Hoyt Thumper Carbine Velocity results..chronographed

[Bigpete]

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Weather cooperated and I got some velocities for my three Hoyt Thumper carbines.

Parameters :

Triple 7 FFFg powder, 50 degrees 45% humidity, oversized by one caliber OP wonder wad, RIO Musket caps. Each gun was shot twice from the bench prior to chronographing velocities and an alcohol swab was run in and out of the bore between shots. 3 shots were then chronographed. Last shot was with chrono removed and fired from standing to assess felt recoil

Gun # 1.............58 Cal 1:38 twist 24" barrel 500 grain minie ball .582 diameter. 100 grains powder

1. 1471 fps
2. 1496 fps
3. 1476 fps
Average 1481 fps SD 13
Recoil no more than a heavy game load in a 2 3/4" 1 1/8 oz 12 ga load

Gun # 2...........54 cal 1:38 twist 24" barrel, 485 grain conical .542 diameter. 110 grains powder

1. 1592 fps
2. 1571 fps
3. 1585 fps
Average 1582 fps SD 10
Recoil not discernably different than the 58 cal

Gun # 3.........54 cal 1:38 twist 21" barrel 425 grain .544 diameter concial. 100 grains powder

1. 1527 fps
2. 1574 fps
3. 1641 fps * powder was compressed harder than above
Average 1590 fps SD 57
Recoil...same as the others

OBSERVATIONS:
1. The powder was fully burning within the barrel. No bright flashes or smoke rings. Observer noted that no great blast/flash more than standard smokeless powder guns and only slightly more smoke.
2. Velocities realized exceed my max expectations by 80 fps to 100 fps in all three guns.
3. Bores are rough and need polishing. Lots of cutter chatter marks on the rifling and the bullet hangs up when seating it. Shot #3 in the 21" gun was seated HARD as it hung up and when pressure was applied it let go and seated much harder than the other two rounds. *I attribute the higher pressure of the third shot to the hard seating.


After cleaning then polishing these bores, I will then shoot for accuracy while adjusting powder loads. The bullets were grouping fairly well considering that I wasn't looking to group and was shifting sight adjustments to center rounds on target.. Surprisingly, the #3 21" gun needed very little adjustment to center rounds.

All in all, very satisfied with the progression. A little fine tuning on these guns, polishing the bores and after the lousy weather of the next week subsides it will be back to the range for some accuracy results.

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@SDSmlf @SOLANCO @Bad Karma @Urban Coyote @Brokenbear @Relic shooter @ETipp @Dale Allen Raby @wganz @TDM @tenngun

Very impressive! I'd be interested to see what my 32" barrel 58 does with a PRB and 110gn of 2f

 

[Thingamajiggy]

Thanks I will order some, have 1 pound of 777 but have never used it, only goex ffg

Don't be afraid to try the goex, I'm shooting the 375gr deerslayers out of my .54 deerstalker (flintlock), with 100gr of goex 2F, pushed 1500 fps. Ended up shooting 90 grs, better group at 100yds but both charge weight loads would touch 3 shots at 50yds.

 

[Jedidiah]

Bobby Hoyt took my GPR from 32 inch .50 cal to 26 inch .58 Smooth. Handles well now!

 

[andy52]

I have a Magnetospeed V2 but have never tried it with muzzleloaders do you have any problems with the bayonet getting fouled with powder residue?

 

[chorizo]

I have a Magnetospeed V2 but have never tried it with muzzleloaders do you have any problems with the bayonet getting fouled with powder residue?

Not on this, using T7 FFFg. The powder seems to be burning completely in the barrel (even the 21" barrel) and T7 burns clean in the first place. Pyrodex made a mess and I haven't shot traditional BP using it.

An issue is getting the bayonet to stay on the barrel with the underribs. I cut a piece of closed cell foam and put a channel in it to use as a mount and that worked well. You need to use the "slug" setting for it to record velocities accurately. Also watch your strings...running the ramrod in and out records as a shot. You will need to delete those from your strings.

 

[chorizo]

Reviewing my velocity data and the preliminary accuracy results from shooting yesterday, My next bore out will be 22" 54 Cal with a 1:32 twist.. Very impressed with the 21" results, especially given that (I believe from observations) the powder charge is burning completely in the barrel.

That will be my "next to the last" bore out I will send to Mr. Hoyt. Both the 21" and a 22" will make handy sling over the back, e-bike ride in to the hunting grounds carbines.

 

[Rawhide67]

How's your shoulder? My White Mtn Carbine with 85 grains of T7 3F and a 325 maxi was not fun at the range after a half dozen shots.

 

[chorizo]

How's your shoulder? My White Mtn Carbine with 85 grains of T7 3F and a 325 maxi was not fun at the range after a half dozen shots.

As I stated above in the original post, just like shooting a shotgun...in fact better. Your rifle load is equivalent to a 3/4 oz shot load in a highbase 2 3/4 in a 28 ga shotshell.. a powder puff load in a shotgun. (325 grains is 3/4 of an oz..high base 1350 fps)

I have routinely shot 100 rounds of 1 1/8 oz 2 3/4" shotshells at 1210 FPS at sporting clays in a day and not had an issue. That is only slightly less to the stoutest load I shot doing this velocity check.

I shot a total of 19 rounds yesterday......less than a morning shooting dove on an opening day. No issue.

 

[Sandro_Ventania]

Reviewing my velocity data and the preliminary accuracy results from shooting yesterday, My next bore out will be 22" 54 Cal with a 1:32 twist.. Very impressed with the 21" results, especially given that (I believe from observations) the powder charge is burning completely in the barrel.

That will be my "next to the last" bore out I will send to Mr. Hoyt. Both the 21" and a 22" will make handy sling over the back, e-bike ride in to the hunting grounds carbine

For you, the size of the barrel did not affect the accuracy?

 

[chorizo]

For you, the size of the barrel did not affect the accuracy?

Barrel length does not affect accuracy as long as you get consistent powder burn. What affects accuracy on a shorter barrel open sight carbine is sight radius. But the 21" has the same sight radius at the 24" barrels as I moved the rear sight back 3".

https://www.thetruthaboutguns.com/the-truth-about-barrel-length-muzzle-velocity-and-accuracy/
Accuracy development, as stated in the OP, is the next stage of shooting so I do not have hard data on accuracy yet

 

[beardedhorse]

Wonder what the .54 barrels for the White Moutain carbines cost. Did you take the breech and snail off the TC and install on the new barrel or did Bobby Hoyt make a breechplug for it?

 

[Bad Karma]

Excellent review of the barrels and I really appreciate the heads up on the Magnetospeed… I’ve been using a Chrony F1 for years now and although it works, it’s a bit of a pain with blackpowder, tends to give error messages often (maybe not as much with T7, less particulate matter blowing over the screens.) and there’s no easy way to deal with the data other than notebooks but that takes shooting time and at my age, I need to make the best of all I have left. Consequently, I’m not using the Chrony as often as I’d like to.

I’m also interested to see the low SD numbers. Pretty close to good Swiss powder which is a concern I’ve had about T7. I really do appreciate your reporting on those matters.

WRT the Hoyt barrels themselves, I’ve had a few show up rough, with tool marks and chatter, a hundred strokes with a few pieces of fine steel wool fixes them right up and their accurate and easy to clean thereafter.

 

[chorizo]

@Bad Karma as there is a v3 out, you can find the V2 cheap. And it takes a chip if you want to store data. The V2 is more than adequate for my needs. Again, you need to use the "slug" preset with the all lead bullets to get accurate data and it records the use of a ramrod as a shot, so you need to delete it from the string but that is easy enough to do and then it calculates your average and SD on the fly for you. It is reliable enough that I use 3 shot strings most of the time vice 5 shot strings. if my SD is low.

I have some diamond polish compound that I am going to hit the barrels with before I head out next week. Also changing the front sights to get the rear sights centered in adjustment and then I will try to develop some accuracy loads

 

[chorizo]

Barrels are honed. 500 strokes each with a tight patch and 400 grit diamond embedded paste. The 58 is going to need more but the 54's turned out smooth with almost all the chatter marks gone. I am going to shoot them first to see what I get. Sights are on order and should be here by Saturday or Monday. Either way, they will be here in time for my next range time that the weather will allow.

Some sore shoulders tomorrow.

 

[TDM]

500 Strokes!!! I doubt I could make 100 without gassing out! You’ll need welding goggles to look at the bore!

 

[chorizo]

500 Strokes!!! I doubt I could make 100 without gassing out! You’ll need welding goggles to look at the bore!

I had the barrels warm!. That was in place of my gym workout today. The 21" shines, the other 54 feels smooth but has some marks still...the 58 doesn't feel smooth yet.

Used a spinjag and this paste
https://www.amazon.com/gp/product/B...tle_o00_s00?ie=UTF8&psc=1&redirectFromSmile=1
But shoot first! It may be just fine.

 

[TDM]

I had the barrels warm!. That was in place of my gym workout today. The 21" shines, the other 54 feels smooth but has some marks still...the 58 doesn't feel smooth yet.

But shoot first! It may be just fine.

I think it’s great that you’re putting that much effort into it, has to payoff. I’ve got my Deerhunter barrel in ok shape now compared to how it was, but it could stand another 100 or so strokes with Bore Brite.

 

[Sandro_Ventania]

I had the barrels warm!. That was in place of my gym workout today. The 21" shines, the other 54 feels smooth but has some marks still...the 58 doesn't feel smooth yet.

Used a spinjag and this paste
https://www.amazon.com/gp/product/B...tle_o00_s00?ie=UTF8&psc=1&redirectFromSmile=1
But shoot first! It may be just fine.

I saw that this paste has up to 200,000 grains!
Ever wonder!

 

[Bad Karma]

@Bad Karma as there is a v3 out, you can find the V2 cheap. And it takes a chip if you want to store data. The V2 is more than adequate for my needs. Again, you need to use the "slug" preset with the all lead bullets to get accurate data and it records the use of a ramrod as a shot, so you need to delete it from the string but that is easy enough to do and then it calculates your average and SD on the fly for you. It is reliable enough that I use 3 shot strings most of the time vice 5 shot strings. if my SD is low.

I have some diamond polish compound that I am going to hit the barrels with before I head out next week. Also changing the front sights to get the rear sights centered in adjustment and then I will try to develop some accuracy loads

Seems like the Hoyt WMC are about the perfect project for your intended purpose. And anyone interested in round ball out of carbines can find something useful here.

I’ve used a grit designed for polishing glass lenses. Similar grits. I’ve also experimented with fire
lapping with some success both muzzleloaders and the other stuff… with all the cleaning involved in fire lapping it’s almost easier to just make a steel wool patch and run a hundred strokes up and down.

 

[chorizo]

I was dissatisfied with the smoothness of the 58 cal bore. Patches still hung up and there were still several tight spots. I had some Wheeler lapping compounds show up yesterday, finally. So I did some more work with 220 grit 200 stokes, followed by 320 grit 150 strokes. 350 more strokes. It still looks like hell, but that is an artifact of using a bore scope.

When I place a dry patch on the jag and get it into the bore, the jag drops to the breech unassisted using a solid brass 3/8" diameter 28" long range rod with handle and there are no longer tight spots. Smooth to patch, not to bore scope. The pictures below are after the additional strokes. The chatter marks are on the lands. No more on these guns until I shoot them and see what I get.

If I am satisfied, I will hit it with 50 strokes of 400 diamond grit paste then 100 of JB paste to final polish then call it good.