Word of Warning-Safety Issue

[kenweekley]

Maybe my own stupidity or ignorance, but here goes. Might prevent a mistake for someone else in the future.

So here is the scenario. New to me GM LRH barrel, existing nipple, 600 gr .500 cal conical 1/4” Durafelt .54 size wad with 80 grains of FFg Swiss by volume.

The bullet and wad load in the barrel fairly easily and seated on the powder well. Several shots and it seemed like excessive pressure. Hammer slammed back. Blow back from the nipple all over the barrel and up to the rear sight. Glad that I wear shooting glasses and double hearing protection.

I knew that 600gr bullet would likely smack pretty hard. But didn’t really know what to expect in terms of recoil. I had only shot round balls in 45 or 54 previously.

Cleaned the barrel and looked at the nipple. The flash hole was huge. The size of a pencil lead tip would fit in it like it was eroded. Get a new 1/4x28 nipple and start shooting again.

Still major signs of excessive pressure. After 8-9 shots I realized that the wrist of the hawken stock was cracked.

Bought a new stock, reduced to 70 grains by volume and still heavy recoil. Accuracy still all over the place. Hammer smacked hard enough to leave a dent in the stock.

Started comparing the witness marks I had created on the ram road. Empty vs. loaded. Seemed to be a couple inches difference. Compared the empty mark and the powder plus bullet length in the clear speed loader and saw a 2inch difference.

I finally realized that even though I thought I was completely seating the bullet on the powder, there was a rough spot in the barrel. It was more than just a crud ring build up as I had throughly cleaned and scrubbed until I had clean patches, had cleaned the barrel several times even.

I finally ended up scrubbing with 0000 steel wool wrapped around a swab. 100 strokes or more to get rid of the rough spot. Now the bullet seats fully as verified by the witness marks.

Still smacks pretty hard, and I have the bruises to prove it, but now have 1” or less groups at 100 yds. 80 gr FFg, 600gr.

I was fortunate not to have had a worse scenario with the excessive pressures. Hopefully this will be a help and warning to someone else. I will be investing in a bore scope for the future so I can be sure of the barrel condition.

What “stupid” things have others learned along the way?

 

[wiscoaster]

Thanks for reporting your experience. Good to be able to learn here from experiences of others.

 

[Urban Coyote]

Thank you for sharing your experience, a lot of egos wouldn't have. You might have just saved some poor soul from making a mistake, similar or otherwise.

I think it would be a good thing if others would share mistakes they make or have seen others make. Like the open powder horn that nearly became a grenade when a trail of loose powder caught a spark and darn near lit a full horn off.

 

[Steve Wagner]

Fired quite a few 385 Hornady Great Plains, lots of PRBs, and about 30, 240 PA conicals with the same nipple before deciding on a hunting load for my .50 Trad Woodsman. Between 125 and 150 shots. After shooting my 1st ML deer [buck], as I reloaded before approaching it, I wondered why I had cocked the rifle after shooting it. Just excitement I figured. Later that week, I shot a doe and it was cocked again. I knew that time I had let the nipple go for too long. Had read about it on this forum but it had slipped my feeble mind. Rough and irregular flash hole that started at about .028 and opened to about .034 [paper clip]. The latter size is fine for my TC Hawkens but not the Traditions. Rifles can be fussy. They tell you what they want. If you listen. A cracked stock is definitely a megaphone. [Just like a cocked hammer}
I had settled on the PA conical. 70 grains of t-7, 2f had worked best with all the projectiles but the PA was really accurate and I liked the ballistics and more moderate recoil. I think the 385's especially put a lot of pressure on the flash holes [and the rifle in general] w the PA's being 2nd. I plan on shooting those and PRB's from here on out and will definitely pay attention to shot count and early warning signs like half cock. How did I miss that ? DOH !!!
I will probably use the 385's for bear hunting. We have 2 kinds here and it is good to be on the overkill side of things when black bear hunting. The other guys like the same places.
Far, far from expert here, but I wonder if you should check to see if you "ringed" your barrel with those spread out loads. Only read about it but it is a real thing. And not good. SW

 

[Steve Wagner]

BTW, I can only imagine that the nipple life when using a 600 grain bullet is very short. Hard on some, if not all, .50 rifles and shoulders too.
That is an amazing amount of pressure. If LRH means long range hunter and a 28 twist, that is even more pressure.
Quite a load ! Will definitely kill on both ends. SW

 

[Sir Boniface Harrison]

I fired my brand new investarm .45 Hawken straight from the shop, without cleaning the barrel out first. This led to a persistant problem - only firing three shots before having to swab out, or taking off the nipple, filling the flash channel with powder, and firing out what had become a 'reluctant' ball. Thanks to fellow forum members, one of whom coached me through what was wrong and what to do, I have solved the problem. The protective lube applied to the rifle in the factory was still present in the barrel, although I had meticulously cleaned the outside. The resulting tarry residue was a real chore to clean out, but thanks to forum help I sorted it out.

 

[kenweekley]

BTW, I can only imagine that the nipple life when using a 600 grain bullet is very short. Hard on some, if not all, .50 rifles and shoulders too.
That is an amazing amount of pressure. If LRH means long range hunter and a 28 twist, that is even more pressure.
Quite a load ! Will definitely kill on both ends. SW

Yes. 1:28 twist. And would likely contribute to a higher pressure than 1:48 or 1:66. Quite honestly don’t know how much effect the twist has on pressure. The online calculators don’t have a parameter for it. One of the calculators p-max.uk estimates 18,369 psi for 80gr, FFg Swiss, 600gr, 28” barrel. I have searched and not found a threshold or general guideline considered “max pressure” for BP. I realize there are many variables. Saw some references to much lower, less than 10,000 psi, due to specific manufacturer proof testing and design limitations. Some comments about anything over 20,000 psi considered as approaching high pressures.

I need to chrono to verify the expected velocity is in the estimated range of 1100-1200 fps.

Also, I appreciate the recommendation to inspect the nipple for erosion every time it is cleaned. I did buy new Ampco Treso nipples as a precaution.