Detonation in reduced recoil loads?

Squeeze

Squeeze

New member
I have a question for the knowledgeable loaders on the forum.

Background: I won a Tikka T-3 at a DU Banquet, and having a number of good bolt guns already, I gave it to my grandson. It is chambered in 308 Win, and at the tender age of 8, I started loading "reduced recoil" rounds for him to learn how to shoot his rifle. I went to the Hodgdon Website, and found a data sheet on loading, where they recommended taking the max. load for a given cartridge(that had H4895 data), reducing the charge by 40%(max load x .6), and use that as a starting load. I picked the Sierra 125 gr. SP bullet, and loaded 28.0 grains of H4895. All good so far. We shot a few of them, and the rifle shot them MOA, so I loaded enough for practice and hunting. This year he is 10 years old, and able to "mentor" hunt under WI deer hunting laws. So we got the rifle on the bench, he shot maybe 20 rounds to zero the scope, and to log the bullet trajectory from 50 to 150 yards. On one 100 yard group, he put them in the same hole! BUT, he mentioned that one of the shots had more recoil...Hmmm, I discounted that as just fatigue, and we wrapped up the range time, with a blessing that he was ready for real deer.

So I am cleaning the cases, and out of the 20 rounds he shot, 4 of them clearly have imprints of the bolt face on the case head! Primers weren't flat, but I did notice an unusual amount of sooting on the case neck, and shoulder. Also both he and his father(also shot the rifle checking scope zero) mentioned they had "specks of stuff" hitting them in the face. They wore eye protection, so there was no issue, but that sure gave me pause! I checked the rifle bore, and there was a lot of powder residue in the bore. There was no sticky bolt lift, and the few cases I looked at on the range didn't have flattened or pierced primers, and I didn't notice any extractor/bolt face marks on the case heads, on the range. I found that when I had the cases clean, ready for de-priming, and annealing.

So my question to the old wise ones is, "Is this reduced recoil round experiencing the phenomena of detonation?". Or is there another explanation?

Squeeze
 
Not really detonation but extremely poor ignition due to lack of pressure and the powder just laying all over inside the case lets much of it go unburned. Detonation is from flash over, or so they say, where part of the powder ignites and gets things moving but just barely and the next pressure wave hits an obstructed barrel thanks to the bullet and at that point things blow out.

One thing you can do is add a bit of toilet paper to the top of the powder charge to seat it agaimst the primer or find a powder that will fill the case up further. The set up of 60 % fill just begs for inconsistency.

Greg
 
Greg,

I like the idea of tissue...Kind of acts like a bore mop for the previous round!
smile.gif
I am not sure shooting burning paper over dry grass is a good idea. But how do I rectify the obvious sign of pressure on the case head? I mean seeing a distinct imprint of the Tikka bolt on the case head makes me anxious.

Squeeze
 
The case s jetting back to th bolt because the case walls sare not expanding fast enough to hold it. A very close chamber/case fit would help. Less shoulder bump.

Greg
 
I've fire formed a lot of cases with the TP and never seen any flaming stuff. A quarter sheet will do it. I prefer Charmin as it is so soft on my baby butt smooth bores plus it is endorsed by Mr.Whipple.

Grrg
 
ive heard of folks using a small fluff of dacron (pillow stuffing) over the powder in the same way as the TP mentioned above.
 
When loading reduced loads for the 45-70 I used that stuff they put in pillows. Kapoc I believe is the name of it.
 
Originally Posted By: MGYSGTWhen loading reduced loads for the 45-70 I used that stuff they put in pillows. Kapoc I believe is the name of it.

Kapok was used in life vests when I was growing up. I didn't even know they made pillows out of it now. Interesting to say the least.

As mentioned dacron is the new darling for the fire forming stuff but I'm five steps away from a lifetime supply of my choice..LOL.

Greg
 
Originally Posted By: Plant.Oneive heard of folks using a small fluff of dacron (pillow stuffing) over the powder in the same way as the TP mentioned above.



Beware, this raises pressures dramatically.

Squeeze, I am not sure that you should be reloading this kind of ammo for someone else, especially their kid. You should shoot 100 or so rounds of what ever you are loading before you load it for someone else.

IMR 4759 is made specifically for reduced loads and H 4895 is supposed to be great also. Some of the Speer manuals have reduced loads in them, go by that and you should be good to go.

Remington sells reduced loads.

Best of luck!
 
Just a guess. I would say that you are so low on pressure the case isn't sealing in the chamber. Sooty necks and incomplete burn, I would increase charge, go to a WW or a magnum primer. I've seen unburned powder strung down the bore like a string of ants. This was a book starting load, and it sounded like a rimfire. Not sure what would have happened had I run another bullet down the barrel. The next row of test loads was half a grain heavier, so after a cleaning, I tried one, and the problem went away. Powder has to deflagrate, and this requires pressure. I don't think the wadding will help, increase the pressure by adding powder.
 
Interesting dilemma! Was about to embark on some H4895 reduced loads myself - in 222 to start. I'd like to see what a mag primer and starting over at the bottom would do. I wonder about the synthetic fibers in the barrel under the heat and pressure that is created in firing the round.....does this create a synthetic fouling of sorts that may be detrimental in the long run? Would the Cream of Wheat thing work here too? Tissue sounds consumable enuf also.

On the bolt face imprint thing, I recall Catshooter (guess I can still mention his name here?) went on a diatribe one time about how he lubed his cases during fireforming to allow the case to slide back easier during fireforming so as to minimize case web stretch. His theory, but kinda made sense to me at the time - allows the case to slide back without gripping the chamber so well upon expansion. Minimum sizing in the first place makes sense too. I'd like to hear what Hodgdon may have to say about it too.
 
Originally Posted By: reddog964...use IMR Trialboss....
.. +1 ..
very easy to load 308 subsonic, and low speed supers with Trailboss.
 
Just call Speer and talk to one of their reloading guys .They will have a load to do what you want with out any of the worry.
 
I found this load data from Winchester with reduced loads.
http://www.wwpowder.com/PDF/Youth%20Loads.pdf
With the same powder and bullet weight it has a minimum of 38 grains, way more than you used. I did find the page on the Hodgdon site with the 60% and they had an example of a 30-06 at 32.something grains.
I would have concerns, if you are having a lot of unburned powder and possible pressure issues , how the loads will work at the lower temperatures of a Wisconsin deer hunt. A bullet stopping in the barrel followed by another would be bad.

Mark
 
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