8x52R Siamese Mauser Paper Patch

[iuvenal]

Sorry to hear about that, I too, have screwed up recently. I've had this obsession with using a pp'd lee tl230-5r in a mosin. Actually started on it last fall, but finally got back around to messing with it and loading some ammo up this weekend. Well, I didn't remove the sticky alox from the boolits before wrapping. I think it was adhesive enough to stick all the way to the target with the slower loadings, so accuracy was...ok. But the hotter loads I loaded were all over the place, so I imagine it was shedding the patch mid-flight. Oh, well, live and learn.

I didn't get to really do much shooting with the Mauser, though using the NRA slow-fire pistol target at 200 yrds, I did get inside the 7 ring with the one shot i tried at that distance. The groups at 100 yrds were about 2-3" in heavy wind, so not as good as before but not back considering the conditions out on the mesa.

[CJR]

iuvenal,

A question. For your Mosin, how are you determining what diameter the CB should be?

Best regards,

CJR

[iuvenal]

Hey CJR,

I slugged it, carefully measured lands+grooves, and sized the bullet to engage the lands. If I recall correctly the bore (land to land) is .302 and the groove is .314. So, I size the boo lit to .305 so it can engage the rifling, and wrap to about .3155-.316 which is sized to .315 (really just a slight smoothing of the patch). My 91/30s throat will not accept anything over .315, and I think this is pretty common, I've read old posts where Nobade was talking about the same thing.

I will say, that the Lee TL230-5r is probably not an ideal paper patch boo lit from what I've read, however I'm going to give it a shot and see if I can get it to work.

-i

[CJR]

iuvanal,

Please explain exactly how you "slugged" it?

Best regards,

CJR

[iuvenal]

Take a PURE lead ball a little larger that the bore, lube it up with something, liquid Alox works well. Place the ball on the muzzle, then starting it gently tap it into the bore with a dowel and rubber mallet. Once you've pushed the slug all the way through the barrel, recover it from the breach end. It will have rifing indentations, measure across the bottom of the indentations for the bore diameter, then measure where it is not marked by the rifling to get groove diameter. This will give you the smallest land/goove diameters in the rifle ONLY. To get more detail about the chamber/throat etc. you will need to do a chamber cast.

Here is a tutorial: http://7.62x54r.net/MosinID/MosinSlug.htm

-i

[CJR]

iuvenal,

That technique works well for new rifles. Unfortunately, when a rifle has been fired a lot,i.e. well used rifles or Milsurps, the forcing cone and the rifling just in front of the forcing cone gets enlarged to a larger diameter than the rest of the barrel. In that situation, when the PPCB gets chambered the forward part of the cylindrical section of the CB is not in contact with the worn rifling. Result? When the round is fired the PPCB can be tilted laterally/yawed by the explosive pressure before it begins its journey down the barrel. Inaccuracy results. High probability your Milsurp has shot lot's of Digressive stick powder loads, which go off like grenades (spiked pressure) with high initial flame temperatures causing plasma gas erosion of the forcing cone and the rifling just in front of the forcing cone.

Fortunately, if we know the rifle has this type of throat erosion the solution is simple, i.e. increase the CB diameter to get good engraving on the forebody of the PPCB when chambered. Some people just use longer OAL to get the engraving required. But that approach is counter-productive because as the OAL increases so does the air-space over the powder which causes inaccuracy. Case fillers then need to be added over the powder to eliminate the air-space. Likewise, that approach gives less and less case neck grip on the PPCB. You can do a chamber cast but I described, on another post, using a simple trick of spray painting(white color) a CB, seated long in a DUMMY round and chambering it to see if you get good engraving marks on the CB.

The accuracy battle, for PPCB, is won or lost before the PPCB starts moving. In severe barrel erosion, i.e. bore diameter enlargement in front of the forcing cone, the CB can have any orientation before it hits the unworn/good rifling. I'd suggest you check a painted CB, seated long, to make sure your CB diameter is correct and you get good engraved marks on the CB (approx. 1/16"-1/8" long when chambered). Hope this helps.

Best regards,

CJR

[iuvenal]

Okay yeah, I'll give that a try tonight. I think I'm okay in that regard, I've placed the PPCB far out in a sized empty case and cammed it home with the bolt, I did notice engraving on the nose well ahead of the patch, but not much attention was paid to it at the time as I was trying to get a seating depth. Having said that, I will paint one white this evening to be absolutly sure. I hope .305 is okay, if I have to go larger I'm going to have to change paper since I'm dealing with such a tight throat. I like this paper, its easy to work with.

Thanks,

-i

[CJR]

iuvenal,

With a larger diameter CB, try the thinner Mead Tracing paper; first (2) wet wraps and then (3) wet wraps. After a couple of days drying see what you get for final diameters.

Best regards,

CJR

[semtav]

I acquired a .321 sizer die and that seems to be the magical number. My .315 push thru die works great once I've run it thru the .321 sizer die first. Now to get my ducks in a row and get some loaded up to test. Maybe next weekend.

[303Guy]

This photo shows a 206 gr boolit that has been chambered in a pretty well worn throated rifle. If one looks carefully the rifling contact areas are visible from just above the case mouth. The boolit is tapered from just forward of the case mouth.

[CJR]

303Guy,

I must be missing something with your 206 gr. PPCB in your "pretty well worn throated rifle". Why would you place a forward tapered PPCB in a "pretty well worn throated rifle" and expect any type of accuracy whatsoever?

I would suspect a straight cylindrical CB, sized to a larger diameter and seated long, would be engraved by more rifling and improve CB alignment and promote better accuracy. Please explain.

Best regards,

CJR

[iuvenal]

303Guy
That is very interesting, I guess I also figured a cylindrical CB would be optimal, but I also figure judging from your past posts that you know how to get worn rifles to shoot. Is it a matter of the engraving simply being sufficient at the wider part of the CB near the case? It does give me hope that the 2305R might actually work, given careful preparation on my part.

I still need to check the engraving on my Mosin, been extremely busy lately....

As for the Mauser, I wrapped up some more WDWW CB tonight, I also cast some soft lead CBs, I'll see how those work, maybe I'll actually make it to the range this wekend.

[303Guy]

The worn bore/throat translates into a very shallow leade. That boolit is engaging the leade from just forward of the neck to the start of the patch. The 'throat' is tapered and the boolit taper matches that taper. In a good throat, a boolit of that length needs to be shaped or it won't chamber (think bore-ride style although those don't fully engage). So in this case the long nose shank fully engages the throat/leade. I have a fired boolit photo somewhere if I can find it.

In the meantime, here is a recovered patch showing full engagement with the bore. This was a very low velocity shot and the wraps were glued together (the idea being to clean/polish the bore) so that's a double layer.

[303Guy]

Well OK, the boolit doesn't really show the rifling impressions (they are there). The paper was squeezed onto it over most of its length though. Soft alloy! That will explain why the paper did not cut through.



Here is a boolit showing clearly the boolit to leade contact.

[CJR]

303Guy,

Thanks for explaining your tapered PPCB. What's your guesstimate of max. velocity/pressure for your load? High velocity/pressure would cut that PP easily. With that type of rifling contact, I would assume it performs well on target. What group sizes are you typically getting with that tapered PPCB?

Best regards,

CJR

[303Guy]

That rifle hasn't been out the house. The load is 3.4gr of Clays - very low pressure. The muzzle end seems more eroded than the the chamber end so I don't really expect much accuracy from it until I trim off the muzzle but I'll range test it first. That should be soon now with the rains coming to an end.

[semtav]

finally gave up on trying to get a .315 sizer to work so I just made on up with the .318 die. yellow notepad paper fit the best. now to just figure out a load and give them a try.

[semtav]

Since I have no idea where to start with powder, I might try a shell with each of the following to see how they shoot.
40 gr 4350
40 gr H4831
40 gr H414
40 gr W748
50 gr H1000
50 gr R22

[semtav]

added a couple more powders to the test:

40 gr W760
40 gr MRP
50 gr Superperformance








W760 and the Superperformance seemed to have the cleanest holes. MRP and 414 might be ok. The RL-22 was a sized after wrapping and fit the case loose so might retry it and test a couple 5 shot groups with the W760 and Superperformance. The Superperformance also had the flattest primer.