Ignition, Hall vs. Turbo

K

KEN HARPER

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This is my version of "Myth Busters".

For years I've seen people on this forum complain about the ignition of Hall actions being so much worse than Turbo actions. I think that we would all agree that variations in ignition are going to affect the muzzle velocity in either a negative or positive way. Being an owner of each action, I decided to try and prove to myself if one action was better or worse than another. To do this I decided that I would use my new CED chronograph using 10 lots of ammo shooting 20 rounds of each lot in each action and comparing the standard deviations between the two actions. Based upon what I had been hearing on the forum I went into this experiment with some bias toward the Turbo. However to my surprise, the standard deviation of each lot was almost identical whether it was shot with the Turbo or with the Hall. Now if someone can provide me with some evidence or devise a better way to determine reliability of ignition to show that the ignition of one action is better than another I'm all ears.
 
Some pretty good information Ken. Might I inquire as to who smithed your two guns and do they have firing pins that are as shipped from action makers, to the best of your knowledge? I ask this because IMHO any action might be better than or worse than intended, probably on a number of considerations.
 
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I only have a Hall but I did a test involving the stock aluminum spring keeper, a single brass keeper, and two brass keepers (which preloaded the spring twice the amount of the others). ES was 20 fps on the aluminum and single brass keeper, and the double brass keeper had an ES of 30+fps. Test was only a 10 shot group with each, but the single brass keeper was/is the best in my rifle.

There was no visible difference in how the pin hit the rim with any setup.
 
Good question Tim. Bill Calfee has modified the Turbo action in some way or another. The Hall action I obtained from Randy Leger (Accu-Shot) but I'm not sure if he modified the firing pin or changed out the spring prior to giving it to me.
 
From what I know, Randy does not tend to modify the Hall's. There have been changes to the firing pins on those over the years.
 
If you want a way of measuring or quantifying the difference between the two, I can provide you with a simple statistical methodology. An "F" test would be a correct and simple means of comparing differences in standard deviations.

Brent
 
I think that every gunsmith has his own way of modifying each and every type of action to improve ignition. I think that the Hall action has recieved undue remarks for ignition. The smiths can do their magic on any action to make them better. I don't own a Hall but two very close friends do and they shoot as good as any gun. I own a Turbo and have shot both actions and see no real difference. I know that the Turbos have things that the smiths do to improve ignition also. So I believe Ken Harper's test was correct in showing that the actions are pretty much equal.

Carp
 
Whatever Ken's test showed pertained to exactly 2 guns...his, at least one of which is not factory standard.
 
BrentD said:
If you want a way of measuring or quantifying the difference between the two, I can provide you with a simple statistical methodology. An "F" test would be a correct and simple means of comparing differences in standard deviations.

Brent
Click to expand...

Could you please, expand on this a bit more. What would improve on measuring variences on extreme spread of the same ammo in a couple guns?
 
Tim,
If you saw the benchrest classifieds a week or so ago, Brian Voelker had a Turbo advertised that was described as the older action. From what he described as improvements to the newer style he did himself. Bill Calfee is now working with Flash on some other improvements that will be version 3 if they are done. But these improvements have been done already by many smiths. Same goes for the Hall action. I don't think that many benchrest smiths leave the actions as is from the manufacturer. They don't always tell you what they did to the action, they hold that as proprietary. I am just saying that Ken found something that doesn't surprise me. Hall actions have at least two different shaped firing pins from Allan that I know of and many smiths stone Turbo firing pins to the shape, width and length that they desire. The older Turbos came with a weaker firing pin spring than they currently do and some smiths even use a spacer beyond that improvement. I don't really know what a factory standard is for a custom action?

Carp
 
The Turbo action I tested was one of the original versions with a bolt stop that was designed very poorly. In fact it sheared off the second time out. The bolt stop has since been redesigned. I believe what Calfee did to my action was to move the trigger hanger back .050 so that there would be more firing pin travel and better ignition. I had no doubts about the ignition of this action. My doubts were with the ignition of the Hall actions arising from some of the comments made by Calfee and others on this forum. At least I have dispelled those doubts to myself if not a few others.
 
I've been worried about the ignition of my action since modifying the shape of the pin myself (in line with Mr. Calfees's recommendations http://www.snipersparadise.com/tsmag/june2004.htm). So is a chrono the best/only method of testing for this?

My results were:

Eley Team 1008-04222 1062fps
1054
1057
1055
1066
1063
1067
Average 1061
ES 13
SD 5.64

Eley Tenex 1008-03093 1074fps
1052
1048
1057
1057
1044
Average 1051
ES 13
SD 5.7

Apart from the average of the Tenex being a long way from what was printed on the box, the ES & SD seem consistent (from such a small sample) - Does an ES of 13fps look OK?
 
Carp said:
Tim,
If you saw the benchrest classifieds a week or so ago, Brian Voelker had a Turbo advertised that was described as the older action. From what he described as improvements to the newer style he did himself. Bill Calfee is now working with Flash on some other improvements that will be version 3 if they are done. But these improvements have been done already by many smiths. Same goes for the Hall action. I don't think that many benchrest smiths leave the actions as is from the manufacturer. They don't always tell you what they did to the action, they hold that as proprietary. I am just saying that Ken found something that doesn't surprise me. Hall actions have at least two different shaped firing pins from Allan that I know of and many smiths stone Turbo firing pins to the shape, width and length that they desire. The older Turbos came with a weaker firing pin spring than they currently do and some smiths even use a spacer beyond that improvement. I don't really know what a factory standard is for a custom action?

Carp
Click to expand...

Well that's very true. There's also a lot of smith's that do nothing, I know because myself and others have helped with a variety of ignition related issues on guns bought for top dollar. There are probably a lot of guys out there that ASSUME their guns have good ignition.
 
KEN HARPER said:
The Turbo action I tested was one of the original versions with a bolt stop that was designed very poorly. In fact it sheared off the second time out. The bolt stop has since been redesigned. I believe what Calfee did to my action was to move the trigger hanger back .050 so that there would be more firing pin travel and better ignition. I had no doubts about the ignition of this action. My doubts were with the ignition of the Hall actions arising from some of the comments made by Calfee and others on this forum. At least I have dispelled those doubts to myself if not a few others.
Click to expand...

Ken,

Is it ignition that is the issue or consistency of ignition? Could be a little of both I guess, but to truly test the ignition, you would need to test under varying conditions. They Turbo mainly relies on the weight of the pin for consistent ignition and the Hall relies on the spring. The firing pin weight never changes, but the spring can be influenced by temperature, oil and grease, and age to name a few.
 
IMO the two major factors affecting the consistency of the velocity of the bullet is the variations of the powder charge and the consistency of the strike of the firing pin which can affect the quality of ignition and therefore the burn rate of the powder. The powder charge in rimfire bullets is so small, less than 2 grains, that a variation of a tenth of a grain one way or another can significantly alter the velocity. It is very difficult for automated, progressive reloaders to drop powder charges this accurately. Unfortunately shooters have no control over the powder charge. However if we have an action that strikes the rim hard one time and weak the next, we or the gunsmith have the ability to modify this to make it more consistent.

Brian, I also found in my testing that the printed velocity was often significantly different than the tested velocity. This was especially true in lots of ammo that were two or more years old.
 
KEN HARPER said:
IMO the two major factors affecting the consistency of the velocity of the bullet is the variations of the powder charge and the consistency of the strike of the firing pin which can affect the quality of ignition and therefore the burn rate of the powder. The powder charge in rimfire bullets is so small, less than 2 grains, that a variation of a tenth of a grain one way or another can significantly alter the velocity. It is very difficult for automated, progressive reloaders to drop powder charges this accurately. Unfortunately shooters have no control over the powder charge. However if we have an action that strikes the rim hard one time and weak the next, we or the gunsmith have the ability to modify this to make it more consistent.

Brian, I also found in my testing that the printed velocity was often significantly different than the tested velocity. This was especially true in lots of ammo that were two or more years old.
Click to expand...

Thanks for the insight Ken, interesting thread this one. It could have been the temperature was close to freezing when I tested and the Tenex was the first string from a cold barrel. I will test again under more controlled conditions the next time.

Would be interested in anyone else's results i.e. is a 13fps spread the norm, excessive or rubbish?
 
I had two guns built this year.A 10.5 # and a sporter both with Hall actions.
The sporter shot great but I struggled thru four matches with the 10.5# gun.I just couldn't shoot a good score with it.I continued to blame myself and my inexperience at shooting in windy conditions which unfortunately are the norm in the North Carolina mountains.Finally at the fifth match the wind stopped.However my shooting did not improve.I now realized one out of every three to five shots was dropping two rings under absolutely calm conditions. We were shooting a morning RBA match and some of the guys who came for the IR 50/50 afternoon match were looking over my shoulder.One of them walked over and picked up an empty case,looked me in the eye,and said "you have an ignition problem.I had the same problem until I had the bolt modified".Later I looked at his cases and the firing pin hit was twice as deep. At his recommendation I sent the bolt to be modified. After the modification the problem was completely eliminated. My conclusion is not that all Hall actions have ignition problems.But if your Hall actioned gun shoots erratically I'd take a good look at the firing pin hit.
 
Brian,

My ES values were generally 20+ or more and my best SD were 5+ but most around 6 or 7. However I was shooting 20-40 shot strings which could be the difference in my results vs. yours.
 
Ignition,Hall vs. Turbo

Beau,
Gordon Eck modified it.I didn't ask what the mods were. Compared to the "Red Box" I burned up trying to get the gun to shoot the cost was insignificant.
 
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