.300 WSM, Bullet O.A.L./Shape

[silhop]

Great discussion and I hope you don't mind if I jump in with this question. Same idea but opposite end. The book says for the 168 ttsx a COAL of 2.840, I can only get 2.500 in my Savage internal mag.

Am I going to have issues with over pressure?

Thanks

pollox,

I thought the same as you, that shorter coal will boost pressure. i found when loading imr 4350 I would run into pressure signs sooner closest to the lands than at a shorter coal. According to barnes, pressure spikes if the bullet doesnt has some interia goin into the lands. Kinda like taking a running start at a locked door. I found in me abolt 1/2 grains of variation really made the difference in the patterns.
cheers

 

[BearClan]

pollox,

I thought the same as you, that shorter coal will boost pressure. i found when loading imr 4350 I would run into pressure signs sooner closest to the lands than at a shorter coal. According to barnes, pressure spikes if the bullet doesnt has some interia goin into the lands. Kinda like taking a running start at a locked door. I found in me abolt 1/2 grains of variation really made the difference in the patterns.
cheers

Yes, Pressure generally decreases as COAL decreases (or distance from the lands increases). If you go to the Barnes Site, in the Newsletters section, you can find one of the Newsletters with data from a test that looked at this very question (pressure vs. COAL). Unfortunately, you wll have to search - I can't remember the month. Velocities (and hence pressures) can also spike when your COAL gets too short (b/c of pressure buildup in the cartridge itself - less room for powder and bullet).

 

[blauber]

.300WSM Results-Primary

I got out and shot 40 rounds today. IMR 4350 starting at: 63.0, 63.5, 63.8, 64.1, 64.4, 64.7, 65.0 & 65.5. I was going to call it quits after viewing the 63to 63.8 gr. 5-shot groups (linear spread of 4-5" at 100yds!).

Then, like magic 64.1 grouped 1MOA, followed with either 1 MOA or sub-MOA groups at the other charge weights. I was amazed as this seemingly small difference paid big dividends.

Now for seating depth: I could not eject a chambered round EVEN at the max cartridge length that the magazine would accept due to the bullet tip getting caught on the ejection port when opening the bolt. Max mag length after the modification is 2.950". I settled for today's shooting at 2.890" as this would fit a hunting scenario.

The bullet was Berger 168 gr VLD which is touted as highly accurate, but initially Berger stated that the bullet had to be on lands (they have since changed their tune, methinks a marketing ploy).

So, in the end, I've decided on this-I will try bullet on lands next. I can hand load the chamber PLUS the top bullet in the magazine is not constrained by the magazine's length (try it with an A-Bolt-the bullet tip rides just atop the magazine when oriented normally). If the bullet in the lands trick improves accuracy next outing, I will seat the chambered bullet and top magazine bullet this way, with the remaining two cartridges in the magazine at maximum magazine length. Ofcourse I will compare POI with this difference.

If you want a pic of the magazine modification, just let me know! On the A-Bolt, I gained 0.070" more clearance...coyotes are in trouble...

Silhop,

Glad to hear RL19 worked for you - it didn't for me. Groups ranged from 1.2" to 1.73" (all I am hoping for is an MOA rifle). Tried Viht550+180 AB, RL19+180 ETips, TTSXs, & MRXs, H4350 + 180TTSXs, RL17+180 TTSXs. Nothing went MOA. Was beginning to think the MOA goal was impossible (have Rem700 XCR RMEF). Then I tried IMR4350 and 4 or 5 groups went MOA - all different charges. Then retried H4350, but with QL data instead of Barnes #3 data (lower Max charge of 63.0g) and got 3 or 4 goups sub-MOA. Then tried IMR4831, and 3 of 5 goups went sub-MOA - the smallest groups was a cloverleaf. Plan to retry RL17 again with QL data (instead of Alliant data). If that doesn't work then I will probably stick with H4350 (not the smallest groups, but POI was virtually the same for all 5 OCW charges of I used.

Sorry - back to topic. Once I find my best powder charge combo, I plan of playing with seating depth. IF THE MOST ACCURATE SEATING DEPTH IS LONGER THAN THE MAGAZINE will allow, I plan on following David Tubbs suggestion (Sierra Advanced Handloading DVD) of keeping the LONG, but must accurate round in the chamber (safety on, of course, bullet color coded), and make the other rounds fit the chamber - You want the first shot to be the most accurate, and it is unlikely you will need/have time for more than two shots where I hunt (Thick, N Ontario bush).

 

[LongBomber]

I haven't looked at the bolt stop on an A bolt in a while, but could you trim back the bolt stop 0.06"? That should allow the loaded rounds to eject.

 

[blauber]

I haven't looked at the bolt stop on an A bolt in a while, but could you trim back the bolt stop 0.06"? That should allow the loaded rounds to eject.

I thought of that idea and it should work. The other way is to elongate the bolt stop channel on the bolt itself-I don't know if either can be done but may check with a gunsmith eventually.

For now, I can release the bolt stop and partially remove the bolt to get a live round out of the ejection port. What a pain in the ass, but I'm a sucker for getting the best out of this investment (LeBaron's only had one left hand left in Ontario!)

 

[LongBomber]

I would think you should be able to use a dremil and cut the channel in the outer bolt body a touch longer. If I remember right the stop is more of a round button on the end of the boltstop. It would be better to take some off of the bolt body I would think.

FWIW I use 67gr 4831 with 165gr TSX or a 165 partition in my 300wsm. I tried several different powder / bullet combos but I found that gave me the best velocity/accuracy mix. I am going to try some RL 17 combo's after the season ends.

 

[lcq]

Mag length is going to be your limiting factor unless you want to use it as a single shot. My AR will shoot 80 grainers if I load em one at a time but that kind of defeats the purpose.

Brian