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Old August 12, 2019, 02:58 PM   #1
FizzyP
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45-70 Huge POI Shifts

TL;DR; I have two types of factory ammunition. One shoots great. The other shoots bad groups with a point of impact radically to the right (10" right at 100 yds and 6" groups). The bad ammo is loaded with the very cost effective Barry's 350gr plated bullet, which is exactly the bullet I was intending to reload for cheap plinking.

Question 1: Does the rifle not like the projectile or the load or some combination of both? Is there a way to tell without a buying a bunch of Berry's bullets, reloading, and praying? I'm intending to load these significantly down from the factory loading (see below). Is it possible it will behave great at 1050 and like garbage at 1350?

Question 2: Is a horizontal POI shift of 10" at 100 yds a common occurrence? Seems like a lot to me.

Here are all the details:

Accurate cheap ammo: Precision One 300 gr Rem. JHP at 2050 FPS. Shoots 1.5" groups for me and probably even better for someone else. Occasional fliers.

Awful cheap ammo: Precision One 350 gr Barry's plated at 1350 FPS. (Trapdoor load)

The rifle: A 1917 Enfield (bolt action), rechambered in 45-70. 24" barrel with unknown twist rate.

Desired load: 350 gr Barry's on top of a minimal Trail Boss charge. I'm shooting for low recoil and subsonic for some fun, maybe ~1050.
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Old August 12, 2019, 03:10 PM   #2
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Welcome to the forum.

Dramatic POI shifts like that suggest stock contact with the barrel is interacting with recoil to introduce muzzle deflection and vibration that the slow round is getting caught in the middle of. Another factor may be the velocity. At 1350 fps you are at the top end of the difficult transonic velocity range within which the drag coefficient peaks (the sound barrier). Driving that same bullet down below the speed of sound at about 950 fps or less will get you completely out of the range in which transonic effects occur and may leave you with no problem at all. You'll have to try it to see.
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Old August 12, 2019, 06:23 PM   #3
FizzyP
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Thanks for the quick reply

Thanks for the quick reply. I'll check out stock/barrel interaction. I'm hoping it's not just the velocity since bullets of approximately that weight and speed are the traditional loads.
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Old August 12, 2019, 06:37 PM   #4
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The factory ammo you have loaded with Berry's really tells you nothing about how Berry's plated bullets might perform with Trail Boss. In my experience, TB has never really delivered any kind of accuracy in rifle cartridges, straight wall or otherwise. IMR 3031 and 4198 would both be better choices IMO.

It seems unlikely that anyone would build a 45-70 with a twist rate too slow to stabilize a 350 grs bullets. If it is, it's pretty useless.

Definitely want to slug the bore. An undersized jacketed bullet might shoot okay while a plated bullet does not. So, getting a read on groove depth vs bullet diameter is step one, then consistency of bore. If, for example, it widens out towards the muzzle end, that would be a problem.

If the Berry's are a good fit, ie circa .002" over groove diameter and there's nothing strangeat chamber end or muzzle (the latter unlikely given performance of the 300 JHP), then Berry's should be a viable bullet (if light, IMO) with the right load.
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Old August 12, 2019, 09:08 PM   #5
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The Berry's weight and stability and length should be fine with respect to the twist rate, but some bullet shapes suffer dynamic instability in the transonic range, despite plenty of spin. The 168-grain Sierra MatchKing will tumble in the transonic range, for example, after maintaining target accuracy to 700 yards or so. I don't think it's a very likely scenario, but the velocity range made me think to throw it out there. Stock contact issues are more likely, given the shift to the right.

I like the idea to check for a bore constriction before the muzzle. I've had the same experience of getting good accurracy from a jacketed bullet in such a barrel and poor accurracy from lead. The elasticity of plated bullets is usually somewhere in between lead and jacketed bullets and I haven't had occasion to see how they compare to lead in this situation, but being loose near the muzzle would be a more probable way to explain the group diameter than my dynamic instability idea.

The way I look for a constriction is to push a pure lead slug just into the muzzle and put an index mark on the back of it and back it out with a cleaning rod from the breech end and measure it with a micrometer. I then put it back using the index mark to find the same land and groove orientation and then push it all the way through to see if I feel resistance along the way and to see if it comes out smaller, due to a constriction. If you have one you can firelapping it out.
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Old August 13, 2019, 08:30 AM   #6
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Besides what Unclenick said, I think LRDGCO is probably closer to the truth. Having some experience with the .45-70 meself, I would rethink your bullet... maybe try just some generic cast bullets over a suitable powder like IMR4198 or AA5744. I know that TrailBoss, Unique, and even 2400 are supposedly good for reduced velocity loads in the .45-70, but I've found better performance (even at the same velocity range) with IMR4198 and AA5744. For example, I was shooting the commercially cast LaserCast 350grn bullet over 31grn IMR4198, it gave me right at 1450fps (out of a 32" barrel) and was accurate out to 700yds.... and this in a rifle I'd never fired before, or developed a load for.

I suspect, besides an obvious mechanical problem like Unclenick suggests, your rifle doesn't particularly like that plated bullet. I have found some instances, pistols in particular, where a plated bullet had horrible accuracy vs a simple cast bullet in the same weight range. Unless you are willing to go all the way... measuring the bore, checking for constriction (I had one in a .44SPC Ruger I was working with, and a common place in a rifle bore is the dovetail cuts for the sights...) and even a chamber cast... you would have to just buy a box of that particular bullet and give it a go with a few powders and see.
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Old August 13, 2019, 05:56 PM   #7
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Thanks for all the good advice, everyone. I think I was avoiding the cast bullets @Charlie_98 is suggesting (which are actually cheaper) just because I only have reloading experience with jacketed bullets and I'm vaguely paranoid about leading. Even if this is a barrel bedding issue, you've convinced me it's time to broaden my horizons and try out some new projectiles. I'll do some experiments and report back.
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Old August 13, 2019, 07:01 PM   #8
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Just FYI... loading cast, and shooting cast, isn't as esoteric as it may sound. There are some things you need to look for, and a few tools to get, but it's just as easy and reasonable as loading jacketed. For me... I only shoot commercially cast bullets, I don't cast nor will I ever, but there are plenty of sources out there for good cast bullets. With the .45-70, properly sized bullets fired at a reasonable velocity are an easy, no muss no fuss proposition.

One tool you will need is something like an Lyman M-die... it properly sizes the case mouth for cast bullets to seat without shaving lead. It does add an extra step, yes.

You should probably slug your barrel, unless the barrel was a commercially manufactured one (I don't know much about rechambers/rebarrels.) You may have to try a different size or two to find the right bullet size for your particular barrel. An improperly sized bullet is probably the leading cause of barrel leading.
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Old August 13, 2019, 11:45 PM   #9
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I was looking at IMR's loading data for 4198 and their starting loads in all bullet weights are pretty warm. 400s at 1954, 300s at 2253. The max loads are hotter. For AA5744 the starting loads are not quite as speedy but still solidly at trapdoor level. Are these powders really comparable to Trail Boss?

If T.B. produces mediocre accuracy I'm not interested in it, for sure. I've seen claims that T.B. produces bad accuracy close to the min charge. No idea if that's true. But, in addition to the pass-it-to-the-kids plinking appeal of T.B. the ultra-light charges drive the price-per-round down pretty far. I was crunching the numbers with some other powders and price per round is significantly higher.

But, like I said, if it's not accurate it's no fun regardless of how cheap and quiet it is to shoot.
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Old August 14, 2019, 12:16 AM   #10
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My experience with TB in rifle cartridges, bottleneck or straight wall is big extreme velocity spreads which delivers poor accuracy at 100 yards plus. Ymmv.

With a light bullet, velocities are going to be rather higher and, in my experience, recoil feels sharper than with heavier bullets where recoil feels like a heavy push rather than a sharp bark.

I suggested IMR 3031 and 45.5 grs with a 350 grs plated bullet is a fairly classic trap door load and will be around 1350 fps H4895 may also be worth exploring as it allows for reduced loading.
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Old August 14, 2019, 09:03 AM   #11
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Are you looking at Trapdoor data? ...that's where you need to be looking.

Starting IMR4198 load with a 300grn bullet is ~1600fps and for a 405grn is 1370 fps.

AA5744 is a powder designed for cartridges like the .45-70 to move big bullets at low pressure, not really as a bottleneck cartridge powder, that's why their data starts low. You can load to the same basic level with IMR4198.

I'm not a big fan of small charges of powder in those big .45-70 cases... powders like Unique. TrailBoss is made to be bulky, for better case fill, but I've never messed with it. I'm experimenting with 2400 right now, but I find it unlikely to surpass the utility of IMR4198 or AA5744.
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Last edited by Unclenick; August 14, 2019 at 10:07 AM. Reason: Corrected 1370 grn to fps
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Old August 14, 2019, 09:09 AM   #12
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I've also had experience with poor accuracy with a Marlin 1894 in .45 Colt. Loading big (260grn) bullets over a reasonable charge of Unique, I was getting shotgun-like patterns... it was horrible. What I found, later, unfortunately, after I traded it off, was the very slow (1:38") rifling wouldn't stabilize the heavy bullets at lower velocity... I either needed to ramp up the charge under the 260grn bullet, or drop to a lighter bullet that would give better velocity... and stabilize the bullet. If I were you, I would gooogle how to measure your barrel twist (easily done, no special tools...)
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Old August 14, 2019, 09:41 AM   #13
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Plated bullets are serviceable in pistol calibers but I would not bother with them in a rifle.
The 400-405 gr Speer and Remington JSPs have good reputations if you don't want to get into cast bullets.
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Old August 14, 2019, 10:12 AM   #14
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FizzyP,

Trail Boss is just different. It's designed to run at low pressures like a modest dose of pistol powder, but its ignition behavior doesn't quite track regular powders. Part of this is because of all the empty space the donut holes leave in the case. Going to a magnum primer (they make more space-filling gas than a standard primer does) can often cut its velocity variation for that reason. Also, a really strong crimp is a big help. I've been favoring the Redding Profile Crimp Die for this. Its crimp starts as a taper crimp but terminates in a roll crimp. This keeps the sharp roll from deflecting brass away from the sides of the bullet to have better friction.

Note that H4198 loads for the trapdoor are lower in velocity than the IMR4198 loads, but produce more velocity variation. This is due to empty space again, and, again, a magnum primer can help with that. So can other cast bullet shooting techniques like putting a tuft of Dacron pillow ticking over the powder before seating the bullet, to keep the powder against the flash hole.
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Old August 14, 2019, 01:10 PM   #15
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"...was avoiding the cast bullets..." Plated bullets are loaded with cast bullet data. Cast are most likely far less expensive than plated too.
Anyway, to find the rifling twist, put a lubed patch(regular solvent) on your cleaning rod and put it in the chamber. Mark the top of the rod(dot with a Sharpie) at both the handle end and at the chamber. Push the rod through the barrel for one complete turn of the handle end dot and mark the chamber end again. Measure the length between chamber dots. That's the twist. One turn in whatever length.
"...Trapdoor data?..." No 350 grain cast data on Hodgdon's site(there might be 350 grain data in their manual.). No data at all on Berry's. Trail Boss TD data is with a 300 grain cast bullet. Runs 1,199 FPS to 1285 FPS.
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Old August 14, 2019, 01:20 PM   #16
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Looking in Lyman Cast Bullet handbook, I see SR4759 and 5744 as the best powders for light loads. 292 cast starts at 1300 fps for a lead bullet. It goes up from there.

Are these plated bullets made for over 1250 fps? some are not.

I have never had any luck with accuracy in plated bullets. This is only in hand guns.

You can also buy coated bullets like Hy Tek and others that will probably shoot better, maybe even excellent. Your rifle is a handloaders good time. Lots of things to try. Lots of those will work well.

David

Edit I just looked up the 350 rifle bullet is ok up to 2,000 fps.
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Old August 14, 2019, 02:42 PM   #17
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It's 45-70. If you are terribly concerned about not having to clean leading, it's about as easy cartridge to roll paper-patched bullets for as there is, and they leave the bore free of metal and even tend to polish it over time.
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Old August 14, 2019, 03:01 PM   #18
FizzyP
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Quote:
Originally Posted by LRDGCO View Post
My experience with TB in rifle cartridges, bottleneck or straight wall is big extreme velocity spreads which delivers poor accuracy at 100 yards plus. Ymmv.

With a light bullet, velocities are going to be rather higher and, in my experience, recoil feels sharper than with heavier bullets where recoil feels like a heavy push rather than a sharp bark.

I suggested IMR 3031 and 45.5 grs with a 350 grs plated bullet is a fairly classic trap door load and will be around 1350 fps H4895 may also be worth exploring as it allows for reduced loading.
The 350 at 1350 load is exactly the horribly performing load from my original post. What I'm really looking for is a cheap 350-450 gr bullet at ~1050. This is purely for plinking fun and a little practice with holdover since it's flies like a brick at that speed.
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Old August 14, 2019, 03:05 PM   #19
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Quote:
Originally Posted by Unclenick View Post
It's 45-70. If you are terribly concerned about not having to clean leading, it's about an easy cartridge to roll paper-patched bullets for as there is, and they leave the bore free of metal and even tend to polish it over time.
I've been researching the paper patch bullets. I'll *definitely* try that out at some point. With 45-70 the reloading options are beyond plentiful. I'm new to it but it's starting to seem like the 12 gauge of rifles. You can practically load it with your pocket change.
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Old August 15, 2019, 08:20 AM   #20
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Quote:
What I'm really looking for is a cheap 350-450 gr bullet at ~1050.
At that low velocity I would probably look at something over Unique, 2400, or TrailBoss. I don't think you can get IMR4198 down that low. 20grn AA5744 and a 405grn bullet will give you about 1200fps, it's bulky enough you shouldn't need a filler for good ignition, and quite honestly, the recoil is nothing to talk about. You could do the same with a 300- or 350grn cast bullet as well.

I can't speak for 2400 or TB, but with Unique I would recommend a filler like a tuft of Dacron... to keep the charge against the primer like Unclenick suggests. I was witness to a case failure in a single-shot rifle... 15grn Unique under a 405 cast. Case head blew out and the shooter almost lost his eye. The only thing we could come up with was either a fatigued piece of brass (unlikely, but had to be considered) or some sort of discharge anomoly with the light charge of Unique... and this is why I'm not wild about Unique in the .45-70. Unique will deliver what you ask... 10grn Unique under a 385grn cast bullet will give 1075fps, but at only 31% case fill... hence the need for a filler to keep the charge back against the primer.
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