300 rum seating test

[FOTIS]

I ran this test in my Standard rifle, Sendero II
93 gr of rl25 was the load used for 3170 fps or so, Using Brian Litz' method of testing different seating depths for (hunting) accuracy. This is listed in the lrh forums.

I started at the lands (too long for my magazine)
Then I sat them .03 .05 .09 and .130 off the lands.
Very interesting experiment.

.03 group

Both .05 and .09 over 1 inch at 100 yards.


.130 is shown below

So much difference from different seating depths.

Next week I will try the same test but with 95 gr of Retumbo. That yields 3115 fps in my gun.

 

[jmad_81]

That is pretty interesting. Going to be doing the same test with some 95 VLD out of my 243 pretty soon. I have two loads with H1000 that shoot around the .6-.7" range. Hopeing I can get them better. I'll have to try this test to see if it helps.

 

[SJB358]

Wow, great shooting. Seems like it isn't always the answer to load at the lands. I don't think any of my best loads are anywhere near the lands. Scotty

 

[FOTIS]

This definitely worked for me for the VLD's at these seating depth increments. I am betting a similar test will work for conventional non-secant ogive bullets. We will see.

 

[RiverRider]

I have always believed, but never verified, that the seating depth sweet spot is periodic and that there are several that might be used. Someday I'd like to conduct a carefully controlled experiment to see what the periodicity looks like.

 

[JD338]

Pop,

Seating depth will affect group size, as well as velocity and pressure. Many rifles will actually have two sweet spots

Can you post a link to the information source? I am interested in why the chosen distances off the lands.

JD338

 

[FOTIS]

Here you go Jim.

http://www.longrangehunting.com/forums/ ... fle-40204/

 

[JD338]

Thanks Fotis!

JD338

 

[Powerstroke]

Thanks POP !

Been playing with some 70gr VLD's out of my .223 - This will help as I haven't seen the results I'd like to.

 

[SJB358]

Good reading. Thanks for the gouge Pop. Scotty

 

[DrMike]

Thanks, Fotis. Your results speak for themselves. I certainly appreciate the information. I'll process it and work on it. The theoretical implications are sufficiently intriguing to justify the expenditure of some gunpowder and a few bullets to generate some practical applications. Fascinating topic.

 

[FOTIS]

This week I will attempt the same test in my 22_250 with ballistip tips. I want to see if this method is unique to the bergers or if it id applicable to other bullets.

 

[rick smith]

That change in seating depth is recommended on the Berger sight. I have run seating depth changes with a variety of bullets/calibers. Have tried the same change with 168gr Bergers in a 30/06 and received similar results. I have had more change with other bullets but not with that much seating depth change. I normally start 10-15 thousants, magazine permiting, off the lands and work-up a load. When the best load shows, I then play with seating depth , 0.005" at a time, and primer changes, but not at the same time.Rick.

 

[FOTIS]

Checked the weather, hot and 59 mph winds on my day off

 

[sithlord6512]

POP (or Anybody Else)

Read the Berger Article - Interesting. Have you had an opportunity to get results for your planned .300 RUM test yet. I don't want this thread left by the wayside.

I am close to selecting a powder for my .300 WSM, so bullet-seating tests are on my to-do list. If this procedure shows similar promise for Non-Berger bullets (e.g., E-Tip), it will potentially save me a lot of barrel wear. Until I came across this thread, I was planning on seating bullets in intervals of .010" starting .020 off the lands to .130" off the lands and using 3-shot groups = 33 Rounds to get me in the ball park, and then try plus/minu .005" around the group that showed the best promise).