210 bergers blowing up?? help 30-378 wby

Roygeterdone,

No offense to Walt as he has set more world record then I could even even dream of but the simple issue her is jumping those thin jacketed bullets into the lands.

In a fresh clean bore you may not see much issue with this. As the barrel gets dirtier, he is right you will get more bullet failures but not really beause of the dirty barrel. More because the bullets are weakened by the freebore jump and then the added friction between the bullet and dirty bore magnify the problem and bullets start dusting.

He is also correct in that the 30-378 Was used extensively as a 1000 yard BR rifle but I suspect there was less then 1% of all those rifles ever made that had freebore. Most are VERY short throated for best accuracy potential and the ability to chase the lands when they start to erode.

One other thing you may want to try is a powder switch. Retumbo is a great powder but you are really out of its useful range with the 30-378. It will work but its pretty quick buring for this size of a round and this bullet weight.

If you look at different load data, most leave out Retumbo once bullet weights get over 180 gr. Some go to 200 gr but those that offer pressure data as well, you will see that Retumbo produces alot of pressure to reach top pressures in this case and generally with a pretty light powder charge.

I would personally look at something like US869 or H-50BMG for this bullet weight. YOu may also want to try a heavier bullet if the rifle will stabilize it.

The heavier the bullet the better this big case will work performance wise. I would try some SMK 220 gr pills and see it they shoot well.

Again, I think your running a bit to fast burning a powder for this case. Were you shooting a 300 RUM I would say you are right on the money but you have another 15 to 18 grains of powder capacity, thats a significant jump.

Yes, if your barrel is worn and rough it will be much harder on the bullets so that is a consideration with the J-4 bullets, just the nature of the beast.

I generally do not recommend them for really high performance rounds. When used properly they work very well but there is a narrow performance window you need to keep them in. If you go over that they will let you down.

#1 key is you either need a stouter bullet or a shorter throat to get things to work consistantly well. Either one will probably solve most of your problems as long as the bore is not extremely rough.

Have you tried to reach the lands by seating the bullets out far. Would limit you to a single shot but for long range this is hardly a disadvantage. May want to try that. If you do I would certainly go to a slower burning powder because seating the bullet out farther will only increase your case capacity.

H-50BMG is very hard to beat in the 30-378 and the new H-US869 may be even better.

Good SHooting!!

Kirby Allen(50)
 
Fifty you are too wise! I believe you are right on track and will try your recomendations, where does retumbo fit into the burn rate chart as compared to 4831,RL22,7828,
h1000 h-50bmg?
Thanks very much for taking time to help on this matter, I know you are a busy man
I cant type worth a darn or I would say more.
My 300 wby I tryed to hit the lands but never could, too much freebore and the bullet was in case only about 1/8"
We have not tryed the 378 but I suspect it may be the same but will try it.
 
If I may add a few points:

Retumbo is faster then H50BMG and similar to H870. I would look at the H50BMG for sure as a powder in the wby. Even consider getting some slow lot WCC872.

If you find that the bullet cannot engrave in the lands BEFORE leaving the case neck, that is a very bad thing. That jump at 65000psi can push the base of the bullet in a variety of directions forcing the bullet to engrave cockeyed to the bore.

Spinning a thin jacketed bullet down a bore less then true puts a great deal of stress on the bullet. Then it leaves and flies like a wobbly football. It never gets a chance to settle down because the rotational stresses tear it apart.

That is a big reason that VLD bullets like to be very close or onto the lands. Helps them get a nice straight start.

I recently had three new rifles to work up. All shot very well but then accuracy went south and pressures went up. It seemed that when new, the throats were all smooth but after a few hundred rds, they roughened up enough to affect pressures/loads/accuracy.

A reduction in powder and things have settled down. They are now shooting the lower loads consistently. Maybe that has also happened to your barrel.

Finally, if there is lots of powder or copper fouling, it might be causing the bullet to have poor grip on the lands.

Try cleaning the bore often and see if that helps. Also, use a strong ammonia cleaner to remove copper fouling. I am always amazed at how poorly some cleaners are at removing copper. Barnes CR10 is my favorite commercial product. With a stiff nylon brush, you should be able to get and keep that bore clean. However, only clean as much or as often as the barrel needs.


Jerry
 
Jerry thank you for the information on powders,
Barns cr-10 is what we have been using too ( but probably not as often as we should) Hopefully tonight My brother can do some of these suggestions, He got home late last night
and was wooped from work and had to leave early, Walt at berger said barns probably had some good cleaner since they have had a lot of problems with there bullets fouling, we will ck to see if we can get the bullets close to the lands on the 378 but I dont think it will happen, the Ocl that
has worked for the bergers is 3.77 we shot probably 80 168gr
bergers threw it and then went to the 210s and started having problems. So we will see what happens and I will keep you guys informed.
 
Roygeterdone,

Retumbo is between H-1000 and H-50BMG in burn rate. Similiar to RL-25 but a bit slower yet in most cases with heavy bullets.

Even if you can not reach the lands, seating the bullet as far out as possible may help your situation. The reason is because the closer your seated to the lands, the lower the velocity of the bullet when it hits the lands. The lower the velocity the less stress there is on the bullet.

You may well not be able to reach the lands but seating the bullet out as far as possible may still help a great deal in getting the bullet to survive the launch.

Give her a try and see what happens. Remember to back off your powder charge and work up again.

I would agree with Jerrys comments as well. Not only are Wby throats long but they also tend to be loose as well. THis is not a Wby issue, this is a factory rifle issue. If you have a custom rifle with freebore, generally the throat diameter is no more then 0.0005" over bullet diameter. In a factory rifle the throat diameter can vary from 0.001" to 0.0015" over bullet diameter. Does not seem alike alot but in a throat, this is very loose.

Kirby Allen(50)
 
Roygeterdone,

CR-10 is a very aggressive copper solvent. When used repeatedly over time, even if used correctly it has been known to etch some bores. I would only recommend using CR-10 or Sweets 7.62 on a very limited basis. For generally cleaning, I do not recommend any aggressive amonia based copper cleaners. This may be contributing to your problem, an etched bore.

Kirby Allen(50)
 
ouch ouch! thank you fifty for that info, I will defantly watch that,that stuff does stink I know that.
 
I had 210 Bergers blow up in a 10 twist no freebore 300 Weatherby at 2930 in the middle of a match. The first two times was with between ten and 20 rounds through the chamber. I figured I must have hit a bird on the way to 1k when all ten didn't show up on the target. Then two matches later I had a guy spotting behind me during my relay and he saw round 9 come apart at around 100 yards. So I cleaned and put another 20 down after the match. Rounds 18 and 19 blew up. Only use them for woodchucks now.

I used 220 SMK for a year and went to the 210 matchkings this year. I have put a hundred or so through it and 35 rounds through it last Saturday, without cleaning, with the same charge and powder as my previous test. Performance similar to Berger. But no blowups.

I played alot with the 30-378 in factory mode. 200 gr Accubonds with 106gr of Retumbo was what it liked. I assumed they tolerated the jump better than others I tried.

Good luck,
Shummy
 
Wow hoyt! that just dont make no scense I bet that ticked you off big time! I think the 210S are out of the picture for us, The 168s seem ok so far.
those jackets must be so sensitive, Too much, thanks for post
 
Shummy, how would you compare the performance of the 210 Sierra to the 220 at 1000 so far? From its published BC, it looks somewhat disappointing. Are you finding it does better than the ballistic charts would predict?
 
This may be off the wall, but with that much freebore are there powders that would have ignition problems due to too low of a pressure? If the bullet has to move as far as you seem to indicate it would seem that some powders, especially in very cold conditions, might not maintain enough pressure to burn.

edge.

( sorry newby question)
 
There is generally enough bullet weight and powder charge weight to promote adiquate ignition but you are correct in that velocity consistancy can increase.

This is one of the main reasons you do not see rifles designed for extreme accuracy to have freebore.

Most of these loads are also loaded up to pretty top end chamber pressures. As such the issue of hangfires is reduced but yes with lower end loads, this can be a real issue.

Kirby Allen(50)
 
JonA,
Drops are nearly interchangeable in my application. "My" BC for 220SMK is .601 and 210SMK is .590. Looks like 210 gives up 60lb energy and an inch in a 10wind at the speeds I ended up with. They shoot slightly better in my rifle.
For reference I figure a .551 for a 200gr Accubond. I can't relate this to any calculated BC, not changed based on speed but rather a single value that I use to shoot stuff from 100 to 1300 yards using a program that calculates very similar to Exbal.

Cart-Bul-Speed-Wght-BC-Scope-Temp-Alt-MM-MOA-Engy-Spd-10Wind-Yards
300wby-SMK-2940-210-0.59-2.05-55-1200-1.05-26.94-1086-1526-70-1022
300wby-SMK-2915-220-0.601-2.05-55-1200-1.05-27.19-1144-1531-69-1022

Hope it helps,
Shummy
 
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