How do you test for if it's the sight?

[tangsight]

Hello again everyone... I have lurked on the edges looking for a thread that might have my answer, but no luck.

I inherited a very nice Pedersoli BPCR in 45-70 when my dad passed away. Per the proof marks, it was manufactured in 1997; I think pop must have bought it almost new. It has sat in my gun safe mostly since then, until recently when a co-worker acquired a similar rifle and we began load development.

Per our chronograph (one of the new Labradar units), I am building very consistent ammo (1230 fps, extreme spread 12, standard deviation 8), but the groups are not there. I am suspicious of my sights, but I don't know of a simple test that would tell me if it's the sights or not. I would be happy to take the blame (I'm 67), but I still see good enough to fly, and my scores haven't turned south yet. I'd be happy to give load and product particulars, but I'm not looking to make this Italy vs America; all I want is: Is there a simple test?

Thanks in advance for any help.

[country gent]

I start by checking the base to rifle to make sure its tight and fitted correctly. I then check the joint where the staff mounts into the base and its swing / swivel and the locator springs fit in its slot on the staff base. I then check windage play repeatability with an indicator and base. Last is the elevation adjustment and lock. On some tang sights there is enough play that just loosening and retighting can make a small change in both windage and or elevation. This is due to tolerences in the eye cup to mount and mount to staff and end play in the thread. Windage can again be due to tolerences end play thread clearences. Some Soule type sights use a spring in them to try to control this but dont do a real good job at it. This can sometimes be controlled by always keeping play in the same direction on the thread. If you have it to the right and need to go left you go left past the correction by a turn or so and come back to it. The locator spring needs to fit the groove in the sights staffs base correctly Or the staff dosnt locate to its true upright position correctly being slightly forward or back. This can cause small elevation issues in itself and also seeing issues thrue the misalighned appeture. The staff when rotated to sighting position should snap securly into place securly with now rock or bounce. The staff base and mount if loose can shift and move. Depending on the sight if may be easier to contact MVA and replace it. Start buy checking evey joint for wiggle or shake buy lightly trying to move it back and forth.

[Don McDowell]

When the sight is locked into it's upright position, can you wiggle the staff fore and aft or side to side?
Sometime even if the velocity is very consistent, the bullet and or lube, case neck tension, to much crimp, etc can bugger up anything resembling a good group.

[Bent Ramrod]

Also check the insert on the front sight and make sure it's tight. If there's a burr or a bit of dirt in the slot, the insert will move slightly every time the rifle recoils. The sight picture will look exactly the same, but the effect on the target is exasperating.

I am assuming here that you have target sights on your rifle; you don't specify. Some people do very well with the ladder rear and the blade front, but it's generally after they have optimized their loading and shooting position with target sights.

Also, if I were you I would develop my loads per their effect on the target and ponder the chrono results later.

[montana_charlie]

Hello again everyone... I have lurked on the edges looking for a thread that might have my answer, but no luck.

I inherited a very nice Pedersoli BPCR in 45-70 when my dad passed away. Per the proof marks, it was manufactured in 1997; I think pop must have bought it almost new. It has sat in my gun safe mostly since then, until recently when a co-worker acquired a similar rifle and we began load development.

Per our chronograph (one of the new Labradar units), I am building very consistent ammo (1230 fps, extreme spread 12, standard deviation 8), but the groups are not there. I am suspicious of my sights, but I don't know of a simple test that would tell me if it's the sights or not. I would be happy to take the blame (I'm 67), but I still see good enough to fly, and my scores haven't turned south yet. I'd be happy to give load and product particulars, but I'm not looking to make this Italy vs America; all I want is: Is there a simple test?

Thanks in advance for any help.
What kind of sights are on the gun?

At what distance are you shooting?

If you have a folding tang sight, can you provide a photo?

[tangsight]

Thanks Country Gent; your suggestions and descriptions tell me I have pretty well looked over the rear sight. I have discovered most of the spots you describe, and there is some of what you talk about, especially in the Soule windage mechanism. There is an Allen screw on the forward side of the staff which tightens everything down, but too tight on that and nothing moves at all, which is maybe better...

To Don McDowell: The same aforementioned Allen screw can secure everything, to the point where there is no wiggle, fore and aft or side to side. But when I tighten it that much, it is very difficult to lower the staff, which is my habit when chambering a round.

To Bent Ramrod: I had thought about the front sight inserts. How could an insert that could move be snugged up? I have windage adjustable Pedersoli target sights front and rear.

To Montana Charlie: Here in Corpus, we shoot ten shot strings plus two foulers at 200 yards, which is all we have. A hundred miles north, I have just joined a club that goes all the way to 500 yards: Atascosa County Rifle and Pistol Club, near Christine, southwest of San Antonio. They will probably be my best bet because they can handle the weapon. I'll figure out a way to send a picture.

[Don McDowell]

Ok your staff is loose in the drum that will give you all manner of of vertical, and no guarantee of keeping horizontal under control.
You need to either get that sight fixed, or get one that doesn't have the slop in it.

[dave roelle]

Come shoot with us at "Yaupon Creek Silhouette association" near Columbus tx.

Google the name and see our websight and facebook page----we usually turn out 20 to 25 shooter for our bigbore matches 2nd and 4th saturday of the month------everyone will be glad to help

Dave

[country gent]

Getting the play out of those mechanisims and joints can be very tedious painstaking work and requires some specialized set ups fixtures to track and check what your doing. Some times its easier to replace or upgrade than fix. The set screw you mention locks the staf windage and would be a pain during a match to loosen and tighten to make adjustments. Also remeber play is due to excess slopp and making a joint tightrer is much harder than loosening one thats to tight.

[GOPHER SLAYER]

tangsight, before you ruin the threads on the tang sight, take it to someone who knows how to use it. If the rifle sat unused since your father bought it there is probably nothing wrong with it. Once you strip the threads on the adjustment screws it is pretty much toast.

[Bent Ramrod]

The inserts are normally either held in the housing by a threaded thimble that screws tightly against the outer margins of the insert, or it is held by an external spring riveted to the top of the housing, which applies pressure to the top of the insert. I don't believe any current designs use the fork (sometimes containing the spirit level) that slides into the bottom of the sight housing, but I'm not up on all the offerings out there.

The first sight is exemplified by the Lyman 17, and unscrewing the thimble, feeling the tabs along the flanges of the insert for movement and then tightening the thimble again and checking for lack of movement should take care of the problem, if it exists. You may have to clean the threads if the thimble doesn't bottom out.

The second type with the little spring on top is used, I believe, by C. Sharps Arms. This is normally a good method of attachment until the proud owner drags the rifle out of a soft case and snags the little spring. Unless it is down tight, the insert will wobble when the gun fires. You can bend the spring back, but I notice a lot of people put a thick rubber band around the sight and barrel and over the spring to keep everything tight.

The old style, with the two pronged fork under the sight housing, can be set right by careful bending of the fork tines until the thing is tight in its tracks and holds the insert tightly.

[country gent]

Bent Ramrod, My CPA has the fork or dovetail type insert and it 2-3 years old now. I believe CPA used MVA sights currently. Mine has the spirit level in the slide and I have a plain one also. They work good and a slight radious to the arms holds the level and insert very securly. The drawback to these is occasionally sliding the rifle into a soft case pulls the slide out and releases the insert. To allieviate this Ive went to the Air glide cases where the rifle sets up right in it.

[tangsight]

Bent Ramrod, I have the little leaf spring. After I check to see if it needs straightening, I'll try the rubber band trick.

Yaupon, my friend has already been in touch with you guys, and I rely on Croft Barker's book. We plan to come up when the weather cools a bit.

Don McDowell, I have to admit to being tempted by a Hoke, which advertises it has a "gibb" to reduce play. A Hoke is not a Soule, however; it has a Vernier scale for windage, and though I would know how to use it, I don't know if I would be buying something more or less robust. The peep on a Hoke appeals to the 19th century in me.

Gopher Slayer, I am afraid I have to admit to purchasing the sights. But despite my descriptions above about applying a torque wrench to a set screw, I have actually been very circumspect. I don't think I've actually broken anything. It's just that Tom Selleck made it look so easy....

[Don McDowell]

I have 3 Hoke sights they are good sights. Baldwin and Kelley are both good , and MVA is probably the cream of the crop.

[montana_charlie]

There is an Allen screw on the forward side of the staff which tightens everything down, but too tight on that and nothing moves at all, which is maybe better...
There is the answer to your opening post.
If you are sure that the front sight insert is immobile, lock the tang sight in position and shoot your groups.
The sight can't move, so any 'looseness' is due to you ... or you haven't found the right load, yet.

[country gent]

Are you shooting a fixed appeture in the rear sight? A hadley eye cup can make a big diffrence with old eyes since the appeture size can be set to let the needed light into the eye and help with "seeing" issues. With the tang sights the old trick of taking the eye piece out leaves the sight unlocked and floating. The hadley eyecup has a wheel with 8 holes or so and a index so the needed appeture can be set to use as needed.

[Hiwall55]

Sounds like you are shooting smokeless if you are at 1230
fps, probably that evil white powder that's to blame.

[EDG]

You can borrow another sight and try it on your rifle.
As long as your sight is locked fairly solid you should be able to get decent groups if you use the right front sight.
I have even been able to get decent groups with the Pedersoli "throw away" sight that has the slip and slide windage.
I use an 8" black bull with a Lyman 17A lollipop front insert. My eyes do not see the thin rimmed front apertures very well but the heavy apertures sold by Lyman are excellent for me.

Just because your chronograph gives consistent velocities does not mean the bullets fit the bore properly and shoot accurately.
I have a Pedersoli about the same age as yours and it is an excellent shooter though I have never chronographed a single round.
I use 500 grn bullets from a Brooks mold that cast about .461 to .462 and I shoot them as cast.

[tangsight]

EDG: You could be right about bullet diameters. I just changed to 20 to 1 (stick on wheel weights to tin) from 30 to 1 (lead to tin) and from the Lyman 457125 round nose to the tapered bore rider 457677.

Hiwall55: And that brings me to the load: 77 grains by weight FFg Goex, screened for fines. 24" drop tube. The bullet is seated 0.23" deep. The cartridge is 3.26" long overall, and thumb chambers. Single 0.030" veggie wad over the powder column. CCI benchrest primers in Remington Peters brass. SPG lube. Bullets are pan lubed. I could not get 1200 fps except through a clean bore with the round nose in 30 to 1. Maybe I could have with 20 to 1, don't know.

Country Gent: Hadley eyepiece. Came with the package.

Montana Charlie: Could it really be that simple? Of course it could! I'll try it tomorrow and report back.

[Hiwall55]

Everything looks good but the Lyman tapered bullet, you don't have to go over 1150 Fps. and use the 457125 RN bullet. I bought that tapered bullet when it first came out and had a lot better luck with the postel and government RN . Also try a paper disk above the primer(coffee filter works good)because that primer is pretty hot. And listen to Don and get a good sight, Hoke or MVA. I think I have 7 or 8 Hoke sights and never had any trouble with them.

[Bent Ramrod]

77 gr of powder under a grease groove boolit seems rather stiff to me in the .45-70 case. Have you tried 70 gr, or 67 gr, on the target, rather than the chronograph?

That Ideal 457125 should shoot ten inches or under at 500 yards out of your rifle.