First time with trapdoor

[hiram]

OK--I got ideas for shooting lower, and this is what I did -- a new, higher front sight.

Cost 1 cent and some time. It's about .420 high. I'll let you know.

I had a little laugh after the job was done. I saw a date, so I got closer-- the date was our bi-centennial, 1976.

[floodgate]

Hiram:

From the tip of the "ramrod" (really a cleaning rod) in your photo - with the multiple jags - it looks like that might be an early (1873 - 1878) .45-70 Trapdoor. Is the cut under the breechblock a straight, continuous arc, or is it flat in the center (i.e, a bit stiffer, with more "meat" in the shallowest section)? That type of ramrod is usually associated with the older '73's - though it may be a replacement - and with the "ski-jump" rear sight. (The later Buffington sight is much like the one on the 1903 Springfields - and was, in fact, their ancestor.)

The early breechblocks were said to be weaker, and were reputed to occasionally fold up in the middle with the later 500-gr. (after 1881 or so) rifle loads, though I've never actually heard of a case. I certainly would go easy on an early-type "trapdoor" - or on any of them. By all means, get the Wolf book - it's the "bible" on loading for these.

I'm old enough (early '80's) to remember going into Robert Abels' shop in New York in the 1950s, and seeing barrels (actual "hogsheads!") stuffed - muzzle-down - with .58 rifle-muskets, and .50-70 and .45-70 Trapdoors, and labeled "Your Pick - $15 each". I spotted examples of the three variant .45-70 "Short Rifles", but went home to verify them in Gluckman's book; when I got back with cash in hand, they were all gone - someone else had grabbed them. Ahhhh....them wuz the days!

Flubgate

[hiram]

Here is a pic of the breech block. Looking at it carefully, there seems to be the remnants of case hardening color.

[hiram]

I slugged the barrel. It's 3 groove as I have read.

The consistencyy of pressure pushing the slug was very even.

The slug measured .455-.456 across one land and one groove.

Has any worked up a size chart or have a similar dimension slug where they have figured out the actual groove size?

Thanks

[Skipper]

This is from an old book......I don't know if it works:

In the case of a barrel with an odd number of grooves this is measured by driving a soft lead slug into the barrel and then measuring the slug's diameter over a land-to-groove cross section and then subtracting the bore diameter. The next step is to double this figure and add it to the bore diameter to get the groove diameter.

[Larry Gibson]

Cut a strip from a beer or soda can 1/2x4". Wrap it around the slug and hold tight pinching it on one side. Snug is tight enough. Mic the diameter and subtract twice the thickness of the can strip. That will give yo a very close measurement of the groove diameter.

Larry Gibson

[Roundball]

My 1889 TD measured .462 and did well with the Lee 405HB as did a Danish RB that measured .464. It's my understanding that TD barrels tended to be .460+ and shooting a .458 bullet would be a disaster. Would suggest using the Lee bullet as cast without sizing.

[bigted]

i have the wolf book and no trapdoor but he recomends the .458/.459 boolits for all dia. barrels from .458 to .462 if memory serves...and got better then average accuracy with his loading recomendations in this exelent book.

sounds like i need a rifle and you need a book...LOL

[Larry Gibson]

Spence Wolf's loading was to replicate the original loads. The original loads were sized at .48 -.459 because they thought, back then, that the bullet needed to obturate (bump up) to fit the bore because of BP fouling. We have learned this is not the best for accuracy even with BP. The Army switched to the 500 gr bullet in 1882 because the 405 gr bullet did not have the mass to effectively obturate even with the 70 gr load. The HB is there to regualte external dimenstions not to expand ala the minie.

Wolf did replicate the service loads and if you follow his instructions the loads will give service load accuracy. However, if you size or fit the bullet to the groove diameter or larger accuracy will most often be better. I discussed this with Spence years back before he passed and he agreed. I also agreed with him though that he had achieved the goal of replicating the service loads.

Bottom line is accuracy will most often be better if the bullet fits correctly and "bumping up" is not depended on. That basic principle applies to smokeless loads as well as BP loads.

Larry Gibson

[TXGunNut]

Wow! Very informative post, Larry. Cleared up a few misconceptions I had. Thanks.

[Larry Gibson]

Much to be said for Spence's book, I have a dog eared old original copy and one of the newer ones from Wolf traders. Well worth the money even if not loading for the TD alone. Lots of good basic info on loads for the 45-70.

I only knew him for a short time and wish it had been longer, RIP Spence.

Larry Gibson

[fouronesix]

Bottom line is accuracy will most often be better if the bullet fits correctly and "bumping up" is not depended on. That basic principle applies to smokeless loads as well as BP loads.

Larry Gibson

Well said. That pretty much sums up what I have found particularly with various old, original BPCR rifles.

The only exception being paper patch-BP loading of rifles like the repro Sharps where that combination seems to favor a form of bore riding engagement of part of the nose that is patched and a shank diameter that is only a couple thous larger than bore diameter. But, I've found the same repro Sharps shoot regular grease groove best when the bullet is sized to groove diameter to about .001" larger than groove.

[hiram]

Larry, using your formula, and understanding that results are close and not totally accurate, the groove size would be .460 on my TD.

I went to the range today with 360g boolits. These were from a group buy here---flat nose, plain base. Results were not good(rifling twist?). I will retry and try the 405HB again also. I also want to try 500g.

[Larry Gibson]

hiram

A .460 is a good tight bore on a TD, my target TD is .461 so you should be able to get decent results. For BP cast the bullets of 20-1 alloy and lube with a BP lub (not sure what "emmert's" is?) I make my own with 5 parts beeswax to 4 parts virgin olive oil. Simple to do so if you don't know how ask and I'll post. The twist is fine for the 360 gr bullets if they fit the groove depth. There is not enough mass to that 360 gr bullet for it to bump up if undersized unless it is almost pure lead. Also suggest a switch to 3F BP.

Larry Gibson

[13Echo]

In my Trapdoor .45-70 and in my friends the Lee 405gr HB did best with a firm crimp over the ogive. This apparently allows enough pressure to build to "bump up" the bullet to fit the barrel. We use the bullet as cast (about 0.460") out of 30:1 alloy over 59grs of Goex ffg to approximate the carbine load. For a full bore service load I use the SAECO 181 bullet version of the 500gr govt bullet cast out of 30:1 and measuring as cast 0.460". Over 70 grs of ffg it does quite well. I do use a light crimp but it is probably not necessary with this bullet and charge. I do not use a magnum primer and I have not enlarged the flasholes like Wolfe recommends. The lube is basically Greenfrog's modified Emmert's (by volume 45% crisco, unsalted, 45% beeswax, 5% canola, and 5% lanolin). Panlubes easily.

Jerry Liles

[jed]

My original trapdoor barrel crown was oblong due to cleaning rod damage. I know if you get Pats and Spence's book alot of confusion goes away. It is mind boggling to think of how much effort they put into their book and the results you can get following their techniques.