Still trying to improve upon the accuracy of my Mod. 70 300WM. I KNOW, a hunting rifle is not required to shoot moa groups, but this one is the only one in my safe that won't.

Have bedded the action, lapped the lugs, floated the barrel (and found it shot a little better w/slight pressure @ end of forend). Crown looks good and have had three different scopes on it. Tried four different powders and seems Retumbo works best and 210BR are better than 215's. Weighed WW brass, uniformed flash holes & pockets and turned necks and 200 gr. Sierra GK's. Have my SD down to 5.3 & ES 12.0. Still averageing 1.75" @ 100 yds (down from about 2.5").

Experimented with OAL last trip to range and 3.340 OAL seemed to round out one four shot group and another 4 shot group loaded to 3.367 OAL overlapped the first just slightly to the right. (Previous & Subsequent groups loaded shorter and longer seemed to string horizontally.

NOW for the question. In checking closer, I find that the OAL (using a bullet comparator) varies as much as .005" from one round to the next. Has anyone else experienced this problem?

My press is an old Herters and has some wear in the linkage, but the Pacific seating die is set so as to force the ram to "cam over" so I can't see how this could be a factor. Anyone have any thoughts on this situation?

Regards,
hm

Once well assembled handloads are made with Sierra bullets it's usually the bedding.

What do the groups look like now? You mentioned that some were horizontal? How are the stock screws tightened? What stock do you have? Does the rifle fire the first shot from a clean cold barrrel into the same place?

Try this. Tighten the front guard screw and leave the middle one loose and the rear one just tight enough to hold the guard. If it shoots like this now the rear bedding must be built up or a sleeve made for the rear screw.

Most 300 WM's are accurate rifles. There are more possiblities for the groups. Not every barrel made is perfect.

Savage99:
"Once well assembled handloads are made with Sierra bullets it's usually the bedding."

Agree with the Sierra's. I usually work up my loads with them, cut back slightly and work back up with Nosler partitions for hunting.

The first shot is usually to the right and slightly higher than shots from fouled barrel. Groups shot w/shorter or longer OAL tend to string from 8 o'clock to 2 o'clock but those loaded between 3.340 & 3.367 took on a more round shape.

The stock is the factory walnut stock which I glass bedded and floated the barrel. It seemed to like a little pressure at forend tip so have added a glass pad there for the next trial. Front and rear action screws are torqued to 40"# and center screw is just barely snug.

I am beginning to have some doubts about this barrel but want to eliminate all other problems first.

Will try loosening the rear screw next trip to the range and see what happens. Thanks for your thoughts.

Regards,
hm

1996,

It's not unusual for me to have that much variation in comparator readings. Usually it's about .002-.004" I figure about .001" for human error and a few for ogive differences.

Try checking neck tension to reduce horizontal spread. Weigh all charges. Try Rl-22.

Don't strain on a gnat regarding hunting accuracy...(But of course we all do!)

Some barrels are bad. The holes are not straight.

I cut a 1.5" section off of an old Mauser barrel just to get a piece of steel tubing really fast. On the cut end the hole was way off center. I put it in the lathe with a live center and turned it true. What a waste of time. I should have just drilled a hole in a piece of bar stock.

I do the same "Sierras in the summer and Partitions in the fall"

Good luck with that rifle.

Steve:
"It's not unusual for me to have that much variation in comparator readings. Usually it's about .002-.004" I figure about .001" for human error and a few for ogive differences."

That must be the case, as I checked a batch of my 30-06 match ammo that I know shoots after I posted the question, and it runs .002-.004" difference, also. Guess I just never checked for variation before.

Guess I'm going to have to get some RL 22 and give it a try. Seems as though it is quite popular so it must work.

You mentioned neck tension. I am turning the case necks and have polished the expander ball in my die. ID of sized necks measure .306". Am I missing anything here?

Thanks for the suggestions.

Regards,
hm

"Tried four different powders and seems Retumbo works best and 210BR are better than 215's. Weighed WW brass, uniformed flash holes & pockets and turned necks and 200 gr. Sierra GK's. Have my SD down to 5.3 & ES 12.0. Still averageing 1.75" @ 100 yds (down from about 2.5")."

After doing all this, as well as bedding and rescoping, if you still aren't getting the accuracy you want, you're looking at a new barrel.

You didn't mention how quickly the barrel fouls. This is oftentimes, although not always, a good indicator of whether or not you have a "good" barrel. Factory barrels (all brands for the most part) are a bit of a crapshoot nowadays, although certainly better on average than they were even ten years ago, and light years ahead of where they were thirty-forty years ago, despite stories of "the good old days". Back then, few hunters actually tested their rifles for accuracy. Of the ones that did, they rarely found it to their liking, especially with the factory ammo that was available at the time. 1.75" groups would have been considered pretty good forty years ago.

I agree on the Sierras, and would also recommend Re 22 for 200 grain bullets in the .300 WM. It sounds to me, though, like you've covered all the bases, and the barrel simply won't let you do what you want to do.

My definition of "hunting accuracy" is at least 1.25 moa for a .30 caliber. Any greater than that, and my confidence begins to erode at ranges over 300 yards. Between my rifles and those I've helped friends develop loads for, we've gotten about twenty-five factory rifles (of pretty much all brands) to shoot "hunting accuracy" or better. Only two rifles (a Ruger and a Browning) were we unable to find at least one good load for. New barrels fixed them pronto.

Norm:
I did fail to mention that this barrel fouls rather quickly and agree that is not a good sign. In fact, the last trip to the range, I believe, the fouling was the worst it has been at only 20 rounds.

Will probably give the RL 22 a try before a trip to the gunsmith for a new barrel, but it is beginning to point more in that direction with each range trip. Besides, one or two more trips and even a good 300 WM barrel would be worn out!


Your observations and suggestions are appreciated. You know the old saying, "two heads are better than mine."

Regards,
hm

Happy Ending!

Well,after correcting a couple of problems with the rifle, it turns out that the biggest problem was/is a Very finicky barrel.

After trying H450, Retumbo, 7828, H4831 SC, and H1000 (tried to find RL22 unsuccesfully), several different 180 & 200 gr. bullets, asst. primers, etc., finally tried IMR 4350 today. Voila....4 shots into 5/8" @ 100 yds., but then couldn't stand prosperity and threw a wide one for a 1 1/4" five shot group. The best 5 shot groups with all other powders averaged about 2.5 to 3"
. Shoulda known to try the 4350 sooner, but all's well that ends well.

Thanks to all for the moral support & suggestions.

Regards,
hm

a few things still come to mind. first of all, fix the crown, even though it doesn't look like it's a problem, it almost certainly isn't quite right.

secondly, you didn't mention how far away you are from the lands. IME generally the closer the better except with x bullets. if you can't currently get to the lands, you can do a few quick and easy modifications to your m 70 that WILL get you to the lands. if this is a problem, plese let me know and i'll post the mods. you need to do.

third, are you sticking to max loads by the book? i'm absolutely NOT an advocate of "hot" loading, but all of the 300 wins that i've worked with liked things hot. by that i mean at or very near book max. i've had to go as much as 3 grains over to get top accuracy. it seems that the slower powders absolutely NEED pressure to burn consistently. as always watch for pressure signs in the brass and rifle when getting toward those upper limits.

fourth, you mentioned that your seating die is adjusted tight enought to the shellholder to cause the press to "cam over". if you are doing this on most other dies you would be trying to crimp the case mouth into a nonexistent cannelure. that will absolutely destroy accuracy. make certain that you are not doing that. you sound like a sophisticated handloader but everybody does have a mind cramp once in awhile.

finally, you mentioned that you lapped the lugs. are you aware that you most likly changed the headspace by a small amount? this is no big deal as you handload, but if you are full length sizing you could be rather sloppy in the cartridge to chamber relationship. you didn't mention neck sizing but if you aren't, start there.

gabe

papaschmud:

quote:

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if you are doing this on most other dies you would be trying to crimp the case mouth into a nonexistent cannelure. that will absolutely destroy accuracy.

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I had been loading w/die backed off for this reason, but when "discovered" the .005" variance in OAL (measeured w/comparator), tried to minimize the error by setting die to "cam over".
I did check this out before setting seating die to be sure no crimp would be applied. A bullet will fall into the neck of a fired case after running the case through the seating die set against shell holder.

I have run right up to max loads listed for most powders and past max on Retumbo. In the past I had found that w/150 gr. bullets my rifle seemed to like the hotter loads of 4350. Interestingly enough, the good results w/4350 & 200 gr. bullets was with a lighter load and appeared to open up with one grain hotter load. My next range trip, plan to increase this load and play with OAL (always single load testing loads anyway, so plan to see if getting close to lands helps this rifle & worry about mag. length later). Currently bullets are jumping .174" to lands.

quote:

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secondly, you didn't mention how far away you are from the lands. IME generally the closer the better except with x bullets. if you can't currently get to the lands, you can do a few quick and easy modifications to your m 70 that WILL get you to the lands.

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This is definately a problem with my rifle. Magazine length is 3.403 and would have to load to 3.516 to touch the lands. There is a spacer @ rear of mag. box which I suspect can be removed but at first glance appears to be welded to box?? If spacer is removed, would have to shorten or replace bolt stop to take advantage of longer mag. Am I on the right track here? You mentioned posting modifications, please do.

quote:

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finally, you mentioned that you lapped the lugs. are you aware that you most likly changed the headspace by a small amount

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Yes, my fired cases now measure out right @ max. in case gauge, but I set my sizing die to just touch the shoulder of fired case so am using the shoulder to headspace the round. I plan to try some Win. Failsafe factory loads to see it they will shoot and use as base line to measure case head expansion. Hoping this added headspace does not prove to be a problem w/factory ammo, but don't think so since it is still within max specs.

Thanks for your input. Look forward to your thoughts & suggestions.

regards,
hm

wow, no wonder you are having a hard time with that rifle .174 is a long way to jump, nothing compared to a weatherby but still.

as for the mods. you will need a new bolt stop, ejector, magazine box, and magazine follower. the bolt stop, ejector, and mag box can be modified but are rather inexpensive for what they are and i think you are just as well off buying them. the mag follower you will need to buy regardless. i would purchase the whole deal from brownell's. the key is to hit their catalog and order the components mentioned for a .300 WEATHERBY.

if you would like to modify that parts you have, i would strongly suggest that you find a .300 weatherby m70 to pattern the ejector and bolt stop off of. a 7 stw, 300 h&h, 375 h&h, or .300 ultra m70 would also have the same components. this is importent so that you not only get the correct length but also the correct angles on the faces of the bolt stop and ejector. As for the mag box, removing the block requires drilling out the welds that hold the block in place. That is rather simple but requires that you finish off the drill holes well and that you remove all the burrs.

if you go the brownell's route, the whole thing should cost around $100. the other thing to think about at this point might be to set the barrel back two threads and rechamber. i would definately have it borescoped before you go to that expense, but most of the winchester factory barrels have been rather good lately and would be well worth the $150 or so that it would cost to have the barrel work done. the upside of going that route would be that you could be certain that everything would be true and the chamber and throat would be ideal. if you don't have anyone to do that work, please let me know and i'll supply you with a few contacts.

good luck whichever way you decide to go.

gabe

Gabe:
A gunsmith friend has a borescope and we looked at the barrel last week. He couldn't see any reason for the problem, throat not eroded, no fouling or rough spots and crown looked good to him. We did not get into the long throat, so he is not aware of that, but he has set back barrels on my target rifles in the past.

Hadn't thought about setting barrel back in lieu of altering/changing magazine, etc., but this sounds like the way to go. This would also allow a tad more lapping of bolt lugs (I quit at about 65-70% contact on one lug as I figured I was getting close to max. headspace for factory ammo).

Thanks for the suggestions.

Regards,
hm