers.
I've got 1 italian rifle, and one C Sharps at the moment, and with the right combo of bullet diameter , powder charge,seating depth etc, they'll both shoot accurate enough to be competitive in matches and certainly have minute of antelope or elk to 300 yds.
If paper patching was simple, grease grooves, never would of made it obsolete and forgotten.

[montana_charlie]

Well, if you're willing to wipe I'm certain groove diameter patching can be made to work in your rifle. It MAY even be possible to get reasonable performance without wiping, but I haven't gotten that far, yet, myself.

With your .484" chamber and .448" bore diameter, you should have an easy time of PP-ing at bore diameter if your cases had walls about .016" thick. But, you have about a quarter inch of groove diameter freebore between the chamber and the leade.

The bullet is going to bump up into that space no matter what, so it seems reasonable to just start at groove diameter to begin with. A .454" bullet (like you just made for me) patched to .460" should put you in business...since you are willing to wipe.

If your paper is pretty thick (like the 25% rag from BACO at .0023"), you might want a .452" bullet. In that event, I have a pretty good mould you can have to mess with. It was made by a guy who does a pretty good job on moulds...and I think your wife even knows him.

I've been seating that bullet .630 in the case mouth, but with your freebore you can probably seat it at about .390".

When Tom posts that chamber drawing, we'll see how close my 'supposing' fits in a Pedersoli.

CM

[Lead pot]

I have several rifles with the tapered lead chamber and every one I can load and shoot with out using a wet patch or blow tube using a GG or PP bullet.
I spent time at the range to see just how many shots I can take with the .45-2.4 with out the tube and still hit what I was shooting at. No you will not get 2MOA with 50 rounds fired at 200 yards but it will be good enough that you will bust 6 bowling pins to splinters with most of the shots hitting them.
I know that I can with out a problem hitting the 600 yard stop sign at the Quigley with just a blow into the receiver now and then with using the lead you see on the cast above.
This can be done with the bullet that Rick posted or a postell at groove diameter or even a patched bullet 2-3 thousands over bore diameter. It's just the way you load your round. This can also be done with your normal 45° chamber end you get now days in most rifles but the lead rings or paper rings or lead fouled throat will give you a problem inserting a round sooner than later.
It's just easier in the old original chambers to make this work.
Look down the bore with a bore scope some day and you will see the same lead in the .22 rim fire rifle that is one they have not changed to the .45 degree yet.
The 45° came about the time the jacketed bullets and smokeless powder came around to help restrict the bullet some to get the smokeless powder to work more efficiently I think, but that is just my thought on this.

Kurt

[Red River Rick]

Okay Gents.

Powder charge plays a part, along with the lubed felt wad or grease cookie.

That's one part of the equation I've never tried.

Alot of hoorah has been put forth about "special" paper patch chambers. While it's true that the gentle slope into the rifling of the old chambers was good, all one needs do is look at what Kenny W, Rick Mulhern, and others can achieve accuracy wise with box stock standard modern chambers.

Mr. M's 50, "The Bastard" (I like that name) has a custom barrel. Is his chamber of standard configuration or did Shiloh cut his something different? What about Mr.W., are all the chamber configurations in his rifles standard as well?

I've got 1 italian rifle, and one C Sharps at the moment, and with the right combo of bullet diameter , powder charge,seating depth etc, they'll both shoot accurate enough to be competitive in matches and certainly have minute of antelope or elk to 300 yds.

Don, the minute of antelope doesn't help me much up here, we don't have any speed goats. But minute of moose................well that's different!

If paper patching was simple, grease grooves, never would of made it obsolete and forgotten.

I figured that everyone just got lazy in the past 100 years and switched to greasers.

With your .484" chamber and .448" bore diameter, you should have an easy time of PP-ing at bore diameter if your cases had walls about .016" thick.

Another factor in this ever changing game. Yes, thicker brass would help considerably. If my memory is right, I think Mr. M and Powderburnerr are using RMC thick walled brass, some where around 0.017" thick.

The bullet is going to bump up into that space no matter what, so it seems reasonable to just start at groove diameter to begin with. A .454" bullet (like you just made for me) patched to .460" should put you in business...since you are willing to wipe.

If your paper is pretty thick (like the 25% rag from BACO at .0023"), you might want a .452" bullet. In that event, I have a pretty good mould you can have to mess with. It was made by a guy who does a pretty good job on moulds...and I think your wife even knows him.

Ha! You Funny Guy Chalie!

I've been seating that bullet .630 in the case mouth, but with your freebore you can probably seat it at about .390".

When Tom posts that chamber drawing, we'll see how close my 'supposing' fits in a Pedersoli.

Good Plan! I'm just as curious as you are!


CM

RRR

[Don McDowell]

Mulherns chambers are standard chambers , unless he modified them for paper patching, something I've not heard or seen him say.
Wasserburgers chamber on his old rifle is standard. Not sure about Dora.

Get some cerrosafe and do a chamber cast. All the drawings in the world won't tell you what the reamer that got crammed up that barrels snout actually looked like. Chamber drawings are good for what might be, but they're worthless for what is..

[RMulhern]

Guys

Both of my Shiloh .45/110 rifles are just that.....Shiloh factory barrels! No custom chambering to my knowledge!!

'THE BASTARD'.....which shoots FANTASTIC with PP.....is a C. Sharps rifle aka stock chamber!!

[Don McDowell]

Guys

Both of my Shiloh .45/110 rifles are just that.....Shiloh factory barrels! No custom chambering to my knowledge!!

'THE BASTARD'.....which shoots FANTASTIC with PP.....is a C. Sharps rifle aka stock chamber!!

So there it is in black and white, its not making a chamber friendly to paper patched bullets, it's making paper patched bullets friendly to the chamber.

[Kenny Wasserburger]

Stock Chambers, vrs special chambers
My Shilohs,
Current size chambers are .482 at the Mouth. My old rifle is .480 and when it was rebarreled in 2005 used the same old chamber size. Dora also was cut with with this old chamber Reamer. Both are stock barrels with old stock chambers.

I always get " I have handloaded for years I know what I am doing", Very seldom do they know what they are doing. Matching the bullet to the bore is a pretty stright forward process, in my opinion, if one is willing to wipe between shots you can shoot exceptional accuracy. I posted before that you can have the very best quailty barrels, yet if its a lousy chamber you wont shoot well. Very few people know how to control fouling well, either, last match I attended was proof enough for me. One good friend was having leading issues with his 45-110 Shiloh and shooting GG bullets, Too much wipping!!! I had him cut back to one single damp patch, (same I was using) for my GG loads on Sunday.

He took 3rd in the Long Range at Alliance.

I have had my moments in Matches where crashed and burned hard. I learn from these, dont give up, Phoenix in 08 was a good example.

End results, 09 in Phoenix was a good example of learning from and impoving.


2010 Phoenix, shot a 245-1x the first day of the cup, with no spotter using the heavy gun and Paper Patch.

KW

[Gunlaker]

I always get " I have handloaded for years I know what I am doing", Very seldom do they know what they are doing.
KW

That's a fact.

I thought I knew what I was doing when I got into this BPCR stuff. I've been at it only a bit longer than a year now. I like to think I'm a quick learner, but mostly I've learned that there is a lot to learn yet

Seems that the two biggest things I've learned are:

1) even though I thought I was good at producing consistent loads I wasn't. Consistency has a whole new meaning.

2) shooting technique really matters with these rifles. The learning curve here is at least as steep, if not more, than making consistent loads. I'm not sure about long distance, but it's certainly true for the 200m shoots I attend.

Chris.

[RMulhern]

Someone may have a load that shoots like JESUS CHRIST was at the trigger from 200 to 300 yards/meters...what have you.....but until it's tested at LONG RANGE.....it may not hit 'diddly-squat' at 800 to 1000!! But if 300 is all you're gonna shoot......doesn't make much difference!!

[Tom Myers]

I finished up the drawings.
Some of the drawings are quite large - 1 pixel to 1/1000 of and inch, so I will just provide links to the web page where they are stored.

Don said it right. drawings of chamber and load fit are worthless unless they are constructed with real, accurate measured dimensional values.

If drawn to accurate, measured scale dimensions and large enough, a lot of insight may be gained into designing and loading for proper throat-leade fit.

Hope this helps.

DT Design Paper Patch Bullet


Pedersoli-Gunn-Trenk bullet from a Victory Mold


Paper Patch loaded to lands in Pedersoli Chamber


Pedersoli Victory Mold in the Pedersoli Chamber


Throat fit of the Paper Patch Bullet



Throat fit of the Pedersoli-Gunn-Trenk Bullet



Full Size Pedersoli Chamber Drawing

Full Size Loaded Paper Patched Bullet Drawing

Full Size Loaded Pedersoli-Gunn-Trenk Bullet Drawing

50% Paper Patch Load Drawing