1200y+ Mosin Smyert Mk 3.7

[farmerboy78]

Accuracy is getting there. I shot a group at 300yards that was one inch. Need a better way of seating bullets though. Right now runout is really bad because of how I am sizing them.

What are the dimensions of the case compared to the 300 wsm? May be able to use a wsm seater die for this cartridge. ..

[Grimstod]

There is a website with lots of info. 54rimproved.com

[ShootnMathews]

I looked at all the specs before. I believe a 300 WSM seater should work. I also thought about using a 300 WSM bushing die to neck size the brass

[Grimstod]

I have been reading my Hornady OAL gauge all wrong, sometimes I wonder if i waisted my money on that thing. Anway I was jumping a whopping 1/8in to the lands. No wonder best I cold do was about .75moa. So I loaded up some much longer to be jammed about .010 and these were really low loads too. Only filled 2/3 of the case. I was not expecting good results from them. Really I was only interested in getting another scope to settle in. But I got some great results. I will have to do a ladder test soon to find a better node. This one has some vertical so I can tighten these up a lot.

[jaysny87]

Pretty darn good groups. What was the load for those as far as bullet, powder and charge weight?

[Grimstod]

Bullet is a Berger VLD Hunting 190gr. Using W760 Lapua brass. This is an improved case so i have 26% more capacity then a regular mosin. 48.5gr. Dont try that in a regular mosin. That would be damgerously high. In the improved case though it only fills 2/3rds of it. I even had one hang fire on me cause its a very light load for this chamber.

[ShootnMathews]

Be careful with those light loads Ben. To low of a charge can be more dangerous than to high of a charge. If there is too much air space in the case ( low powder charge) then instead of a controlled burn down the barrel you can end up with a detonation in the chamber. Basically, if you end up too light on the powder, you made a hand held pipe bomb.

[jaysny87]

the 54r improved becomes more and more appealing to me as i see more about it. But i think i will wait until some more concrete loads are developed before i tread those waters.
It looks like you guys are on the right track so far though. keep up the good work! like i said i find these developments very interesting.

[Grimstod]

Thanks. The 54r has been necked up and down by the Fins and russians but non of them ever tried altering the parent case. This is a such an easy wildcat to make. I have ideas for two more myself but that will be another day.

Last weekend i was going to get my dies modified more to suit this case better but did not have enough time. Maybe this weekend though. Something else my rofle needs os to have the rifing pin Bushed. I could easally atain 300WSM MV if i could fire hotter loads. Right now i cannot even fill the case before a primer pops becaus almost a 1/16in of gap is in my firing pin hole around the firing pin. Stronger firing pin spring would also be a good adition.

[Grimstod]

This load def has some vertical. Bottom right is warm up and fowling shots to get bore conditions stable then the group top left was looking really good until some one at the range started asking me about my rifle. When i went to fore the last shot conditions had changed and that bullet on the right took me from .25moa to about .4moa. I don't mind talking about my gun just not when i am trying to run a condition. I shot this load mainly to worm up the gun and get the bore conditions stable.

Did a ladder test. Had five shots in one hole at 300yards !! Going to make it hard to select a load lol. I Need to do a ladder test at 500 not 300.