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Gator
07-26-2009, 12:25 AM
http://img.photobucket.com/albums/v13/Gator/243Primerswith37grVargetwith87grVMa.jpg

CCI BR2 Primers shot in a .243 Win. - 87 Gr. Hornady VMAX with 37 gr. Varget. This is my first AR syle rifle and I am at a loss for ideas.
Was not supposed to be a hot load but this weapon has been giving me fits on top of fits. It's a Remington R-25 made by DPMS (as you know is owned by Remington as well as Bushmaster) with a 1:10 twist. I bought the rifle and immediately borescoped the barrel upon arrival and everything looked great. I shoot moly in everything I have (4 - 6x284's, 1 - 6.5x284, 1- 6x47 -- all with 1:8 twist rate) and tried it in this barrel after break-in. After 50 rounds with moly I borescoped it (wasn't shooting worth a darn) and there was only moly about the first 4" from the breech. I fire lapped it with 15 coated bullets and borescoped again and it looked like a new barrel.

Now I have right at 350 rds down the tube and it still shoots erratic. Some excellent groups - some terrible.
Nightforce 5.5 x 22 x 56 NXS with Warne Rings (going to change to TPS Rings) and have just installed a Geissele Two stage trigger. I love the trigger once I got it set right. I am shooting non-moly bullets for now but may try moly again if I can't get this figured out.
I know there are some avid shooters here - so if you have any suggestions I am all ears. I have been a long range / tactical shooter for about fourteen years and been reloading for 30+ years so I have tried all of the simple fixes already. Cases are prepped like I was shooting 1000 yd. matches. The chamber seems a little long for a 1:10 twist and the 87 grain boat tail is barely at the bottom of the neck. I have been shooting necked down .308 brass made by Winchester, Remington, and new Lapua brass and all seem to shoot the same.
One thing I can tell you in case you are looking at purchasing one of these rifles is - IT IS HARD ON BRASS. Beats the crap out of it when it extracts it.
If I don't get it straightened out with new rings and maybe a muzzle brake then I will replace the barrel with a custom from one of the major barrel manufacturers.
My current load is 45.2 grs of H4350 - .010 off the lands.
Necks turned and bullet concentricity is dead on.
One thing I have noticed is the bore is much tighter than my other 6mm's when running a patch down the bore with the same size patch and using the same jag.


Any ideas?

Bob Ford
07-26-2009, 10:03 AM
I suspect #1 the throat of the camber to be off center. #2 the crown to be not parallel with bore.
#3 try a match bullet by Sierra, tougher construction.

Chamber cast including first .5 inch of bore to check #1. Solution careful use of throat reamer / or cut free bore.

#2 re-crown.

I would try #3 first as that is cheapest.

Bob

deltaenterprizes
07-26-2009, 10:30 AM
What is the length of the brass?
My first high powered rifle was a Rem 788 in 243 Win and since the 243 brass was more expensive I made mine from 308 Win. I found that the cases were at least .010'' shorter than factory .243 Win.
Why pics of fired primers?

gzig5
07-28-2009, 10:01 AM
I'm at work so I can't see your pics but I can tell you that 37 Gr Varget under an 87gr bullet should not be too hot in a.243, even for an AR. I am not an expert on AR's, but I would strongly recommend that you stop using H4350 in it. That powder is too slow and the port pressure is going to be excessive and might explain why your brass is being punished. Varget / RE15 are about as slow as you should go in an AR based rifle, especially with the standard port location. I would also check your neck thickness on the reformed .308 cases. The necks are going to be thicker than factory .243 brass and could give you erratic pressure problems. Double check your trim length.

An AR is more likely to pierce primers at a given pressure than a bolt gun because there is less mass in the firing pin and less spring pressure than a bolt rifle. The firing pins are typically a bit loose in the hole as well.

Greg

Gator
07-30-2009, 12:39 AM
Sorry guys for not getting back sooner.
Shot the rifle again yesterday with 45.0 gr. H4350
Here is the results:
http://img.photobucket.com/albums/v13/Gator/TargetforR-2545gr43507-28-09.jpg

Groups was more consistant than before. Readjusted my zero after the nine shot group - then shot the three shot group.
Bob,
The chamber is very centered. Spent brass is .0005 concentric. Pretty good for a factory chamber job anyways.

Crown: I can't get the barrel off yet to check the crown but it looks pretty good with the borescope (nicks or anything) and with 10X loupe I can't see anything but it could be off center and I wouldn't be able to see that. Something to check for though.

Bullet: I did shoot the 85 gr. HPBT but they were not Matchkings.
They shot pretty consistant with 43.4 gr. H4350 and will be my hunting load for pigs.

I do have the cerrosafe to make a chamber cast but haven't had the time - yet. I know it has a long freebore and it will need to be rechambered when I get the wrenches to remove the barrel.

Brass has not been trimmed as it is much shorter than the chamber. Don't have the dim. close at the moment but I will never have to trim the brass before it has expanded primer pockets or starts separating below the case head.

Greg,
I thought the same thing when I ordered the rifle and was looking at the powder burn rate chart. I shoot R22 in all my 6x284's and was a little leary of the 4350 powders but about 75% of all the load data I found on the net with a 1:10 twist shows to use the 4350 powder. Only ones that deviate is the ones that can get the N560 or likewise powders.
All case necks are turned to .013 thickness and neck tension is sized accordingly - not tight at all.

Borescoped the barrel again after cleaning from last outing. Shows some throat was but not bad at all. I have new rings ordered and will install and lap them in but will be busy for next couple of weeks and will not get time to shoot much or at all.

I posted the pics to show someone else what to look for in a overpressured load - even though mine was not supposed to be too hot. This is the first time I have had the anvil fall out like this and I have shot some pretty hot loads with my 6x284's. I'm probably just a hot rodder at heart but not a suicidal kamikaze.

Thanks to all for the suggestions.

Larry M.

38_Cal
07-30-2009, 12:52 AM
Doing some guess work here, sight unseen, but here goes: Are you running mixed batches of brass in the same group? If so, your groups are darned good. Especially on the brass made from .308, are you cleaning up or uniforming primer pockets? Could be that you're getting the diameter a bit oversized on the pockets and getting higher pressure on the primer, not necessarily on the load. How about flash holes? Could your deburring tool be opening that up? If so, see above. Have you tried any factory .243 ammo in it? Did you get the same results on the primers? I second the motion on powder choices, you want to keep your port pressure to a reasonable level.

Good luck,

David Kaiser
Montezuma, IA

Boucher
08-07-2009, 07:31 PM
What I have learned shooting lots of 6mm bullets. All in bolt guns.
IMR 4350 best overall accuracy often best velocity.
IMR 4064 good accuracy and velocity below 85 gr bullet weight.
Win 760 may be better than 4350
Win 748 very similar to 4064
IMR 3030 is a sleeper never the highest velocity but probably the most overall consistent through a range of pressure and velocity.

There may be newer and better things avaliable now as I have not done much in the last five years or so.

MTNGUN
08-08-2009, 06:24 PM
I posted the pics to show someone else what to look for in a overpressured load - even though mine was not supposed to be too hot. This is the first time I have had the anvil fall out like this and I have shot some pretty hot loads with my 6x284's.

Primer condition is not a reliable indication of pressure. in any event, we haven't seen the outside of your primers, only the inside.

I've never experienced anvils falling out either, but when did they fall out ? When the case extracted, or when you decapped the case ? If they are falling out when you decap the case, I wouldn't lose sleep over it.

I have a Marlin 357 that will pierce primers with certain 38 special level loads, yet it never pierces primers with full house 357 loads. The pierced primers in the Marlin are probably due to a sloppy firing pin hole and sloppy headspace, not high pressure. That said, pierced primers are still a practical problem and should be avoided.

I'm not an AR guy so I can't give offer any constructive advice. Thanks for posting.

Yankee1
08-11-2009, 01:37 AM
Is it possible that the loaded cartridge has runout and not concentric?
If so loosen the stem nut and hold the press handle up while sizing in order to have the neck sizing plug centered by the plug and while holding upward on the press handle tighten the nut again. Because the plug was held in the cone shape of the neck it should be centered perfect. Recheck the concentricity again to check your adjustment. I know you said the runout after firing was OK but how about before firing? If its off before firing the bullet could be presenting itself to the leade wrong.
Yankee1

Seastar
08-11-2009, 08:18 PM
I inherited, from my father, a remington Model 10 pump and a no name 12 gauge that belonged to my Grandfather.
The 1927 Model 10 is a great gun and I use it frequently.
The double from Granpa is a different story.
The action locks up tight and everything works well, hammers, safety, ejectors.
However, the barrels are TWIST.
They are bright and shiney inside but I know that means nothing.
I have never fired it.
When I was 12 or 13, in the 1940s, I remember my grandfather hunting with the gun using smokeless powder loads.
I wonder if I could use it with Goex blackpowder or Pinnacle loads?
What would you do to "proof" the barrels.
If it blows up it blows up.
I would like to take it into the field again.
Bill

JCHannum
08-11-2009, 08:26 PM
The enemy of twist barrels was rust, not pressure. If the gun has been cleaned and maintained properly, it could be OK to use with low pressure loads.

You might ask or poke around on the double gunshop forum, there is a lot of good information and some very knowledgeable contributors there. The subject comes up frequently in one form or another.

http://www.doublegunshop.com/forums/ubbthreads.php?ubb=cfrm

Bob Ford
08-11-2009, 11:12 PM
In the 1960s I had a friend that lost his left hand to a damascus barreled double. It was rusted between the ribs and could not be seen inside or outside the barrel. My advice do not fire with any load.

Bob

ulav8r
08-11-2009, 11:49 PM
If you really want to fire the double, there is one safe way assuming the action is sound. Use gauge reducing liners, they will give the strength of modern steel barrels and keep the gun original. You could make your own from 20 gauge barrels if you have a suitable lathe.

Seastar
08-19-2009, 04:42 PM
Liners are a really good Idea.
Thanks for the suggestion.
Does anyone know who makes 12 to 20 liners?
I didn't mean to hijack the OP's thread but some how my post ended up here.
Sorry bout that----
Bill

ulav8r
08-21-2009, 02:48 PM
http://www.briley.com/index.asp?PageAction=VIEWCATS&Category=57

I did not look through their other styles. I have read that Briley makes a top notch product but have never seen one in the flesh. I think at one time Savage might have had tubes available but do not know about any other vendors. Read the Briley sight, use their descriptions for a google search.

Hollowbuilt
08-21-2009, 11:13 PM
These look like just what you get in the deprimer catchall. They don't look to be symptomatic of anything. If these were on the bench after you fired them, then yes, too much pressure. If these are just what you got depriming the cases, then no big deal, unless you have loose primers when reloading the brass.
Chris