load data for 7mm LRM

[AZShooter]

Moombaskier,

Thanks for sharing the specifics of the new 7 LRM reamer throating. The suggested .025" jump is shorter than what Kiwi Nate suggested for the 7mm LRM in his article on the 7mm Practical: "To avoid finicky performance, its best to have some freebore with this design, approximately .250". The case capacity is just a little too much to do otherwise." Any way you slice it the freebore is far shorter than the 7 RUM! This is very useful knowledge.

I have been using a PT&G reamer for a 7mm/375. (full length shoulder and short neck) I recently installed an old barrel on my LA Ruger that has a lengthened mag box. Box is still too short yielding a .210" jump to rifling! I shot this package just to see how the jump would work. It didn't. Thankfully the rechambered 284 win barrel was something that I won't be using and can be thrown away. It WAS funny to use a 21" barrel for the test. Pet loads of H-1000 and 180 berger hybrid yielded 2900 and change. I didn't see the fireball but I'd bet there was some significant flame in front of the barrel and it was LOUD.

I have concluded that I will send my reamer back to PT&G to shorten the throat length so I can kiss the rifling with max OAL to fit Ruger's magazine then seat bullet an additional .025" or so. I will also buy a throating reamer so I can lengthen the throat for other rifles with longer magazines.

I have a worn out Lilja barrel that is currently a 257. It is a beauty #5 fluted SS 28" long. I am going to have Dan Pederson re-bore and re-rifle it for 7mm. This way I can get some value out of this expensive barrel. Am going to use a faster twist as I would like to try the upcoming 195 Berger.

Looking forward to more updates from you or tdean on your results.

 

[tdean]

i got me a dial indicator on vice grips and did not move off zero when loosened guard screw, of course you have to make sure its balanced so gravity doesn't pull it out see pic, note i did this test after i dremeled out where it was hitting action, i know there was stress because i could feel it when i loosened screw with my hand on foreend, cant feel it now

 

[tdean]

i ended up doing test with and without clamp holding stock rigid to table

 

[AZShooter]

Very creative way to test your bedding. Best on finding a good load.

 

[tdean]

Will be testing again this weekend

 

[AZShooter]

Tried some retumbo yesterday in the previously mentioned 7mm/375 with 180 hybrids. Got same accuracy as the best load with 74 gr of H-1000 and gained 90 fps for 3030 fps from 26" barrel. Did not work up to max load but am close.

Some US 869 is coming in Friday. Will give it a try next along with refining the retumbo load sometime next week.

Just in case any readers didn't read the earlier posts, while the 7mm/375 is similar it is not a 7mm LRM. Case is larger so don't duplicate the above load data in a 7 LRM.

 

[speeders]

Anyone try 168 gr Nosler LRAB? Any load data and results if so. 175 grain accubonds are tough to find.

Thanks.

 

[bamadawg2009]

My gunsmith tried some in his with a 1-8 twist barrel and said its too fast for the 168s and never got any kind of accuracy out of them. I don't know anybody with a 7LRM with a 1-9 twist because they all shoot 180s or 175s.

 

[AZShooter]

1 in 8 twist isn't too fast for a 168. I had a 1 in 7 twist and shot bullets as light as 140 accubond from a 30" 7 Rem mag around 3350 fps.

 

[tdean]

another trip to the range another kick in the cods

this target is shot at 100 yds 71 H-1000 still a little sticky bolt lift and some minor extractor marks, calling bs on gunwerks 72.8 load

this target is shot .040 off lands 180 berger vld gm210M primer, .001 neck tension

 

[tdean]

this target is at 100 yds

71 h-1000 .020 off lands, same story on pressure, im thinking this combo likes the berger to jump because this group sucked and .040 was better

 

[tdean]

shooting off bench with bipod, either gun sucks or rubber bipod is jumping around on concrete bench when i shoot, it is pretty violent and blows me off target, im loading the bipod putting as much pressure as i can forward without moving the gun and squeezing rear bag, i have started shooting everything off a bipod when i hunt and shoot steel long range, i can shoot one hole groups with supressed 308 off bipod

going back tomorrow with same load .040 off and another .060 off

 

[tdean]

i just figured when i got a krieger barrel, blueprinted action, and a proven gunwerks chamber reamer i could get .5 moa pretty easy, thats what i get for figuring


could it be copper fowling, i took gunwerks advise and have not run any sweets through this gun but instead used the water based kg products, more specifically kg carbon and kg copper

 

[tdean]

Ran a little sweets not even a hint of blue, that's a first

Gues kg 12 works and Krieger barrels are smooth