RPR shoots terribly for no apparent reason?

Wanted to run something by the group and get some feedback. My RPR usually shoots well under MOA at 100yds and had been doing so up until I put it away for the winter last year. I took it out today and something seems to have changed.

I started off with a slightly hotter load than I usually shoot (41.5gr H4350 w/ 140gr Hornady ELD - Lapua Small Rifle brass w/ a Fiocchi lead free primer) and it was solidly "Ok". Just over 1MOA and no real pressure signs, out side of maybe a very, very slight swipe. When I went back to my H4350 39.5gr load (the one that usually shoots well under 1MOA) it printed a shotgun pattern all over the target at 100yds.

I'm willing to accept that I might be the problem here and had an off day but wondering what else it could be or if anyone else has ever experienced something like this before.

<*(((>< - thats my first thought, will be giving it a very thorough cleaning ASAP

Infidel, LoonWulf - I checked the scope rings and mounts and they seemed ok. I've never messed with the action screws and up till now never even heard of them. Any pointers on what to look for or how to troubleshoot? I was also shooting off of front and rear sandbags

Chuck R. said:

Besides the scope rings, take a look at the rail. You might have to remove your scope to get at the rail screws depending on your ring spacing.

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What would I be looking for with the rail screws?

tarosean said:

was it the exact same bullet? (140gr H-ELD)

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Yup, same exact bullet.

Something just clicked however...I do recall adjusting my scopes POA lower immediately prior to shooting my worst group of the day, only about 1 inch but I wonder if something shook loose internally or otherwise went sideways with the scope internals?

tarosean said:

hmmm... what were the ambient temps when you "parked" it vs now?

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Pretty close, about a 10-15 degree difference. With H4350 I'd hope that wouldn't represent a problem, my understanding is that its one of the most temp stable powders out there, but willing to listen if I'm mistaken.

bfoosh006 said:

Check to make sure everything is tight... and the 39.5 load... was it loaded last year as well ?

Or freshly made ?

If from last year.. it could be the bullets have "bonded" to the brass cases... re-seat them slightly shorter, to break the bond.

This is especially possible if you ultra-sonically cleaned the cases... and didn't lube the inside of the case necks.

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Whoa...yes to all of the above. Ultra sonically cleaned, no lube and all assembled last year...there's no way I would have ever guessed that

bfoosh006 said:

Check to make sure everything is tight... and the 39.5 load... was it loaded last year as well ?

Or freshly made ?

If from last year.. it could be the bullets have "bonded" to the brass cases... re-seat them slightly shorter, to break the bond.

This is especially possible if you ultra-sonically cleaned the cases... and didn't lube the inside of the case necks.

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BTW - I never lube the necks of my cases when seating bullets so two questions if you don't mind.

First, if I wet tumble with stainless steel media is this likely to occur as well, or just with ultrasonic cleaning? Also, would a dry neck lube suffice, or should it be some type of wet lube?

bfoosh006 said:

Sorry for taking so long to respond....@mercervillerental

Ultra Sonic cleaning can so thoroughly clean the brass.... it can cause issues without some kinda lube.

This article explains it better then I can... and years ago,, I had some 44Mag reloads "cold fuse" / "pressure fuse" together... brand new Hornady 300gr XTP and brand new Horn. 44Mag brass... made up a few dummy rounds...Heavy crimp... and being cheap I went to take the dummies apart with a kinetic puller....

NO amount of bone crushing blows would move the jacket from the brass case... on the other hand, those same blows did start moving the jacketed core out thorough the HP.. Took me decades to figure it out..

Anyway, as a result of those 44Mag rds I took a keen interest in stuff like this.

http://bulletin.accurateshooter.com...sonic-cleaning-some-advice-on-bullet-seating/

http://bulletin.accurateshooter.com/2007/12/tech-tip-dry-lube-for-ultrasonically-cleaned-case-necks/

http://bulletin.accurateshooter.com/2008/08/two-tips-for-better-ultrasonic-cleaning/

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@bfoosh006 - no apologies necessary, thank you so much for the info and wisdom. Gave the rifle a top to bottom cleaning, assembled some new rounds, reseated some of the old ones and hoping to shoot soon. Will report back results

Doc7 said:

I am interested to know about this and watchimgnwith interest. Did the old rounds have any noticeable feel to them when you reseated?

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@Doc7 - not especially, but I only reseated them very, very slightly so I may not have noticed