cant get a 432 bullet into SBH cylinder

[mattd]

Barrel is 429, throats are 431. sizing to 432. 2 cylinders take em pretty easy if the brass is clean, if its dirty I have to push hard to get em in. 2 more are always hard, 2 more are a no go. what do I do about that?

[High Desert Hunter]

I would size to .431 or even .430, I size my bullet for my SBH a blued 7 1/2" barreled version to .430, and get excellent accuracy, and little to no leading with my 429421, and excellent accuracy with no leading with the 305gr Lee WFNGC.

[Djones]

Send the cylinder to member Dougguy. he will even the cylinders out. He worked on my Ruger speed six cylinders and did a fantastic job.

http://castboolits.gunloads.com/member.php?29606-DougGuy

[GhostHawk]

Wonders why you went 3 thousandths over instead of 1 or 2?

[LUCKYDAWG13]

how does it shoot with boolits sized at .430 / .431 ? if it not broke don't fix it

[Silver Jack Hammer]

I found a similar situation with my 3 screw SBH, you have to seat your boolits deeper into the brass. I can't even get 429" to chamber with a 44-250-K. Seat 'em deep, over your driving band. Be sure to reduce your powder charge accordingly. Instead of 10 grains of Unique, I use 9 grains of Unique because I'm seating .1" deeper or the COL is .1" less. I have not experimented with a RN boolit but I found it was the wider driving band hanging up on the tight cylinder internal dimensions. When seating them deep my SBH takes .431" boolits all day, no problems.

[DougGuy]

All seating deeper does, is create a second problem to get around the first problem. Send me the cylinder.

mattd you have basically the same cylinder I had in my SBH. Ruger used to gang ream cylinders 3 holes at a time on a Hitachi machine, they would replace reamers as they wore, not all at one time. Since the newer reamers cut larger holes than worn ones, you have 3 different throat diameters from 3 different reamers on the same cylinder. They run in pairs because they would index, ream 3, then index again one hole over, and ream the other 3. Next cylinder..

The best thing to do is to size all the smaller throats to the same size as the larger throats, then size boolits to match. The thing you want to do, is get all 6 throats the same diameter because if left with different throat sizes, pressures are greater on the tighter throats, and lower on the looser throats so this affects how the gun recoils in the hands of the shooter, it will shoot to different points of impact with differing throat sizes because of changes in pressure. Once all the throats are the same size, and even, groups improve because the gun shoots more consistently. You end up sizing the booilt to be a slip fit in the cylinder throats using only finger pressure and it will shoot great afterwards.


When seating them deep my SBH takes .431" boolits all day, no problems. Yes that will get the loaded rounds to chamber but if it won't pass a .429" through the throats, you are firing your .431s through a 6-port sizing die!

[.429]

Make sure your crimp is sufficient, but not excessive. If they still don't chamber, send it to Doug. He did a good job on a 357 for me.

[mattd]

Wonders why you went 3 thousandths over instead of 1 or 2?

I did go .001 over.... my throat size. a 431 bullet will just slightly hang up and is easy to push thru the throat. been awhile, but I think I was having leading issues at 431 w a few diff alloys, which is why I honed out to 432. plus my 444 likes 432.

I wasn't thinking it was the throats, but maybe narrow cylinders. with the 429244 bullet, and the lee 200 RN the rim of the brass will stick out about an 1/8", but from Doug's description of the process it doesn't sound like the cylinders would be tapered, so must be the throats.

[DougGuy]

I did go .001 over.... my throat size. a 431 bullet will just slightly hang up and is easy to push thru the throat. been awhile, but I think I was having leading issues at 431 w a few diff alloys, which is why I honed out to 432. plus my 444 likes 432.

I wasn't thinking it was the throats, but maybe narrow cylinders. with the 429244 bullet, and the lee 200 RN the rim of the brass will stick out about an 1/8", but from Doug's description of the process it doesn't sound like the cylinders would be tapered, so must be the throats.

The charge holes are actually tapered. If they weren't you would have to carry a maul to beat the brass out after firing. The throats are not tapered. There is a chamfer at the end of the charge hole, it forms the transition from the charge hole to the throat. The mouth of the case goes right up against the edge of the chamfer, and sometimes into the chamfer depending on how long the case is, but the diameter of the boolit ahead of the case mouth -should- go into the cylinder throat. You shouldn't have to seat deeper in the case to chamber a loaded round, so if the throat diameter being tight is what is stopping it, that's why we ream the throats.

A lot of people think the cylinder is the important part, and they size the boolits to fit in the cylinder. This is not really the best way UNLESS the cylinder throats are of sufficient diameter i.e. .001" to .002" above groove diameter, and IF they are all even. Having uneven throats is almost as bad as having tight throats, since it really messes with pressures. We can weigh all our charges to get them the most consistent so we have best accuracy and small groups but the cylinder throats if they are uneven can throw all this careful preparation out the window because they cause uneven pressures from shot to shot. Just like putting more powder in some of the cases and less in others. No difference.

The cylinder, is a guide. It is a tool, that guides the boolit from the loaded ammunition, into the cylinder throat, and into the barrel. That's it's job, and to contain the pressures of ignition. The boolit is the important part between the two of them, it's diameter and how round it is needs to be insured so it seals in the bore and shoots accurately. We need to conform the cylinder to the boolit, not the other way around.

[Silver Jack Hammer]

DougGuy, I'd like to have you open up my SBH cylinder to accept my 44-250-K at .431".

My SBH accepts 429421 crimped behind the driving band at .431" but not RCBS's 44-250-K crimped behind the driving band. The driving band of 44-250-K is much wider.

I'd like to have you open up the cylinder so I can load 44-250-K crimped behind the driving band so I won't have to seat the boolits deep and crimp over the driving band.

[EdS]

I'm experiencing some of the issues mentioned in this thread. My 3-screw SBH is OK with .430"-.431" but I believe it would do better with .432" cast. My problem is finding a mould that drops .432" with 3-3-94 alloy. I placed a WTB ad, but no responses. Any help here would be greatly appreciated. Thanks, Ed

[DougGuy]

Anyone that is interested in cylinder throat work may send a PM and we will get the ball rolling. Turnaround time is a week or less and it is very affordable. You can get a cylinder reamed for less than the cost of a cheapo pair of grips..

EdS have you read any of the threads about lapping a mold or beagling? Both are ways to get the mold to drop larger boolits.

[mattd]

Just tried pushing a 432 Thompson bullet thru the cylinder. I can't push it thru the throat, but it goes much further then when loaded in the brass, the nose will stick out of the cyl. So I think the brass, with the fat bullet, is getting hung up in the tapered charge hole before touching the throat. is there anything that can be done about that, or is the answer to go back to 431?

[DougGuy]

Well, if you can't push it through the throat, the throat is too tight. I shoot .432" in my SBH and I have zero issues with the charge holes, they chamber with no effort, they fall right in with an audible "plunk." You have uneven throats, as well as tight throats. I would stick with the .432" and ream the throats until your boolits are a slip fit in the throats. Kill 2 birds with one stone.

[mattd]

I'll have to have you even them up. Maybe after deer season. But this is as far as this dummy round is going in, and I can see from the front of the cylinder that nothing is in the throat. So not sure if opening the throats will let me shoot 432 anyway.

[DougGuy]

Whatever the largest throat is, is what they need to be. Mine was .4322" or thereabouts and I did the rest to match the largest one, then figured out a .432" goes in all 6 really evenly. I can pin your cylinder and find the largest throat, size a boolit to fit it and size the rest of the throats to the same amount of drag on the boolit.